OpenMAX 

OpenMAX is a royalty-free, cross-platform set of C-language programming interfaces
that provides abstractions for routines especially useful for audio, video, and still
images. OpenMAX is intended for devices that process large amounts of multimedia data
in predictable ways.

Developed by the Khronos Group, who also maintain the OpenGL standard. Being used for Maemon 5 as a standardised interface for media playback. That means a standard interface for doing work using the DSP part of OMAP3. 

720×400 MPEG-4 video at 24 fps. Essentially gst-openmax is using TI’s OpenMAX IL
implementation, which is using the DSP on the OMAP 3530 to decode the video.

The CPU usage on the ARM side is about 10% which leaves plenty of room to decode audio or
anything else. When debugging is turned off on the dsp-bridge kernel driver, the CPU
usage is less, but it’s more unstable

This is interesting, because I read that using a NEON (SMID for ARMv7) optimised decoder one can do 720p without having to worry about feeding data to the DSP. I guess you'd be using a fair amount (all?) of the ARM side in this case, but otoh how many use cases would involve watching 720p video and needing to do something else with the ARM? 

NEON accelerated mplayer and the popular NEON accelerated omapfbplay which
gives you fullscreen 720p decoding.