[Theora] Theora performance

Ralph Giles giles at xiph.org
Thu Mar 17 19:00:58 PST 2005

On Fri, Mar 18, 2005 at 01:26:28AM +0100, Pau Garcia i Quiles wrote:

> My company is evaluating open source codecs for a video solution we are 
> starting to develop in one month, and I have some questions about Theora.

Thanks for looking at theora.

> How good is the performance of Theora? Is it possible to encode it real time?

Depends on how fast your machine is, of course. The code hasn't seen much
optimization work, so it's not as fast as it could be. I'd suggest trying
the MMX version available from http://svn.xiph.org/branches/theora-mmx/

It should have no trouble compressing standard def (720x480 at 30p or 
720x576 at 25p) in realtime on a 2 GHz (x86) machine.

> What about streaming Theora inside an OGG, OGM or Matroska container? Does it 
> work any good? Which is the highest bitrate Theora can reach?

Ogg is the recommended native format for theora video (along with vorbis
audio) and streaming works great. See http://mirror.fluendo.com/ for some 
example streams. The latest release of our icecast streaming server 
supports ogg theora out of the box.

The highest bitrate is ridiculously large. Some reasonable set points
are around 1 kbps for SD and around 320 kbps for 1/4 SD, though many
people say theora degrades more gracefully at lower bitrates than
other codecs.

Hope that helps, and let us know if you have any other questions.


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