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sstvdec
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Made image data decode functions more legible

master
colaclanth 2019-07-15 22:38:21 +01:00
parent eac609d300
commit 002f42f850
1 changed files with 23 additions and 21 deletions
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sstv/decode.py
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@ -222,24 +222,21 @@ class SSTVDecoder(object):
"""Decodes image from the transmission section of an sstv signal"""
window_factor = self.mode.WINDOW_FACTOR
pixel_window = round(self.mode.PIXEL_TIME * window_factor *
self._sample_rate)
centre_window_time = (self.mode.PIXEL_TIME * window_factor) / 2
pixel_window = round(centre_window_time * 2 * self._sample_rate)
image_data = []
seq_start = 0
if self.mode.HAS_START_SYNC:
# Start at the end of the initial sync pulse
seq_start = self._align_sync(transmission, start_of_sync=False)
else:
seq_start = 0
for line in range(self.mode.LINE_COUNT):
image_data.append([])
if self.mode.CHAN_SYNC > 0 and line == 0:
# align seq_start to the beginning of the previous sync pulse
# Align seq_start to the beginning of the previous sync pulse
sync_offset = self.mode.CHAN_OFFSETS[self.mode.CHAN_SYNC]
seq_start -= round((sync_offset + self.mode.SCAN_TIME)
* self._sample_rate)
@ -249,20 +246,22 @@ class SSTVDecoder(object):
if chan == self.mode.CHAN_SYNC:
if line > 0 or chan > 0:
# Set base offset to the next line
seq_start += round(self.mode.LINE_TIME *
self._sample_rate)
# align to start of sync pulse
# Align to start of sync pulse
seq_start += self._align_sync(transmission[seq_start:])
pixel_time = self.mode.PIXEL_TIME
if self.mode.HAS_MERGE_SCAN:
# Robot mode has half-length second scan
if chan % 2 == 1:
pixel_time = self.mode.MERGE_PIXEL_TIME
pixel_window = round(pixel_time * window_factor *
self._sample_rate)
centre_window_time = (pixel_time * window_factor) / 2
pixel_window = round(centre_window_time * 2 *
self._sample_rate)
for px in range(self.mode.LINE_WIDTH):
@ -271,15 +270,13 @@ class SSTVDecoder(object):
px_sample = round(seq_start + (chan_offset + px *
pixel_time - centre_window_time) *
self._sample_rate)
section = transmission[px_sample:px_sample+pixel_window]
freq = self._peak_fft_freq(section)
pixel_area = transmission[px_sample:px_sample+pixel_window]
freq = self._peak_fft_freq(pixel_area)
image_data[line][chan].append(SSTVDecoder._calc_lum(freq))
progress_bar(line, self.mode.LINE_COUNT - 1,
"Decoding image... ", self.log_basic)
progress_bar(line, self.mode.LINE_COUNT - 1, "Decoding image... ")
log_message("...Done!")
return image_data
def _draw_image(self, image_data):
@ -290,30 +287,35 @@ class SSTVDecoder(object):
else:
col_mode = "RGB"
image = Image.new(col_mode,
(self.mode.LINE_WIDTH, self.mode.LINE_COUNT))
width = self.mode.LINE_WIDTH
height = self.mode.LINE_COUNT
image = Image.new(col_mode, (width, height))
pixel_data = image.load()
for y in range(self.mode.LINE_COUNT):
ryby = y % 2
log_message("Drawing image data...")
for x in range(self.mode.LINE_WIDTH):
for y in range(height):
odd_line = y % 2
for x in range(width):
if self.mode.COLOR == spec.COL_FMT.GBR:
pixel = (image_data[y][2][x],
image_data[y][0][x],
image_data[y][1][x])
elif self.mode.COLOR == spec.COL_FMT.YUV:
pixel = (image_data[y][0][x],
image_data[y-ryby][1][x],
image_data[y-(ryby-1)][1][x])
image_data[y-odd_line][1][x],
image_data[y-(odd_line-1)][1][x])
else:
pixel = (image_data[y][0][x],
image_data[y][1][x],
image_data[y][2][x])
pixel_data[x, y] = pixel
if self.mode.COLOR == spec.COL_FMT.YUV:
image = image.convert("RGB")
log_message("...Done!")
return image