[sclug] Linux compatible Digital TV hardware?

Alex Butcher lug at assursys.co.uk
Tue Jan 15 11:22:09 UTC 2008

On Tue, 15 Jan 2008, Dickon Hood wrote:

> On Tue, Jan 15, 2008 at 10:30:59 +0000, Alex Butcher wrote:
> : On Tue, 15 Jan 2008, Sebastian Malcolm wrote:
> : >(1) Graphic Card - PCI, PCIe-8x, PCIe-4x or PCIe-1x (or PCIe-16x with
> : >http://www.orbitmicro.com/global/express-adapter-p-755.html)
> : >I've been told that I should be able to get a very sharp image at the full
> : >native 1366x768 resolution using a DVI to HDMI adaptor or cable


> : >Any suggestions on a card with DVI (or HDMI) output that would be able to
> : >do
> : >the H.264 decoding


> : My experience with my MythTV system is that the nVidia cards with the
> : proprietary driver are probably about as good as it gets, sadly. There
> : aren't any HD DVB broadcasts outside of Sky and London yet,
> The London HD-on-DVB-T trial has ended.
> : so there's no
> : need to worry about H.264 yet either, I reckon.
> It's coming, though.  Not sure when.

My point was that it's largely a software issue, the drivers get updated
fairly regularly, and graphics cards fall in price quickly. Buy only what
you need now, and wait and see if you need to spend more in a couple of
years' time.


> : >Any reasons to buy a Card instead of USB?
> : Tidiness?
> Less host CPU usage, too.  USB really is quite evil.

Not sure this is a massive problem in practice; recording 3 channels
simultaneously uses 8% of my Celeron's CPU. Hardly a big deal.


> : Decoding the MPEG stream is a software process, and it'd be therefore down
> : to support for your sound output device as to whether you could get 5.1 out
> : of your SPDIF socket. Again, no broadcast 5.1 yet, as far as I know.
> Correct, although there is some Pro-Logic stuff encoded in the PCM output
> stream as usual on some services.

Assuming output via SPDIF, then I think it's safe to assume he also has an
external processor which'll probably manage to do something with a Pro-Logic
signal. :-)


> : >- preferably under ?100
> : According to pricerunner, Nova-T starts from 25 quid, Nova-T-500 (dual)
> : starts from 50 quid.
> Nova-T is a budget card with no output hardware.

The OP is planning on using DVI output, and I use a VGA-to-SCART cable, both
of which are better quality than the composite/S-Video outputs found on VGA
cards and TV cards with output hardware.

> It's quite capable of dropping the complete multiplex to the host, which
> allows you to record all the services on that multiplex simultaneously. 
> This may be useful, although as MythTV *still* can't do it, it may not.

It's coming; 'multirec' is the jargon, and it's in SVN, but being tweaked.
VDR does it already, I gather. One of the hard bits are the heuristics for
scheduling; which should be favoured - a single high priority broadcast on a
different multiplex, or a number of lower-priority broadcasts on the same
multiplex? What if the total of all the lower priorites is greater than that
of the single high priority broadcast?

> The 500, assuming it's the PVR 500, is a 'full-featured' card, with output
> hardware.  It filters on the card, and may not be capable of passing the
> complete multiplex.  It also has decoder hardware on board, which is
> useful for low-spec hosts.

No, the Nova-T-500 is just two USB Nova-Ts together with a USB-to-PCI
bridge: see <http://www.hauppauge.co.uk/pages/products/data_novat500.html>
and <http://www.mythtv.org/wiki/index.php/Hauppauge_WinTV_Nova-T_500_PCI>. I
used to have problems with signal strength when I was using two Nova-Ts, but
seem to get more reliable signal strength using a single Nova-T and a
Nova-T-500, despite that increasing the number of tuners from two to three.
I bought my Nova-T-500 from insight.com a few months ago, and didn't get one
of the infamous 'Diversity' cards that don't work with Linux (Hauppauge will
exchange, free of charge, but it's a faff).

Best Regards,
Alex Butcher, Bristol UK.                           PGP/GnuPG ID:0x5010dbff

"[T]he whole point about the reason why I think it is important we go for
identity cards and an identity database today is that identity fraud and
abuse is a major, major problem. Now the civil liberties aspect of it, look
it is a view, I don't personally think it matters very much."
  - Tony Blair, 6 June 2006 <http://www.number-10.gov.uk/output/Page9566.asp>

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