[sclug] Linux compatible Digital TV hardware?

Dickon Hood sclug at splurge.fluff.org
Tue Jan 15 11:05:02 UTC 2008

On Tue, Jan 15, 2008 at 10:30:59 +0000, Alex Butcher wrote:
: On Tue, 15 Jan 2008, Sebastian Malcolm wrote:

: >I've got two hardware selections I need to make that I'd like advice with 
: >to
: >ensure we get the best possible picture quality with a minimum of setup
: >hassle; I'm happily running a Xen setup on this machine using stock Ubuntu
: >kernel so I'd rather not recompile a custom kernel.

: >(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, so I don't
: >need to spend the premium on a graphics card with built-in HDMI output or
: >will I require that to watch Blue-Ray or HD-DVD with a Linux movie player?
: >Any suggestions on a card with DVI (or HDMI) output that would be able to 
: >do
: >the H.264 decoding to offload that from my CPU(s) that could be busy with
: >recording video and/or compiling code? I've read that the nVidia drivers
: >lack the "PureVideo" capability that exists in their Windows drivers to
: >enable hardware accelerated decoding of H.264 video. I've read that 
: >nVidia's
: >GeForce 6-series (>=6150) will at least do some hardware acceleration of
: >MPEG-2 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.

: It'll probably turn up in
: the nVidia drivers at some point, though. I use a Geforce 440MX in a Celeron
: 1.7GHz system, which is quite good enough to record 3 SD channels
: simultaneously, whilst playing another.

: >(2) USB DVB-T Reciever?
: >I've reviewed the long list of USB DVB-T devices on LinuxTV.org Wiki and
: >some of the info on MythTV.org but I'm looking for some more opinions for
: >what spend (my girlfriend's) money on...

: Not sure why you'd prefer USB. On the other hand, the Hauppauge Nova-T-500
: dual tuner is USB internally, so there's very little in it. I use one of
: these plus an old single-tuner Nova-T in my MythTV/FC8 box with no real
: issues (bar losing a multiplex due to poor reception from time to time).

Not all the USB devices will ship the entire multiplex to the host CPU for
filtering.  This may or may not be an issue for you.

: >Any reasons to buy a Card instead of USB?

: Tidiness?

Less host CPU usage, too.  USB really is quite evil.

: >Perhaps to get 5.1 surround sound (SPDIF output) if that is broadcast here
: >in the UK?

: DVB is just MPEG over radio, so I don't see what you're getting at here.

AC3 5.1 encoded sound in the bitstream.  As yet, no, not present on
SD Freeview, but the BBC HD stream had it, and the DVB-S HD streams have

: 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.

: >We're wondering if any of you have a working configuration or any
: >recommendations of any decent brands, which support Linux. Our criteria is
: >that when used with appropriate software such as Kaffiene or MythTV are:
: >- must be able to record and watch digital channels.
: >- pause live TV option
: >- preferably dual (can record one channel and watch another) but not
: >necessary

: Not sure you'll get a dual tuner in a single USB device.

There's technically no reason -- a multiplex is only about 27Mb/s, after
all -- but I've not seen one, either.

: >- a USB stick rather than a card so we can use it in other laptops around
: >the house and when on the move

Assuming you have reception.  Portability is less useful than you'd

: Right, handy, I suppose. On the other hand, if you have them installed in
: your MythTV backend, you can just stream the recordings over WiFi or
: Ethernet to your laptops.

I'd avoid wifi.  It can be done with a decent AP, but not all seem to be
able to handle the packets per second.

: >- 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.  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.

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.

: >- obviously must be Linux compatible.
: >- remote control is preferable but not essential

: The Nova-T-500 requires updated drivers for the remote to work, apparently.
: This doesn't bother me, as I use the remote sensor attached to my older
: Nova-T which JFWs with FC8's standard kernel and drivers. Both come with a
: IR handset, batteries and sensor (at least in the retail packs).

: >- connects to the wall aerial (we live in an apartment block so we doubt we
: >have good reception with a stand alone aerial)

Signal around here isn't all that good anyway...

: You might well want to invest in a decent amplifier/splitter, too. I have an
: SLx 4 way model that I got from Argos, but it might be worthwhile trying to
: find something a bit more 'pro' and a bit less 'consumer'. I made up my own
: flyleads to avoid the use of gender changers and to keep the cable lengths
: as short as possible. Unfortunately, I share a communal aerial between 12
: other sockets distributed amongst 6 other homes...

: >- would be _very_ nice extra to be able to receive (decode?) HDTV in the UK
: >and Australia, but I don't know if that means it must be able to decode
: >MPEG-2 or MPEG-4 ( H.264?). I think that in Australia 1080i is available 
: >via
: >a MPEG-2 broadcast but here in the UK and elsewhere deploying HDTV the
: >digital video stream will be MPEG-4, eventually?

Current DVB standards deploying in the UK are MPEG 4 H.264 (not just MPEG
4; that's something different).  Sky is using 720p50 for some content, and
1080i25 for others; the BBC is sticking to 1080i25 until 1080p50 becomes
possible.  17Mb/s per channel, roughly, for both these standards on dsat;
they're looking at about 5Mb/s for Freeview, if that ever happens.  It'll
look crap.

: AFAICS, this is a software issue. The card just pulls the MPEG streams off
: the tuned broadcast multiplex and dumps it on the PCI bus.

Near enough.  The full-featured cards may not handle H.264 in hardware on
the output.  This may or may not matter, depending on how future-proof you
want it.  Frankly, given we're some years off HD on DVB-T, it probably

Dickon Hood

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