[media] doc: v4l: selection: choose pixels as units for selection rectangles
Pixels were preferred units for selection rectangles over driver-dependent units for almost all use cases. Therefore the units were fixed to pixels. Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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@ -84,9 +84,7 @@ configure the cropping targets before to the composing targets.</para>
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areas that can be sampled is given by the <constant> V4L2_SEL_TGT_CROP_BOUNDS
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areas that can be sampled is given by the <constant> V4L2_SEL_TGT_CROP_BOUNDS
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</constant> target. It is recommended for the driver developers to put the
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</constant> target. It is recommended for the driver developers to put the
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top/left corner at position <constant> (0,0) </constant>. The rectangle's
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top/left corner at position <constant> (0,0) </constant>. The rectangle's
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coordinates are expressed in driver dependant units, although the coordinate
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coordinates are expressed in pixels.</para>
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system guarantees that if sizes of the active cropping and the active composing
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rectangles are equal then no scaling is performed. </para>
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<para>The top left corner, width and height of the source rectangle, that is
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<para>The top left corner, width and height of the source rectangle, that is
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the area actually sampled, is given by the <constant> V4L2_SEL_TGT_CROP_ACTIVE
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the area actually sampled, is given by the <constant> V4L2_SEL_TGT_CROP_ACTIVE
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@ -103,10 +101,10 @@ not later.</para>
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<para>The composing targets refer to a memory buffer. The limits of composing
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<para>The composing targets refer to a memory buffer. The limits of composing
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coordinates are obtained using <constant> V4L2_SEL_TGT_COMPOSE_BOUNDS
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coordinates are obtained using <constant> V4L2_SEL_TGT_COMPOSE_BOUNDS
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</constant>. All coordinates are expressed in natural unit for given formats.
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</constant>. All coordinates are expressed in pixels. The rectangle's top/left
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Pixels are highly recommended. The rectangle's top/left corner must be located
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corner must be located at position <constant> (0,0) </constant>. The width and
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at position <constant> (0,0) </constant>. The width and height are equal to the
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height are equal to the image size set by <constant> VIDIOC_S_FMT </constant>.
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image size set by <constant> VIDIOC_S_FMT </constant>.</para>
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</para>
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<para>The part of a buffer into which the image is inserted by the hardware is
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<para>The part of a buffer into which the image is inserted by the hardware is
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controlled by the <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target.
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controlled by the <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target.
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@ -145,10 +143,9 @@ the cropping targets.</para>
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<para>The cropping targets refer to the memory buffer that contains an image to
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<para>The cropping targets refer to the memory buffer that contains an image to
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be inserted into a video signal or graphical screen. The limits of cropping
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be inserted into a video signal or graphical screen. The limits of cropping
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coordinates are obtained using <constant> V4L2_SEL_TGT_CROP_BOUNDS </constant>.
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coordinates are obtained using <constant> V4L2_SEL_TGT_CROP_BOUNDS </constant>.
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All coordinates are expressed in natural units for a given format. Pixels are
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All coordinates are expressed in pixels. The top/left corner is always point
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highly recommended. The top/left corner is always point <constant> (0,0)
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<constant> (0,0) </constant>. The width and height is equal to the image size
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</constant>. The width and height is equal to the image size specified using
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specified using <constant> VIDIOC_S_FMT </constant> ioctl.</para>
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<constant> VIDIOC_S_FMT </constant> ioctl.</para>
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<para>The top left corner, width and height of the source rectangle, that is
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<para>The top left corner, width and height of the source rectangle, that is
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the area from which image date are processed by the hardware, is given by the
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the area from which image date are processed by the hardware, is given by the
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@ -163,13 +160,10 @@ limitations.</para>
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bounding rectangle.</para>
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bounding rectangle.</para>
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<para>The part of a video signal or graphics display where the image is
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<para>The part of a video signal or graphics display where the image is
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inserted by the hardware is controlled by <constant> V4L2_SEL_TGT_COMPOSE_ACTIVE
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inserted by the hardware is controlled by <constant>
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</constant> target. The rectangle's coordinates are expressed in driver
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V4L2_SEL_TGT_COMPOSE_ACTIVE </constant> target. The rectangle's coordinates
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dependant units. The only exception are digital outputs where the units are
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are expressed in pixels. The composing rectangle must lie completely inside the
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pixels. For other types of devices, the coordinate system guarantees that if
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bounds rectangle. The driver must adjust the area to fit to the bounding
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sizes of the active cropping and the active composing rectangles are equal then
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no scaling is performed. The composing rectangle must lie completely inside
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the bounds rectangle. The driver must adjust the area to fit to the bounding
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limits. Moreover, the driver can perform other adjustments according to
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limits. Moreover, the driver can perform other adjustments according to
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hardware limitations. </para>
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hardware limitations. </para>
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