[FFmpeg-trac] #7613(avfilter:new): Change in bayer dithering output in paletteuse

[FFmpeg]

#7613: Change in bayer dithering output in paletteuse
--------------------------------------+------------------------------------
               Reporter:  llogan      |                  Owner:
                   Type:  defect      |                 Status:  new
               Priority:  normal      |              Component:  avfilter
                Version:  git-master  |               Keywords:  paletteuse
             Blocked By:              |               Blocking:
Reproduced by developer:  0           |  Analyzed by developer:  0
--------------------------------------+------------------------------------
 aba926e7d654b6dfab680130c92e571ee9a956f0 changed the output when using
 `dither=bayer:bayer_scale=0`. Other `bayer_scale` values and dithering
 modes appear not to be affected.

 Create palette:
 {{{
 $ ffmpeg -i ../fate-suite/h264/lossless.h264 -filter_complex palettegen
 palette.png
 ffmpeg version N-92681-g0e833f615b Copyright (c) 2000-2018 the FFmpeg
 developers
   built with gcc 8.2.1 (GCC) 20181127
   configuration:
   libavutil      56. 24.101 / 56. 24.101
   libavcodec     58. 42.100 / 58. 42.100
   libavformat    58. 24.100 / 58. 24.100
   libavdevice    58.  6.101 / 58.  6.101
   libavfilter     7. 46.101 /  7. 46.101
   libswscale      5.  4.100 /  5.  4.100
   libswresample   3.  4.100 /  3.  4.100
 Input #0, h264, from '../fate-suite/h264/lossless.h264':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: h264 (High 4:4:4 Predictive),
 yuv420p(progressive), 640x480, 60 fps, 60 tbr, 1200k tbn, 120 tbc
 Stream mapping:
   Stream #0:0 (h264) -> palettegen
   palettegen -> Stream #0:0 (png)
 Press [q] to stop, [?] for help
 Output #0, image2, to 'palette.png':
   Metadata:
     encoder         : Lavf58.24.100
     Stream #0:0: Video: png, rgba, 16x16 [SAR 1:1 DAR 1:1], q=2-31, 200
 kb/s, 60 fps, 60 tbn, 60 tbc
     Metadata:
       encoder         : Lavc58.42.100 png
 [Parsed_palettegen_0 @ 0x557cb7bab3c0] 255(+1) colors generated out of
 75404 colors; ratio=0.003382
 frame=    1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.01 bitrate=N/A
 speed=0.127x
 video:1kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 }}}

 Create GIF:
 {{{
 ffmpeg -i ../fate-suite/h264/lossless.h264 -i palette.png -filter_complex
 paletteuse=dither=bayer:bayer_scale=0 output.gif
 ffmpeg version N-92681-g0e833f615b Copyright (c) 2000-2018 the FFmpeg
 developers
   built with gcc 8.2.1 (GCC) 20181127
   configuration:
   libavutil      56. 24.101 / 56. 24.101
   libavcodec     58. 42.100 / 58. 42.100
   libavformat    58. 24.100 / 58. 24.100
   libavdevice    58.  6.101 / 58.  6.101
   libavfilter     7. 46.101 /  7. 46.101
   libswscale      5.  4.100 /  5.  4.100
   libswresample   3.  4.100 /  3.  4.100
 Input #0, h264, from '../fate-suite/h264/lossless.h264':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: h264 (High 4:4:4 Predictive),
 yuv420p(progressive), 640x480, 60 fps, 60 tbr, 1200k tbn, 120 tbc
 Input #1, png_pipe, from 'palette.png':
   Duration: N/A, bitrate: N/A
     Stream #1:0: Video: png, rgba(pc), 16x16 [SAR 1:1 DAR 1:1], 25 tbr, 25
 tbn, 25 tbc
 Stream mapping:
   Stream #0:0 (h264) -> paletteuse:default
   Stream #1:0 (png) -> paletteuse:palette
   paletteuse -> Stream #0:0 (gif)
 Press [q] to stop, [?] for help
 Output #0, gif, to 'output.gif':
   Metadata:
     encoder         : Lavf58.24.100
     Stream #0:0: Video: gif, pal8, 640x480, q=2-31, 200 kb/s, 60 fps, 100
 tbn, 60 tbc (default)
     Metadata:
       encoder         : Lavc58.42.100 gif
 frame=   10 fps=0.0 q=-0.0 Lsize=    1120kB time=00:00:00.18
 bitrate=50983.6kbits/s speed=0.542x
 video:1119kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 0.076859%
 }}}

 Compare hashes:
 {{{
 $ ./ffmpeg -v error -i output-master.gif -f hash -hash md5 -
 MD5=ab06399b69365047f68745fb6dc22a94

 $ ./ffmpeg -v error -i output-8518294.gif -f hash -hash md5 -
 MD5=52047bc0e9a4a6961127832844f925cc
 }}}

 Change is visually obvious. Reported by user Mithgol.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7613>
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