[FFmpeg-devel] [PATCH] Initialize ssrc properly in the RTP muxer

[Reimar Döffinger]

On Sun, Mar 28, 2010 at 11:50:04AM +0300, Martin Storsj? wrote:
> On Sun, 28 Mar 2010, Michael Niedermayer wrote:
> 
> > 
> > On Sun, Mar 28, 2010 at 01:23:48AM +0200, Martin Storsj? wrote:
> > > On Sun, 28 Mar 2010, Luca Abeni wrote:
> > > 
> > > > Hi Martin,
> > > > 
> > > > On Sat, 2010-03-27 at 20:43 +0200, Martin Storsj? wrote:
> > > > > When transmitting multiple RTP streams, their SSRC values should be 
> > > > > unique. Currently, the RTP muxer has this hardcoded to 0. The attached 
> > > > > patch replaces this (and also sets base_timestamp) using 
> > > > > ff_get_random_seed().
> > > > 
> > > > Both ssrc and the initial timestamp used to be set with random(), but
> > > > this has been changed because of security issues. If security people
> > > > agree that ff_random_get_seed() can be used here, then I am of course ok
> > > > with this patch.
> > > 
> > > Ok - if ff_random_get_seed() isn't allowed, av_gettime() or whatever is ok 
> > > for me, too, as long as multiple streams don't have the same SSRC...
> > 
> > leaking the system time might not be ideal
> > 
> > ff_random_get_seed() should be ok though
> 
> Ok, applied.
> 
> And leaking the system time is more or less required (and done for other 
> fields already) in RTP anyway, since it sends current realtime timestamps 
> for all data anyway...

IIRC only the delta is required. Also its precision can be reduced to be non-critical.