[mythtv] RFC: Dealing with overlapping video-sources/channels

[Michael Kedl]

Well, I can say I want to do the exact same thing you do and have been
putting it off.

I have the 2nd tuner card (one for tuner and one for svideo) and the
cable spicket and wondered about exactly this issue.

I'll try to think about it some and make some useful comments later; but
my gut feeling is you will need the detailed mapping to make things work
for everyone.  For instance off air tuners can pick up maybe 10 channels
around here, all on the cable except one.  And of course the numbers are
totally different.   And the HDTV guys (when they get it working) will
want to make those channels in as "preferred" instead of off cable.

I'm not quite sure how to tie that all in with the EPG yet either.  I
haven't tried setting up two different sources for channels.

Cheers,
Mike

On Wed, 2003-04-02 at 10:25, Geoffrey Hausheer wrote:
> I have two overlapping video sources setup in myth:
> analog: 1-98
> digital: 1- 600
> the 1-98 channels are identical with a few exceptions (there are some
> channels on the 'analog' that  I can't get with 'digital)
> I am attempting to use my tuner-card for the analog section, and use the
> S-Video in with an IR-Blaster controlling  my digital cable box for the
> digital channels.
> 
> Myth is not particularly happy with this setup though.  It  has no
> knowledge that channel '2' on analog and channel '2' on digital are
> identical, so they both show up on the listing, and when I choose to
> record 'Any showing on this channel' it will assign it to always record
> off either the analog or the digital, and it won't pick the best one for
> the given showing.  The whole point of this setup is to let me record 2
> programs at the same time, so I'd like myth to choose whichever one is
> not recording at the moment.
> 
> This seems to be a limitation of the way channels are stored (using
> unique channel-ids...so channel 2 is either 1002 or 2002), and since myth
> always refers to a channel by its ID, it  has no way of knowing  they are
> the same.
> 
> So I'm soliciting suggestions as to how to fix this.
> 
> I had two ideas about it:
> 1) Use an equivalence table that maps equivalent channel-ids.
> 
> 2) Create non-overlapping video-sources (in my case 'common',
> 'digital-only', 'analog-only') and allow a video device to be attached to
> multiple sources.
> 
> option 2 is much easier to implement, however is has some drawbacks: 
> specifically, fine-tuning/brightness/etc will only be defined once, so if
> 2 capture cards need different tuning adjustments, we're out of luck. 
> The solution would be to create a new table which has only fine-tuning
> information per-source, and leave the accessible channels in a different
> table.
> 
> option 1 is more flexible (I could map channel 512 as being equivalent to
> channel 2 for instance), but defining the equivalence table in a way that
> is easy to access may be tricky (it either needs to be referenced per
> 'real' channel, or be cross-referenced with all cannel-ids), and it
> requires a lot of modifications to the source to support the lookups.
> 
> Also to keep in mind is allowing a preference. I'd prefer that myth try
> to use the analog tuner when watching livetv, since it can change
> channels much more rapidly, but obviously if I want to watch channel 230
> it needs to switch to digital.
> 
> .Geoff 
-- 
Michael Kedl <kedlm at knology.net>