[Sugar-devel] ogg video specs...

[Benjamin M. Schwartz]

Sameer Verma wrote:
> What specs should I encode Ogg video to for playback on an XO? We will have
> a booth with a few XOs at AMCIS (http://amcis2009.org) and I'd like to play
> Big Buck Bunny in a loop. The Ogg on their site freezes on the XO.
> http://www.bigbuckbunny.org/index.php/download/

In general, CPU usage is determined almost entirely by bitrate and resolution.
Using OLPC's 8.2.1 release software, I just tested the version from

http://people.xiph.org/~greg/video/ytcompare/bbb_theora_486kbit.html (Note
that this is only the first half of the movie)

That one has an overall bitrate of 486kbps, including Theora and Vorbis,
and a resolution of 480x270.  The parameters were chosen to match
Youtube's "HQ" profile.  It runs smoothly full-screen on my XO-1, using an
average of 20% CPU, but peaking to 90% momentarily during high motion
moments.  You can probably afford to go to a little bit higher bitrate or
resolution than this, but not much...unless you choose a long decode
buffer, to smooth out CPU/frame variations.  If you do that, you can
probably double or triple the bitrate (and correspondingly increase the
resolution) with no problem.

For encoding, you'll want to make sure you're using the latest Theora
encoder, which is now 1.1beta1.  The decoder in 1.1beta1 is also faster;
depending on how much work you want to do, you should consider loading
that onto the XOs.

--Ben

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