[gst-devel] RTPBIN lip sync problem with delayed RTCP

[Wim Taymans]

On Mon, 2008-08-04 at 17:22 +0530, Rahul Mittal wrote:
> Hi Guys,
> 
> 
> I am writing this application that takes in an RTP live stream as an
> input using RTPbin.
> 
> The problem i am getting is that if the RTP packets are received
> before any RTCP packet than no offset is calculated ( since there is
> no RTCP) and all the RTP packets received before the first RTCP packet
> are pushed further down the pipeline without any offset applied to
> their timestamps.
> 
> Shouldnt all these initial RTP packets be buffered or dropped till we
> calculate the offset?
> 
> This induces lip sync issue with all the initial packets. Can somebody
> suggest on what should be the ideal way to do it.

Dropping packets before receiving RTCP is not always desirable, RTCP
packets could simply never arrive. The way RTP sync works is that you
perform a best-effort sync until you get the RTCP packets for both
streams.

That said, I would not object to adding a property to rtpbin to drop
packets before all streams received sync info (off by default). 

Wim

> 
> Thanx 
> 
> Rahul
> 
> 
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