[Live-devel] Delay problem of the first RTCP "SR" packet

[Steve Ha]

Hi David,
The RFC-6051 seems good for quickly synchronization, but it requires a big
effort to adapt to the current library and I am not sure if it is worth
enough to do so.
I don't understand your issue well so I have no idea. Sorry.

Steve.

On Fri, Jan 22, 2021 at 8:44 PM David Gessel <gessel at blackrosetech.com>
wrote:

> Steve,
>
> I am having some issues with sync due to either late or ignored SR packet
> timestamps. Ross provided a really good answer to my question - to which I
> owe a response and am working toward (side-quests have intervened as a
> kernel update once again broke my e1000e network driver and this time the
> fixes are not fixin' the problem - totally irrelevant to this).
>
> In any event there is a standard defined to extend the RTP packet
> structure to include NTP time stamps, RFC 6051, precisely to enable more
> rapid synchronization of multi-source RTSP streams. I feel Live555 would
> benefit from at least having the capability of optionally adding RFC6051
> NTP header extensions.
>
> -David
>
>
>
> -------- Original Message --------
> Subject: Re: [Live-devel] Delay problem of the first RTCP "SR" packet
> From: Ross Finlayson <finlayson at live555.com>
> To: LIVE555 Streaming Media - development & use <live-devel at us.live555.com
> >
> Date: 2021-01-22 10:01+0300
>
> >
> >
> >> On Jan 22, 2021, at 4:05 PM, Steve Ha <steveha at u2sr.com> wrote:
> >>
> >> My question is how can I force the first RTCP "SR" packet to be
> delivered at the same time as the first RTP packet so that the RTSP client
> could get all frames with correct PTS?
> >
> > Basically, you can’t.  (But even if you could, there’d be no guarantee
> that it would be received, as it (like all RTCP (and RTP packets) are
> datagrams.)
> >
> > However, our RTSP server implementation *does* send an initial RTCP
> “SR”, before the first RTP packet, precisely for this reason.  (See
> “OnDemandServerMediaSubsession.cpp”, line 550.)
> >
> >
> > Ross Finlayson
> > Live Networks, Inc.
> > http://www.live555.com/
> >
> >
> > _______________________________________________
> > live-devel mailing list
> > live-devel at lists.live555.com
> > http://lists.live555.com/mailman/listinfo/live-devel
> >
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