[Libav-user] Decoding RTP streams with in-band SDP

Eric Reichert ereichert at trafficland.com
Fri Sep 16 16:06:05 EEST 2016

On 9/16/16, 8:30 AM, "Libav-user on behalf of Carl Eugen Hoyos" <libav-user-bounces at ffmpeg.org on behalf of ceffmpeg at gmail.com> wrote:

    2016-09-16 14:24 GMT+02:00 Eric Reichert <ereichert at trafficland.com>:
    > The streams I’m working with are of the Annex B variety.
    I would have expected that the rtp specification for H.264
    requires the video stream not to be in this format, am I
    Can you provide such a stream (or even better a patch
    to FFmpeg that allows to create a stream so a possible
    fix can be tested)?
    Carl Eugen
    Libav-user mailing list
    Libav-user at ffmpeg.org

RFC 3984/6184 do not prescribe Annex B.  The old version of our software has to convert the 3984/6184 formatted H.264 into the Annex B format in order for (the ancient version of) FFMPEG to decode the video.  That is, the old version of our software parses the RTP, reassembles the NAL Units from the fragmentation units, and adds the start codes before submitting the NAL units to the decoder.

Does that answer your question?  It could be that I don’t understand the question or the specs well enough.

As far as providing a stream, I can provide tons of network captures carrying streams of that type.  How shall I get them to you?

Regarding a patch, it would be months before I could get anything submitted.  My C skills aren’t great and I don’t know the FFMPEG codebase that well.

By the way, thanks for the help and your continued work.  You’ve got a tough job answering all the questions.

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