[Libav-user] FFPlay (and VLC) cannot process av_sdp_create()'d SDP file for RTP stream

[Weiß Christoph]

Dear all,
I'm using the FFMpeg development libraries to generate an embedded application streaming camera images via RTP. My current example is based on the muxing.c example from FFMpeg 2.7. I use the av_sdp_create to dump the SDP before avformat_write_header and the program streams RTP packets indefinitely afterwards. With a little work, I'm able to extract a video file from packets received on the destination in Wireshark.
The content of the generated SDP is:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 224.1.1.1
t=0 0
a=tool:libavformat 57.25.100
m=video 5555 RTP/AVP 96
b=AS:400
a=rtpmap:96 MP4V-ES/90000
a=fmtp:96 profile-level-id=1
However, when I try to receive the video with ffplay, I get the following messages:
[sdp @ 0xb0400480] Could not find codec parameters (Video: mpeg4, yuv420p)
[sdp @ 0xb0400480] Estimating duration from bitrate, this may be inaccurate
test.sdp: could not find codec parameters

Is there anything missing in this SDP?
I also tried to receive the stream with VLC with the same depressing result. I also tried to use other codecs (mainly MPEG2VIDEO) during transmission, the received RTP packets seem correct in Wireshark, but playback also fails. I am at a loss about the SDP.


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