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

[Ron]

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 ...


 Cheers,
 Ron