[theora] Page breaks when encoding ogg/theora

Ralph Giles giles at xiph.org
Thu Jun 12 15:17:38 PDT 2008

On 11-Jun-08, at 1:48 AM, Claus Höfele wrote:

> Neither the DirectShow filters nor VideoLan can display the ogg  
> file when using ogg_stream_pageout(). VLC pops up a window for a  
> short time, but doesn't display anything.

This looks like a player bug. Both files are valid, and the only  
difference in the packet streams (according to oggzdump) is in the  
frequency of timestamps, due to the different pagination. They both  
play identically with gstreamer and the libtheora player_example.

The issue is exacerbated by your chroma-key purple frames which  
compress really well, so all three seconds of video end up in a  
single page. Does the same thing happen with real output?

To work around the problem, try flushing every n frames or so, and  
see if there's a value of n for which directshow starts working. This  
is a good idea anyway, to limit buffering requirements when the video  
is multiplexed with audio.


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