[mythtv] pcHDTV: dual input

Jason Hoos jhoos at thwack.net
Mon Dec 29 16:25:02 EST 2003

On 12/29/2003 1:30 PM, Chris Eldredge wrote:
> So now for my proposed solution:  the bttv driver declares 
> "Television" as
> the input source for the main coaxial input, but nothing for 
> the auxiliary
> input.  If the driver made available "Main Coaxial" and "Aux Coaxial"
> inputs instead, MythTV can be configured using its existing 
> features to
> correctly perform resource allocation / conflict resolution.

I looked into doing this at some point way back when, but I didn't get very
far (it wasn't my primary goal at the time).  The biggest problem from what
I recall was that the bttv driver source doesn't really have any provision
in it for dealing with multiple tuners (the data structure that defines the
card's capabilities has a single int in it that tells the driver which input
the tuner is, which would likely need to be changed to allow a list of some
sort).  The original driver doesn't have a way of dealing with multiple
antenna inputs either, although the pcHDTV version of the driver works
around that by adding a new constant to the API (videodev.h I think, or
something similar) to specify that the second coax be used.  I don't know if
there's anything in the newer V4L2 stuff to cope with multiple tuner inputs
or not.

> The disadvantage is you wouldn't be able to tune NTSC signals 
> from UHF/VHF
> antenna.  But does anybody do that?

Actually, it may already be possible to do this, although I haven't
attempted it yet.  If I remember right, recently someone added a column to
the channels table that specified whether a channel was
NTSC/PAL/ATSC/whatever, and presumably from there Myth invokes (or could be
changed to invoke) the correct class for HDTV vs. analog.  Taking that a
step further, I wonder if that mechanism could be extended (or another field
added to the channels table) to control which coax the signal came from.
Hopefully whoever made that change can comment further... :)


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