[mythtv] DVB todo list (was: DVB & mythchannels)

Kenneth Aafloy ke-aa at frisurf.no
Mon Aug 18 15:18:00 EDT 2003

Edward Wildgoose wrote:
> > Another addition to the todo-list: channel changing in LiveTV is slow. 
> > Kenneth wanted to get exact numbers, where exactly it's spending the 
> > time and what's the culprit.
> The time is consistent with changing a DVB channel, plus some time to
> buffer the output.  ie mythtv is not instant changing on analogue,
> the time taken with DVB seems to be the time taken under analogue PLUS
> the time taken to retune the DVB.  
> It's not clear to me why DVB takes so long to retune, especially when
> the channel is on the same mux anyway... Seems to be constant time
> regardless of whether you are tuning to the same stream or a different
> stream.  I suspect things can be done to improve this at the driver level
> for example.

The tune_it in libdvbdev is slow (~1200ms on my system), which I got down
to ~400ms (~10ms on the same mux) by redoing it in dvbchannel
(just dropped that function). I have not had a chance to rework this to
Ben's requirements for inclusion into CVS.

It also does not deal with anything other than DVB-S.

I'll try to make some changes to the tune_it function instead,
and submit those changes sometime in the future.


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