#7122 closed defect (fixed)

Massive artefacts when decoding clearvideo

Reported by: cehoyos Owned by:
Priority: normal Component: avcodec
Version: git-master Keywords: clv
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no

Description

The low-bitrate samples from ticket #6842 show massive artefacts when decoded with current FFmpeg.

$ ffmpeg -i clv1_100kbps.rm -qscale 2 out.avi
ffmpeg version N-90597-g673604e Copyright (c) 2000-2018 the FFmpeg developers
  built with gcc 6.3.0 (GCC)
  configuration: --enable-gpl
  libavutil      56. 13.100 / 56. 13.100
  libavcodec     58. 17.100 / 58. 17.100
  libavformat    58. 10.100 / 58. 10.100
  libavdevice    58.  2.100 / 58.  2.100
  libavfilter     7. 14.100 /  7. 14.100
  libswscale      5.  0.102 /  5.  0.102
  libswresample   3.  0.101 /  3.  0.101
  libpostproc    55.  0.100 / 55.  0.100
Input #0, rm, from 'clv1_100kbps.rm':
  Duration: 00:00:03.20, start: 0.000000, bitrate: 74 kb/s
    Stream #0:0: Video: clearvideo (CLV1 / 0x31564C43), yuv420p, 320x240, 100 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
Please use -q:a or -q:v, -qscale is ambiguous
Stream mapping:
  Stream #0:0 -> #0:0 (clearvideo (native) -> mpeg4 (native))
Press [q] to stop, [?] for help
Output #0, avi, to 'out.avi':
  Metadata:
    ISFT            : Lavf58.10.100
    Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 320x240, q=2-31, 200 kb/s, 15 fps, 15 tbn, 15 tbc
    Metadata:
      encoder         : Lavc58.17.100 mpeg4
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
frame=   32 fps=0.0 q=2.0 Lsize=     250kB time=00:00:03.20 bitrate= 638.9kbits/s speed= 123x
video:243kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 2.757215%

The output video is recognizable but looks very ugly.

Change History (8)

comment:1 Changed 20 months ago by richardpl

  • Resolution set to invalid
  • Status changed from new to closed

comment:2 Changed 20 months ago by cehoyos

Would you like to elaborate?

comment:3 Changed 20 months ago by richardpl

Can you prove this is not bug in encoder?

comment:4 Changed 20 months ago by cehoyos

The look of the artefacts indicated an issue with the decoder to me, is there any reason to assume that the files are broken?

comment:5 Changed 20 months ago by richardpl

Yes. all other files decode ok.

comment:6 Changed 20 months ago by cehoyos

Which other files?

comment:7 Changed 20 months ago by cehoyos

  • Resolution invalid deleted
  • Status changed from closed to reopened

Piotr kindly verified the issue with RealPlayer.

comment:8 Changed 19 months ago by cehoyos

  • Resolution set to fixed
  • Status changed from reopened to closed
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