[mythtv] Ticket #7818: allow preffered input group forscheduling

David Engel david at istwok.net
Wed Dec 30 04:27:29 UTC 2009


On Tue, Dec 29, 2009 at 07:23:41PM -0500, Daniel Kristjansson wrote:
> On Tue, 2009-12-29 at 17:34 -0600, David Engel wrote:
> > cardid/cardinputid is a hold over from days gone by, but it is still
> > used for analog cards.  For example, many (most?) analog cards support
> > tuner, s-video and composite inputs, but only one can be used at a
> > time.  To handle this, the scheduler considers all inputs with the
> > same cardid as implicily belonging to the same input group.  That
> > could probably be done completely with inputgroups now, but the
> > configuration would be tedious.
> 
> If it would speed up the BUQ it could certainly be done behind the
> scenes. Even in the digital world there are multi-input cards some
> of which allow simultaneous use and some which do not. We haven't
> had to deal with that with respect to the DVB drivers, but only
> because they don't support the concept yet. My hope is that the
> Linux DVB API will eventually catch up with Linux V4L API.

I doubt it would have any effect on speed.  In all of my past testing,
the time spent in the BUQ has been dominated by the join on
oldrecorded to check for duplicates.  Something causes mysql to be
inefficient when comparing subtitle and/or description, at least in a
join condition.  

Hmm, I just noticed *.description is defined as text.  I wonder what
impact it would have if it was changed to varchar.  A very quick
google indicates there might very well be a noticable performance
difference between text and varchar in mysql.  I've made a note to try
it when I get a chance.

Back to the capturecard vs. cardinput issue, I think it's worth
looking into eventually doing away with inputs just to clean things
up.  We have to have inputgroups to handle inter-card conflicts so we
might as well use them for all conflicts.

David
-- 
David Engel
david at istwok.net


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