[FFmpeg-trac] #7686(avfilter:new): Wrong decision of pixel format in filtergraph

[FFmpeg]

#7686: Wrong decision of pixel format in filtergraph
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             Reporter:  mfcc64      |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avfilter
              Version:  git-master  |               Resolution:
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by mfcc64):

 A more severe example

 {{{
 % ffmpeg -loglevel verbose -filter_complex "aevalsrc=0:d=0.1, showcqt,
 format=bgr24" -f null -

 [Parsed_showcqt_1 @ 0xe63ec0] auto-inserting filter 'auto_resampler_0'
 between the filter 'Parsed_aevalsrc_0' and the filter 'Parsed_showcqt_1'
 [auto_scaler_0 @ 0xe67980] w:iw h:ih flags:'bilinear' interl:0
 [Parsed_format_2 @ 0xe64f80] auto-inserting filter 'auto_scaler_0' between
 the filter 'Parsed_showcqt_1' and the filter 'Parsed_format_2'
 [Parsed_aevalsrc_0 @ 0xe634c0] sample_rate:44100 chlayout:mono
 duration:100000
 [auto_resampler_0 @ 0xe67b80] ch:1 chl:mono fmt:dblp r:44100Hz -> ch:2
 chl:stereo fmt:flt r:44100Hz
 [Parsed_showcqt_1 @ 0xe63ec0] video: 1920x1080 yuv420p 25/1 fps, bar_h =
 524, axis_h = 32, sono_h = 524.
 [Parsed_showcqt_1 @ 0xe63ec0] fft_len = 8192, cqt_len = 1920.
 [Parsed_showcqt_1 @ 0xe63ec0] nb_cqt_coeffs = 44508.
 [Parsed_showcqt_1 @ 0xe63ec0] audio: 44100 Hz, step = 294.
 [auto_scaler_0 @ 0xe67980] w:1920 h:1080 fmt:yuv420p sar:1/1 -> w:1920
 h:1080 fmt:bgr24 sar:1/1 flags:0x2
 }}}

 While showcqt actually supports rgb24, the filtergraph chooses yuv420p ->
 bgr24 rather than rgb24 -> bgr24. This is a problem because supported
 pixel/sample format is currently undocumented in filters' documentation.
 If it is documented, a user for example can carefully insert format=rgb24
 before format=bgr24.

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Ticket URL: <https://trac.ffmpeg.org/ticket/7686#comment:2>
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