[FFmpeg-trac] #4111(avcodec:new): h261 encoding produces glitches with -qscale 2

[FFmpeg]

#4111: h261 encoding produces glitches with -qscale 2
--------------------------------------+---------------------------------
               Reporter:  cehoyos     |                  Owner:
                   Type:  defect      |                 Status:  new
               Priority:  normal      |              Component:  avcodec
                Version:  git-master  |               Keywords:  h261
             Blocked By:              |               Blocking:
Reproduced by developer:  0           |  Analyzed by developer:  0
--------------------------------------+---------------------------------
 The following command shows recurring artefacts in the output file (every
 twelfth frame) that are not shown with {{{-qscale 3}}}
 {{{
 $ ffmpeg -f lavfi -i testsrc=s=cif -qscale 2 -vcodec h261 -threads 1 -t 10
 -mbd 2 out.avi
 ffmpeg version N-67684-g12630fa Copyright (c) 2000-2014 the FFmpeg
 developers
   built on Nov 15 2014 13:07:53 with gcc 4.7 (SUSE Linux)
   configuration: --enable-gpl
   libavutil      54. 11.100 / 54. 11.100
   libavcodec     56. 12.101 / 56. 12.101
   libavformat    56. 12.103 / 56. 12.103
   libavdevice    56.  3.100 / 56.  3.100
   libavfilter     5.  2.103 /  5.  2.103
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  1.100 /  1.  1.100
   libpostproc    53.  3.100 / 53.  3.100
 Input #0, lavfi, from 'testsrc=s=cif':
   Duration: N/A, start: 0.000000, bitrate: N/A
     Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 352x288
 [SAR 1:1 DAR 11:9], 25 tbr, 25 tbn, 25 tbc
 Please use -q:a or -q:v, -qscale is ambiguous
 Output #0, avi, to 'out.avi':
   Metadata:
     ISFT            : Lavf56.12.103
     Stream #0:0: Video: h261 (H261 / 0x31363248), yuv420p, 352x288 [SAR
 1:1 DAR 11:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc56.12.101 h261
 Stream mapping:
   Stream #0:0 -> #0:0 (rawvideo (native) -> h261 (native))
 Press [q] to stop, [?] for help
 frame=  250 fps=0.0 q=2.0 Lsize=     591kB time=00:00:10.00 bitrate=
 484.0kbits/s
 video:579kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 2.002101%
 }}}
 The same artefacts are shown without {{{-mbd 2}}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4111>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker