[mythtv-users] Probably a FAQ Question (HD, MythTV, Cable Card, and Comcast)

Ivan Kowalenko ivan.kowalenko at gmail.com
Tue Apr 10 19:25:02 UTC 2007


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On Apr 10, 2007, at 15.02, David Frascone wrote:

>
> Ok, after reading quite a bit, and searching quite a bit, I have  
> come to a few conclusions:
>
> There is no Cable Card hardware for MythTV to use, so getting to  
> Comcast's HD and premium channels is not possible with a tuner card.

Partially correct. CableCARD will likely never have official Linux  
support due to piracy concerns. However, capturing via FireWire,  
depending on your box and region, should be possible. You should be  
able to get some channels in HD, but in most cases you can't get  
premium channels. Also, depending on the service and area, QAM256- 
capable HD capture cards can get HD channels via the cable line, but  
I don't know much about this.

> But -- what about using a STB and blasting IR?

Common configuration for people who want digital cable, however it  
probably isn't the best option, for what you want. Some people find  
it hit-and-miss, some people find it rock solid.

> What I'm trying to do is replace the dain-bramaged Comcast DVR with  
> a MythTV setup in my basement.  I want to install a couple of tuner  
> cards in my file server, and use it as a MythTV "receiver".

You mean as a back-end. First, dump the ComCast DVR. You're just  
wasting money on it, and it's slower than some other cable boxes I  
hear. You can probably use the straight HD-box for FireWire, or just  
use a cheaper digital cable box. Keep in mind, this'll require a  
decent amount of RAM (I have 256 MB for a single analog tuner).

> Then, I want to add a nice looking, small, (perhaps diskless)  
> MythTV display computer to my TV.

Ahh, a front-end. Another common design. This can range from a hacked  
XBox to a laptop to a custom built micro-ATX system running off of a  
CompactFlash card. However, for high-def content you're going to  
require a powerful CPU. An nVidia graphics card is recommended, with  
a certain numbered nVidia driver (I forget the latest version) so you  
can use XvMC to off load some of the HD decoding to the GPU. The  
nVidia GeForce FX5200 seems to be a favorite of the MythTV crowd, is  
XvMC capable, and is quite cheap.

> So, the receiver needs to be at least a dual-tuner setup, and needs to
> record HD.

Unless you're going directly from the cable line, you're going to  
need two cable boxes.

> Is this possible?  I'm guessing there is a way to blast IR to two  
> (or more) Set Top Boxes, and to capture the output of the HD  
> Comcast Set Top Boxes via component, HDMI, etc.

There is no HDMI-capture solution, and HDCP aims to try and prevent  
any from ever existing. IR Blasters are common place, but have a wire  
range of reliability. For your situation, aiming for either direct- 
cable or FireWire capturing would be best, since this would obtain  
the highest quality signal, with the least amount of processing time  
(FireWire capture just writes the raw MPEG-2 stream to disk).

> Or, do I just need to wait patiently until there are HD tuner cards  
> out there with cable card support?

ATi is already selling a CableCARD-capable capture device, but we'll  
probably never see CableCARD for Linux, at least not legally (in the  
US). Either go with one of the existing HD capture cards (you can at  
least get your Free-To-Air HD signals on that), or a FireWire card.

> "Free advice is worth what you pay for it"

Not with this list! ;)

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