[MPlayer-dev-eng] mp3 decoding performance on ARM

[Diego Biurrun]

On Mon, Aug 14, 2006 at 09:57:20PM +0300, Siarhei Siamashka wrote:
> On Monday 14 August 2006 01:29, Michael Niedermayer wrote:
> 
> So I guess that replacing all the other performance critical macros with
> optimized versions,  ffmp3 could probably get much faster and closer to
> libmad. But that's probably outside of scope of this mailing list, maybe it
> is better to subscribe to ffmpeg mailing list and submit any ffmpeg related
> patches there.

Yes, subscribing to ffmpeg-devel is not a bad idea, although the author
of ffmp3 (Michael) reads this mailing list, so patches are unlikely to
get lost.

> > > But I also found the following link which is advertised to have fast
> > > fixed point mp3 decoder (17MHz for decoding 128kbit soundtrack):
> > > https://datatype.helixcommunity.org/mp3dec.html
> > >
> > > Using above statistics, libmad cpu requirements estimate is 31MHz, and it
> > > is somewhat higher than helix decoder advertised numbers. Surely mplayer
> > > itself adds some overhead in demuxing and buffering, but probably helix
> > > decoder is worth trying. Now trying to figure out how to get its sources
> > > from CVS and what is that RPSL license :-)
> >
> > something which probably has nothing to do with the word free or open ...
> 
> Well, it is presented as GPL compatible (did not have time to read the whole
> text though): https://community.helixcommunity.org/content/rpsl

The OSI lists it as open source license.  Unfortunately there is no
information about it on the FSF/GNU pages.

After a quick glance at it I have doubts about it's GPL compatibility.
Also, it's not directly presented as GPL-compatible.  Read the footnote
about the GPL again..

> I had a quick look at it, API seems to be quite clean and simple, so wrapping
> it into a decoder module for MPlayer and testing performance should be not too
> hard. If it is really very fast, it would make sense reading its license more
> carefully to check whether it can be legally used as an external decoder :-)

I'd check this first to avoid wasting your time..

Diego