[mythtv-users] MythTV and HDTV?

[Jeff Dubin]

On Tuesday 15 June 2004 13:09, various folks wrote:

>> setting up Myth to PVR for it... can Myth handle HDTV? I'm assuming I'd
>> need some special capture card, which I have not seen anywhere... so my
>> inital thoughts are "No"

> Note that decoding HDTV seems to require a fast processor (on the order
> of 3GHz).

Some HDTV cards (none of which have linux drivers, sadly) have integrated
hardware MPEG2 decoders, or have windows-based "DXVA" (DirectX Video
Acceleration) enabled software decoders which offload a decent bit of the
MPEG decoding to your graphics card (i.e. ATI Radeon, etc.), significantly
reducing the CPU requirements.  I don't know what exactly is being done
under this DXVA mode, or, more specifically, if (read: when) this can be
accomplished under Linux, but it would be a major step towards lowered CPU
requirements for HD viewing (my Athlon 2000 runs at ~40% CPU decoding
1080i with DXVA drivers).

> There's a new card out with CAM support that's supposed to be able to
> tune HDTV over cable; it's supposed to have Linux drivers, but I haven't
> heard of anyone actually using it yet.  In any event, I doubt it would
> be useful for DirecTV.

It sounds like you're talking about QAM (quadrature amplitude modulation)
support, which is the modulation type used by many (most?) cable systems
for delivering digital cable.  AFAIK, the only card which officially and
fully supports this currently is the "FusionHDTV 3 Gold QAM" by Dvico
(www.dvico.com).  Again, no linux drivers.  That could change though.
According to posts I've seen on this Australian DVB-T form
(http://robdvd.radfiles.net/viewforum.php?f=18), Dvico is looking to help
anyone interested in developing a Linux driver.  There's rumors that
someone is developing OS X drivers for it, and one person mentioned that
they were starting Linux development (though, since he's in Australia, it
probably won't be ready to be used in the US for ATSC or QAM reception
without some additional code).  So, there is hope.

One other option, if you already have a Windows box hanging around, might
be use xCaster (http://streamxpress.net/xcaster/).  It uses your HD card
under windows to output a multicast stream over your LAN which can be
played back with something like VLC (www.videolan.org).  I'm not sure if
Myth has multicast video streaming support, but it doesn't sound like the
kind of thing which would be impossible to implement.

In any case, this won't help you for encrypted satellite (DirecTV, Dish)
viewing under Myth.  But just being able to get a digital broadcast signal
into Myth would be huge for me.

Jeff