NineBall, do you have enough slots in your HTPC and $$$ to dedicate one card per antenna so that there is no combining? I'm going to be doing that myself to solve any aiming compromises once and for all. I'll use one of my older antennas (a 4-bay bowtie) for Vancouver UHFs into one ATSC card and probably a GH10 with the latest collinear rod improvements for the SeaTac UHF stations. I'm contemplating a third ATSC card for my CM1111 VHF/FM to get 3 SeaTac VHF-HI stations after February, with that antenna's output split to an NTSC card for picking up any Canadian analogue stations coming in through the back door or side lobes, and also for the FM Radio stations. I run MythTV so this is all workable.

As much as I would love to use a switch, this one antenna array would feed into multiple tuners on my HTPC so using a switch could cause lost feeds that I would be expecting.

As stampeder says, with multiple tuners there should be a RF input for each, then no A-B switch is needed. One antenna downlead into each tuner and change channels in software.

As for the tuners, I'm not sure I can do that with VMC and I don't think I can switch from it as my wife (and I really) have grown accustomed to the interface and all the VMC applications I have installed for us. The most I could do would be 4 ATSC and 2 NTSC without a mobo upgrade. With 1 tuner:1 antenna, would there not be problems with wanting 2 stations from the same antenna though? My current planned ATSC tuner card internally splits a single feed to 2 tuners, and I had planned on a distribution amp for moving up to more tuners in the future if required.

With 1 tuner:1 antenna, would there not be problems with wanting 2 stations from the same antenna though?Yep come to think of it you're right for the most part: MythTV can record all subchannels on a digital channel simultaneously, but not more than one major channel at once. Curses, foiled again! I guess I'll just have to matrix all my antennas into one distributed feed. Oh joy, that'll be easy... NOT ;)

The most I could do would be 4 ATSC and 2 NTSC without a mobo upgrade. With 1 tuner:1 antenna, would there not be problems with wanting 2 stations from the same antenna though?
Holy smokes, four tuners, four RF inputs ? In that case, from each antenna downlead use a splitter into two tuners. Then you can get 2 stations from the same antenna ??

No. The earlier postings here already describe the UVSJ devices that solve the problem.

Cheers

What I'm asking is if you use an HTPC, and if so, have you considered a card per antenna as an alternative to UVSJ devices. That's what I was hoping to talk about. :)

Yes, that's in the cards come February 2009. These yagis I'm building are for our local channels, and using them frees up the top of the tower array (dual PR-8800s) for distant PBS digital only, wired directly into a dedicated digital tuner.

Right now, one yagi pair is dedicated to a single analog tuner. But the 3-way switchboxes I'm building will eventually permit either analog tuner to access either antenna pair, plus the top-of-tower array if necessary.

EDIT: The software really doesn't like to deal with specific channels being available only on specific tuners -- doable, but messy. So it's better to have as few special antenna+tuner combos as possible.

That's why I had all of this stuff together in one thread originally, so that questions like yours would be covered here already! :)

Right now, I'm hunting for a PC ATSC tuner card that can equal the tuner in my my el-cheapo Viewsonic TV. Nobody seems to have done any kind of semi-controlled comparison of reception quality for those yet. But that is definitely a topic for a different thread! :)

Cheers

I just reinstalled my Ati TV Wonder VE card. Right now, Im recording with Dscaler and the ffdshow mpeg2 encoder. Any suggestions on another mpeg2 decoder ? Im looking to record at about 2.1 Gigs per hour.

Any suggestions on another mpeg2 decoder ? Im looking to record at about 2.1 Gigs per hour.
Another decoder?? That's usually software, and is only used for playback. If you meant encoder, then those are only for analog, and it's best to use a tuner card with a built-in hardware encoder -- takes practically zero CPU that way.

The MythTV box here can record 4 (soon to be 6) channels simultaneously at just a few percent of CPU usage (Core2 Duo 1.8GHz), with all encoding done in hardware.

For channels with commercials, though, one entire core is consumed by the commercial flagging task during recording. Actually, it would like to use one core per tuner card for that, but I limit it, so it has to queue the commflag tasks one at a time.

Playback (decoding) of an HD stream chews up an entire core, though.

?? Cheers

Yeah encoding. I cant believe I typed decoder.
Hardware encoding is best, and pretty much required for decent HD encoding, but Im going to wait until tuner cards come out with 6th gen tuners at least, like on the CECBs. In the meantime, Im still looking for a better software encoder.

ATSC DTV (HD, SD) streams are already encoded into MPEG2 for transmission, so no encoding is done or needed at all on the receiver end of things.

For analog TV, encoding is necessary. But I doubt that we'll see many new analog encoder cards in the future, since O.T.A. analog is mostly vanishing in 2009(USA) and 2011(Canada).

The newer gen chipsets really only benefit ATSC (DTV). So if you want better encoding for your remaining analog channels, then just get a used PVR-150 or PVR-250 card cheap off of eBay -- should be lots of them there now and in the near future!

Cheers

The most I could do would be 4 ATSC and 2 NTSC without a mobo upgrade. With 1 tuner:1 antenna, would there not be problems with wanting 2 stations from the same antenna though?
You could attach more ATSC tuners externally with an HDHomeRun unit, and more tuners of either type by using USB2 tuners.

But yeah, the wanting 2 stations from the same antenna issue is what really defeats the "one tuner per antenna" concept. :)

My approach to this dilema is to have MythTV directly control some antenna switches (using a channel_change script), as described/discussed in this other thread (http://www.digitalhome.ca/forum/showthread.php?t=96054).

Cheers

Yes, I'm aware I can get more tuners in with the HD Homerun and USB tuners (hoping my friend can get me a Hauppauge WinTV-HVR-850 tomorrow if for nothing besides making aiming easier with it and my laptop on the roof). I doubt I'll need more than the 2 tuners I plan using anytime in the near future though; maybe once I have kids jockeying for the TV as well.

You could attach more ATSC tuners externally with an HDHomeRun unit ...


I am kind of confused what is the potential of this HDHomeRun unit.

The product page state - Multiple computers can use the HDHomeRun - tuners are automatically allocated as needed.

Assuming both ATSC tuners are connected to two antenna and there are 2 PCs on the network, can each PC can watch/record 2 different programs simultaneously from the same HDHomeRun unit?

An HDHomeRun is a box with two independent tuners, each with its own antenna/cable input jack, sharing a single 100mb/sec ethernet interface.

You plug it into the home network, and then the two tuners are available for use by any computers on that network.

Each tuner can only do one thing at a time, and can only stream DTV to a single computer at a time.

There are two principal advantages to this kind of design

1. It doesn't use up any slots on the PC motherboard, which is good because most HTPCs only have 2-3 slots total.

2. Very simple and universal software interface -- one can record videos simply by saving the network stream (MPEG2) to a file. On Linux, for example, this can be as simple as using the generic netcat (or socat) tool to just dump the stream directly to a file from the command line.

The various PVR software packages (MythTV, SageTV..) do know about HDHomeRun, though, and have nifty GUI interfaces to use it just like other tuners.

Cheers

Hauppauge WinTV-HVR-850 tomorrow
But the reviews on it are very poor for the enclosed software. And so far, no good 3rd party software AFAIK.

MythTV on Linux fully supports the HVR-850.

Hey, 300ohm: care to pick one up for me and mail it to me here? But only if you're planning to go there to get one for yourself.

Unfortunately, I have too many other stores on my list tomorrow before 11am. I know I dont have a chance in heck to get thru them with all the lines, heh.

ATSC DTV (HD, SD) streams are already encoded into MPEG2 for transmission, so no encoding is done or needed at all on the receiver end of things.

I know that. But the heavy duty cpu processing comes in when you want to encode at a different resolution or bitrate than what is broadcast. From the reviews, 1080i broadcasts work out an highly overclocked quad core pretty well, encoding with say an mpeg4 codec like divX with a 900 kbs bitrate.
Youre right if you say I should capture first and then compress it later. But it would be nice to do it in one step.