WebRTCBin: weird delay before stream starts

[Nirbheek Chauhan]

On Thu, Mar 24, 2022 at 1:09 PM Florian Echtler <floe at butterbrot.org> wrote:
>
> On 24/03/2022 07:46, Nirbheek Chauhan wrote:
> > On Thu, Mar 24, 2022 at 3:00 AM Florian Echtler <floe at butterbrot.org> wrote:
> >> Therefore, I've tried to just set the config interval to 1 (1 second) right now,
> >> and that seems to have made quite a difference - thank you!
> >
> > You're welcome!
>
> 😁️👍️ BTW, how does the browser figure this out if the information isn't in the
> H.264 stream at first? "Sideloading" from the SDP?
>

Some SPS/PPS information is in the SDP, but browsers also rely on
getting the information from the H264 bitstream. I can't say why
things worked in the other cases without looking deeper.

> >> One partly-related follow-up question: I've originally taken the pipeline
> >> description from a bit of webrtc-bin example C code, but I've never fully
> >> understood the reason for having two queues with exactly these max-size
> >> parameters. Could you (or anyone else) fill in a bit of detail here?
> >
> > I don't think those parameters are needed. Where did you see that?
>
> https://gitlab.freedesktop.org/gstreamer/gst-examples/-/blob/master/webrtc/sendonly/webrtc-unidirectional-h264.c#L242
>

I suspect that it's needed there because of v4l2src, but I am not sure.

> Based on the other examples I've seen, it's still a good idea to wrap the
> encoder between two queues, correct? (just maybe not with these parameters)
>

Yes.

Cheers,
Nirbheek