[mythtv-users] Quick and dirty workaround

Bruce Markey bjm at lvcm.com
Thu Aug 5 15:29:49 EDT 2004

Matt Morgan wrote:

> Thanks. I guess it seems strange to me only because I can't imagine why 
> I wouldn't want it to do that. In other words, shouldn't mythtv just 
> default to that, when I'm using an external channel changing program? 
> That's a rhetorical question, don't worry about answering it.

If you're using the tuner input it should assume that it is used
for tuning to the channel. If you are using coax from an external
tuner (VCR, cable box) it still needs to know the preset channel
for the signal.

Low channels are more susceptible to interference so most cities
have either a channel 3 or channel 4 but not both. Devices that
have a coax output have a switch or option to choose 3 or 4 as
the output. If you have to use a coax input, you have to tell
myth which preset channel to use and that is why this option

Since you use 3, I assume there is likely a channel 4 in your area.
If you tune your regular TV to 3 without the cable box, you'll
probably see a snowy image of channel 4. The coax uses a carrier
signal on a frequency which will be affected by this interference
which degrades the signal. S-video or composite do not use a
carrier frequency but have a simple analog amplitude and don't
have this problem and don't have to be tuned to a frequency.

> I guess you're saying, if I did it that way, mythtv would know that I'm 
> tuning wih the external tuner and not try to tune on the TV card. Wihch 
> would solve my immediate problem, the one you're answering. But in the 

Again, you have to tell it what preset frequency the tuner needs
to be tuned to which is what this option does.

> The only reason I used coax is because it's, as far as I know, the only 
> way to get output from the cable box with only one cable. Because 
> S-video does not carry audio. And I like the tidiness of having only one 
> cable. And then my tuner card (PVR-250) doesn't have other audio input, 
> at least I can't see any, so I didn't know where to plug in the 
> audio-out component cables anyway, if I used S-video for the video.

If it has s-video or composite inputs it has to have an audio
input also. It's a stereo mini-jack, the hole that isn't the
IR input for the remote. you can get a cord with the video and
audio cables bundled together at any electronics store. You also
need a two female RCA to male stereo mini-jack adapter.

--  bjm

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