Video decode and ARM in the XO-1.75

[Benjamin M. Schwartz]

If OLPC engineers will soon be selecting an ARM SoC for 1.75, one
criterion might be video playback performance, and possibly even playback
performance in Theora, given the hassles so far with MPEG-4.

If so, the two following pages may be of interest:
http://wss.co.uk/pinknoise/theorarm/
http://www.schleef.org/blog/2009/11/11/theora-on-ti-c64x-dsp-and-omap3/

According to these pages,
(1) A contemporary ARM Cortex A8 such as the one in the Beagle Board can
decode DVD-resolution Theora in real time in pure software.
(2) If XVideo or similar basic overlay acceleration is available, then the
CPU can decode 1280x720 "HD" video at 24 fps (i.e. 720p movie playback)
(3) If the chipset includes a TI C64x+, that chip can decode Theora at
640x360 at 24 fps, independent of the CPU.

These two software projects are in early development at the moment, but I
expect them to be stable, usable, and maybe slightly faster by next year.

Other things to consider are power usage during video playback (does the
DSP help?) and video-conferencing, which requires simultaneous encode and
decode.

--Ben

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