As you probably guessed from the title, I am a newbie to both MythTV and to Linux in general. A good start Oh, I'm based in the UK.

Anyway, I have a 500MHz PC which I would like to convert to a PVR, with a view to upgrading the CPU at some stage in the future when I get hooked! Ideally I would like to utilise a DVB-T card of some description and am considering either the Nebula DigiTV or the Hauppauge Nova-t PCI card.

My understanding is that the DigiTV card has hardware MPEG coding, whereas the Nova-T doesn't but does have a TV out facility which the DigiTV doesn't. Is this assumption correct?

I need some advice though please folks! As a complete Linux novice, can anyone tell me
a) which card I am likely to have the least amount of problem getting to work
b) which setup would be best to use (Knoppix MythTV )
c) anythin else that would be of use!

Many thanks for any help that you can provide

Even with hardware encoding that machine is going to be rather underpowered. It almost certainly will not be able to watch live TV in real time.

Really? That's a bit of a bummer and no mistake. Does the DVB card not just decode the MPEG stream from the aerial, bypassing the CPU? How does it work?

I have a Creative DXR3 card which be pressed into use if this would help?

Many thanks,
Chris

You're missing the other part of the equation, which is decoding and data transfer. While that's easier then encoding, it still takes a certain amount of horsepower.

Watching live TV on my system (specs below) uses about 15% of the CPU. Figure my CPU is roughly 5x faster than yours and may well have some accelerated instructions for this kind of stuff, and a memory bus anywhere from 3x to 5x faster, ... and it just doesn't scale. Especially since what I'm measuring is average CPU usage, and to support smooth continuous playback you probably don't want that to go above 50%, so that the peak load doesn't hit the ceiling. Remember that this is essentially "realtime" work, where latency is a key factor.

Working DMA is important for reliable recording and smooth playback for mirrored reasons, here the latency issue is not so much about peak loads but continous bulk throughput. With the MPEG-2 stream coming out of card at ~650Kps you can't get too far behind without overflowing your buffers.

OBTW - This is an FAQ question. You should go read it.

Many thanks for the advice, it is quite informative and having (previously!) read the FAQ, I was a little concerned about my CPU. Having said that, the minimum official Hauppauge specs are a 450Mhz for the PVR 250 and 500MHz for the PVR 350.

My original question(s) was actually which card to go for, the Nova-T or the Nebula - I can't find an answer to [bold]that[/bold] in the FAQ, as its obviously a matter of personal opinion. I was just after some opinions really.

Many thanks for your advice, I will take heed and reconsider my options. In the meantime, any additional advice would be gratefully received.

Hey, Christos, looks like you are trying to make exactly the same box that I have spend the weekend covering bits of paper with trying to work out the best combination to get Freeview straight into a dedicated computer.

We should be able to help each other out over the next month.

Neither the DigiTV nor the Nova-T have MPeg encoders - they don't need them - Freeview broadcasts in MP2 format. All they need to do is tune into to aerial signal and dump the data stream straight onto a hard drive at 2GB/hour at full resolution and quality. Take no notice of specs for any cards other than the DigiTV or Nova-T for recording. Take every bit of notice of everyone else for playback.

Somewhere this weekend I saw a report from someone that upgraded their WinTV MythTV box to a Nova-T MythTV box, and added loads of parameters and other Linux babble that I do not yet understand. I will hunt for that again this evening - I have to go to work now

Sandeater

Here it is

http://www.ethics-gradient.net/myth/

.

Oh, and I think (but could be wrong) that the DVB-T standard is not used in USA, hence the low amount of info available for us.
The DVB-S standard used on cable and satellite is slightly different.

Hey Sandeater, good to hear from you!

I think you are right about about the DVB-T format in the States, that appears to be the vibe that I've been picking up from various sources.

So how far have you got - have you purchased everything you need yet? What spec CPU are you using?

Christos

I have not bought anything yet. The first purchase will be a Nova-T PCI card. I'm simply choosing this one because the guy in the link managed to use two at once and wrote-up how he did it.

On the shelf I have a spare AthlonXP 1600+, cooler, 40GB Hard Drive.

In my desktop I have an AthlonXP 3200+ and an NVidia 4200Ti. I have been thinking of replacing the 4200Ti with a 6800 for a while, so the 4200Ti has a good chance of becoming the MythTV playback card, especially if I can underclock it and remove the fan to make it silent.

I will initially try to build the system in my desktop (so that I only have to buy the Nova-T card), check that everything works (it will - it does for the guy in the link somewhere above), then keep running the CPU at lower and lower speeds until I find out what the minimum spec is that I can use, then build a system that is that speed

Using the minimum spec is a heat/noise driven issue rather than a cost one - I want to build the system in a hi-fi seperates case to match my existing hi-fi, so things are going to be a bit cramped / hot, and I want the system to be quiet, not noisy like my desktop, so I need to minimise (or eliminate) the number of fans. Ultimately, I would like to use the Cyrix series of processors that do not use fans, on a tiny mini-ATX motherboard (170mx170mm).

I will then add wireless LAN to connect the MythTV to the desktop upstairs and so that MP2 can be streamed all over the house, whether to the desktop, MythTV, or laptop.

Ah, a low power mobile processor! Of course!