[mythtv] Input switching question

David Engel gigem at comcast.net
Wed Feb 15 22:00:59 UTC 2006

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

David Engel
gigem at comcast.net

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