[mythtv-users] Multi-Input Cards

Brian Wood beww at beww.org
Sat Sep 11 14:32:34 UTC 2010

On Saturday, September 11, 2010 08:14:30 am mike at grounded.net wrote:
> > The real question is do you want something that can let you record 2 or 4
> > channels at once, or a single card that has 2 or
> > 4 inputs?
> Cost will determine the end result justification :). But, the wish list, I
> can answer. 
> > Also, do you need on-board encoding, or do you plan to use software
> > encoding.
> Would very much prefer hardware, on-board encoding to free up CPU as much
> as possible. 
> > A unit with 4 encoders would be expensive, a pair of PVR-500s is probably
> > the only easy Myth-compatible solution.
> Yes, someone mentioned this card and they aren't very costly.
> > It really depends on your precise application. If it's a security or just
> >a monitoring process you can get a multiplexer
> > that will take 4 analog inputs and put them onto a single NTSC screen,
> > which would then require only a single encoder.
> I mentioned it in another reply but basically, I have multiple satellite
> receivers, media servers, cd/dvd player, etc, along with a number of
> security cameras around the house. Each item is of course at least SD or
> HD and everything is installed in the basement which is where I house my
> home theater gear. When we want to watch hi-res, we head for the living
> room. When SD or less is fine, we tune in on any TV in the house.
> Problem is, all of the channels are mono video modulators. I tried stereo
> units but found them too expensive when I built this so went with mono. I
> came across myth years ago but it was overly complex at the time, things
> have gotten better so wondered if I could use this to finally get at least
> proper SD if not HD to my TV's over the house network.
> > If you want 4 standard Myth encoders, you will need either 4 PVR encoders
> > (2 500s), or a LOT of CPU to encode 4 frame
> > grabbers at once.
> I suppose I could also use multiple backends no? I would prefer one main
> box but if I can't do it, so be it.

Sounds like you have/had a pretty good setup. Using NTSC modulators is a good solution, but limited to SD as you 
mentioned. Unfortunately ATSC modulators are very expensive, though it would work well, but require digital TVs at each 
potential viewing site.

The only viable solution for HD is probably the HD-PVRs, as you can probably get component outputs from most of your 

The best technical approach within practical economic limits is probably an HD-PVR for each satellite receiver, and a 
PVR-150/500 for the DVD players and security cameras, since they are SD at best. This would eliminate any need for 
software encoding. If you have more than 2 SD sources you could get another PVR-500, or a single PVR-150. This means, of 
course, that you  would need sufficient PCI slots to accomodate them.

The HD-PVR is about the only solution for baseband HD for Myth, all other sources (OTA, firewire, QAM) are already encoded 
streams and just need to be recorded to disk. Of course the HD-PVR depends on the "analog hole", if that gets closed the 
HD-Fury might be the only solution, but they are pricey, and I'm not sure if they can be used with Myth (yet).

You could use slave B/Es, especially if you run out of PCI slots, but the above setup would work with a single backend.

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