[linux-dvb] How to handle multiple frontends?

Ralph Metzler rjkm at metzlerbros.de
Sun Jan 14 21:29:30 CET 2007

Klaus Schmidinger writes:
 > I'm wondering how an application is supposed to handle
 > devices with multiple frontends.
 > Let's assume a device that provides
 >   dvb/adapter0/frontend0        DVB-S
 >   dvb/adapter0/frontend1        DVB-T
 > so that it can receive both DVB-S and DVB-T. Does this
 > mean that it can simultaneously receive one DVB-S transponder
 > and one DVB-T transponder? Or can it receive either a DVB-S
 > *or* a DVB-T transponder, but not both at the same time?

Hmmm, good question. I only have some devices which can do 
simultaneous reception. But I think there are some with 
different tuners sharing TS outputs as well.
Since the open is not handled by the driver itself we also cannot lock
the frontend accesses against each other.

Maybe those should be handled like one multi-protocol frontend?
Not sure if Manu's multi-proto stuff would also handle this across
different tuners. We would need another layer of abstraction.

Or should just the demuxes lock against each other? So, if one 
demux has filters set, the other one will not accept any.
I guess the frontends themselve work at the same time, they 
just share the same TS input?

We'll definitely need some better input handling for those new cards.
E.g. if you have 2 demuxes connected to 2 frontends or data from the
PC, 1 or 2 decoders on the card, one or more of those new USB CAMs serving
one of several cards, etc. 
I'm starting to do some hacking with something like modified V4 API +
multi-proto frontends + other goodies ...


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