[Ffmpeg-devel] MPEG-2 Acceleration Under Mac OS X - Can We Move This Forward?
galenz at zinkconsulting.com
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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