[gst-devel] TI OMAP DSP support

g the_ether2 at yahoo.co.uk
Thu Jan 17 00:42:26 CET 2008


--- Josep Torra Valles <j.torra at telefonica.net> wrote:
> First I think that you should get more knowledge
> about the N8x0
> architecture and the OMAP SoC in order to be able to
> understand the
> scenario for your project.

My "project" is simply to decode MPEG video. As stated
previously the core elements I intend to use are
already available as plug-ins to GStreamer.

My questions have been whether GStreamer already has
implemented any DSP acceleration and if not, what the
performance hit of their absence is compared to the
potential stated by TI.

> > ffmpeg and xvid are available as plug-ins for
> > GStreamer and presumably work on Maemo 2008. What

> If just crosscompile you will have something
> working, but it doesn't
> mean that the performance will be enough to get VGA
> at 30 fps.

As stated above, the MPEG decoders ffmpeg and xvid are
already available as plug-ins for GStreamer. I have
merely asked what the performance is. Maybe someone
has already optimised one or both of these for ARM and
/ or the DSP portion of the OMAP2420.

As previously mentioned, a TI article specifically
states that there is a GStreamer plug-in that uses the
DSP and yet I cannot find any mention of its existance
on the GStreamer site.

> I also wrote some assembly to accelerate video
> decoding on ARM5e and
> ARM6 cores and I think that probably on ARM6(400
> MHz) you can achieve
> more video decoding speed than using the DSP(133
> MHz).

The clock frequency isn't the only part. What matters
is what work is done per cycle. The DSP obviously has
an important part to play. That's why it's there in
the first place. Given the choice, doing all the
processing purely on the ARM core and not using the
DSP for any task is silly - especially for video
decoding.

g.


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