[Spice-devel] Usage of Celt library with Spice...

[Marc-André Lureau]

Hi

----- Original Message -----
> Hi,
> 
> On Thu, Oct 27, 2011 at 05:01:51PM -0700, Naga Mohan Pothula wrote:
> > I noticed celt 0.11.1 had released but still spice uses
> > celt 0.5.1.3 which is very old version.It is clearly mentioned in
> > Building instruction at wiki.   celt = 0.5.1.3 (this is important,
> > newer
> > versions use a different protocol)
> > 
> > Is there any specific reason why spice still uses celt 0.5.1.3?
> 
> The problem with celt is that they don't guarantee that the audio
> data
> generated by celt version X can be decoded by version Y. This means
> that
> the server running a spiced VM and the client connecting to this VM
> need to
> use exactly the same CELT version if we want to be 100% sure they'll
> understand each other.
> 
> We decided to arbitrarily settle on the 0.5.1.3 version because it's
> what
> was current at the time this decision was made. Since we want clients
> to be
> able to communicate with older servers, upgrading to the latest CELT
> version would be a bit of work.
> 
> However, they recently (with the 0.11.1 version or so) announced that
> the
> bitstream format (the format of the audio data) would be stable from
> now on
> *unless they encounter a critical flaw in it* which would force them
> to
> change it. In my opinion, this means it would make sense to start
> adding
> support for this format, marking it experimental until the bitstream
> is
> officially frozen, and keeping the 0.5.1.3 support. The protocol
> includes
> capability checks so this would be doable.
> 
> Last but not least, I'm not sure where CELT is going these days, as I
> understand it it's being merged into OPUS and all work is being done
> there.

Just a reminder that there is a 1y old patch for celt update (with caps nego), and that some distro were thinking of shipping it iirc, but I think we managed to convince them not too.

https://gitorious.org/~elmarco/spice/elmarco-spice/commit/e310493a3e5a28f4b41dbc13cfaad7f982bca651

regards