[FFmpeg-devel] Extracting NTP timestamp from RTCP

Fred Rothganger frothga at sandia.gov
Tue Oct 22 19:06:14 CEST 2013

Greetings FFMPEG developers!

It has been many years since I lurked this list, and perhaps few of you 
will remember me after all this time.

I am working on a server that stores video from multiple IP cameras and 
gives out clips based on time-of-day when the recording started. I need 
to get the absolute timestamp contained in the RTCP messages from the 

It seems the simplest way to do this is to read the field 
RTPDemuxContext.first_rtcp_ntp_time (libavformat/rtpdec.h). Right now I 
have an incredibly bad hack in my own code which includes copies of all 
the necessary structs to upack the data (since these are not part of the 
public interface).

I would like to do this in a much cleaner manner. In order of preference:
* You tell me there is already an interface for it, and I am an idiot to 
have missed it.
* I add the necessary AVOption structures to get at it, and submit a patch.

Please advise.

-- Fred

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