[theora] conference talks

Ralph Giles giles at xiph.org
Sat Oct 21 00:24:19 PDT 2006

On Sat, Oct 21, 2006 at 09:02:54AM +0200, Pau Amaro-Seoane wrote:

> I am a bit puzzled... what's the difference between OGM vorbis+divx3
> and Ogg theora? Is OGM vorbis+divx3 free software? Are files encoded
> with OGM vorbis+divx3 smaller or larger? And can a default GNU/Linux
> installation play OGM vorbis+divx3 files? 

Before there was theora, people put vorbis audio and divx video together 
into the ogg container to make OGM (for ogg movie) files. This offered 
the space savings of vorbis over mp3 and the better streaming of ogg 
over avi.

However, divx is based on the MPEG-4 (H.263) video codec and as such is 
subject to patent license fees. It's not free and cannot be played by 
default in many linux distributions. There is FLOSS software to play 
it, but it cannot be distributed in many jurisdictions. Since our 
mission at Xiph is to provide open and free multimedia technology, we 
don't encourage people to make such files now that we have the free 
theora video codec.

Your files are pretty big, so I imagine a theora version would be 
comparable or better.

> BTW how did you find out they are OGM vorbis+divx3 files?? I had no
> idea... I asked computer support to encode the raw data into theora
> ogg...

I couldn't get them to pay on MacOS X with our quicktime components 
(which don't support ogm) So I looked at the file to see why.

They got it half right. It's Ogg, but not Ogg Theora.

You can use http://validator.annodex.org/ to check if your files are 
proper, if you like.


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