[Ffmpeg-devel] MPEG-2 Acceleration Under Mac OS X - Can We Move This Forward?

galenz at zinkconsulting.com galenz
Tue Aug 29 04:27:51 CEST 2006

On Aug 28, 2006, at 7:09 PM, Nigel Pearson wrote:

>> Also, is it possible to extend to functionality of the
>> code to allow decoding of other codecs than MPEG-2?
> 	Anything is possible (the GPU
> vendors talk about MPEG4 assist too),
> but I think that is very unlikely.
> From my understanding of it,
> Apple only uses HW assist for DVDs.
> 	John has reverse-engineered this,
> and it is possible he knows what parts
> of the API do aspects like ICT
> (useful for some other codecs),
> but that is a lot more work.
> --
> Nigel Pearson, nigel at ind.tansu.com.au|"Gentlemen,
> Telstra Net. Eng., Sydney, Australia | you can't fight in here
> Office: 9202 3900    Fax:  9261 3912 | - this is the war room!"
> Mobile: 0408 664435  Home: 9792 6998 |     Dr Strangelove

My understanding of John's implementation is that he's handing off  
the MPEG-2 in a fairly whole manner. I believe we had discussed this  
and you would have to do another layer of reverse engineering to get  
down to the very specific functions like IDCT. I have a hard time  
imagining the gains being nearly so great, however, unless you were  
accessing GPU functions specifically for MPEG-4, h.264, etc. And as  
we all know, graphics vendors aren't terribly helpful with  
documentation. With Accellent, it's nice that by relying on Apple's  
API, it abstracts the code from the specific GPU, so it makes the  
application a lot more portable between systems, new and old.

I'm presently reinstalling the developer tools (don't ask why) and  
once that finishes in a few minutes, I will look over the code again.  
But frankly, I'm not likely to glean much inspiration because I'm not  
qualified to turn this into something very useful unless somebody  
volunteers to let me ask countless stupid questions and I try to  
figure out what end is up. Once upon a time ago, I worked full time  
doing behind the scenes web programming, but that's a far leap from  
this. Sure, it's still object-oriented programming, but that's about  


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