Wonky Gibbon Ramblings

Question

So, what is the difference between one TV card and another; given you can buy dual tuner cards that will allow you to record two channels of DVB-T for next to nothing – what do the more expensive cards give you?

This has been bothering me since my last post on my Windows 7 MCE. Indeed its been bothering me ever since I did my original tests with Windows 7 RC1. That build seemed rather better in terms of responsiveness than the actual Windows 7 one did. There are of course lots of differences between the systems. One was RC Ultimate edition, the other the released Home premium, different disk drives as well – but one thing I had overlooked was the TV Tuner Card. Due to a problem with the Black Gold Signature cards (you can’t use two together under Windows 7 as you could in XP), when I built the final system I replaced the single Black Gold card I had used in the RC with a new Dual Tuner card from Peak.

In terms of the recorded programs, the Peak card has produced excellent results – but in this very underpowered, single core setup it has struggled to encode data when the machine was doing other things such as fast forwarding a different program being watched simultaneously.

Putting the single Black Gold tuner back in to the system, revolutionised it. It’s as quick as Windows MCE 2005 ever was.

Answer

And that’s the difference, the more expensive cards do much more of the encoding effort, relieving the burden from the CPU. Freeing it up to be responsive to user requests (such as “Fast Forward my program please” or “can I see the Guide whilst my program still plays please”) without crashing.

Conclusion

Which brings you to a simple choice:
It’s relatively easy to build a great PVR around an old motherboard, CPU and Windows 7, if you add high end TV tuners (encoders) and an average Graphics card (decoder) because all the heavy duty processing isn’t being done by the old hardware. It’s beeing done by dedicated high end video encoders in the TV tuner, or in the dedicated MPEG2 decoding pipeline of the Graphics card. Which rather bursts the balloon on the sense of acheivement to be honest. But for a machine which lives under the TV which is only used as a telly, does make a lot of sense.

But if you want a more versatile all round machine for which watching TV is only one of it’s role, then you just have to get something with a lot more CPU muscle, preferably with multiple cores so that it’s responsive. You then don’t need high end encoders and cheaper cards such as the Peak, will more thasn do the job. Stability might still be an issue though – as an asside, I notice that the machine is much less prone to crashing now. Fast Forward (when recording something else), was a bit risky previously. Makes sense really. Dedicated hardware encoders and decoders always do just that – encode/decode video. A CPU by contrast can be nagged by any one of a zillion different systems to interrupt what it’s doing and just quickly do something else. Which is all fine until it hits something that is time, or timing critical. Bang.

It still hasn’t cost that much. A new Black Gold Dual Tuner card is £80 which even when added to the cost of the new graphics – is under £100. Which is cheaper than buying a new motherboard, RAM, CPU – and you’d still have to buy the graphics card anyway. But it’s not the saving you’d hope for – particularly when you consider that you can buy good dedicated dual tuner PVR’s for less than double the price of the Black Gold card.