[FFmpeg-trac] #1555(undetermined:new): WebM: Silent track not taken into account if followed by a noisy track

[FFmpeg]

#1555: WebM: Silent track not taken into account if followed by a noisy track
-------------------------------------+-------------------------------------
               Reporter:  cehoyos    |                  Owner:
                   Type:  defect     |                 Status:  new
               Priority:  normal     |              Component:
                Version:  git-       |  undetermined
  master                             |               Keywords:
             Blocked By:             |               Blocking:
Reproduced by developer:  0          |  Analyzed by developer:  0
-------------------------------------+-------------------------------------
 (issue 2445)
 I will upload a webm sample that plays different with Firefox and ffplay -
 both ffmpeg and ffplay ignore the initial silence.
 {{{
 $ ffmpeg -i res_silence_then_sound.webm -qscale 2 out.avi
 ffmpeg version N-42605-g5784a46 Copyright (c) 2000-2012 the FFmpeg
 developers
   built on Jul 18 2012 20:29:06 with gcc 4.3.2
   configuration: --cc=/usr/local/gcc-4.3.2/bin/gcc --enable-gpl --enable-
 libopenjpeg --enable-libvorbis --enable-libspeex --enable-libmp3lame
 --enable-libtheora --extra-ldflags=-lm --enable-libvpx --enable-libxavs
 --enable-x11grab --enable-libass
   libavutil      51. 65.100 / 51. 65.100
   libavcodec     54. 41.100 / 54. 41.100
   libavformat    54. 17.100 / 54. 17.100
   libavdevice    54.  1.100 / 54.  1.100
   libavfilter     3.  2.100 /  3.  2.100
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0. 15.100 /  0. 15.100
   libpostproc    52.  0.100 / 52.  0.100
 Input #0, matroska,webm, from 'res_silence_then_sound.webm':
   Metadata:
     creation_time   : 2010-12-24 06:39:05
   Duration: 00:00:35.58, start: 0.000000, bitrate: 1105 kb/s
     Stream #0:0: Video: vp8, yuv420p, 640x352, SAR 1:1 DAR 20:11, 25 fps,
 25 tbr, 1k tbn, 1k tbc
     Stream #0:1: Audio: vorbis, 48000 Hz, stereo, s16
 Please use -q:a or -q:v, -qscale is ambiguous
 Output #0, avi, to 'out.avi':
   Metadata:
     ISFT            : Lavf54.17.100
     Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 640x352 [SAR
 1:1 DAR 20:11], q=2-31, 200 kb/s, 25 tbn, 25 tbc
     Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, s16
 Stream mapping:
   Stream #0:0 -> #0:0 (vp8 -> mpeg4)
   Stream #0:1 -> #0:1 (vorbis -> libmp3lame)
 Press [q] to stop, [?] for help
 frame=  858 fps= 90 q=2.0 Lsize=    6666kB time=00:00:35.52
 bitrate=1537.3kbits/s
 video:6123kB audio:477kB subtitle:0 global headers:0kB muxing overhead
 0.995196%
 [libmp3lame @ 0x90c2a80] 1 frames left in que on closing
 }}}
 out.avi is broken / severe A/V desync.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1555>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker