[FFmpeg-trac] #3150(avcodec:new): H.261 encoding: "-cmp rd" ruins image quality

FFmpeg trac at avcodec.org
Mon Nov 18 17:39:08 CET 2013

#3150: H.261 encoding: "-cmp rd" ruins image quality
             Reporter:  maikmerten  |                     Type:  defect
               Status:  new         |                 Priority:  normal
            Component:  avcodec     |                  Version:  git-master
             Keywords:              |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
 Summary of the bug:
 How to reproduce:

 ffmpeg -i /tmp/test.y4m -f h261 -vb 256k -cmp rd /tmp/test.h261

 ffmpeg version N-58246-g7d0e927 Copyright (c) 2000-2013 the FFmpeg
   built on Nov 18 2013 17:15:01 with gcc 4.8 (Ubuntu/Linaro

 Test sequence used is

 Bitrate of the file is very much inflated by specifying the -cmp rd
 option, yet picture quality is severely affected by blockyness. Apparently
 the encoder is forced into aggressive quantization.

 Attached picture shows one representative frame of video output.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/3150>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker

More information about the FFmpeg-trac mailing list