Reading RTCP packets from an IP camera using FFMPE

问题:

I am using the ffmpeg C library. I need to intercept RTCP packets from the camera in order to get the timestamp from the Sender Report. Is there any method or structure in the ffmpeg that gives me this information? I am completely stuck but I am not able to solve that problem.

Any help will be appreciated. Thanks in advance,

回答1:

Finally I had to hack into the ffmpeg library like this:

        // Patch for retrieving inner ffmpeg private data
        RTSPState* rtsp_state = (RTSPState*) context->priv_data;
        RTSPStream* rtsp_stream = rtsp_state->rtsp_streams[0];
        RTPDemuxContext* rtp_demux_context = (RTPDemuxContext*) rtsp_stream->transport_priv;

        // Decode the NTP time from the 64 bit structure
        uint64_t ntp_time = rtp_demux_context->last_rtcp_reception_time;
        uint32_t seconds = (uint32_t) ((ntp_time >> 32) & 0xffffffff);
        uint32_t fraction  = (uint32_t) (ntp_time & 0xffffffff);
        double useconds = ((double) fraction / 0xffffffff);

And I finally get timestamp information.