[mythtv-users] Digital cable question?

[Ray Olszewski]

At 03:20 PM 10/22/2003 -0700, Nick Deng wrote:
>It sounds dumb, but I post it anyway. My impression is my cable (digital) 
>signal comes from the
>box, so my mythTV just may not work as it is supposed to  (scheduled 
>recording, I meant)?
>
>Please give me some clarification, although it is kind of a simple if not 
>stupid

Not a stupid question, but a FAQ nonetheless. I don't recall if the Myth 
HowTo addresses it in basic enough form (if not, perhaps it should), so let 
me try once more here.

If your TV signal comes through a digital-cable box, or a satellite-TV box, 
you cannot use the built-in tuner of the video-capture card in your MythTV 
backend to select channels. Instead, you need to connect the external 
device to appropriate ports on the MythTV backend's video-capture card; 
this usually means Composite-In and associated audio (the familiar trio of 
red-white-yellow RCA plugs), though some devices may support S-Video 
connections. Then you need to change channels on the external device.

In principle, you can use MythTV to change channels on your external 
(digital-cable or satellite-TV) device in either of two ways.

One, an "IR blaster" device can be used to output infra-red signals that 
correspond to the ones used by the external device's remote control. Myth 
uses the Linux application "lirc" to do this. Section 8.7 of the Myth HowTo 
has some information about this option, though you will probably need to 
search the mythtv-users list archives and the information at the lirc home 
site (http://www.lirc.org/) for moe information about how to make this 
work, espedially with newer hardware than what the Myth HowTo covers.

Two, some external devices can be controlled by a serial connection between 
them and a device like a MythTV PC or a commercial DVR (e.g., a TiVo). 
Exactly what (if anything) will work for you here depends on the details of 
your external hardware. Your best bet is to find out the exact model of 
external device you will be using and search for information specific to it 
in the mythtv-users mailing list archive.