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[media] doc-rst: improve display of notes and warnings 

There are several notes and warning mesages in the middle of
the media docbook. Use the ReST tags for that, as it makes
them visually better and hightlights them.

While here, modify a few ones to make them clearer.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
hifive-unleashed-5.1
Mauro Carvalho Chehab 2016-07-10 11:57:43 -03:00
parent fed7b888f6
commit 706f8a9975
69 changed files with 591 additions and 525 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/media/uapi/cec/cec-func-close.rst
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@ -32,8 +32,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
Closes the cec device. Resources associated with the file descriptor are
freed. The device configuration remain unchanged.

4
Documentation/media/uapi/cec/cec-func-ioctl.rst
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@ -38,8 +38,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
The :c:func:`ioctl()` function manipulates cec device parameters. The
argument ``fd`` must be an open file descriptor.

4
Documentation/media/uapi/cec/cec-func-open.rst
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@ -45,8 +45,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
To open a cec device applications call :c:func:`open()` with the
desired device name. The function has no side effects; the device

4
Documentation/media/uapi/cec/cec-func-poll.rst
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@ -29,8 +29,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
With the :c:func:`poll()` function applications can wait for CEC
events.

4
Documentation/media/uapi/cec/cec-intro.rst
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@ -3,8 +3,8 @@
Introduction
============
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
HDMI connectors provide a single pin for use by the Consumer Electronics
Control protocol. This protocol allows different devices connected by an

38
Documentation/media/uapi/cec/cec-ioc-adap-g-caps.rst
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@ -31,8 +31,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
All cec devices must support the :ref:`CEC_ADAP_G_CAPS` ioctl. To query
device information, applications call the ioctl with a pointer to a
@ -63,7 +63,7 @@ returns the information to the application. The ioctl never fails.
- ``name[32]``
- The name of this CEC adapter. The combination ``driver`` and
``name`` must be unique.
``name`` must be unique.
- .. row 3
@ -72,7 +72,7 @@ returns the information to the application. The ioctl never fails.
- ``capabilities``
- The capabilities of the CEC adapter, see
:ref:`cec-capabilities`.
:ref:`cec-capabilities`.
- .. row 4
@ -81,7 +81,7 @@ returns the information to the application. The ioctl never fails.
- ``version``
- CEC Framework API version, formatted with the ``KERNEL_VERSION()``
macro.
macro.
@ -100,10 +100,10 @@ returns the information to the application. The ioctl never fails.
- 0x00000001
- Userspace has to configure the physical address by calling
:ref:`CEC_ADAP_S_PHYS_ADDR`. If
this capability isn't set, then setting the physical address is
handled by the kernel whenever the EDID is set (for an HDMI
receiver) or read (for an HDMI transmitter).
:ref:`CEC_ADAP_S_PHYS_ADDR`. If
this capability isn't set, then setting the physical address is
handled by the kernel whenever the EDID is set (for an HDMI
receiver) or read (for an HDMI transmitter).
- .. _`CEC-CAP-LOG-ADDRS`:
@ -112,9 +112,9 @@ returns the information to the application. The ioctl never fails.
- 0x00000002
- Userspace has to configure the logical addresses by calling
:ref:`CEC_ADAP_S_LOG_ADDRS`. If
this capability isn't set, then the kernel will have configured
this.
:ref:`CEC_ADAP_S_LOG_ADDRS`. If
this capability isn't set, then the kernel will have configured
this.
- .. _`CEC-CAP-TRANSMIT`:
@ -123,11 +123,11 @@ returns the information to the application. The ioctl never fails.
- 0x00000004
- Userspace can transmit CEC messages by calling
:ref:`CEC_TRANSMIT`. This implies that
userspace can be a follower as well, since being able to transmit
messages is a prerequisite of becoming a follower. If this
capability isn't set, then the kernel will handle all CEC
transmits and process all CEC messages it receives.
:ref:`CEC_TRANSMIT`. This implies that
userspace can be a follower as well, since being able to transmit
messages is a prerequisite of becoming a follower. If this
capability isn't set, then the kernel will handle all CEC
transmits and process all CEC messages it receives.
- .. _`CEC-CAP-PASSTHROUGH`:
@ -136,7 +136,7 @@ returns the information to the application. The ioctl never fails.
- 0x00000008
- Userspace can use the passthrough mode by calling
:ref:`CEC_S_MODE`.
:ref:`CEC_S_MODE`.
- .. _`CEC-CAP-RC`:
@ -153,7 +153,7 @@ returns the information to the application. The ioctl never fails.
- 0x00000020
- The CEC hardware can monitor all messages, not just directed and
broadcast messages.
broadcast messages.

80
Documentation/media/uapi/cec/cec-ioc-adap-g-log-addrs.rst
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@ -35,8 +35,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
To query the current CEC logical addresses, applications call the
:ref:`CEC_ADAP_G_LOG_ADDRS` ioctl with a pointer to a
@ -68,10 +68,10 @@ by a file handle in initiator mode (see
- ``log_addr`` [CEC_MAX_LOG_ADDRS]
- The actual logical addresses that were claimed. This is set by the
driver. If no logical address could be claimed, then it is set to
``CEC_LOG_ADDR_INVALID``. If this adapter is Unregistered, then
``log_addr[0]`` is set to 0xf and all others to
``CEC_LOG_ADDR_INVALID``.
driver. If no logical address could be claimed, then it is set to
``CEC_LOG_ADDR_INVALID``. If this adapter is Unregistered, then
``log_addr[0]`` is set to 0xf and all others to
``CEC_LOG_ADDR_INVALID``.
- .. row 2
@ -80,9 +80,9 @@ by a file handle in initiator mode (see
- ``log_addr_mask``
- The bitmask of all logical addresses this adapter has claimed. If
this adapter is Unregistered then ``log_addr_mask`` sets bit 15
and clears all other bits. If this adapter is not configured at
all, then ``log_addr_mask`` is set to 0. Set by the driver.
this adapter is Unregistered then ``log_addr_mask`` sets bit 15
and clears all other bits. If this adapter is not configured at
all, then ``log_addr_mask`` is set to 0. Set by the driver.
- .. row 3
@ -91,10 +91,10 @@ by a file handle in initiator mode (see
- ``cec_version``
- The CEC version that this adapter shall use. See
:ref:`cec-versions`. Used to implement the
``CEC_MSG_CEC_VERSION`` and ``CEC_MSG_REPORT_FEATURES`` messages.
Note that :ref:`CEC_OP_CEC_VERSION_1_3A <CEC-OP-CEC-VERSION-1-3A>` is not allowed by the CEC
framework.
:ref:`cec-versions`. Used to implement the
``CEC_MSG_CEC_VERSION`` and ``CEC_MSG_REPORT_FEATURES`` messages.
Note that :ref:`CEC_OP_CEC_VERSION_1_3A <CEC-OP-CEC-VERSION-1-3A>` is not allowed by the CEC
framework.
- .. row 4
@ -103,17 +103,17 @@ by a file handle in initiator mode (see
- ``num_log_addrs``
- Number of logical addresses to set up. Must be ≤
``available_log_addrs`` as returned by
:ref:`CEC_ADAP_G_CAPS`. All arrays in
this structure are only filled up to index
``available_log_addrs``-1. The remaining array elements will be
ignored. Note that the CEC 2.0 standard allows for a maximum of 2
logical addresses, although some hardware has support for more.
``CEC_MAX_LOG_ADDRS`` is 4. The driver will return the actual
number of logical addresses it could claim, which may be less than
what was requested. If this field is set to 0, then the CEC
adapter shall clear all claimed logical addresses and all other
fields will be ignored.
``available_log_addrs`` as returned by
:ref:`CEC_ADAP_G_CAPS`. All arrays in
this structure are only filled up to index
``available_log_addrs``-1. The remaining array elements will be
ignored. Note that the CEC 2.0 standard allows for a maximum of 2
logical addresses, although some hardware has support for more.
``CEC_MAX_LOG_ADDRS`` is 4. The driver will return the actual
number of logical addresses it could claim, which may be less than
what was requested. If this field is set to 0, then the CEC
adapter shall clear all claimed logical addresses and all other
fields will be ignored.
- .. row 5
@ -122,9 +122,9 @@ by a file handle in initiator mode (see
- ``vendor_id``
- The vendor ID is a 24-bit number that identifies the specific
vendor or entity. Based on this ID vendor specific commands may be
defined. If you do not want a vendor ID then set it to
``CEC_VENDOR_ID_NONE``.
vendor or entity. Based on this ID vendor specific commands may be
defined. If you do not want a vendor ID then set it to
``CEC_VENDOR_ID_NONE``.
- .. row 6
@ -141,7 +141,7 @@ by a file handle in initiator mode (see
- ``osd_name``\ [15]
- The On-Screen Display name as is returned by the
``CEC_MSG_SET_OSD_NAME`` message.
``CEC_MSG_SET_OSD_NAME`` message.
- .. row 8
@ -150,7 +150,7 @@ by a file handle in initiator mode (see
- ``primary_device_type`` [CEC_MAX_LOG_ADDRS]
- Primary device type for each logical address. See
:ref:`cec-prim-dev-types` for possible types.
:ref:`cec-prim-dev-types` for possible types.
- .. row 9
@ -159,9 +159,9 @@ by a file handle in initiator mode (see
- ``log_addr_type`` [CEC_MAX_LOG_ADDRS]
- Logical address types. See :ref:`cec-log-addr-types` for
possible types. The driver will update this with the actual
logical address type that it claimed (e.g. it may have to fallback
to :ref:`CEC_LOG_ADDR_TYPE_UNREGISTERED <CEC-LOG-ADDR-TYPE-UNREGISTERED>`).
possible types. The driver will update this with the actual
logical address type that it claimed (e.g. it may have to fallback
to :ref:`CEC_LOG_ADDR_TYPE_UNREGISTERED <CEC-LOG-ADDR-TYPE-UNREGISTERED>`).
- .. row 10
@ -170,9 +170,9 @@ by a file handle in initiator mode (see
- ``all_device_types`` [CEC_MAX_LOG_ADDRS]
- CEC 2.0 specific: all device types. See
:ref:`cec-all-dev-types-flags`. Used to implement the
``CEC_MSG_REPORT_FEATURES`` message. This field is ignored if
``cec_version`` < :ref:`CEC_OP_CEC_VERSION_2_0 <CEC-OP-CEC-VERSION-2-0>`.
:ref:`cec-all-dev-types-flags`. Used to implement the
``CEC_MSG_REPORT_FEATURES`` message. This field is ignored if
``cec_version`` < :ref:`CEC_OP_CEC_VERSION_2_0 <CEC-OP-CEC-VERSION-2-0>`.
- .. row 11
@ -181,9 +181,9 @@ by a file handle in initiator mode (see
- ``features`` [CEC_MAX_LOG_ADDRS][12]
- Features for each logical address. Used to implement the
``CEC_MSG_REPORT_FEATURES`` message. The 12 bytes include both the
RC Profile and the Device Features. This field is ignored if
``cec_version`` < :ref:`CEC_OP_CEC_VERSION_2_0 <CEC-OP-CEC-VERSION-2-0>`.
``CEC_MSG_REPORT_FEATURES`` message. The 12 bytes include both the
RC Profile and the Device Features. This field is ignored if
``cec_version`` < :ref:`CEC_OP_CEC_VERSION_2_0 <CEC-OP-CEC-VERSION-2-0>`.
@ -350,8 +350,8 @@ by a file handle in initiator mode (see
- 6
- Use this if you just want to remain unregistered. Used for pure
CEC switches or CDC-only devices (CDC: Capability Discovery and
Control).
CEC switches or CDC-only devices (CDC: Capability Discovery and
Control).

4
Documentation/media/uapi/cec/cec-ioc-adap-g-phys-addr.rst
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@ -34,8 +34,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
To query the current physical address applications call the
:ref:`CEC_ADAP_G_PHYS_ADDR` ioctl with a pointer to an __u16 where the

36
Documentation/media/uapi/cec/cec-ioc-dqevent.rst
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@ -32,8 +32,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
CEC devices can send asynchronous events. These can be retrieved by
calling the :ref:`CEC_DQEVENT` ioctl. If the file descriptor is in
@ -91,14 +91,14 @@ state did change in between the two events.
- ``lost_msgs``
- Set to the number of lost messages since the filehandle was opened
or since the last time this event was dequeued for this
filehandle. The messages lost are the oldest messages. So when a
new message arrives and there is no more room, then the oldest
message is discarded to make room for the new one. The internal
size of the message queue guarantees that all messages received in
the last two seconds will be stored. Since messages should be
replied to within a second according to the CEC specification,
this is more than enough.
or since the last time this event was dequeued for this
filehandle. The messages lost are the oldest messages. So when a
new message arrives and there is no more room, then the oldest
message is discarded to make room for the new one. The internal
size of the message queue guarantees that all messages received in
the last two seconds will be stored. Since messages should be
replied to within a second according to the CEC specification,
this is more than enough.
@ -157,7 +157,7 @@ state did change in between the two events.
- ``state_change``
- The new adapter state as sent by the :ref:`CEC_EVENT_STATE_CHANGE <CEC-EVENT-STATE-CHANGE>`
event.
event.
- .. row 6
@ -167,7 +167,7 @@ state did change in between the two events.
- ``lost_msgs``
- The number of lost messages as sent by the :ref:`CEC_EVENT_LOST_MSGS <CEC-EVENT-LOST-MSGS>`
event.
event.
@ -186,8 +186,8 @@ state did change in between the two events.
- 1
- Generated when the CEC Adapter's state changes. When open() is
called an initial event will be generated for that filehandle with
the CEC Adapter's state at that time.
called an initial event will be generated for that filehandle with
the CEC Adapter's state at that time.
- .. _`CEC-EVENT-LOST-MSGS`:
@ -196,7 +196,7 @@ state did change in between the two events.
- 2
- Generated if one or more CEC messages were lost because the
application didn't dequeue CEC messages fast enough.
application didn't dequeue CEC messages fast enough.
@ -215,9 +215,9 @@ state did change in between the two events.
- 1
- Set for the initial events that are generated when the device is
opened. See the table above for which events do this. This allows
applications to learn the initial state of the CEC adapter at
open() time.
opened. See the table above for which events do this. This allows
applications to learn the initial state of the CEC adapter at
open() time.

122
Documentation/media/uapi/cec/cec-ioc-g-mode.rst
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@ -30,8 +30,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
By default any filehandle can use
:ref:`CEC_TRANSMIT` and
@ -89,7 +89,7 @@ Available initiator modes are:
- 0x0
- This is not an initiator, i.e. it cannot transmit CEC messages or
make any other changes to the CEC adapter.
make any other changes to the CEC adapter.
- .. _`CEC-MODE-INITIATOR`:
@ -98,8 +98,8 @@ Available initiator modes are:
- 0x1
- This is an initiator (the default when the device is opened) and
it can transmit CEC messages and make changes to the CEC adapter,
unless there is an exclusive initiator.
it can transmit CEC messages and make changes to the CEC adapter,
unless there is an exclusive initiator.
- .. _`CEC-MODE-EXCL-INITIATOR`:
@ -108,10 +108,10 @@ Available initiator modes are:
- 0x2
- This is an exclusive initiator and this file descriptor is the
only one that can transmit CEC messages and make changes to the
CEC adapter. If someone else is already the exclusive initiator
then an attempt to become one will return the EBUSY error code
error.
only one that can transmit CEC messages and make changes to the
CEC adapter. If someone else is already the exclusive initiator
then an attempt to become one will return the EBUSY error code
error.
Available follower modes are:
@ -140,9 +140,9 @@ Available follower modes are:
- 0x10
- This is a follower and it will receive CEC messages unless there
is an exclusive follower. You cannot become a follower if
:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC-MODE-NO-INITIATOR <CEC-MODE-NO-INITIATOR>`
was specified, EINVAL error code is returned in that case.
is an exclusive follower. You cannot become a follower if
:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC-MODE-NO-INITIATOR <CEC-MODE-NO-INITIATOR>`
was specified, EINVAL error code is returned in that case.
- .. _`CEC-MODE-EXCL-FOLLOWER`:
@ -151,11 +151,11 @@ Available follower modes are:
- 0x20
- This is an exclusive follower and only this file descriptor will
receive CEC messages for processing. If someone else is already
the exclusive follower then an attempt to become one will return
the EBUSY error code error. You cannot become a follower if
:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC-MODE-NO-INITIATOR <CEC-MODE-NO-INITIATOR>`
was specified, EINVAL error code is returned in that case.
receive CEC messages for processing. If someone else is already
the exclusive follower then an attempt to become one will return
the EBUSY error code error. You cannot become a follower if
:ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>` is not set or if :ref:`CEC-MODE-NO-INITIATOR <CEC-MODE-NO-INITIATOR>`
was specified, EINVAL error code is returned in that case.
- .. _`CEC-MODE-EXCL-FOLLOWER-PASSTHRU`:
@ -164,14 +164,14 @@ Available follower modes are:
- 0x30
- This is an exclusive follower and only this file descriptor will
receive CEC messages for processing. In addition it will put the
CEC device into passthrough mode, allowing the exclusive follower
to handle most core messages instead of relying on the CEC
framework for that. If someone else is already the exclusive
follower then an attempt to become one will return the EBUSY error
code error. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>`
is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified, EINVAL
error code is returned in that case.
receive CEC messages for processing. In addition it will put the
CEC device into passthrough mode, allowing the exclusive follower
to handle most core messages instead of relying on the CEC
framework for that. If someone else is already the exclusive
follower then an attempt to become one will return the EBUSY error
code error. You cannot become a follower if :ref:`CEC_CAP_TRANSMIT <CEC-CAP-TRANSMIT>`
is not set or if :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>` was specified, EINVAL
error code is returned in that case.
- .. _`CEC-MODE-MONITOR`:
@ -180,13 +180,13 @@ Available follower modes are:
- 0xe0
- Put the file descriptor into monitor mode. Can only be used in
combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise EINVAL error
code will be returned. In monitor mode all messages this CEC
device transmits and all messages it receives (both broadcast
messages and directed messages for one its logical addresses) will
be reported. This is very useful for debugging. This is only
allowed if the process has the ``CAP_NET_ADMIN`` capability. If
that is not set, then EPERM error code is returned.
combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise EINVAL error
code will be returned. In monitor mode all messages this CEC
device transmits and all messages it receives (both broadcast
messages and directed messages for one its logical addresses) will
be reported. This is very useful for debugging. This is only
allowed if the process has the ``CAP_NET_ADMIN`` capability. If
that is not set, then EPERM error code is returned.
- .. _`CEC-MODE-MONITOR-ALL`:
@ -195,15 +195,15 @@ Available follower modes are:
- 0xf0
- Put the file descriptor into 'monitor all' mode. Can only be used
in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise EINVAL
error code will be returned. In 'monitor all' mode all messages
this CEC device transmits and all messages it receives, including
directed messages for other CEC devices will be reported. This is
very useful for debugging, but not all devices support this. This
mode requires that the :ref:`CEC_CAP_MONITOR_ALL <CEC-CAP-MONITOR-ALL>` capability is set,
otherwise EINVAL error code is returned. This is only allowed if
the process has the ``CAP_NET_ADMIN`` capability. If that is not
set, then EPERM error code is returned.
in combination with :ref:`CEC_MODE_NO_INITIATOR <CEC-MODE-NO-INITIATOR>`, otherwise EINVAL
error code will be returned. In 'monitor all' mode all messages
this CEC device transmits and all messages it receives, including
directed messages for other CEC devices will be reported. This is
very useful for debugging, but not all devices support this. This
mode requires that the :ref:`CEC_CAP_MONITOR_ALL <CEC-CAP-MONITOR-ALL>` capability is set,
otherwise EINVAL error code is returned. This is only allowed if
the process has the ``CAP_NET_ADMIN`` capability. If that is not
set, then EPERM error code is returned.
Core message processing details:
@ -222,74 +222,74 @@ Core message processing details:
- ``CEC_MSG_GET_CEC_VERSION``
- When in passthrough mode this message has to be handled by
userspace, otherwise the core will return the CEC version that was
set with
:ref:`CEC_ADAP_S_LOG_ADDRS`.
userspace, otherwise the core will return the CEC version that was
set with
:ref:`CEC_ADAP_S_LOG_ADDRS`.
- .. _`CEC-MSG-GIVE-DEVICE-VENDOR-ID`:
- ``CEC_MSG_GIVE_DEVICE_VENDOR_ID``
- When in passthrough mode this message has to be handled by
userspace, otherwise the core will return the vendor ID that was
set with
:ref:`CEC_ADAP_S_LOG_ADDRS`.
userspace, otherwise the core will return the vendor ID that was
set with
:ref:`CEC_ADAP_S_LOG_ADDRS`.
- .. _`CEC-MSG-ABORT`:
- ``CEC_MSG_ABORT``
- When in passthrough mode this message has to be handled by
userspace, otherwise the core will return a feature refused
message as per the specification.
userspace, otherwise the core will return a feature refused
message as per the specification.
- .. _`CEC-MSG-GIVE-PHYSICAL-ADDR`:
- ``CEC_MSG_GIVE_PHYSICAL_ADDR``
- When in passthrough mode this message has to be handled by
userspace, otherwise the core will report the current physical
address.
userspace, otherwise the core will report the current physical
address.
- .. _`CEC-MSG-GIVE-OSD-NAME`:
- ``CEC_MSG_GIVE_OSD_NAME``
- When in passthrough mode this message has to be handled by
userspace, otherwise the core will report the current OSD name as
was set with
:ref:`CEC_ADAP_S_LOG_ADDRS`.
userspace, otherwise the core will report the current OSD name as
was set with
:ref:`CEC_ADAP_S_LOG_ADDRS`.
- .. _`CEC-MSG-GIVE-FEATURES`:
- ``CEC_MSG_GIVE_FEATURES``
- When in passthrough mode this message has to be handled by
userspace, otherwise the core will report the current features as
was set with
:ref:`CEC_ADAP_S_LOG_ADDRS` or
the message is ignore if the CEC version was older than 2.0.
userspace, otherwise the core will report the current features as
was set with
:ref:`CEC_ADAP_S_LOG_ADDRS` or
the message is ignore if the CEC version was older than 2.0.
- .. _`CEC-MSG-USER-CONTROL-PRESSED`:
- ``CEC_MSG_USER_CONTROL_PRESSED``
- If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set, then generate a remote control key
press. This message is always passed on to userspace.
press. This message is always passed on to userspace.
- .. _`CEC-MSG-USER-CONTROL-RELEASED`:
- ``CEC_MSG_USER_CONTROL_RELEASED``
- If :ref:`CEC_CAP_RC <CEC-CAP-RC>` is set, then generate a remote control key
release. This message is always passed on to userspace.
release. This message is always passed on to userspace.
- .. _`CEC-MSG-REPORT-PHYSICAL-ADDR`:
- ``CEC_MSG_REPORT_PHYSICAL_ADDR``
- The CEC framework will make note of the reported physical address
and then just pass the message on to userspace.
and then just pass the message on to userspace.

114
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@ -33,8 +33,8 @@ Arguments
Description
===========
Note: this documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
.. note:: This documents the proposed CEC API. This API is not yet finalized
and is currently only available as a staging kernel module.
To receive a CEC message the application has to fill in the
:c:type:`struct cec_msg` structure and pass it to the :ref:`CEC_RECEIVE`
@ -67,8 +67,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``ts``
- Timestamp of when the message was transmitted in ns in the case of
:ref:`CEC_TRANSMIT` with ``reply`` set to 0, or the timestamp of the
received message in all other cases.
:ref:`CEC_TRANSMIT` with ``reply`` set to 0, or the timestamp of the
received message in all other cases.
- .. row 2
@ -77,9 +77,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``len``
- The length of the message. For :ref:`CEC_TRANSMIT` this is filled in
by the application. The driver will fill this in for
:ref:`CEC_RECEIVE` and for :ref:`CEC_TRANSMIT` it will be filled in with
the length of the reply message if ``reply`` was set.
by the application. The driver will fill this in for
:ref:`CEC_RECEIVE` and for :ref:`CEC_TRANSMIT` it will be filled in with
the length of the reply message if ``reply`` was set.
- .. row 3
@ -88,11 +88,11 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``timeout``
- The timeout in milliseconds. This is the time the device will wait
for a message to be received before timing out. If it is set to 0,
then it will wait indefinitely when it is called by
:ref:`CEC_RECEIVE`. If it is 0 and it is called by :ref:`CEC_TRANSMIT`,
then it will be replaced by 1000 if the ``reply`` is non-zero or
ignored if ``reply`` is 0.
for a message to be received before timing out. If it is set to 0,
then it will wait indefinitely when it is called by
:ref:`CEC_RECEIVE`. If it is 0 and it is called by :ref:`CEC_TRANSMIT`,
then it will be replaced by 1000 if the ``reply`` is non-zero or
ignored if ``reply`` is 0.
- .. row 4
@ -101,9 +101,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``sequence``
- The sequence number is automatically assigned by the CEC framework
for all transmitted messages. It can be later used by the
framework to generate an event if a reply for a message was
requested and the message was transmitted in a non-blocking mode.
for all transmitted messages. It can be later used by the
framework to generate an event if a reply for a message was
requested and the message was transmitted in a non-blocking mode.
- .. row 5
@ -120,10 +120,10 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``rx_status``
- The status bits of the received message. See
:ref:`cec-rx-status` for the possible status values. It is 0 if
this message was transmitted, not received, unless this is the
reply to a transmitted message. In that case both ``rx_status``
and ``tx_status`` are set.
:ref:`cec-rx-status` for the possible status values. It is 0 if
this message was transmitted, not received, unless this is the
reply to a transmitted message. In that case both ``rx_status``
and ``tx_status`` are set.
- .. row 7
@ -132,8 +132,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``tx_status``
- The status bits of the transmitted message. See
:ref:`cec-tx-status` for the possible status values. It is 0 if
this messages was received, not transmitted.
:ref:`cec-tx-status` for the possible status values. It is 0 if
this messages was received, not transmitted.
- .. row 8
@ -142,9 +142,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``msg``\ [16]
- The message payload. For :ref:`CEC_TRANSMIT` this is filled in by the
application. The driver will fill this in for :ref:`CEC_RECEIVE` and
for :ref:`CEC_TRANSMIT` it will be filled in with the payload of the
reply message if ``reply`` was set.
application. The driver will fill this in for :ref:`CEC_RECEIVE` and
for :ref:`CEC_TRANSMIT` it will be filled in with the payload of the
reply message if ``reply`` was set.
- .. row 9
@ -153,15 +153,15 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``reply``
- Wait until this message is replied. If ``reply`` is 0 and the
``timeout`` is 0, then don't wait for a reply but return after
transmitting the message. If there was an error as indicated by a
non-zero ``tx_status`` field, then ``reply`` and ``timeout`` are
both set to 0 by the driver. Ignored by :ref:`CEC_RECEIVE`. The case
where ``reply`` is 0 (this is the opcode for the Feature Abort
message) and ``timeout`` is non-zero is specifically allowed to
send a message and wait up to ``timeout`` milliseconds for a
Feature Abort reply. In this case ``rx_status`` will either be set
to :ref:`CEC_RX_STATUS_TIMEOUT <CEC-RX-STATUS-TIMEOUT>` or :ref:`CEC_RX_STATUS-FEATURE-ABORT <CEC-RX-STATUS-FEATURE-ABORT>`.
``timeout`` is 0, then don't wait for a reply but return after
transmitting the message. If there was an error as indicated by a
non-zero ``tx_status`` field, then ``reply`` and ``timeout`` are
both set to 0 by the driver. Ignored by :ref:`CEC_RECEIVE`. The case
where ``reply`` is 0 (this is the opcode for the Feature Abort
message) and ``timeout`` is non-zero is specifically allowed to
send a message and wait up to ``timeout`` milliseconds for a
Feature Abort reply. In this case ``rx_status`` will either be set
to :ref:`CEC_RX_STATUS_TIMEOUT <CEC-RX-STATUS-TIMEOUT>` or :ref:`CEC_RX_STATUS-FEATURE-ABORT <CEC-RX-STATUS-FEATURE-ABORT>`.
- .. row 10
@ -170,9 +170,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``tx_arb_lost_cnt``
- A counter of the number of transmit attempts that resulted in the
Arbitration Lost error. This is only set if the hardware supports
this, otherwise it is always 0. This counter is only valid if the
:ref:`CEC_TX_STATUS_ARB_LOST <CEC-TX-STATUS-ARB-LOST>` status bit is set.
Arbitration Lost error. This is only set if the hardware supports
this, otherwise it is always 0. This counter is only valid if the
:ref:`CEC_TX_STATUS_ARB_LOST <CEC-TX-STATUS-ARB-LOST>` status bit is set.
- .. row 11
@ -181,9 +181,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``tx_nack_cnt``
- A counter of the number of transmit attempts that resulted in the
Not Acknowledged error. This is only set if the hardware supports
this, otherwise it is always 0. This counter is only valid if the
:ref:`CEC_TX_STATUS_NACK <CEC-TX-STATUS-NACK>` status bit is set.
Not Acknowledged error. This is only set if the hardware supports
this, otherwise it is always 0. This counter is only valid if the
:ref:`CEC_TX_STATUS_NACK <CEC-TX-STATUS-NACK>` status bit is set.
- .. row 12
@ -192,9 +192,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``tx_low_drive_cnt``
- A counter of the number of transmit attempts that resulted in the
Arbitration Lost error. This is only set if the hardware supports
this, otherwise it is always 0. This counter is only valid if the
:ref:`CEC_TX_STATUS_LOW_DRIVE <CEC-TX-STATUS-LOW-DRIVE>` status bit is set.
Arbitration Lost error. This is only set if the hardware supports
this, otherwise it is always 0. This counter is only valid if the
:ref:`CEC_TX_STATUS_LOW_DRIVE <CEC-TX-STATUS-LOW-DRIVE>` status bit is set.
- .. row 13
@ -203,9 +203,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- ``tx_error_cnt``
- A counter of the number of transmit errors other than Arbitration
Lost or Not Acknowledged. This is only set if the hardware
supports this, otherwise it is always 0. This counter is only
valid if the :ref:`CEC_TX_STATUS_ERROR <CEC-TX-STATUS-ERROR>` status bit is set.
Lost or Not Acknowledged. This is only set if the hardware
supports this, otherwise it is always 0. This counter is only
valid if the :ref:`CEC_TX_STATUS_ERROR <CEC-TX-STATUS-ERROR>` status bit is set.
@ -224,9 +224,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- 0x01
- The message was transmitted successfully. This is mutually
exclusive with :ref:`CEC_TX_STATUS_MAX_RETRIES <CEC-TX-STATUS-MAX-RETRIES>`. Other bits can still
be set if earlier attempts met with failure before the transmit
was eventually successful.
exclusive with :ref:`CEC_TX_STATUS_MAX_RETRIES <CEC-TX-STATUS-MAX-RETRIES>`. Other bits can still
be set if earlier attempts met with failure before the transmit
was eventually successful.
- .. _`CEC-TX-STATUS-ARB-LOST`:
@ -251,8 +251,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- 0x08
- Low drive was detected on the CEC bus. This indicates that a
follower detected an error on the bus and requests a
retransmission.
follower detected an error on the bus and requests a
retransmission.
- .. _`CEC-TX-STATUS-ERROR`:
@ -261,9 +261,9 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- 0x10
- Some error occurred. This is used for any errors that do not fit
the previous two, either because the hardware could not tell which
error occurred, or because the hardware tested for other
conditions besides those two.
the previous two, either because the hardware could not tell which
error occurred, or because the hardware tested for other
conditions besides those two.
- .. _`CEC-TX-STATUS-MAX-RETRIES`:
@ -272,8 +272,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- 0x20
- The transmit failed after one or more retries. This status bit is
mutually exclusive with :ref:`CEC_TX_STATUS_OK <CEC-TX-STATUS-OK>`. Other bits can still
be set to explain which failures were seen.
mutually exclusive with :ref:`CEC_TX_STATUS_OK <CEC-TX-STATUS-OK>`. Other bits can still
be set to explain which failures were seen.
@ -308,8 +308,8 @@ queue, then it will return -1 and set errno to the EBUSY error code.
- 0x04
- The message was received successfully but the reply was
``CEC_MSG_FEATURE_ABORT``. This status is only set if this message
was the reply to an earlier transmitted message.
``CEC_MSG_FEATURE_ABORT``. This status is only set if this message
was the reply to an earlier transmitted message.

11
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@ -15,8 +15,9 @@ The information about the frontend tuner locking status can be queried
using :ref:`FE_READ_STATUS`.
Signal statistics are provided via
:ref:`FE_GET_PROPERTY`. Please note that several
statistics require the demodulator to be fully locked (e. g. with
FE_HAS_LOCK bit set). See
:ref:`Frontend statistics indicators <frontend-stat-properties>` for
more details.
:ref:`FE_GET_PROPERTY`.
.. note:: Most statistics require the demodulator to be fully locked
(e. g. with FE_HAS_LOCK bit set). See
:ref:`Frontend statistics indicators <frontend-stat-properties>` for
more details.

4
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@ -8,8 +8,8 @@
Digital TV API
##############
**NOTE:** This API is also known as **DVB API**, although it is generic
enough to support all digital TV standards.
.. note:: This API is also known as **DVB API**, although it is generic
enough to support all digital TV standards.
**Version 5.10**

26
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@ -20,13 +20,13 @@ Also, the union didn't have any space left to be expanded without
breaking userspace. So, the decision was to deprecate the legacy
union/struct based approach, in favor of a properties set approach.
NOTE: on Linux DVB API version 3, setting a frontend were done via
:ref:`struct dvb_frontend_parameters <dvb-frontend-parameters>`.
This got replaced on version 5 (also called "S2API", as this API were
added originally_enabled to provide support for DVB-S2), because the
old API has a very limited support to new standards and new hardware.
This section describes the new and recommended way to set the frontend,
with suppports all digital TV delivery systems.
.. note:: On Linux DVB API version 3, setting a frontend were done via
:ref:`struct dvb_frontend_parameters <dvb-frontend-parameters>`.
This got replaced on version 5 (also called "S2API", as this API were
added originally_enabled to provide support for DVB-S2), because the
old API has a very limited support to new standards and new hardware.
This section describes the new and recommended way to set the frontend,
with suppports all digital TV delivery systems.
Example: with the properties based approach, in order to set the tuner
to a DVB-C channel at 651 kHz, modulated with 256-QAM, FEC 3/4 and
@ -93,12 +93,12 @@ Example: Setting digital TV frontend properties
return 0;
}
NOTE: While it is possible to directly call the Kernel code like the
above example, it is strongly recommended to use
`libdvbv5 <https://linuxtv.org/docs/libdvbv5/index.html>`__, as it
provides abstraction to work with the supported digital TV standards and
provides methods for usual operations like program scanning and to
read/write channel descriptor files.
.. attention:: While it is possible to directly call the Kernel code like the
above example, it is strongly recommended to use
`libdvbv5 <https://linuxtv.org/docs/libdvbv5/index.html>`__, as it
provides abstraction to work with the supported digital TV standards and
provides methods for usual operations like program scanning and to
read/write channel descriptor files.
.. toctree::

8
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@ -9,10 +9,10 @@ Examples
In this section we would like to present some examples for using the DVB
API.
NOTE: This section is out of date, and the code below won't even
compile. Please refer to the
`libdvbv5 <https://linuxtv.org/docs/libdvbv5/index.html>`__ for
updated/recommended examples.
..note:: This section is out of date, and the code below won't even
compile. Please refer to the
`libdvbv5 <https://linuxtv.org/docs/libdvbv5/index.html>`__ for
updated/recommended examples.
.. _tuning:

5
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@ -36,8 +36,9 @@ Arguments
Description
===========
WARNING: This is a very obscure legacy command, used only at stv0299
driver. Should not be used on newer drivers.
.. warning::
This is a very obscure legacy command, used only at stv0299
driver. Should not be used on newer drivers.
It provides a non-standard method for selecting Diseqc voltage on the
frontend, for Dish Network legacy switches.

4
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@ -144,8 +144,8 @@ struct dvb_frontend_info
- Capabilities supported by the frontend
NOTE: The frequencies are specified in Hz for Terrestrial and Cable
systems. They're specified in kHz for Satellite systems
.. note:: The frequencies are specified in Hz for Terrestrial and Cable
systems. They're specified in kHz for Satellite systems
.. _fe-caps-t:

6
Documentation/media/uapi/dvb/fe-read-status.rst
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@ -40,9 +40,9 @@ used to check about the locking status of the frontend after being
tuned. The ioctl takes a pointer to an integer where the status will be
written.
NOTE: the size of status is actually sizeof(enum fe_status), with
varies according with the architecture. This needs to be fixed in the
future.
.. note:: The size of status is actually sizeof(enum fe_status), with
varies according with the architecture. This needs to be fixed in the
future.
.. _fe-status-t:

8
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@ -42,10 +42,10 @@ to send a 22kHz tone in order to select between high/low band on some
dual-band LNBf. It is also used to send signals to DiSEqC equipment, but
this is done using the DiSEqC ioctls.
NOTE: if more than one device is connected to the same antenna, setting
a tone may interfere on other devices, as they may lose the capability
of selecting the band. So, it is recommended that applications would
change to SEC_TONE_OFF when the device is not used.
.. attention:: If more than one device is connected to the same antenna,
setting a tone may interfere on other devices, as they may lose the
capability of selecting the band. So, it is recommended that applications
would change to SEC_TONE_OFF when the device is not used.
.. _fe-sec-tone-mode-t:

10
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@ -48,11 +48,11 @@ the ones that implement DISEqC and multipoint LNBf's don't need to
control the voltage level, provided that either 13V or 18V is sent to
power up the LNBf.
NOTE: if more than one device is connected to the same antenna, setting
a voltage level may interfere on other devices, as they may lose the
capability of setting polarization or IF. So, on those cases, setting
the voltage to SEC_VOLTAGE_OFF while the device is not is used is
recommended.
.. attention:: if more than one device is connected to the same antenna,
setting a voltage level may interfere on other devices, as they may lose
the capability of setting polarization or IF. So, on those cases, setting
the voltage to SEC_VOLTAGE_OFF while the device is not is used is
recommended.
Return Value

4
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@ -29,8 +29,8 @@ The frontend can be accessed through ``/dev/dvb/adapter?/frontend?``.
Data types and ioctl definitions can be accessed by including
``linux/dvb/frontend.h`` in your application.
NOTE: Transmission via the internet (DVB-IP) is not yet handled by this
API but a future extension is possible.
.. note:: Transmission via the internet (DVB-IP) is not yet handled by this
API but a future extension is possible.
On Satellite systems, the API support for the Satellite Equipment
Control (SEC) allows to power control and to send/receive signals to

12
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@ -92,10 +92,12 @@ Generic Error Codes
- Permission denied. Can be returned if the device needs write
permission, or some special capabilities is needed (e. g. root)
.. note::
Note 1: ioctls may return other error codes. Since errors may have side
effects such as a driver reset, applications should abort on unexpected
errors.
#. This list is not exaustive; ioctls may return other error codes.
Since errors may have side effects such as a driver reset,
applications should abort on unexpected errors, or otherwise
assume that the device is in a bad state.
Note 2: Request-specific error codes are listed in the individual
requests descriptions.
#. Request-specific error codes are listed in the individual
requests descriptions.

12
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@ -251,11 +251,13 @@ I/O control requests
be useful of receivers that have otherwise narrow band receiver that
prevents them to be used with some remotes. Wide band receiver might
also be more precise On the other hand its disadvantage it usually
reduced range of reception. Note: wide band receiver might be
implictly enabled if you enable carrier reports. In that case it
will be disabled as soon as you disable carrier reports. Trying to
disable wide band receiver while carrier reports are active will do
nothing.
reduced range of reception.
.. note:: Wide band receiver might be
implictly enabled if you enable carrier reports. In that case it
will be disabled as soon as you disable carrier reports. Trying to
disable wide band receiver while carrier reports are active will do
nothing.
.. _lirc_dev_errors:

11
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@ -35,11 +35,12 @@ The struct :ref:`v4l2_audio <v4l2-audio>` returned by the
The :ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` and
:ref:`VIDIOC_G_AUDOUT <VIDIOC_G_AUDOUT>` ioctls report the current
audio input and output, respectively. Note that, unlike
:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` these ioctls return a
structure as :ref:`VIDIOC_ENUMAUDIO` and
:ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>` do, not just an index.
audio input and output, respectively.
.. note:: Note that, unlike :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` and
:ref:`VIDIOC_G_OUTPUT <VIDIOC_G_OUTPUT>` these ioctls return a
structure as :ref:`VIDIOC_ENUMAUDIO` and
:ref:`VIDIOC_ENUMAUDOUT <VIDIOC_ENUMAUDOUT>` do, not just an index.
To select an audio input and change its properties applications call the
:ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` ioctl. To select an audio

25
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@ -166,11 +166,11 @@ struct v4l2_buffer
output device because the application did not pass new data in
time.
Note this may count the frames received e.g. over USB, without
taking into account the frames dropped by the remote hardware due
to limited compression throughput or bus bandwidth. These devices
identify by not enumerating any video standards, see
:ref:`standard`.
.. note:: This may count the frames received e.g. over USB, without
taking into account the frames dropped by the remote hardware due
to limited compression throughput or bus bandwidth. These devices
identify by not enumerating any video standards, see
:ref:`standard`.
- .. row 10
@ -297,8 +297,10 @@ struct v4l2_plane
stream, applications when it refers to an output stream. If the
application sets this to 0 for an output stream, then
``bytesused`` will be set to the size of the plane (see the
``length`` field of this struct) by the driver. Note that the
actual image data starts at ``data_offset`` which may not be 0.
``length`` field of this struct) by the driver.
.. note:: Note that the actual image data starts at ``data_offset``
which may not be 0.
- .. row 2
@ -367,10 +369,11 @@ struct v4l2_plane
-
- Offset in bytes to video data in the plane. Drivers must set this
field when ``type`` refers to a capture stream, applications when
it refers to an output stream. Note that data_offset is included
in ``bytesused``. So the size of the image in the plane is
``bytesused``-``data_offset`` at offset ``data_offset`` from the
start of the plane.
it refers to an output stream.
.. note:: That data_offset is included in ``bytesused``. So the
size of the image in the plane is ``bytesused``-``data_offset``
at offset ``data_offset`` from the start of the plane.
- .. row 8

20
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@ -15,9 +15,9 @@ offset into a video signal.
Applications can use the following API to select an area in the video
signal, query the default area and the hardware limits.
**NOTE**: Despite their name, the :ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>`,
:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_S_CROP
<VIDIOC_G_CROP>` ioctls apply to input as well as output devices.
.. note:: Despite their name, the :ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>`,
:ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and :ref:`VIDIOC_S_CROP
<VIDIOC_G_CROP>` ioctls apply to input as well as output devices.
Scaling requires a source and a target. On a video capture or overlay
device the source is the video signal, and the cropping ioctls determine
@ -38,9 +38,9 @@ support scaling or the :ref:`VIDIOC_G_CROP <VIDIOC_G_CROP>` and
:ref:`VIDIOC_S_CROP <VIDIOC_G_CROP>` ioctls. Their size (and position
where applicable) will be fixed in this case.
**NOTE:** All capture and output devices must support the
:ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>` ioctl such that applications can
determine if scaling takes place.
.. note:: All capture and output devices must support the
:ref:`VIDIOC_CROPCAP <VIDIOC_CROPCAP>` ioctl such that applications
can determine if scaling takes place.
Cropping Structures
@ -144,8 +144,8 @@ reopening a device, such that piping data into or out of a device will
work without special preparations. More advanced applications should
ensure the parameters are suitable before starting I/O.
**NOTE:** on the next two examples, a video capture device is assumed;
change ``V4L2_BUF_TYPE_VIDEO_CAPTURE`` for other types of device.
.. note:: On the next two examples, a video capture device is assumed;
change ``V4L2_BUF_TYPE_VIDEO_CAPTURE`` for other types of device.
Example: Resetting the cropping parameters
==========================================
@ -207,7 +207,7 @@ Example: Simple downscaling
Example: Selecting an output area
=================================
**NOTE:** This example assumes an output device.
.. note:: This example assumes an output device.
.. code-block:: c
@ -246,7 +246,7 @@ Example: Selecting an output area
Example: Current scaling factor and pixel aspect
================================================
**NOTE:** This example assumes a video capture device.
.. note:: This example assumes a video capture device.
.. code-block:: c

4
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@ -15,7 +15,9 @@ Conventionally V4L2 video capture devices are accessed through character
device special files named ``/dev/video`` and ``/dev/video0`` to
``/dev/video63`` with major number 81 and minor numbers 0 to 63.
``/dev/video`` is typically a symbolic link to the preferred video
device. Note the same device files are used for video output devices.
device.
.. note:: The same device file names are used for video output devices.
Querying Capabilities

6
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@ -19,8 +19,10 @@ both sides and finally call :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>`
for both capture and output to start the codec.
Video compression codecs use the MPEG controls to setup their codec
parameters (note that the MPEG controls actually support many more
codecs than just MPEG). See :ref:`mpeg-controls`.
parameters
.. note:: The MPEG controls actually support many more codecs than
just MPEG. See :ref:`mpeg-controls`.
Memory-to-memory devices can often be used as a shared resource: you can
open the video node multiple times, each application setting up their

9
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@ -6,11 +6,10 @@
Effect Devices Interface
************************
**Note**
This interface has been be suspended from the V4L2 API implemented
in Linux 2.6 until we have more experience with effect device
interfaces.
.. note::
This interface has been be suspended from the V4L2 API.
The implementation for such effects should be done
via mem2mem devices.
A V4L2 video effect device can do image effects, filtering, or combine
two or more images or image streams. For example video transitions or

9
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@ -14,10 +14,11 @@ this interface, which borrows structures and ioctls of the
:ref:`Video Overlay <overlay>` interface.
The OSD function is accessible through the same character special file
as the :ref:`Video Output <capture>` function. Note the default
function of such a ``/dev/video`` device is video capturing or output.
The OSD function is only available after calling the
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl.
as the :ref:`Video Output <capture>` function.
.. note:: The default function of such a ``/dev/video`` device is video
capturing or output. The OSD function is only available after calling
the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl.
Querying Capabilities

4
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@ -14,7 +14,9 @@ Conventionally V4L2 video output devices are accessed through character
device special files named ``/dev/video`` and ``/dev/video0`` to
``/dev/video63`` with major number 81 and minor numbers 0 to 63.
``/dev/video`` is typically a symbolic link to the preferred video
device. Note the same device files are used for video capture devices.
device.
..note:: The same device file names are used also for video capture devices.
Querying Capabilities

17
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@ -17,10 +17,11 @@ plants needed cooling towers this used to be the only way to put live
video into a window.
Video overlay devices are accessed through the same character special
files as :ref:`video capture <capture>` devices. Note the default
function of a ``/dev/video`` device is video capturing. The overlay
function is only available after calling the
:ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl.
files as :ref:`video capture <capture>` devices.
.. note:: The default function of a ``/dev/video`` device is video
capturing. The overlay function is only available after calling
the :ref:`VIDIOC_S_FMT <VIDIOC_G_FMT>` ioctl.
The driver may support simultaneous overlay and capturing using the
read/write and streaming I/O methods. If so, operation at the nominal
@ -235,10 +236,10 @@ exceeded are undefined. [3]_
:ref:`VIDIOC_S_FBUF <VIDIOC_G_FBUF>`,
:ref:`framebuffer-flags`).
**Note**: this field was added in Linux 2.6.23, extending the structure.
However the :ref:`VIDIOC_[G|S|TRY]_FMT <VIDIOC_G_FMT>`
ioctls, which take a pointer to a :ref:`v4l2_format <v4l2-format>`
parent structure with padding bytes at the end, are not affected.
.. note:: This field was added in Linux 2.6.23, extending the
structure. However the :ref:`VIDIOC_[G|S|TRY]_FMT <VIDIOC_G_FMT>`
ioctls, which take a pointer to a :ref:`v4l2_format <v4l2-format>`
parent structure with padding bytes at the end, are not affected.
.. _v4l2-clip:

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@ -14,10 +14,10 @@ at devices capable of receiving and/or transmitting RDS information.
For more information see the core RDS standard :ref:`iec62106` and the
RBDS standard :ref:`nrsc4`.
Note that the RBDS standard as is used in the USA is almost identical to
the RDS standard. Any RDS decoder/encoder can also handle RBDS. Only
some of the fields have slightly different meanings. See the RBDS
standard for more information.
.. note:: Note that the RBDS standard as is used in the USA is almost
identical to the RDS standard. Any RDS decoder/encoder can also handle
RBDS. Only some of the fields have slightly different meanings. See the
RBDS standard for more information.
The RBDS standard also specifies support for MMBS (Modified Mobile
Search). This is a proprietary format which seems to be discontinued.

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@ -72,14 +72,14 @@ reported on one (or several) V4L2 device nodes.
Pad-level Formats
=================
**Warning**
.. warning::
Pad-level formats are only applicable to very complex device that
Pad-level formats are only applicable to very complex devices that
need to expose low-level format configuration to user space. Generic
V4L2 applications do *not* need to use the API described in this
section.
**Note**
.. note::
For the purpose of this section, the term *format* means the
combination of media bus data format, frame width and frame height.

17
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@ -143,13 +143,16 @@ functions are always available.
To start and stop capturing or displaying applications call the
:ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` and
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctls. Note that
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` removes all buffers from
both queues and unlocks all buffers as a side effect. Since there is no
notion of doing anything "now" on a multitasking system, if an
application needs to synchronize with another event it should examine
the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or
outputted buffers.
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctls.
.. note::
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` removes all buffers from
both queues and unlocks all buffers as a side effect. Since there is no
notion of doing anything "now" on a multitasking system, if an
application needs to synchronize with another event it should examine
the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or
outputted buffers.
Drivers implementing DMABUF importing I/O must support the
:ref:`VIDIOC_REQBUFS <VIDIOC_REQBUFS>`, :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`,

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@ -84,17 +84,20 @@ themselves than is possible with
particular, this ioctl gives the dimensions of the N-dimensional array
if this control consists of more than one element.
It is important to realize that due to the flexibility of controls it is
necessary to check whether the control you want to set actually is
supported in the driver and what the valid range of values is. So use
the :ref:`VIDIOC_QUERYCTRL` (or
:ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>`) and
:ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>` ioctls to check this. Also
note that it is possible that some of the menu indices in a control of
type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
will return an error). A good example is the list of supported MPEG
audio bitrates. Some drivers only support one or two bitrates, others
support a wider range.
.. note::
#. It is important to realize that due to the flexibility of controls it is
necessary to check whether the control you want to set actually is
supported in the driver and what the valid range of values is. So use
the :ref:`VIDIOC_QUERYCTRL` (or :ref:`VIDIOC_QUERY_EXT_CTRL
<VIDIOC_QUERYCTRL>`) and :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>`
ioctls to check this.
#. It is possible that some of the menu indices in a control of
type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
will return an error). A good example is the list of supported MPEG
audio bitrates. Some drivers only support one or two bitrates, others
support a wider range.
All controls use machine endianness.
@ -181,10 +184,10 @@ Codec Control Reference
Below all controls within the Codec control class are described. First
the generic controls, then controls specific for certain hardware.
Note: These controls are applicable to all codecs and not just MPEG. The
defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
were originally made for MPEG codecs and later extended to cover all
encoding formats.
.. note:: These controls are applicable to all codecs and not just MPEG. The
defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
were originally made for MPEG codecs and later extended to cover all
encoding formats.
Generic Codec Controls
@ -2282,13 +2285,15 @@ MFC 5.1 Control IDs
``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
Reaction coefficient for MFC rate control. Applicable to encoders.
Note 1: Valid only when the frame level RC is enabled.
.. note::
Note 2: For tight CBR, this field must be small (ex. 2 ~ 10). For
VBR, this field must be large (ex. 100 ~ 1000).
#. Valid only when the frame level RC is enabled.
Note 3: It is not recommended to use the greater number than
FRAME_RATE * (10^9 / BIT_RATE).
#. For tight CBR, this field must be small (ex. 2 ~ 10). For
VBR, this field must be large (ex. 100 ~ 1000).
#. It is not recommended to use the greater number than
FRAME_RATE * (10^9 / BIT_RATE).
``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
Adaptive rate control for dark region. Valid only when H.264 and
@ -4107,14 +4112,16 @@ transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
the receiver or transmitter subdevice that implements them, so they are
only exposed on the ``/dev/v4l-subdev*`` device node.
Note that these devices can have multiple input or output pads which are
hooked up to e.g. HDMI connectors. Even though the subdevice will
receive or transmit video from/to only one of those pads, the other pads
can still be active when it comes to EDID (Extended Display
Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
Content Protection System, :ref:`hdcp`) processing, allowing the
device to do the fairly slow EDID/HDCP handling in advance. This allows
for quick switching between connectors.
.. note::
Note that these devices can have multiple input or output pads which are
hooked up to e.g. HDMI connectors. Even though the subdevice will
receive or transmit video from/to only one of those pads, the other pads
can still be active when it comes to EDID (Extended Display
Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
Content Protection System, :ref:`hdcp`) processing, allowing the
device to do the fairly slow EDID/HDCP handling in advance. This allows
for quick switching between connectors.
These pads appear in several of the controls in this section as
bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad

35
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@ -47,17 +47,20 @@ Arguments
Regardless of the device type and the direction of data exchange it
should be set to ``PROT_READ`` | ``PROT_WRITE``, permitting read
and write access to image buffers. Drivers should support at least
this combination of flags. Note the Linux ``video-buf`` kernel
module, which is used by the bttv, saa7134, saa7146, cx88 and vivi
driver supports only ``PROT_READ`` | ``PROT_WRITE``. When the
driver does not support the desired protection the
:ref:`mmap() <func-mmap>` function fails.
this combination of flags.
Note device memory accesses (e. g. the memory on a graphics card
with video capturing hardware) may incur a performance penalty
compared to main memory accesses, or reads may be significantly
slower than writes or vice versa. Other I/O methods may be more
efficient in this case.
.. note::
#. The Linux ``videobuf`` kernel module, which is used by some
drivers supports only ``PROT_READ`` | ``PROT_WRITE``. When the
driver does not support the desired protection, the
:ref:`mmap() <func-mmap>` function fails.
#. Device memory accesses (e. g. the memory on a graphics card
with video capturing hardware) may incur a performance penalty
compared to main memory accesses, or reads may be significantly
slower than writes or vice versa. Other I/O methods may be more
efficient in such case.
``flags``
The ``flags`` parameter specifies the type of the mapped object,
@ -73,11 +76,13 @@ Arguments
One of the ``MAP_SHARED`` or ``MAP_PRIVATE`` flags must be set.
``MAP_SHARED`` allows applications to share the mapped memory with
other (e. g. child-) processes. Note the Linux ``video-buf`` module
which is used by the bttv, saa7134, saa7146, cx88 and vivi driver
supports only ``MAP_SHARED``. ``MAP_PRIVATE`` requests copy-on-write
semantics. V4L2 applications should not set the ``MAP_PRIVATE``,
``MAP_DENYWRITE``, ``MAP_EXECUTABLE`` or ``MAP_ANON`` flag.
other (e. g. child-) processes.
.. note:: The Linux ``videobuf`` module which is used by some
drivers supports only ``MAP_SHARED``. ``MAP_PRIVATE`` requests
copy-on-write semantics. V4L2 applications should not set the
``MAP_PRIVATE``, ``MAP_DENYWRITE``, ``MAP_EXECUTABLE`` or ``MAP_ANON``
flags.
``fd``
File descriptor returned by :ref:`open() <func-open>`.

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@ -245,12 +245,14 @@ available. The :ref:`select() <func-select>` or :ref:`poll()
To start and stop capturing or output applications call the
:ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` and :ref:`VIDIOC_STREAMOFF
<VIDIOC_STREAMON>` ioctl. Note :ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>`
removes all buffers from both queues as a side effect. Since there is
no notion of doing anything "now" on a multitasking system, if an
application needs to synchronize with another event it should examine
the struct ::ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured
or outputted buffers.
<VIDIOC_STREAMON>` ioctl.
.. note:::ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>`
removes all buffers from both queues as a side effect. Since there is
no notion of doing anything "now" on a multitasking system, if an
application needs to synchronize with another event it should examine
the struct ::ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured
or outputted buffers.
Drivers implementing memory mapping I/O must support the
:ref:`VIDIOC_REQBUFS <VIDIOC_REQBUFS>`, :ref:`VIDIOC_QUERYBUF

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@ -17,9 +17,11 @@ identifier (enum :ref:`v4l2_quantization <v4l2-quantization>`) to
specify non-standard quantization methods. Most of the time only the
colorspace field of struct :ref:`v4l2_pix_format <v4l2-pix-format>`
or struct :ref:`v4l2_pix_format_mplane <v4l2-pix-format-mplane>`
needs to be filled in. Note that the default R'G'B' quantization is full
range for all colorspaces except for BT.2020 which uses limited range
R'G'B' quantization.
needs to be filled in.
.. note:: The default R'G'B' quantization is full range for all
colorspaces except for BT.2020 which uses limited range R'G'B'
quantization.
.. _v4l2-colorspace:

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@ -536,11 +536,13 @@ Colorspace DCI-P3 (V4L2_COLORSPACE_DCI_P3)
The :ref:`smpte431` standard defines the colorspace used by cinema
projectors that use the DCI-P3 colorspace. The default transfer function
is ``V4L2_XFER_FUNC_DCI_P3``. The default Y'CbCr encoding is
``V4L2_YCBCR_ENC_709``. Note that this colorspace does not specify a
Y'CbCr encoding since it is not meant to be encoded to Y'CbCr. So this
default Y'CbCr encoding was picked because it is the HDTV encoding. The
default Y'CbCr quantization is limited range. The chromaticities of the
primary colors and the white reference are:
``V4L2_YCBCR_ENC_709``.
.. note:: Note that this colorspace does not specify a
Y'CbCr encoding since it is not meant to be encoded to Y'CbCr. So this
default Y'CbCr encoding was picked because it is the HDTV encoding. The
default Y'CbCr quantization is limited range. The chromaticities of the
primary colors and the white reference are:
@ -752,10 +754,10 @@ reference are:
- 0.316
Note that this colorspace uses Illuminant C instead of D65 as the white
reference. To correctly convert an image in this colorspace to another
that uses D65 you need to apply a chromatic adaptation algorithm such as
the Bradford method.
.. note:: This colorspace uses Illuminant C instead of D65 as the white
reference. To correctly convert an image in this colorspace to another
that uses D65 you need to apply a chromatic adaptation algorithm such as
the Bradford method.
The transfer function was never properly defined for NTSC 1953. The Rec.
709 transfer function is recommended in the literature:
@ -886,9 +888,9 @@ reference are identical to sRGB. The transfer function use is
with full range quantization where Y' is scaled to [0…255] and Cb/Cr are
scaled to [-128…128] and then clipped to [-128…127].
Note that the JPEG standard does not actually store colorspace
information. So if something other than sRGB is used, then the driver
will have to set that information explicitly. Effectively
``V4L2_COLORSPACE_JPEG`` can be considered to be an abbreviation for
``V4L2_COLORSPACE_SRGB``, ``V4L2_YCBCR_ENC_601`` and
``V4L2_QUANTIZATION_FULL_RANGE``.
.. note:: The JPEG standard does not actually store colorspace
information. So if something other than sRGB is used, then the driver
will have to set that information explicitly. Effectively
``V4L2_COLORSPACE_JPEG`` can be considered to be an abbreviation for
``V4L2_COLORSPACE_SRGB``, ``V4L2_YCBCR_ENC_601`` and
``V4L2_QUANTIZATION_FULL_RANGE``.

7
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@ -17,9 +17,10 @@ Description
This format is similar to
:ref:`V4L2_PIX_FMT_SBGGR8 <V4L2-PIX-FMT-SBGGR8>`, except each pixel
has a depth of 16 bits. The least significant byte is stored at lower
memory addresses (little-endian). Note the actual sampling precision may
be lower than 16 bits, for example 10 bits per pixel with values in
range 0 to 1023.
memory addresses (little-endian).
..note:: The actual sampling precision may be lower than 16 bits,
for example 10 bits per pixel with values in tange 0 to 1023.
**Byte Order.**
Each cell is one byte.

7
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@ -15,9 +15,10 @@ Description
===========
This is a grey-scale image with a depth of 16 bits per pixel. The most
significant byte is stored at lower memory addresses (big-endian). Note
the actual sampling precision may be lower than 16 bits, for example 10
bits per pixel with values in range 0 to 1023.
significant byte is stored at lower memory addresses (big-endian).
.. note:: Tthe actual sampling precision may be lower than 16 bits, for
example 10 bits per pixel with values in range 0 to 1023.
**Byte Order.**
Each cell is one byte.

5
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@ -16,8 +16,9 @@ Description
This is a grey-scale image with a depth of 16 bits per pixel. The least
significant byte is stored at lower memory addresses (little-endian).
Note the actual sampling precision may be lower than 16 bits, for
example 10 bits per pixel with values in range 0 to 1023.
.. note:: The actual sampling precision may be lower than 16 bits, for
example 10 bits per pixel with values in range 0 to 1023.
**Byte Order.**
Each cell is one byte.

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@ -39,11 +39,12 @@ To query and select the standard used by the current video input or
output applications call the :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and
:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctl, respectively. The
*received* standard can be sensed with the
:ref:`VIDIOC_QUERYSTD` ioctl. Note that the
parameter of all these ioctls is a pointer to a
:ref:`v4l2_std_id <v4l2-std-id>` type (a standard set), *not* an
index into the standard enumeration. Drivers must implement all video
standard ioctls when the device has one or more video inputs or outputs.
:ref:`VIDIOC_QUERYSTD` ioctl.
..note:: The parameter of all these ioctls is a pointer to a
:ref:`v4l2_std_id <v4l2-std-id>` type (a standard set), *not* an
index into the standard enumeration. Drivers must implement all video
standard ioctls when the device has one or more video inputs or outputs.
Special rules apply to devices such as USB cameras where the notion of
video standards makes little sense. More generally for any capture or

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@ -26,13 +26,14 @@ To query and change tuner properties applications use the
:ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` ioctls, respectively. The
struct :ref:`v4l2_tuner <v4l2-tuner>` returned by :ref:`VIDIOC_G_TUNER <VIDIOC_G_TUNER>`
also contains signal status information applicable when the tuner of the
current video or radio input is queried. Note that :ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>`
does not switch the current tuner, when there is more than one at all.
The tuner is solely determined by the current video input. Drivers must
support both ioctls and set the ``V4L2_CAP_TUNER`` flag in the struct
:ref:`v4l2_capability <v4l2-capability>` returned by the
:ref:`VIDIOC_QUERYCAP` ioctl when the device has
one or more tuners.
current video or radio input is queried.
.. note:: :ref:`VIDIOC_S_TUNER <VIDIOC_G_TUNER>` does not switch the
current tuner, when there is more than one at all. The tuner is solely
determined by the current video input. Drivers must support both ioctls
and set the ``V4L2_CAP_TUNER`` flag in the struct :ref:`v4l2_capability
<v4l2-capability>` returned by the :ref:`VIDIOC_QUERYCAP` ioctl when the
device has one or more tuners.
Modulators

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@ -86,13 +86,14 @@ available.
To start and stop capturing or output applications call the
:ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>` and
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctl. Note
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` removes all buffers from both
queues and unlocks all buffers as a side effect. Since there is no
notion of doing anything "now" on a multitasking system, if an
application needs to synchronize with another event it should examine
the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or
outputted buffers.
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` ioctl.
.. note:: ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` removes all buffers from
both queues and unlocks all buffers as a side effect. Since there is no
notion of doing anything "now" on a multitasking system, if an
application needs to synchronize with another event it should examine
the struct :ref:`v4l2_buffer <v4l2-buffer>` ``timestamp`` of captured or
outputted buffers.
Drivers implementing user pointer I/O must support the
:ref:`VIDIOC_REQBUFS <VIDIOC_REQBUFS>`, :ref:`VIDIOC_QBUF <VIDIOC_QBUF>`,

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@ -33,7 +33,7 @@ Arguments
Description
===========
**Note**
.. note::
This is an :ref:`experimental` interface and may
change in the future.

2
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@ -35,7 +35,7 @@ Arguments
Description
===========
**Note**
.. note::
This is an :ref:`experimental` interface and may
change in the future.

6
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@ -37,8 +37,10 @@ To query the capabilities of the DV receiver/transmitter applications
initialize the ``pad`` field to 0, zero the reserved array of struct
:ref:`v4l2_dv_timings_cap <v4l2-dv-timings-cap>` and call the
``VIDIOC_DV_TIMINGS_CAP`` ioctl on a video node and the driver will fill
in the structure. Note that drivers may return different values after
switching the video input or output.
in the structure.
.. note:: Drivers may return different values after
switching the video input or output.
When implemented by the driver DV capabilities of subdevices can be
queried by calling the ``VIDIOC_SUBDEV_DV_TIMINGS_CAP`` ioctl directly

6
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@ -47,8 +47,10 @@ field, set the ``pad`` field to 0, zero the reserved array of struct
structure. Drivers fill the rest of the structure or return an ``EINVAL``
error code when the index is out of bounds. To enumerate all supported
DV timings, applications shall begin at index zero, incrementing by one
until the driver returns ``EINVAL``. Note that drivers may enumerate a
different set of DV timings after switching the video input or output.
until the driver returns ``EINVAL``.
.. note:: Drivers may enumerate a different set of DV timings after
switching the video input or output.
When implemented by the driver DV timings of subdevices can be queried
by calling the ``VIDIOC_SUBDEV_ENUM_DV_TIMINGS`` ioctl directly on a

10
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@ -40,8 +40,8 @@ fill the rest of the structure or return an ``EINVAL`` error code. All
formats are enumerable by beginning at index zero and incrementing by
one until ``EINVAL`` is returned.
Note that after switching input or output the list of enumerated image
formats may be different.
.. note:: After switching input or output the list of enumerated image
formats may be different.
.. _v4l2-fmtdesc:
@ -111,8 +111,10 @@ formats may be different.
#define v4l2_fourcc(a,b,c,d) (((__u32)(a)<<0)|((__u32)(b)<<8)|((__u32)(c)<<16)|((__u32)(d)<<24))
Several image formats are already defined by this specification in
:ref:`pixfmt`. Note these codes are not the same as those used
in the Windows world.
:ref:`pixfmt`.
.. attention:: These codes are not the same as those used
in the Windows world.
- .. row 7

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@ -73,25 +73,21 @@ the device supports. Only for the ``V4L2_FRMIVAL_TYPE_DISCRETE`` type
does it make sense to increase the index value to receive more frame
intervals.
Note that the order in which the frame intervals are returned has no
special meaning. In particular does it not say anything about potential
default frame intervals.
.. note:: The order in which the frame intervals are returned has no
special meaning. In particular does it not say anything about potential
default frame intervals.
Applications can assume that the enumeration data does not change
without any interaction from the application itself. This means that the
enumeration data is consistent if the application does not perform any
other ioctl calls while it runs the frame interval enumeration.
.. note::
Notes
=====
- **Frame intervals and frame rates:** The V4L2 API uses frame
**Frame intervals and frame rates:** The V4L2 API uses frame
intervals instead of frame rates. Given the frame interval the frame
rate can be computed as follows:
::
frame_rate = 1 / frame_interval

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@ -72,9 +72,9 @@ the ``type`` field to determine the type of frame size enumeration the
device supports. Only for the ``V4L2_FRMSIZE_TYPE_DISCRETE`` type does
it make sense to increase the index value to receive more frame sizes.
Note that the order in which the frame sizes are returned has no special
meaning. In particular does it not say anything about potential default
format sizes.
.. note:: The order in which the frame sizes are returned has no special
meaning. In particular does it not say anything about potential default
format sizes.
Applications can assume that the enumeration data does not change
without any interaction from the application itself. This means that the

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@ -127,12 +127,14 @@ of the corresponding tuner/modulator is set.
- ``modulation``
- :cspan:`2` The supported modulation systems of this frequency
band. See :ref:`band-modulation`. Note that currently only one
modulation system per frequency band is supported. More work will
need to be done if multiple modulation systems are possible.
Contact the linux-media mailing list
(`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__)
if you need that functionality.
band. See :ref:`band-modulation`.
.. note:: Currently only one modulation system per frequency band
is supported. More work will need to be done if multiple
modulation systems are possible. Contact the linux-media
mailing list
(`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__)
if you need such functionality.
- .. row 8

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@ -41,8 +41,8 @@ structure or return an ``EINVAL`` error code when the index is out of
bounds. To enumerate all audio outputs applications shall begin at index
zero, incrementing by one until the driver returns ``EINVAL``.
Note connectors on a TV card to loop back the received audio signal to a
sound card are not audio outputs in this sense.
.. note:: Connectors on a TV card to loop back the received audio signal
to a sound card are not audio outputs in this sense.
See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct
:ref:`v4l2_audioout <v4l2-audioout>`.

4
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@ -233,8 +233,8 @@ at index zero, incrementing by one until the driver returns ``EINVAL``.
- The input is connected to a device that produces a signal that is
flipped vertically and does not correct this before passing the
signal to userspace. Note that a 180 degree rotation is the same
as HFLIP | VFLIP
signal to userspace.
.. note:: A 180 degree rotation is the same as HFLIP | VFLIP
- .. row 8

4
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@ -51,8 +51,8 @@ return the ``EINVAL`` error code when the index is out of bounds. This is a
write-only ioctl, it does not return the current audio output attributes
as ``VIDIOC_G_AUDOUT`` does.
Note connectors on a TV card to loop back the received audio signal to a
sound card are not audio outputs in this sense.
.. note:: Connectors on a TV card to loop back the received audio signal
to a sound card are not audio outputs in this sense.
.. _v4l2-audioout:

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@ -65,8 +65,10 @@ If ``start_block`` and ``blocks`` are both set to 0 when
:ref:`VIDIOC_G_EDID <VIDIOC_G_EDID>` is called, then the driver will set ``blocks`` to the
total number of available EDID blocks and it will return 0 without
copying any data. This is an easy way to discover how many EDID blocks
there are. Note that if there are no EDID blocks available at all, then
the driver will set ``blocks`` to 0 and it returns 0.
there are.
.. note:: If there are no EDID blocks available at all, then
the driver will set ``blocks`` to 0 and it returns 0.
To set the EDID blocks of a receiver the application has to fill in the
``pad``, ``blocks`` and ``edid`` fields, set ``start_block`` to 0 and

16
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@ -125,10 +125,12 @@ still cause this situation.
the payload. If :ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` finds that this value is
less than is required to store the payload result, then it is set
to a value large enough to store the payload result and ``ENOSPC`` is
returned. Note that for string controls this ``size`` field should
not be confused with the length of the string. This field refers
to the size of the memory that contains the string. The actual
*length* of the string may well be much smaller.
returned.
.. note:: For string controls, this ``size`` field should
not be confused with the length of the string. This field refers
to the size of the memory that contains the string. The actual
*length* of the string may well be much smaller.
- .. row 3
@ -261,8 +263,10 @@ still cause this situation.
- Which value of the control to get/set/try.
``V4L2_CTRL_WHICH_CUR_VAL`` will return the current value of the
control and ``V4L2_CTRL_WHICH_DEF_VAL`` will return the default
value of the control. Please note that you can only get the
default value of the control, you cannot set or try it.
value of the control.
.. note:: You can only get the default value of the control,
you cannot set or try it.
For backwards compatibility you can also use a control class here
(see :ref:`ctrl-class`). In that case all controls have to

14
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@ -128,12 +128,14 @@ To change the radio frequency the
- With this field applications can determine how audio sub-carriers
shall be modulated. It contains a set of flags as defined in
:ref:`modulator-txsubchans`. Note the tuner ``rxsubchans`` flags
are reused, but the semantics are different. Video output devices
are assumed to have an analog or PCM audio input with 1-3
channels. The ``txsubchans`` flags select one or more channels for
modulation, together with some audio subprogram indicator, for
example a stereo pilot tone.
:ref:`modulator-txsubchans`.
.. note:: The tuner ``rxsubchans`` flags are reused, but the
semantics are different. Video output devices
are assumed to have an analog or PCM audio input with 1-3
channels. The ``txsubchans`` flags select one or more channels
for modulation, together with some audio subprogram indicator,
for example, a stereo pilot tone.
- .. row 7

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@ -40,8 +40,8 @@ output device, applications initialize the ``type`` field of a struct
driver fills in the remaining fields or returns an ``EINVAL`` error code if
the sliced VBI API is unsupported or ``type`` is invalid.
Note the ``type`` field was added, and the ioctl changed from read-only
to write-read, in Linux 2.6.19.
.. note:: The ``type`` field was added, and the ioctl changed from read-only
to write-read, in Linux 2.6.19.
.. _v4l2-sliced-vbi-cap:

22
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@ -391,9 +391,9 @@ To change the radio frequency the
carrier for a monaural secondary language. Only
``V4L2_TUNER_ANALOG_TV`` tuners can have this capability.
Note the ``V4L2_TUNER_CAP_LANG2`` and ``V4L2_TUNER_CAP_SAP`` flags
are synonyms. ``V4L2_TUNER_CAP_SAP`` applies when the tuner
supports the ``V4L2_STD_NTSC_M`` video standard.
.. note:: The ``V4L2_TUNER_CAP_LANG2`` and ``V4L2_TUNER_CAP_SAP``
flags are synonyms. ``V4L2_TUNER_CAP_SAP`` applies when the tuner
supports the ``V4L2_STD_NTSC_M`` video standard.
- .. row 9
@ -500,10 +500,11 @@ To change the radio frequency the
- 0x0004
- The tuner receives a Second Audio Program. Note the
``V4L2_TUNER_SUB_LANG2`` and ``V4L2_TUNER_SUB_SAP`` flags are
synonyms. The ``V4L2_TUNER_SUB_SAP`` flag applies when the current
video standard is ``V4L2_STD_NTSC_M``.
- The tuner receives a Second Audio Program.
.. note:: The ``V4L2_TUNER_SUB_LANG2`` and ``V4L2_TUNER_SUB_SAP``
flags are synonyms. The ``V4L2_TUNER_SUB_SAP`` flag applies
when the current video standard is ``V4L2_STD_NTSC_M``.
- .. row 6
@ -578,9 +579,10 @@ To change the radio frequency the
- Play the Second Audio Program. When the tuner receives no
bilingual audio or SAP, or their reception is not supported the
driver shall fall back to mono or stereo mode. Only
``V4L2_TUNER_ANALOG_TV`` tuners support this mode. Note the
``V4L2_TUNER_MODE_LANG2`` and ``V4L2_TUNER_MODE_SAP`` are
synonyms.
``V4L2_TUNER_ANALOG_TV`` tuners support this mode.
.. note:: The ``V4L2_TUNER_MODE_LANG2`` and ``V4L2_TUNER_MODE_SAP``
are synonyms.
- .. row 6

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@ -135,14 +135,15 @@ EINVAL
EIO
``VIDIOC_DQBUF`` failed due to an internal error. Can also indicate
temporary problems like signal loss. Note the driver might dequeue
an (empty) buffer despite returning an error, or even stop
capturing. Reusing such buffer may be unsafe though and its details
(e.g. ``index``) may not be returned either. It is recommended that
drivers indicate recoverable errors by setting the
``V4L2_BUF_FLAG_ERROR`` and returning 0 instead. In that case the
application should be able to safely reuse the buffer and continue
streaming.
temporary problems like signal loss.
.. note:: The driver might dequeue an (empty) buffer despite returning
an error, or even stop capturing. Reusing such buffer may be unsafe
though and its details (e.g. ``index``) may not be returned either.
It is recommended that drivers indicate recoverable errors by setting
the ``V4L2_BUF_FLAG_ERROR`` and returning 0 instead. In that case the
application should be able to safely reuse the buffer and continue
streaming.
EPIPE
``VIDIOC_DQBUF`` returns this on an empty capture queue for mem2mem

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@ -39,16 +39,16 @@ similar to sensing the video standard. To do so, applications call
:ref:`v4l2_dv_timings <v4l2-dv-timings>`. Once the hardware detects
the timings, it will fill in the timings structure.
Please note that drivers shall *not* switch timings automatically if new
timings are detected. Instead, drivers should send the
``V4L2_EVENT_SOURCE_CHANGE`` event (if they support this) and expect
that userspace will take action by calling :ref:`VIDIOC_QUERY_DV_TIMINGS`.
The reason is that new timings usually mean different buffer sizes as
well, and you cannot change buffer sizes on the fly. In general,
applications that receive the Source Change event will have to call
:ref:`VIDIOC_QUERY_DV_TIMINGS`, and if the detected timings are valid they
will have to stop streaming, set the new timings, allocate new buffers
and start streaming again.
.. note:: Drivers shall *not* switch timings automatically if new
timings are detected. Instead, drivers should send the
``V4L2_EVENT_SOURCE_CHANGE`` event (if they support this) and expect
that userspace will take action by calling :ref:`VIDIOC_QUERY_DV_TIMINGS`.
The reason is that new timings usually mean different buffer sizes as
well, and you cannot change buffer sizes on the fly. In general,
applications that receive the Source Change event will have to call
:ref:`VIDIOC_QUERY_DV_TIMINGS`, and if the detected timings are valid they
will have to stop streaming, set the new timings, allocate new buffers
and start streaming again.
If the timings could not be detected because there was no signal, then
ENOLINK is returned. If a signal was detected, but it was unstable and

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@ -82,10 +82,12 @@ fills the rest of the structure or returns an ``EINVAL`` error code when the
``id`` or ``index`` is invalid. Menu items are enumerated by calling
``VIDIOC_QUERYMENU`` with successive ``index`` values from struct
:ref:`v4l2_queryctrl <v4l2-queryctrl>` ``minimum`` to ``maximum``,
inclusive. Note that it is possible for ``VIDIOC_QUERYMENU`` to return
an ``EINVAL`` error code for some indices between ``minimum`` and
``maximum``. In that case that particular menu item is not supported by
this driver. Also note that the ``minimum`` value is not necessarily 0.
inclusive.
.. note:: It is possible for ``VIDIOC_QUERYMENU`` to return
an ``EINVAL`` error code for some indices between ``minimum`` and
``maximum``. In that case that particular menu item is not supported by
this driver. Also note that the ``minimum`` value is not necessarily 0.
See also the examples in :ref:`control`.
@ -184,9 +186,10 @@ See also the examples in :ref:`control`.
- The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_BOOLEAN``,
``_BITMASK``, ``_MENU`` or ``_INTEGER_MENU`` control. Not valid
for other types of controls. Note that drivers reset controls to
their default value only when the driver is first loaded, never
afterwards.
for other types of controls.
.. note:: Drivers reset controls to their default value only when
the driver is first loaded, never afterwards.
- .. row 8
@ -301,9 +304,10 @@ See also the examples in :ref:`control`.
- The default value of a ``V4L2_CTRL_TYPE_INTEGER``, ``_INTEGER64``,
``_BOOLEAN``, ``_BITMASK``, ``_MENU``, ``_INTEGER_MENU``, ``_U8``
or ``_U16`` control. Not valid for other types of controls. Note
that drivers reset controls to their default value only when the
driver is first loaded, never afterwards.
or ``_U16`` control. Not valid for other types of controls.
.. note:: Drivers reset controls to their default value only when
the driver is first loaded, never afterwards.
- .. row 8
@ -722,11 +726,12 @@ See also the examples in :ref:`control`.
control changes continuously. A typical example would be the
current gain value if the device is in auto-gain mode. In such a
case the hardware calculates the gain value based on the lighting
conditions which can change over time. Note that setting a new
value for a volatile control will have no effect and no
``V4L2_EVENT_CTRL_CH_VALUE`` will be sent, unless the
``V4L2_CTRL_FLAG_EXECUTE_ON_WRITE`` flag (see below) is also set.
Otherwise the new value will just be ignored.
conditions which can change over time.
.. note:: Setting a new value for a volatile control will have no
effect and no ``V4L2_EVENT_CTRL_CH_VALUE`` will be sent, unless
the ``V4L2_CTRL_FLAG_EXECUTE_ON_WRITE`` flag (see below) is
also set. Otherwise the new value will just be ignored.
- .. row 9

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@ -43,16 +43,16 @@ will return V4L2_STD_UNKNOWN. When detection is not possible or fails,
the set must contain all standards supported by the current video input
or output.
Please note that drivers shall *not* switch the video standard
automatically if a new video standard is detected. Instead, drivers
should send the ``V4L2_EVENT_SOURCE_CHANGE`` event (if they support
this) and expect that userspace will take action by calling
:ref:`VIDIOC_QUERYSTD`. The reason is that a new video standard can mean
different buffer sizes as well, and you cannot change buffer sizes on
the fly. In general, applications that receive the Source Change event
will have to call :ref:`VIDIOC_QUERYSTD`, and if the detected video
standard is valid they will have to stop streaming, set the new
standard, allocate new buffers and start streaming again.
.. note:: Drivers shall *not* switch the video standard
automatically if a new video standard is detected. Instead, drivers
should send the ``V4L2_EVENT_SOURCE_CHANGE`` event (if they support
this) and expect that userspace will take action by calling
:ref:`VIDIOC_QUERYSTD`. The reason is that a new video standard can mean
different buffer sizes as well, and you cannot change buffer sizes on
the fly. In general, applications that receive the Source Change event
will have to call :ref:`VIDIOC_QUERYSTD`, and if the detected video
standard is valid they will have to stop streaming, set the new
standard, allocate new buffers and start streaming again.
Return Value

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@ -76,10 +76,10 @@ then 0 is returned. Nothing happens in the case of ``VIDIOC_STREAMON``,
but ``VIDIOC_STREAMOFF`` will return queued buffers to their starting
state as mentioned above.
Note that applications can be preempted for unknown periods right before
or after the ``VIDIOC_STREAMON`` or ``VIDIOC_STREAMOFF`` calls, there is
no notion of starting or stopping "now". Buffer timestamps can be used
to synchronize with other events.
.. note:: Applications can be preempted for unknown periods right before
or after the ``VIDIOC_STREAMON`` or ``VIDIOC_STREAMOFF`` calls, there is
no notion of starting or stopping "now". Buffer timestamps can be used
to synchronize with other events.
Return Value

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@ -35,7 +35,7 @@ Arguments
Description
===========
**Note**
.. note::
This is an :ref:`obsolete` interface and may be removed
in the future. It is superseded by

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@ -51,9 +51,11 @@ using the :ref:`VIDIOC_DQEVENT` ioctl.
- ``type``
- Type of the event, see :ref:`event-type`. Note that
``V4L2_EVENT_ALL`` can be used with VIDIOC_UNSUBSCRIBE_EVENT for
unsubscribing all events at once.
- Type of the event, see :ref:`event-type`.
.. note:: ``V4L2_EVENT_ALL`` can be used with
:ref:`VIDIOC_UNSUBSCRIBE_EVENT` for unsubscribing all events
at once.
- .. row 2