[FFmpeg-devel] [PATCH] sdp: Emit only one c= line for multiple streams, if they have the same destination

Martin Storsjö martin
Thu Oct 7 10:36:50 CEST 2010


On Wed, 6 Oct 2010, Martin Storsj? wrote:

> On Wed, 6 Oct 2010, Luca Abeni wrote:
> 
> > On 10/05/2010 03:52 PM, Martin Storsj? wrote:
> > > On Tue, 5 Oct 2010, Luca Abeni wrote:
> > > 
> > > > I'll have a look at this patch later (or tomorrow). Can you provide an
> > > > ffmpeg command line generating an SDP that vlc cannot read?
> > > > (I never managed to produce such SDPs, and I use ffmpeg to stream
> > > > sessions with multiple streams almost dayly).
> > > 
> > > Hmm, yes, when storing the SDP to a file and playing it from there, it
> > > seems to work ok.
> > > 
> > > In my case, I'm sending the SDP over SAP (RFC 2974), and in that case, VLC
> > > refuses to play it unless there's only one c= line.
> > 
> > Uhmm... Is this a vlc (or live555) issue/bug? Last time I played with SAP,
> > I do not remember it adding any constraints to the SDP (so, every valid
> > SDP should be accepted...).
> 
> Probably a live555 issue. I don't know of any additional constraints 
> either.
> 
> If sending multiple streams to vlc/live555 in the same SDP, they must also 
> both be sent to the same port(!), but that's of easy to enable/disable 
> with an option in the SAP muxer.
> 
> > Anyway, even if this is a vlc bug I am ok with adding a workaround. So,
> > the patch is good in principle; the code also looks good. But I'd like
> > to have a better look at it first... Give me 1 day or 2 :)
> 
> Ok, no problem.

As stated in the other thread, this patch seemed to be based on an 
incorrect conclusion while debugging, so patch dropped for now.

// Martin



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