[linux-dvb] UDP encapsulated MPEG{2,4} TS into dvbsnoop?

Nico Sabbi Nicola.Sabbi at poste.it
Fri Oct 12 11:04:51 CEST 2007


Il Friday 12 October 2007 10:43:01 Alexander E. Patrakov ha scritto:
> Sigmund Augdal wrote:
> > payload type 96 and 97 is in the "dynamic payload type" range
> > according to current rfcs.
>
> OK.
>
> >> The question is, still, how to play this.
> >
> > To play it you will need a SDP that describes what the ESes is.
> > My guess is that is is in fact some kind of VOD service and not
> > actually convensional TV.
>
> The names in the "scan" output do correspond to well-known TV
> stations.
>
> I have tried to extract the RTP payload from the dump using a
> simple C program. The result is that the payload of each packet
> starts with the same bytes (another header?). I tried to guess the
> length of this header and remove it (tried all even lengths between
> 0 and 20 bytes), and then decode the result as raw mp2, mp3, aac,
> mpeg4, h261, h264 and h264 data with ffmpeg. No luck yet, although
> the h261 codec announces the frame size (apparently for cellphones)
> and refuses to decode further.
>
> What to do next?


if in the SDP of the broadcast transmission there's some kind of
configuration (base64-encoded) string (generally known as
"extradata" ) then you won't get ffmpeg (or any other decoder) decode
the raw ESs without passing the extradata before feeding it the
payloads.
This is the common practice for that abomination that is RT[SC]P,
which encourages this splitting between extradata and payloads
even for formats that may have headers in-stream like H26x and
Mpeg4.

Your best best is to use ffmpeg or vlc directly on the udp:// or 
rtp:// transmissions you receive from the dvbnet interface



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