[streaming] Re: Streaming from raw MPEG-4

[Johann Ransay]

On Friday 24 November 2006 18:47, Jeff Poole wrote:
> On Wed, November 22, 2006 4:44 pm, Nico Sabbi wrote:
> > Jeff Poole wrote:
> >>nc -l -p 3975 -u | mplayer -
> >>(tell netcat to listen for udp traffic on port 3975, and then pipe that
> >> to
> >>mplayer which reads from stdin)
> >
> > twisted
> >
> >>It usually spits out a few errors until it actually detects a header (I
> >>believe it's VOL headers that keep getting sent) and then it starts
> >>playing the video perfectly.  But I don't know of a way to get MPlayer to
> >>stream it back out.
> >
> > mplayer udp://ip:port
>
> I thought that just made mplayer read the data from UDP, not stream it
> back out?  If you are trying to give me an easier way to get the data into
> mplayer, I should point out that I tried that and it didn't seem to work.
> Looking at the data more, it appears that the data stream starts with a
> VideoObject, containing a VideoObjectLayer...and those headers repeat
> regularly, presumably to allow one to connect in the middle of a stream.
> But there is no VisualObject header, and I believe that is a problem.  I
> think mplayer seeks until it finds some sort of header it can use, and
> then tries to make the best of it.  But a more strict decoder would
> probably look for the VisualObject header, ensure that the type is "0001"
> (video), and then move from there.  Especially since the spec says you can
> only repeat VideoObjectLayer headers in video, a decoder would want to see
> that before it would think the stream looked valid.  At least, that's my
> view -- I'm no expert.  Maybe I need to wrap this thing in a VisualObject
> and maybe try to put it in an RTP stream for VLC to take in?  Would RTP be
> the easiest?  Any ideas?
>
>
> Jeff

You could probably use liveMedia libraries or modify a test program like 
testMPEG4VideoStreamer or testOnDemandRTSPServer 
(http://www.live555.com/liveMedia/#testProgs) to build a RTSP server that 
reads its data from raw MPEG-4 ES/UDP.

Johann

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