[Spice-devel] RFC on sound codec refactoring

[Marc-André Lureau]

----- Original Message -----
> On Fri, Oct 04, 2013 at 01:16:24PM -0500, Jeremy White wrote:
> > Yes, he pointed out some issues back in August when this last came up
> > (primarily supporting 'old' clients if you're sampling at 48K).  That's
> > the bit I'm not entirely clear on just yet, and hope to research a bit
> > further.
> 
> I'll look at your patches in more details later, but moving code out of
> snd_channel.c sounds interesting ;)
> Quick answer regarding the resampling, Opus wants to get 48kHz audio data,
> so when using Opus, you've got to tell QEMU to give you that. If you are
> talking to a client with Opus support, then it's all good, you encode to
> Opus and that's it. If you are talking to a client without Opus support,
> then you have to fallback to celt, which expects 44.1kHz input (at least,
> if I'm not mistaken, and the way we use it in spice). You can't dynamically
> tell QEMU that you no longer want 48kHz but that you want 44.1kHz instead,

Instead of having to resample, can't we fix qemu (and spice headers) to use 48khz by default? It seems the client doesn't suffer this limitation and could be compatible, since it receives frequency from the server.

> so you have to downsample yourself the audio from 48 to 44.1 yourself
> before sending it.
> I'll try to clean up the patches I had so far this week.