[theora] buggy encoder ??

Michael A. Peters mpeters at mac.com
Sun Sep 20 20:19:47 PDT 2009

Gregory Maxwell wrote:
> On Sun, Sep 20, 2009 at 8:16 PM, Michael A. Peters <mpeters at mac.com> wrote:
>> I just looked at some of my ogg files created on Ubuntu jaunty via ffmpeg.
>> According to ogginfo:
>> -=-
>> User comments section follows...
>>         encoder=Lavc52.20.0
>> Negative granulepos on vorbis stream outside of headers. This file was
>> created by a buggy encoder
>> -=-
>> Is that something I should worry about, and if so, do I just need to
>> update the theora libs or do I need to update ffmpeg as well?
> You should probably avoid creating Ogg/Theora files with ffmpeg if you
> can.  FFmpeg2theora would be the preferred alternative.   I believe
> the current ffmpeg doesn't have the muxer problems that cause that
> message, but fixes/improvements to theora related support in ffmpeg
> proper tend to be slow in coming.

The problem I had with ffmpeg2theora, maybe one I can solve by playing 
with options, I use ffmpeg 2 pass encoding to create a h.264 .mp4 file.

With one quality setting, ffmpeg2theora produces a visually inferior 
file with a smaller file size. Bump up the quality setting by a factor 
of 1, and the file is visually better but much larger.

With ffmpeg, I was able to get a visually satisfactory file very close 
to size of the h.264 encoded version so that people who want the 
ogg/theora version do not have to either suffer noticeably lower quality 
or noticeably larger file size.

More information about the theora mailing list