[vlc-devel] RTSP-Streaming, frames dropped when RTCP sender report arrives

Rémi Denis-Courmont remi at remlab.net
Wed Jun 8 11:02:25 CEST 2011


On Wed, 8 Jun 2011 10:09:53 +0200, Max Göttner - d.stream
<max.goettner at dstream.de> wrote:
> is there a known bug concerning the following issue?
> I receive a RTSP 4000kbit mpeg4 / h264 stream without transcoding from a
> camera via UDP. My LibVlc version is 1.1.9. I observe that camera and
> client exchange RTCP sender report and receiver report packets at
> intervals. However if and only if the first sender report arrives one or
> two frames are not written to the video-file, although the according udp
> packets arrive.
> Any suggestions? Thanks in advance.

A/V synchronization is not reliable until after the first RTCP-SR has been
received by the client. Normally, well behaved RTSP server should send an
RTCP-SR packet immediately when the RTP session is first setup to avoid
this. See RFC6051 for more details, especially §2.1.1 for RTSP.

Rémi Denis-Courmont

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