[Ffmpeg-devel] [PATCH] Optimization of 'dct_unquantize_h263_intra' for ARM (armv5te)

[Siarhei Siamashka]

On Wednesday 03 January 2007 00:25, M?ns Rullg?rd wrote:

> >> It is a pity that ARMv5TE does not have SIMD instructions, it would be
> >> much better to use SIMD for this code, but at least this ARM optimized
> >> function is still a lot faster than gcc generated code and provides
> >> about ~3% overall improvement on this video file.
> >
> > Nokia 770 is supposed to have both an ARM and a DSP... is there an SDK
> > to program the DSP?
>
> Yes, there is something available.  I haven't had time to look into it
> yet.

I also did not have time to look into DSP programming yet. But here are 
some links for getting information.

Project working on support for OMAP DSP in linux:
http://dspgateway.sourceforge.net

Some PDF docs about C55x DSP itself (they also contain references to other 
docs which are quite interesting):
http://focus.ti.com/lit/ug/spru098/spru098.pdf
http://focus.ti.com/lit/ug/spru393/spru393.pdf
http://focus.ti.com/lit/ug/spru376a/spru376a.pdf

An old thread in maemo developers mailing list:
http://maemo.org/pipermail/maemo-developers/2005-December/002153.html

Anyway, it looks like some specialized piece of hardware which is not so
easy to to develop code for. It is hard to find examples of open source
projects using it. I have read that speex codex (http://speex.org/) has some
support for TI C5X DSPs but did not look into its sources. Also I'm uncertain
about the future of this DSP and also wonder if it will be still used in Nokia
770 successor device (most likely it will, but who knows?). At the same time, 
ARM is a power efficient general purpose processor architecture which is here
to stay for a long time :)

By the way, M?ns, do you still have Nokia 770 device, free time and motivation
to continue optimizing ffmpeg for it?