[mythtv-users] OTA/DTV tuner-card related questions, recommendations

Douglas Peale Douglas_Peale at comcast.net
Thu Jan 20 05:30:46 UTC 2011

On 01/19/2011 09:06 PM, James Miller wrote:
> Dear All:
> I recently--in the wake of the realization that the cable package my apt. building supplies does not get all public
> broadcasting stations I like to watch--decided to drag out and experiment with the converter box I got with my gov't rebate
> some months ago. The results were encouraging while I had it hooked up to an old analog TV: I got pretty decent reception with
> the old rabbit-ears antenna I was using, and it seemed most OTA stations came in well most of the time. That got me thinking
> how I could get those stations into my myth box (mythbuntu 10.04, P4 2.6, 1.75 GB RAM, PVR150 and BT878 capture cards).
>> From the research I did on the web so far I came realize I could probably 
> save myself some headaches by forsaking the converter box (Zinwell zat-970a) and just getting a capture card capable of tuning
> in these DTV broadcasts--that because making myth operate the converter box could be a real challenge, especially for someone
> with my modest technical abilities. Yes, I've done nothing with LIRC or infrared or anything like that and am content to
> interact with my myth box using a keyboard with a 12' extension on it.
> Let me start off by asking whether it's true that getting mythtv to communicate with my converter box could be a real
> challenge? If so, the following.
> I try to stick with trailing edge hardware--as you'll note from the hardware description I gave above. I'm sure there are all
> kinds of wonderful new DTV-capable, mythtv-compatible capture cards that, in addition to giving a crystal-clear HD picture,
> will even walk the dog, do the dishes, and take out the garbage. And they're probably priced somewhere at what people who
> drool over the latest-greatest hardware might consider bargain prices. But I'm not too interested in that sort of thing: it
> would just be overkill considering my other hardware--which includes an old Dell Dimension 31" monitor that only does 800x600
> resolution anyway (no HDTV here for the foreseeable future).
> No, I'd be more interested in a DTV-capable capture card that was considered a decent card several years ago. And a used one
> would be even better, since the price is likely to be lower. I've heard that the BBTI air2pc card works under myth, and also
> read that the Dvico fusion HDTV5 RT Gold might be a good way to go. But even while I'm looking for a good bargain on one of
> those, I wanted to ask on this list for further recommendations.
> So, can anyone offer further recommendations for an older DTV tuner card that plays well with myth and that will allow me to
> pick up the local OTA broadcasts I'd like to record?
> Thanks,
> James
> PS Yeah, any DTV tuner card I get will replace the BT878--with which I've never been very happy.

You have a horrible misconception of OTA digital TV.

The simplest thing for a tuner to do is to stream the already compressed HDTV digital signal directly to the hard disk. The
signal is already HD.
To get an SD signal as you imply you want, one must first decompress the HD signal, re-scale it to SD, then decompress before
saving to disk. This is extremely processor intensive, and an older PC would be incapable of doing this in real time.

If you really want an SD signal, you should save the HD signal to disk in real time, and once it is recorded, trans-code it
(over night on your slow system) to SD.

HDHomeRun is a reliable & simple to use ATSC/QAM tuner that works well with MythTV. There are many USB tuners, PCI tuners, and
even PCI Express tuners available for cheaper.

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