[mythtv-users] Not your everyday newbie questions

Robert Denier denier at umr.edu
Tue Oct 11 17:38:03 UTC 2005


On Tue, 2005-10-11 at 12:51 -0400, R. Stavros Bezas wrote:
> For the last few weeks I have been browsing every single website I  
> can possibly imagine that deals with creating your own HD PVR HTPC.  
> Without owning a HD set or service presently I find myself a touch  
> limited when it comes to specific hardware connections/setups. I am  
> well versed with the signals themselves but none of the company  
> proprietary things that will definetly impact how you set up your box.
> 
> I'd like to lay out my understanding of how to setup a system  
> (backend and fronted in one box to start) so I can see exactly what I  
> need to make my decisions on as well as to help out others in my  
> position in the future. Please add any input you can.
> 
> Starting from the signal itself. I plan to get DirecTV but may resort  
> to Comcast if tree cover is an issue. Let's just assume DirecTV is 

You might give a closer look at comcast.  There is a chance that a cable
box is available that has firewire that may even work with myth.  This
is likely the best quality video you can get, if its available and it
works.  I've never looked into the details as cable is not available
here.

>  
> available. The signal will come into through the wall via RG6 and I  
> am assuming I will need to terminate it at their Satellite box.

Yes.
> 
>  From the Satellite box which method do I use to bring it into the  
> MythBox? 

Typically you will use a hauppauge pvr 150(captures 1 signal) or pvr
500(captures 2 signals).  This adds 
1) A Digital/Analog conversion in the sat box.
2) An A/D conversion in the pvr card.
3) Some additional losses recompressing the video the mpeg2 video.

This is why getting the signal in its original mpeg2 native form from a
cable box has some value.  Of course I'm not sure how well, or if this
really works..

You will also need either a serial connection to the satellite receiver
to change channels or an ir blaster.

> My first thought would have been through Component/DVI or

Nice try :) Afaik no cards exist that will do either.  A talented
electrical engineer might build a card, given enough time and money, but
well, I find it likely that attempting to sell such a device would
resort in some kind of legal issue.  Also, if your talking hdtv, you
would need a _VERY_ fast machine to compress it from the raw data, or
additional hardware on the board to deal with real time mpeg2
compression.  All in all the creation of such a card while technically
probably feasible, is just not likely to happen anytime soon.

There are cards that receive over the air compressed hdtv signals that
work with myth, but then your limited to those channels.

>   
> other video transport methods but reading through I find myself more  
> confused as talk about Firewire comes into play as well as inputting  
> the signal directly into the box. All sorts of questions about  
> encrypted signals now come into my mind. This topic is very important  
> to me as I can't seem to get a straight answer.
Sorry, I'm not expert on firewire as the solution does not apply here.
I use dish network with an ir blaster.

> (I plan to be purchasing a Samsung 61" DLP (HLR6167W) which contains  
> almost every sort of connection available and the rest of the  
> equipment has not been purchased so the sky is the limit when it  
> comes to type of setup)

I wonder if that tv can do a 1:1 pixel mapping from your computer via a
dvi cable.  It might be something to look into..  Of course, if your
only watching video it doesn't matter so much.

> After I have the signal into the MythBox (for simplicity let's assume  
> just one tuner card, although the software side of multiple cards  
> perplexes me as well!)

Multiple cards are for picture in picture or recording one program while
watching another/etc..  Also of course it allows multiple stations to
see a picture..

>  it obviously needs to get to the television.  
> This is where a video card that supports a HD-OUT method (component,  
> HDMI, DVI, etc.) comes in. 

I'm not sure any cards support hdmi out.  I have a dvi->hdmi cable, but
the vizio l32 I have doesn't really support any usefull resolutions that
way.  I'm returning it for a winbook 32 inch though.

At any rate you want dvi/hdmi, if possible.

> This sounds quite simple to me, but again,  
> I believe firewire has entered the mix and that just confuses me as 

Firewire as it was originally used is for motion jpeg compressed video
from a DV camera.  There is also mpeg2 over firewire which I think is a
standard, but I could be wrong.  Directv had a receiver that did mpeg2
over firewire, but I think that was something non standard and not
useful.
>  
> to how that could interact. If you do use firewire on either input/ 
> output, would I still need a tuner card or video card?

Well in theory you would just need a firewire port on your backend and a
video card (suggest nvidia) with dvi on your frontend.

> 
> Other issues of note:
> As I've said I've done some research and come to see that the pcHDTV  
> card does not decode NTSC (SD) signals. Does this mean I will have to

I've no idea, but it is a trivial problem.  Just put a 150 card in as
well.

>   
> have multiple cards to get the full spectrum of channels from my  
> service? Is the control seamless through the Myth interface? 

I don't have two cards in yet, but I would assume so..

> My goal  
> is to make this box operate as simply as possible. I currently use  
> ReplayTV with a basic analog signal, it could not work more simple.

I'm not sure myth is at the point of simple.  Maybe once you get
everything figured out...  

> 
> When it comes to installing my Satellite service, is there a certain  
> box or features I should request that would simplify the task of  
> creating this PVR? Also, same question for Comcast or other cable  
> providers if Satellite falls though.

Well there is little point in paying for pvr fees from your satellite
provider if those boxes are going to myth.  Probably you want ordinary
satellite receivers for the ones that go to myth.

On the other hand dish network does have two hdtv receivers.  One even
has a built in pvr.  If you are looking for simple and done, with the
absolute best picture possible, well its going to be hard to beat that
one, especially when myth doesn't have a way to record non over the air
hdtv channels unless you can somehow get them through firewire from your
cable systems.

> 
> The software side I have yet to address as that can all be handled  
> once I have the hardware in place. I anticipate that to be relatively  
> painless compared to creating the box up to and including IR blasters/ 
> serial connections,etc.

Good luck.  It is all doable.  It really depends on your patience and
your knowledge of linux.  I believe there are guides around for fedora ?
from red hat.  It can take a great deal of time though...

-Robert




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