[mythtv-users] MythTV and a DirecTV HD reciever

[Richard Freeman]

James W. Mills wrote:
> So, here is my question.  What do I need in order for MythTV to capture
> incoming HD signal from my direcTV tuner?  I see several PCI cards like
> the HD-5500 that allow OTA capture, but do not specifically say yay or
> nay to DirecTV.
> 

I'm pretty sure you're up the creek if you want HD.  You can capture SD
TV from your HD receiver by using the S-video output.  Looking at the
manual online it looks like the DirecTV receivers do not output
compressed HDTV at all (typically this is done via firewire).  Instead
it outputs either component or HDMI - which is uncompressed.

The problem is that the HDMI data stream is probably running the better
part of 1Gb/s (I'm not HD expert, but figure 1080x~1920 x about 24 bpp x
30 fps).  Even if your system bus could spool 1Gb/s to your hard drive
and you had enough RAID to accept it, your drives are going to fill up
in a matter of minutes.  The only way to store HD video is to compress
it, but it takes racks full of equipment to do that in real-time.  The
way DVRs record HD is to capture the already-compressed broadcast signal
directly (about 6-12MB/s).  The DirecTV HD Tivo does this.  The problem
is that they don't let the compressed signal leave the box.

In a "few" years the hardware may be cheap enough to compress the HD
signal on the fly, at which time you can record DVI or HDMI directly
(assuming it isn't encrypted by then).

For now you need to either record off the air or find a receiver that
supplies a firewire output that isn't encrypted.

Somebody else might know better/different.  I use DirecTV myself - two
ancient ebayed receivers sitting under my desk.  I'm sure the customer
service rep was puzzled when I activated them and deactivated my R15
(hey, at least I got a free hard drive for my months of failed-to-record
shows).