[Ffmpeg-devel] int vs. float: Hard Numbers

[Adam Thayer]

I would certainly say that the AC3 stuff is not the fault of the platform,
but rather the implementation of the library that does the decoding. Apple's
own DVD player software does decoding of AC3 in software as well, and
achieves respectable performance all the way back to 400Mhz G3 systems. 

The article about porting Doom III to the PPC wasn't really about the PPC
per se, but Apple's platform, which introduces some things that they just
couldn't work around. The PPC itself wasn't at fault, but rather the
libraries Apple was providing, especially OpenGL.

Multimedia currently operates much differently than something like Doom 3,
so the pipeline issues Aspyr was having are nowhere near as bad, and Apple
themselves are optimizing towards multimedia in the graphics pipeline at the
moment.

When a 400Mhz G4 can utilize Altivec and XviD to churn out 10 fps on
encoding, the PPC itself isn't the root of the problem. My guess? We simply
need more people doing PPC optimizations. Any particular bottleneck in
libavcodec someone is aware of, or any PPC stuff on the TODO list? ;)

- Adam

-----Original Message-----
From: ffmpeg-devel-bounces at mplayerhq.hu
[mailto:ffmpeg-devel-bounces at mplayerhq.hu] On Behalf Of Mike Melanson
Sent: Friday, May 20, 2005 3:52 PM
To: FFMpeg development discussions and patches
Subject: Re: [Ffmpeg-devel] int vs. float: Hard Numbers

Diego Biurrun wrote:
> For multimedia?  Not really.  Many codecs do not work since you cannot
> load binary DLLs and a few others have horrible performance like AC3.  I
> cannot watch DVDs on my 1.5GHz G4 since liba52 takes around 90% CPU...

	Ouch... though to be fair, none of these complaints fault the PPC 
specifically. The AC-3, well, it sounds like something was implemented 
incorrectly.

	For a fascinating comparison of x86 vs. PPC for multimedia purposes,

check out some articles from a few months ago about porting Doom III to 
PPC. Performance problems abounded on the PPC.

-- 
	-Mike Melanson

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