[libav-bugs] [Bug 320] New: -crf with libvpx/WebM doesn't seem to work

bugzilla-daemon at aruru.libav.org bugzilla-daemon at aruru.libav.org
Mon Jun 18 17:34:59 CEST 2012


https://bugzilla.libav.org/show_bug.cgi?id=320

           Summary: -crf with libvpx/WebM doesn't seem to work
           Product: Libav
           Version: 0.8
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: utilities
        AssignedTo: bugzilla at libav.org
        ReportedBy: olau at hardworking.dk


According to this table

https://docs.google.com/spreadsheet/ccc?key=0AvWxUS1XGCPAdGNtNW10a2p4c1VwdG1VZk1uMl9MUEE&hl=en#gid=0

-crf somenumber is supposed to turn on constant quality mode. But it doesn't
seem to work, no errors but I just get the standard 200k bitrate limit, see
output below. I realize this table is for ffmpeg, but I suppose the semantics
should be the same?

What I expect to happen is that I set the quality and the encoder figures out
how much space that needs to take, as happens with libx264.


$ avconv -i input.mov -y -threads 3 -s 686x386 -aspect 686:386 -ss 30 -t 10
-codec:v libvpx -crf 18 -codec:a libvorbis -ar 22050 -b:a 128k output.webm
avconv version 0.8.3-6:0.8.3-1, Copyright (c) 2000-2012 the Libav developers
  built on Jun  9 2012 12:59:47 with gcc 4.7.0
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x96b35e0] max_analyze_duration reached
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537199360
    compatible_brands: qt  
    creation_time   : 2010-04-06 02:15:52
  Duration: 00:13:02.25, start: 0.000000, bitrate: 10939 kb/s
    Stream #0.0(eng): Video: h264 (Main), yuv420p, 960x540, 10637 kb/s, 25 fps,
25 tbr, 2500 tbn, 5k tbc
    Metadata:
      creation_time   : 2010-04-06 03:42:07
    Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, s16, 297 kb/s
    Metadata:
      creation_time   : 2010-04-06 03:42:07
    Stream #0.2(eng): Data: tmcd / 0x64636D74
    Metadata:
      creation_time   : 2010-04-06 03:42:52
[buffer @ 0x96bab20] w:960 h:540 pixfmt:yuv420p
[scale @ 0x96bb220] w:960 h:540 fmt:yuv420p -> w:686 h:386 fmt:yuv420p
flags:0x4
[libvpx @ 0x98f9440] v1.1.0
Output #0, webm, to 'output.webm':
  Metadata:
    major_brand     : qt  
    minor_version   : 537199360
    compatible_brands: qt  
    creation_time   : 2010-04-06 02:15:52
    encoder         : Lavf53.21.0
    Stream #0.0(eng): Video: libvpx, yuv420p, 686x386 [PAR 1:1 DAR 343:193],
q=-1--1, 200 kb/s, 1k tbn, 25 tbc
    Metadata:
      creation_time   : 2010-04-06 03:42:07
    Stream #0.1(eng): Audio: libvorbis, 22050 Hz, stereo, s16, 128 kb/s
    Metadata:
      creation_time   : 2010-04-06 03:42:07
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> libvpx)
  Stream #0:1 -> #0:1 (aac -> libvorbis)
Press ctrl-c to stop encoding
frame=  250 fps=  3 q=0.0 Lsize=     331kB time=9.98 bitrate= 271.8kbits/s   
its/s    
video:221kB audio:102kB global headers:3kB muxing overhead 1.605169%

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