[mythtv-users] More Beginner Questions

Rich West Rich.West at wesmo.com
Sun Jan 21 20:55:27 UTC 2007

Greg Kettmann wrote:
> Well, I've spent many hours reading and there are still times when I 
> think I get more confused instead of less.  It's a little disconcerting 
> the direction of the cable companies, etc.  All I want to do is time 
> shift my favorite shows, like we've done for years since the advent of 
> the VCR.  Oh well.
> In a previous post I indicated I'm interested in HDTV since I don't 
> currently have that functionality (with my DirecTiVo).  The comments, 
> plus further reading, indicate that this probably isn't a great starting 
> point.  One of the major reasons for that would be the lack of an HDTV / 
> Analog card.  Since I need to buy an analog card anyway I should 
> probably start there and then build up.  I just want to keep in mind 
> where I'd like to end up and not buy components which are not sufficient 
> for the final vision.  So, for example, I'll start with a system with 
> enough horsepower to output/decode an HD stream. 
> I have Comcast (I don't intend to use MythTV with DirecTV).  I think I 
> understand the tuner cards and will probably get a Hauppauge card.  They 
> are Linux friendly, have on board MPEG encode (and decode) and seem 
> reasonably priced. 
> That leaves me with three question areas:
> 1)  Digital TV.  It seems that, other than resolution, there is little 
> difference between HDTV and Digital TV.  That is, if I go to buy a 
> "digital" tuner it will likely just be an HDTV tuner.  Since the signal 
> is digital there is no need for MPEG-2 encoding.  Then the only issue is 
> the source of the signal.  For me that is Comcast and that would be 
> DVB-C (cable) and the signals would be QAM.  Most digital channels would 
> be encrypted and not viewable.  Those available OTA would not be 
> encrypted and I can get the digital signals which could be in many 
> resolutions including up to HD (1080i).  There also seems to be an 
> ability to control, and get signal from, some set top boxes.  However, I 
> don't currently have a Comcast set top box and so I don't much care 
> about this option (yet). 
> 2)  TV-out - Keep in mind that I'd eventually like HD.  My TV is capable 
> of this.  The Hauppauge PVR-350 does composite out but I suspect it's 
> the standard RGB and I think HD requires YPbPr.  Is this correct?  I 
> believe my TV will take either.  If the PVR-350 won't work then it looks 
> like an NVidia card should be considered, however, although they list 
> "composite" output I don't find any definitions of the RBG / YPbPr 
> aspect.  Do I have something wrong?  The only writeup I've seen on HD 
> output used a device (for a bit over $100) that converted a standard VGA 
> type monitor jack into a composite/YPbPr signal.  I'd prefer something 
> on a card.  The obvious issue is how to I connect the MythTV box to the 
> television at the desired resolutions and it's still unclear how to do 
> this. 
> 3)  Infrared - Again the PVR-350 solves this.  I have no idea what to do 
> if it's not on the card.  This is the Infrared pickup for a remote.  
> Reading has suggested to get a universal remote but it appears I need to 
> get a tuner card that includes a remote so that I can get the IR 
> pickup.  I presume I just toss the included remote (along with a half 
> dozen others :-)  ). 
> Thank you for any clarifications.  GGK
(long.. and I apologize for the length.. but since I just went through 
the same thing, I thought I would share as much as I possibly could)

For the record, I'm using MythTV with DirecTV.  I literally just phased 
out my hacked DirecTivo in favor of a whole-house MythTV setup.  WAF 
(wife approval factor) is way up. :)

Having just gone through all of what you are about to do, I would 
recommend thinking about *how* you would like the end design.  I 
purchased a PVR-150 (model 1024) from newegg which came with the remote 
and IR blaster.  That is fine and dandy if you are going to have a basic 
system that will outright replace the DirecTivo.  However, that is only 
the tip of the iceberg with Mythtv.  Mythtv is full client-server based, 
which means that, if you can do it, you can set up a machine in a closet 
with a couple of tuners in it which performs all of the recording, and 
you can have any number of machines acting as frontends (one for each 
TV).  In this scenario, the 1024 model of the PVR-150 is really not 
necessary and you'd be better off with model 274 of the PVR-150 (same 
card, just without the remote and IR blaster), with a cost savings 
difference of about $25-$35 (approx) depending on where you get it from.

Digital TV is an entirely different beast than HDTV.  Digital TV is 
simply that: the cable company has taken the SD analog signal and 
converted it in to a digital stream that is sent (via UDP) to the cable 
company's set top box.  Digital TV does allow cable companies to send 
you *any* picture format, though, since it is entirely TCP/IP based 
networking.  Everything comes across as packets.  However, you need a 
set-top-box capable of decoding the digital signal and (1) spewing out 
standard definition and (2) spewing out HD signal.

Digital TV alone doesn't mean better picture quality since it relies on 
the quality of the source.  In some ways, it is the cable company's way 
of trying to close the 'analog hole', but, politics aside, there 
probably is a slight improvement in the picture quality over straight 
analog cable to the same location since analog cable experiences a fair 
amount of signal loss along the path, whereas digital tv is simply 
packets that are not impacted by loss of signal during the transmission 
from the cable company to the consumer.  Digital TV is probably best 
defined as a transport mechanism.

HDTV is step up at the SOURCE of the signal.  The picture quality is 
improved when it is recorded and transmitted.  Via the cable companies, 
it is passed along to the consumer via Digital TV.

For TV-out, it should be mentioned that, officially, Mythtv no longer 
supports the PVR-350.  For the best picture between your mythtv frontend 
and your TV, you are limited by what your TV can support.  Now, if you 
can do DVI or VGA out to your TV, you're set since that picture is 
already progressive and you can push it up to the limits of the TV 
(however, you will have to do a fair bit of tweaking on the Mythtv side 
to "up-convert" displaying interlaced video, but that's a different 
topic).  nVidia cards are good for displaying on most devices.  ATI are 
also good, but I have no experience with them and Mythtv.. others might 
have some input here.  I personally used all 6200's only because I had 
them available (now my desktop machine are lacking!).  I have a PNY 6200 
with the HD breakout box that came with the card which allows it to talk 
out via component video (YPbPr).  It was a little tricky to set up, but, 
once set up, it works like a champ.

IR is actually the easy part.  You can either build-your-own IR receiver 
that is compatible with lirc, buy a capture card with an IR receiver 
built in to it (which limits you to the type of remote you can use and 
you need to be near the machine with the card in it (aka: it would pose 
a problem if you had it in a closet and you had a dummy front-end by 
your tv), buy a name brand IR receiver (The can run $30 or more), or buy 
a home-made one for $20.  The latter two allow for you to use nearly 
*any* remote, so long are you are willing to 'teach' lirc how to 
understand your remote, and provide the most flexibility.  I went with 
the IR receiver with the 6ft cord from www.irblaster.info/receiver.html 
since, although I do a lot of DIY, I figured he has done it a lot more 
than I have so the chance for failure there was slim.

I personally have only worked with DirecTV and MythTV, with SD DirecTV 
at that.  I have not tried any of this with Comcast or HDTV.  Most 
people, from what I have read on the list, do buy an HD receiver card 
(like the pchdtv ones) and capture over-the-air HD signals.  I haven't 
done that myself, but I plan to. :)


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