Mailinglist Archive: radeonhd (427 mails)

["Bridgman, John" <John.Bridgman@xxxxxxx>]

An XvMC implementation would be a good way to get comfortable with 
shader-processed video, but the same approach could be used for both motion 
comp and in-loop deblocking of H.264, you'd just need a different API. 

I sometimes wonder if it might be easier to just add the shader code to 
ffmpeg/libavcodec and have it run directly over the drm. That would give more 
flexibility for incrementally moving the "acceleration point" further up the 
stack as more work is completed. 

-----Original Message-----
From: Michael Cree [mailto:mcree@xxxxxxxxxxxx] 
Sent: Tuesday, May 12, 2009 5:51 PM
To: Alex Deucher
Cc: Rafał Miłecki; Anders Eriksson; Matthias Hopf; Christiaan van Dijk; 
Christian König; radeonhd@xxxxxxxxxxxx
Subject: Re: [radeonhd] RS690 full-HD performance

On 13/05/2009, at 3:42 AM, Alex Deucher wrote:
> > > Video decode is mostly done on shaders (at least motion
> > > compensation)
> > > on that hardware.  We've released the 3D engine information on these 
> > > chips so this could be implemented now if anyone was so inclined.
> >
> > Can you be more specific about this, please? I'm really intereseted
>
> There are several stages in the decode part of the pipeline.  idct and 
> mc are the main ones.  On r1xx-r5xx (including rs6xx), we do the mc 
> part for the decode using the 3D engine (shaders on r3xx+, special 
> instructions on r1xx-r2xx).  R6xx and r7xx chips have a special 
> dedicated UVD block for video decode.  We plan to review that block to 
> see if we can release any of it, but no promises.  Regardless, you 
> could do mc on r6xx/r7xx using shaders as well.  For MPEG1/2 you could 
> implement an XvMC driver and implement mc using shaders.  I believe 
> intel does this.  The problem is XvMC doesn't support newer formats 
> like H.264 or whatever.

Now this is really interesting.  I have some experience in image processing.  
While I have never really specifically worked on video codecs I am quite 
familiar with the mathematics of discrete Fourier transforms and the like, and 
currently have a student working on FPGA implementations of the FFT.

I definitely would be interested in coding up the IDCT and MC.  I would have to 
learn about the shaders.

It's a bummer XvMC doesn't support h.264 as that is the codec I ultimately 
would be most interested in.  (My computer is powerful enough to decode MPEG2 
but not MPEG4).

The main problem is time.  I don't know if I can put much effort into this.  
Then again, if I could score a publication or two from it that  
might help justify some work time or getting a student to do this.   
Implementing IDCT and MC probably won't achieve that - I'm assuming that it's 
well known, but maybe implementing some signal processing for image ranging on 
GPU at the same time...  Hmm, I'm starting to ramble - I'll have a think about 
this.

Cheers
Michael.

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