[linux-dvb] Technicalities of channel searching

[Dave Chapman <dave@dchapman.com>]

Hello,

I am slightly confused over what tuning information is _required_ for the 
DVB-S card to receive a channel, and would be grateful for some 
clarification.  (The background to these questions is my search for "feeds", 
for which not all of the tuning information is always known).

>From what I understand, the frequency, polarity, symbol rate and fec give you 
access to a transport stream, which is split into small (188 byte) packets 
identified by their PIDs.  The Siemens card seems to auto-detect the fec - is 
it possible to auto-detect the symbol rate, or do you have to test various 
symbol rates "manually"?  The latter seems to be the way that "pscan" works.

However, when searching for feeds (e.g. at 31.5W, 10967V, sr 5632, vpid 308, 
apid 256 - 1.1m dish in London), pscan-0.5 doesn't find a PMT in the stream - 
but I can tune into a clear signal using VDR.  How would I go about 
automatically searching for such transmissions?

To summarise, my question is: is it technically possible to determine what 
video and audio streams are in a TS without any further information?

Best wishes,

Dave.


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