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

[Justin The Cynical]

On 1/19/11 10:58 PM, James Miller wrote:

*snip*

> Interesting explanation. And there's a lesson to be learned here as
> well: never hesitate to display your ignorance--you could end up
> learning some things that, had you feigned greater knowledge, you may
> well not have. I do have a larger disk I've been planning to put in for
> some time (500GB), so it's evident that will be a prerequisite.

And more.  That 500GB drive will fill up quicker than you imagine.


> monitor displays looks more than adequate to me, in all honesty. But I'm
> not sure I could watch an HD broadcast on that monitor, even if I wanted
> to, could I? So converting to SD may not be a matter of wanting this or
> that, but a question of necessity.

Yes you can.  Your system, if not misconfigured, should scale the video
down to the resolution your display uses.  When I added my first DTV
tuner (older Air2PC card), I was still running my system at 320i/p (MSI
6200 AGP).  The video subsystem scaled the 1080i/720p images down to fit
the screen and the difference in visual quality was noticeable.


> To summarize, OTA DTV is HD by definition. If you don't have hardware
> capable of displaying HD and want to watch/record OTA DTV using mythtv,
> you'll need to transcode the broadcast--which, if done in real time, is
> likely to turn your old hardware into a mass of molten metal and
> plastic. If done subsequent to recording the broadcast, the transcoding
> will work, but you're liable to perish of old age before the job
> completes. And all this in the name of progress!

Incorrect on both points.

Over The Air Digital Television does /not/ mean high definition, it just
means the signal contains digital information vs analogue.

I still have some OTA channels in my area that broadcast SD video
streams (one station sends out both on different sub-channels).

And as I mentioned above with my system when I added/converted to
digital, I was watching HD broadcasts on my old SD projection set, no
transcoding needed.


> I don't have a PCIExpress slot in this machine. It's gotta be PCI or
> USB. And brand names and model numbers would be most helpful: I presume
> there are all kinds of bargains to be had, but not every capture device
> that is as inexpensive as I'd like is necessarily going to work with
> myth, right?

Why does it have to be one or the other?

The SiliconDust HD HomeRun is a stand alone device that sits on the
network.  They have two models in production for the ATSC (primarily US)
market, a single tuner and a dual tuner.  And with their redesigned
tuners announced (much smaller footprint), the original design may be
dropping in price.  MSRP on a new dual tuner, older beige design, is
$149.99 US dollars, with the single tuner at $79.99 (street prices are
usually lower).  They occasionally go on sale as well.  Up front, it may
seem to be a bit more expensive than a PCI/PCIe tuner, but if one looks
at what the HDHR offers, it's the better bang for the buck.

And frankly, after having dealt with PCI tuners and then getting the
HDHR, I wonder why I didn't get one sooner.

They Just Freaking Work(tm).

The only fiddling I've ever had to do with mine in the few years I've
had it was for firmware upgrades (and that was only because I read
reports that it helped reception).  I could have left it at the original
firmware level and been perfectly happy with it's performance.


> Let me ask this in closing. As I understand it, my PVR150 does some
> processing of the signal before dumping it to the hard drive, correct? I
> realize HD enthusiasts would consider it sacrilege, and that hardware
> manufacturers would rather have their toenails pulled out by the roots
> than to even think of designing something that would do this, but I
> gotta ask anyway: is there some HD tuner card that can help my old P4
> reduce the HD to SD in something like the way the PVR150 (if I've
> understood correctly how it works) processes the signal before dumping
> it to the hard disk?

The PVR150 encodes the analogue signal to MPEG2, and that's about it.
Personally, I consider 'processing' something like de-interlacing or
noise filtering, which, last I checked/heard, the card doesn't do.

As for the HD tuner card, I'm not aware of any card that will transcode
the digital signal resolution to one that differs from the original.

Assuming that I am correct and there isn't a card that will do this, my
opinion on your choices are[1]:

* Upgrade the system to something more powerful

* Upgrade the video to something that supports MPEG2 acceleration (you
didn't list your current kit, so I can't say if what you have now is enough)

* Transcode the stored video file into a lower resolution

And as always, IANAL, YMMV, IMO, YYMV, and so on...

[1] This assumes that your system can't playback a 1080i MPEG2 file
    without issue.  I'd try it first.  You can find 1080i clips around
    online, just do a search.