[mythtv-users] Myth HD - requirements?

Phill Wiggin alamar at gmail.com
Tue Jul 18 18:47:21 UTC 2006


On 7/18/06, Jeff_Mitchell at accessbusinessgroup.com
<Jeff_Mitchell at accessbusinessgroup.com> wrote:
>
> All-
>
> I've been a Myth user since 0.14, and am currently quite happy with a setup
> using 2 PVR-250s and a small, quiet frontend on our main television.  While
> I'm not looking to upgrade to HDTV quite yet (it'll probably be a year or
> two), I've started doing a little research, and I wanted to get some
> information about what other Myth users are doing for HDTV.
>

I'm running tests with my local HDTV coming over my cable line (QAM),
but others use antannae to pick up digital broadcast (Over-the-Air or
OTA) signals.  The pcHDTV card can do either. I'm opting for QAM
(tunes over the cable-line) because I live in an area w/o good OTA
reception.

> First of all, how are people using Myth to record HDTV?  I see a few
> mentions of the pcHDTV card, but looking at the site for the card itself,
> I'm not quite sure if it's dumping the HDTV stream to disk, encoding it to
> MPEG2 (like the PVR-250) for a smaller stream, or what.  It looks like a
> reasonably-priced card, but I'm curious as to what alternatives I might be
> missing.  Any clarification would be helpful.

(Someone correct me if I'm wrong.)

HDTV streams are already MPEG2. The pcHDTV dumps the stream directly
to your harddrive; no re-encoding is done.

There are other HDTV cards, but I haven't used them. I'd suggest
searching the list:

http://www.gossamer-threads.com/lists/mythtv/users/

> I'm in the United States, so I'm wondering if US residents are worrying
> about DRM on the streams now, or the possibility of it being implemented
> later.

I'm in the US and am definately concerned about DRM.  Some cable
companies encrypt their HD streams, however they're _supposed_ to
leave channels being broadcast OTA in their area un-encrypted. (as I
understand it)  So, if you can get a channel w/ an OTA antanna, it
should be unencrypted over your cable (though this isn't always the
case).  I can only get about 4 channels unencrypted over my cable line
w/ the pcHDTV.

Some people use the Firewire connection from their HD cable boxes,
though I don't know if that gives full HD resolution or if it's
downsampled, but I believe it's unencrypted.

> I think once it becomes time to buy a HDTV-capable TV, I can take care of
> getting it connected to a Myth box, but if people want to share their
> experience doing that, I'd love to read it.

I'm using an nVidia 5200FX graphics card with a DVI->HDMI converter
cable.  There are other options, of course.  (again, try searching the
list)

> Finally, any anecdotal evidence about what kind of grunt is required for a
> frontend playing back a HDTV stream?

IIRC, you're looking at needing a 3+Ghz processor if you don't use
XvMC. If you use XvMC, you can get away with less of a processor, but
depending on your system, XvMC may be difficult to get working right
(or at all).  (search the archives for XvMC, nVidia, processor...
might give some results)

> Thanks for reading.  Any advice or information would be appreciated.
>
> -Jeff

Hope some of this answers some questions, or spurs more. =)

--Phill W.


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