[linux-dvb] Re: Suggestion for channel tuning

[Felix Domke <tmbinc@gmx.net>]

> Has anyone else had any experience of tuning like this?  It seems to me
that
> ISO-13818 is implying that the only parameters needed to tune a channel is
> the service_id.  This makes sense to me - at least on Astra 28, the
channels
> change PIDs quite frequently.
Hm i thought one need the network_id (or even transponder_id?) as well, but
i'm not sure.

at the moment i'm storing a list of transponders (with transport_stream_id,
network_id and frontend-specific tuning parameters - one could get them via
the NIT, i think, but that's very slow then... the en300468 says that one
could (or should) store the NIT for faster tuning, which implies for me that
it's the only thing one should cache.), together with a service list
(service_id, service_name and service-type).

if the user selects one channel, i first tune to the transponder, get the
PAT, PMT and then tune in the channel.

i think it may make sense to store some "default" pids there, for faster
zapping. if there are other PIDs given in the PMT, one could change after
reading the PMT and store them as new default settings.

one HAVE to go trough the SDT to support, for example, NVOD the correct way.

but my code still sucks, because it waits too often and slows down the whole
thing (especially user input).

i'm thinking of rewriting it so i use a event-driven mainloop (like the
glib), where one can read the tables in the background (especially the EIT),
handling user input and, for example, have some kind of callback (or
signal/slot) when the EIT data is there to display it. there could be
another signal which informs the decoder of changed PIDs (maybe they change
WHILE we're looking that channel?)

there is somehow no real open-source library that does this properly.

maybe we could write such a library, based on the nokia-api and maybe QT
(without that gui-stuff of course), since i don't like gtk/glib really much
(too much OO C-code ;), but maybe gtk is better, we'll see.

bye,
felix domke



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