[mythtv] Input switching question

Jerry Rubinow jerrymr at gmail.com
Wed Feb 15 22:19:09 UTC 2006

On 2/15/06, David Engel <gigem at comcast.net> wrote:
> On Wed, Feb 15, 2006 at 12:37:56PM -0800, Bruce Markey wrote:
> > In the core scheduler logic there is nothing new or difficult. The
> > opposite case of a DVB card able to record two streams from the
> > same card has often been discussed with the assumption that this
> > would be a radical change for scheduling but that isn't true either.
> Bruce is bang on here.  FWIW, some of this has already by thought
> about, there just hasn't been a need for it yet.
> > only one can be used. For illustration, I'll use letters for 'input
> > groups'.
> This also fits in somewhat with one of the ways I've considered
> supporting analog and digital on a single DVB card like my Fusion
> HDTV5.  Note the following change to your example.
> > Card Type input inputid source  InputGroup
> >
> > 1    bttv coax      1   cable        A
> > 2    ivtv coax      2   cable        B
> > 2    ivtv s-video   3   STB-cable    B
> > 3    DVB  DVB       4   DVB          C
> > 3    DVB  DVB       5   DVB          D
> > 4    HD   HD        6   STB-firewire B
>   5    DVB  coax      7   cable QAM    E
>   6    v4l  coax      8   cable        E
>   6    v4l  s-video   9   STB-cable    E
> Cards 5 and 6 are physically the same card.  It is split into two
> virtual cards because Myth doesn't support multiple types for the same
> card.  IG E is used to make sure that only 1 of inputs 7, 8 or 9 can
> be used at a time.
> IMHO, the hardest part of all of this is the local/remote encoder link
> changes that would be needed.  Currently, when a recording is started,
> the scheduler fires off a command to that card to stop whatever you
> are doing and start recording this.  With IG changes, the "stop
> whatever you are doing" would no longer only cross inputs on the same
> card, it could inputs on different cards and even cards in different
> backends.
> David

Why is that?  If the scheduler wants to start recording on (in the
above example) card 2 ivtv s-video, in IG B, it can only do so if the
other inputs in IG B (ivtv coax and HD) are already not busy, right? 
If they're not busy, the scheduler only needs to send the "stop
whatever you're doing" to the particular input it wants to use.  If
the other inputs in the IG are busy, it wouldn't be sending the signal
in the first place.

What am I missing (I'm assuming there's something)?


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