Hello,

I am trying to receive a live h.264 multicast stream.  I can view it
with VLC, but FFMPEG or my own libav-based applciation take minutes
before they can figure out what to do with the stream.  I am trying to
figure out what is different about VLC and my application.

The video comes from cameras connected to a Mango DSP-based server which
uses VLC and some other processing to stream the packets.

I can see other live h.264 multicast streams fine with FFMPEG and my
application, but they are not being streamed with this server setup.  

The vlc command line is:

vlc 'rtsp://10.10.32.200/?multicast/h264?cam=0'

This Mango server then converts those packets to the multicast address
232.0.0.11:7170.  (I'm not exactly sure how or what else it does.)

When I try to grab the stream with FFMPEG, I see h264-related error
messages right away (log linked below).  Then, after a long wait
(sometimes about 5-10 minutes), I see the output messages from
libavformat where it has detected some of the stream parameters such as
the screen resolution and time base information.  Now, I have actually a
seen a couple times where after more waiting it starts to generate
frames.

Here is an example of an FFMPEG command line I have used:

> ffmpeg -i imPath0.sdp -y  out.mp4

Here is the snippet of code that calls libav*.  It's pretty standard:

http://davehenning.com/pages/code_snippet.c

Here is the complete console log of a trial from my laptop:

http://davehenning.com/pages/impath_console_log.txt

Here is the SDP file that I used to actually generate a frame:

http://davehenning.com/pages/imPath0.sdp

I have also used this SDP file, which is generated by the server, but
that hasn't worked yet:

http://davehenning.com/pages/stream.sdp

Can anyone give me a hint on what I might need to do when invoke
ffmpeg/libav* in order to see the video consistently and in a reasonable
amount of time?  

Does anyone have an idea why VLC sees it no problem every time?

Thanks,
Dave ...


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