[libav-tools] encoding ogg vorbis files

Ralf Jung post at ralfj.de
Sun Jun 3 14:20:57 CEST 2012


Hi list,

I am having strange problems encoding audio files using libvorbis: I use a 
command like this

avconv -i input.flv -acodec libvorbis -aq 3 -vn output.ogg

to get the audio stream of a video file encoded as ogg. However, opening the 
resulting ogg file in VLC reveals strange seeking problems: The current 
timestamp as shown by VLC is updated only every 2 seconds, and if I click 
somewhere in the seek bar it takes up to 1 second for VLC to continue playing.
If however I open the ogg file in Audacity and re-export it to an ogg file, 
the ogg file created will not have such problems. The seek bar and current 
timestamp is updated smoothly, and seeking works without noticeable delay. The 
same holds for ogg files created using the KDE audiocd: KIO-slave, which 
internally directly uses libvorbis.

Is this a problem in the file, or in VLC? Amarok using the VLC backend has the 
same problem, using the gstreamer backend, both files work smoothly. What do 
Audacity and the KIO slave do differently than avconv, and is there any 
command-line option I could use to change that?

I am using Debian testing:
$ avconv -version
avconv version 0.8.2-6:0.8.2-2, Copyright (c) 2000-2011 the Libav developers
  built on May 16 2012 21:00:23 with gcc 4.7.0
avconv 0.8.2-6:0.8.2-2
libavutil    51. 22. 1 / 51. 22. 1
libavcodec   53. 35. 0 / 53. 35. 0
libavformat  53. 21. 0 / 53. 21. 0
libavdevice  53.  2. 0 / 53.  2. 0
libavfilter   2. 15. 0 /  2. 15. 0
libswscale    2.  1. 0 /  2.  1. 0
libpostproc  52.  0. 0 / 52.  0. 0
$ vlc --version
VLC media player 2.0.1 Twoflower (revision 2.0.1-0-gf432547)
VLC version 2.0.1 Twoflower (2.0.1-0-gf432547)
Compiled by buildd on brahms.debian.org (May 14 2012 23:08:19)
Compiler: gcc version 4.7.0 (Debian 4.7.0-8)

Kind regards,
Ralf

PS: Please keep me CC'ed in replies.

PPS: The avconv manpage mentions the "ff* tools" in the Demuxers section. 
Looks like a leftover from the tool renaming ;-)


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