[Ffmpeg-devel] [PATCH] fix mpegaudiodec on ARM and benchmark

[Guillaume POIRIER]

Hi,

On 9/13/06, Siarhei Siamashka <siarhei.siamashka at gmail.com> wrote:
> On Wednesday 13 September 2006 11:50, Guillaume POIRIER wrote:
> > On 9/12/06, Siarhei Siamashka <siarhei.siamashka at gmail.com> wrote:
> > > On Thursday 24 August 2006 11:30, Guillaume Poirier wrote:

[..]

> > > > Some of the improvement involve using IPP, others to use inline asm.
> > >
> > > Thanks I also checked this code. As far as I understand it, most of the
> > > improvements from this forked version are already included into ffmpeg
> > > (revision 4311). The things that are left are some Zaurus specific video
> > > drivers and patches for libmpeg2 code.
> >
> > Please do double check. I'm not 100% sure, but last time I checked the
> > changelog showed that he had re-written some calls to IPP with
> > hand-written asm routines.
> >
> > I have send a patch some time ago which contained the differences
> > between current code in FFmpeg and the one in mplayer-w100 and AFAIR,
> > there were some unmerged code.
>
> Maybe you are right, but this Zaurus port has a lot of code using IWMMX
> instructions which are not supported on my Nokia 770 device. So I can't test
> if all this code works correctly and can't provide much help with merging it
> into ffmpeg. It would be better to have this code checked by someone actually
> using a device with ARM XScale cpu.

Ah, now I understand since you said this on another mail:

> So theoretically 3 types of ARM machines can supported:
> 1. armv4 (probably some older StrongARM machines)
> 2. armv5te (TI OMAP1710 (arm926ej-s core) on Nokia 770)
> 3. armv5te + iwmmx instructions (Intel XScale on Zaurus)

It's just that I thought that all recent ARM (such as the on on
Nokia770) supported iwmmx instructions.

Thanks for clarifying this.

BTW, in your own experience, is it better (in terms of being able to
extract all the computing juice out of the transistors) to have a
CPU+DSP setup or a CPU that supports SIMD?
I bet that for a smartphone (such as 770, right?), there's no option
besides having a dedicated DSP onboard for all the GSM stuff...
whereas for a PDA, a CPU + SIMD seems to be quite useful...

What do you think about it?

Guillaume
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