[Spice-devel] [PATCH] make celt to be optional

[Alon Levy]

On Wed, Jun 13, 2012 at 01:22:43AM +0930, Ron wrote:
> 
> Hi Alon,
> 
> On Tue, Jun 12, 2012 at 06:03:58PM +0300, Alon Levy wrote:
> > On Tue, Jun 12, 2012 at 09:11:24AM -0400, Marc-André Lureau wrote:
> > > Hi
> > > 
> > > ----- Mensaje original -----
> > > > The ideal solution would be to have support for Opus, I think Marc
> > > > André
> > > > and Alon had started to look into that, but that's not done yet :(
> > > 
> > > No, I didn't. Long time ago I proposed we have celt unstable flag, which
> > > would be completely broken in most cases but would also have made debian
> > > folks happy.
> > > 
> > > As long as the bitstream is not frozen, we can't use opus, or we will
> > > have the same problems as with celt today.
> > 
> > OPUS is frozen. The problem I had when trying to use it was that it uses
> > a sampling rate of 48000 and we have 44110. That required changes to
> > qemu/spice interface and I stopped there.
> 
> Opus operates in the frequency domain, so it doesn't actually have a
> "sampling rate" at all so far as the codec is concerned.  The library
> API supports converting that to and from the time domain at 48k or any
> integer fraction of that rate down to 8k.  For 'oddball' rates you
> simply need to pass the input or output through a resampler, of which
> code for many is widely available.   The opusenc and opusdec reference
> tools support files at any sampling rate you might dream up or encounter.
> 
> Why exactly do you need 44.1?  Many (most?) sound cards don't support
> that rate anyway and will require it to be resampled to 48k before
> being played on them in any case ...
> 

I wasn't talking about opus internals at all, since I don't understand
them. I was just commenting on where I bumped into a wall when I tried
to update spice to use opus. I'll need to go back and look at my tree,
but I am just speaking of api problems, not about the codec itself,
which is perfectly opaque to me (like celt is right now - spice doesn't
care about the codec).

> 
>  Cheers,
>  Ron
> 
> 
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