[mythtv-users] Multi-Standard support

Rod Smith mythtv at rodsbooks.com
Thu Dec 6 16:33:04 UTC 2007

On Thursday 06 December 2007 10:22:49 Keith Akins wrote:
> Thanks for the input.  I was afraid of that.  I have zero experience with
> Linux.  Without knowing the MythTV program at all (a friend just directed
> me here last night) it seems like once you set the backend for NTSC, that's
> what you get.  I'm wondering if you can have two back ends, with seperate
> cards on them, or even looking at the same tuner card, accessed by one
> front end...  Guess I should download the program and fiddle around with it
> a bit.

I don't know of any way to have two backends control a single tuner card. If 
you were to somehow finagle in a configuration that would do this, I'd expect 
it would be dangerous, in the sense that both backends might try to access 
the tuner at the same time, which would almost certainly not work.

I just checked and found that the backend configuration utility has an overall 
setting for NTSC vs. PAL (or other formats). I didn't notice any obvious 
overrides for this in the tuner or inputs screens, although there is a 
setting for the input frequency table (US broadcast, US cable, etc.). I don't 
know if the overall setting applies to ALL the backends or if you could set 
one backend to function on NTSC and another on PAL. If so, you could set up 
two backends to do the job. It might even be possible to get one backend to 
function inside a virtual machine, thus using just one computer for the task. 
This would be a very advanced configuration for a Linux newbie to attempt, 

If most of your recording would be via one format and you just want to record 
one or two items a week in the other, you could set up MythTV for the 
dominant system and then use another program or even a set of scripts to 
handle the other one using a dedicated tuner. MythTV would ignore this tuner, 
and you could drop the recordings from it into the MythTV videos directory. 
This would obviously not be as convenient as having a fully integrated 
system, but it might be an acceptable compromise if you don't want to record 
a lot off of the secondary system.

On the output end, you shouldn't have problems. MythTV automatically detects 
the video format and autoconverts it to whatever your TV or monitor uses. 
I've watched videos that originate on PAL systems, with 25fps frame rates, on 
my NTSC TV here in the US. With most videos, this causes no problems; 
however, I have seen one or two PAL videos that yield somewhat jerky motion. 
I've never gone the other way, so I can't promise it would work equally well.
Rod Smith

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