[FFmpeg-trac] #4542(undetermined:new): vc1 gray decoding produces artefacts

[FFmpeg]

#4542: vc1 gray decoding produces artefacts
-------------------------------------+-------------------------------------
               Reporter:  cehoyos    |                  Owner:
                   Type:  defect     |                 Status:  new
               Priority:  normal     |              Component:
                Version:  git-       |  undetermined
  master                             |               Keywords:  vc1 gray
             Blocked By:             |  regression
Reproduced by developer:  0          |               Blocking:
                                     |  Analyzed by developer:  0
-------------------------------------+-------------------------------------
 The following produces ugly artefacts since
 e5c3b51cd1ba5167ac224c41b905928f1bd0eb8d
 {{{
 $ ffmpeg -flags +gray -i fate-suite/vc1/SA00040.vc1 -qscale 2 out.avi
 ffmpeg version N-71990-gc97d30f Copyright (c) 2000-2015 the FFmpeg
 developers
   built with gcc 4.7 (SUSE Linux)
   configuration: --enable-gpl --enable-gray
   libavutil      54. 23.101 / 54. 23.101
   libavcodec     56. 38.100 / 56. 38.100
   libavformat    56. 32.100 / 56. 32.100
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 16.101 /  5. 16.101
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  1.100 /  1.  1.100
   libpostproc    53.  3.100 / 53.  3.100
 [vc1 @ 0x2e5b380] Failed to open codec in av_find_stream_info
 [NULL @ 0x2e5bda0] ignoring invalid SAR: 0/0
 Input #0, vc1, from 'fate-suite/vc1/SA00040.vc1':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: vc1 (Advanced), yuv420p, 176x144 [SAR 1:1 DAR
 11:9], 25 tbr, 1200k tbn, 25 tbc
 Please use -q:a or -q:v, -qscale is ambiguous
 Output #0, avi, to 'out.avi':
   Metadata:
     ISFT            : Lavf56.32.100
     Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 176x144 [SAR
 1:1 DAR 11:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc56.38.100 mpeg4
 Stream mapping:
   Stream #0:0 -> #0:0 (vc1 (native) -> mpeg4 (native))
 Press [q] to stop, [?] for help
 frame=   15 fps=0.0 q=2.0 Lsize=      92kB time=00:00:00.64
 bitrate=1176.4kbits/s
 video:86kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 6.992713%
 }}}
 Note that the input is shown as {{{vc1 (Advanced), yuv420p}}} although
 reading the source code, it should be {{{vc1 (Advanced), gray}}}.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4542>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker