[FFmpeg-devel] [PATCH] Runtime detection for the number of processors/cores

[Roman Shaposhnik]

On Wed, 2008-05-21 at 17:45 -0400, Alexander Strange wrote:
> > On a related note: I still don't quite understand why MPEG based
> > codecs don't allow for higher degree of parallelism. Unlike DV codec
> > which I've just tested on a nice Maramba box (2 CPUs, 16 cores,
> > 128 execution units) and it scaled pretty much linearly to the
> > # of cores, the MPEG based ones just refused to go higher than 4.
> 
> They only scale to the number of slices in a frame, and then only to  
> the first 8 of those, I think. Adding slices is the only way to  
> guarantee parallelism in a codec like this, but it always hurts  
> compressibility, which is much more important.

I see. That makes sense. Thanks for the explanation. 

> I'm working on it - for intra codecs frame-threading works perfectly  
> so far, but for all the other codecs with backreferences I ran into  
> some trouble with the buffer API. That shouldn't take too long to get  
> around, though, and then I can get on with reading mpegvideo.

Is there any way of exploiting GOP properties of the stream as well?
Or would it break the current model too much?

Thanks,
Roman.