rtpsession: NACKs are not being sent

[Olivier Crête]

Hi,

It's generally the feature, the rtpjitterbuffer was meant to be a ssrc-
ignorant, but the rtpssrcdemux element will set it:
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/blob/main/subprojects/gst-plugins-good/gst/rtpmanager/gstrtpssrcdemux.c#L855

That said, for this case, I think it probably makes sense to
rtpjitterbuffer to set the ssrc.

Olivier

On Fri, 2022-08-19 at 13:33 +0400, David Grinberg via gstreamer-devel
wrote:
> So I’ve checked rtpjitterbuffer source code and it doesn’t set SSRC,
> but neither does anyone (rtprtxreceive, rtpssrcdemux etc). Is this a
> bug?
> 
> https://gitlab.freedesktop.org/gstreamer/gstreamer/-/blob/main/subprojects/gst-plugins-good/gst/rtpmanager/gstrtpjitterbuffer.c#L4136
> 
> > 19 авг. 2022 г., в 13:13, David Grinberg <green.grinya at gmail.com>
> > написал(а):
> > 
> > Setting profiles and payload map didn’t help :( 
> > But I’ve found out that GstRTPRetransmissionRequest does not
> > contain SSRC. For now a trivial fix is to manually set it inside
> > some probe, but it would be nice to know why that happens, my guess
> > is that it is rtpssrcdemux (which i dont use) who sets ssrc
> > 
> > > 19 авг. 2022 г., в 00:28, Olivier Crête
> > > <olivier.crete at collabora.com> написал(а):
> > > 
> > > Hi,
> > > 
> > > It seems like you are completely right that it's not used.
> > > 
> > > Your code also seems to be missing the "payload-type-map"
> > > property on
> > > the rtxrtpreceive element, but that shouldn't prevent the
> > > requests from
> > > being sent.
> > > 
> > > I think you also need to set the rtp-profile property on
> > > rtpsession to
> > > avfp or savpf.
> > > 
> > > Olivier
> > > 
> > > > On Thu, 2022-08-18 at 23:43 +0400, David Grinberg via
> > > > gstreamer-devel
> > > > wrote:
> > > > Hi, I’ve already asked my question here -
> > > >  
> > > > https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1386
> > > > 
> > > > Suggestion of adding rtcp-fb-nack=(boolean)true didn’t work,
> > > > also
> > > > there isn’t any reference to rtcp-fb-nack in rtpsession code
> > > > (though
> > > > it is used by webrtcbin). 
> > > > The problem is that find_source fails and I don’t really know
> > > > why
> > > 
> > > -- 
> > > Olivier Crête
> > > olivier.crete at collabora.com

-- 
Olivier Crête
olivier.crete at collabora.com