Unable to lock onto H.264 multicast stream from SDP file ...

headers Sandy Walsh | 27 Aug 16:52

Hi!

We have a live multicast stream initiated from another process. This 
creates the following active .SDP file:

v=0
o=MangoDSP 126 14843616424497153183 IN IP4 192.168.0.62
s=Mango DSP Audio/Video
m=video 7170 RTP/AVP 96
a=rtpmap:96 H264/90000
c=IN IP4 232.0.0.11
a=fmtp:96 
packetization-mode=1;profile-level-id=42001E;sprop-parameter-sets=Z0KAHkLaAtD0QA==,aEjgGody
a=control:__StreamID=270385256

When we try to open it with FFMpeg, it takes forever to lock onto the 
stream and/or it just hangs. With verbose output here are the last 
messages we see:

ffmpeg -v 10 -i stream7.sdp
FFmpeg version 0.5, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --prefix=/opt/local --disable-vhook --enable-gpl 
--enable-postproc --enable-swscale --enable-avfilter 
--enable-avfilter-lavf --enable-libmp3lame --enable-libvorbis 
--enable-libtheora --enable-libdirac --enable-libschroedinger 
--enable-libfaac --enable-libfaad --enable-libxvid --enable-libx264 
--mandir=/opt/local/share/man --enable-shared --enable-pthreads 
--cc=gcc-4.0
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 0 / 52.20. 0
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    1. 4. 0 /  1. 4. 0
  libswscale     1. 7. 1 /  1. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Apr 15 2009 09:26:41, gcc: 4.0.1 (Apple Inc. build 5490)
[NULL @ 0x1808600] video codec set to : h264
H.264/RTP Packetization Mode: 1
H.264/RTP Profile IDC: 42 Profile IOP: 0 Level: 1e
H.264/RTP Extradata set to 0x1319dc0 (size: 21)!

Anyone see anything blatant that would cause ffmpeg not to like this?

However, if we open the stream as unicast via openRTSP and then pipe the 
output through FFMpeg it works fine.

Could there be some sort of network packet wrapper on the stream that 
ffmpeg can't deal with, but can once openRTSP in brought into the mix 
... or could it be a unicast vs. multicast issue?

Any hints would be greatly appreciated.

Thanks in advance,
Sandy