[mythtv] dvbsections.cpp / dvbchannel.cpp Changes In Progress

Taylor Jacob rtjacob at earthlink.net
Wed Aug 25 10:14:04 EDT 2004

> On Sun, 22 Aug 2004, Taylor Jacob wrote:
>> The channels table will add a few fields for each service.  (ServiceID,
>> Reference to dvb_transport, pmtcache (which will be removed later on
>> when Auto-PID functionality is tested and working for dvbcam
> I'd say that even when Auto-PID works, leave in a PID cache to speed up
> channel changes.

The more I have looked into this I am begining to wonder what makes channel changes take so long. 
I have been able to get the current PAT almost instantly upon a LOCK being obtained by the tuner,
and I tried last night for a few hours on MANY different services.. Feed transponders, true TV

I am starting to wonder if either the current code for pulling the PAT/PMT is making it take as
long as it does, or if locks on the db connection are slowing it down..  I need to run some more
test to determine if this is true, but so far it seems like there is no reason to not always use
Auto PID.  It also could be just opening the PIDs and starting the RingBuffer up, but I don't have
a non-dvb card in my system setup right now so I don't know what an average channel change time is
in general for myth.

Also by always capturing the PMT you can find out if a service has moved with the
ServiceMoveDescriptor, and make the tuner re-tune before the recorder gets fired off (since this
would all be happening in Channel), where as if you just read a cached copy from the Database and
tune to those PID you might completely miss the program.  This also could be a trigger down the
road for a rescan of the services available on the network.

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