new plugin for changing channels (DirecTV w/serial port) (1 Viewer)

[David Abineri]

Thanks, mm, this is very illuminating and sorts out many of the issues I was having as I try to read up on this PC DVR issue.

Are there no capture cards that capture 1080p? It would seem logical that someone would have done this by now.

Out or curiosity, after the satellite STB tunes the signal and sends it out to the capture card (or the TV), is it encoded for protection in any way at that point?

Finally, am I correct that in order to build a PC DVR I need a capture card, PC with sufficient speed and memory, video card with sufficient memory, a large enough power supply to power it all and a large HD to store all the video? Sometimes they will specify a dual core processor to go with a particular card. Why is the processing speed not sufficient ie 3GHz?

Many thanks for your time again, Dave

 

[mm1352000]

Hi again Dave

Are there no capture cards that capture 1080p?

Not that I know of. The Colossus and HDPVR do 1080i max. Tuners with capture inputs will be very much inferior as most only handle SD.

It would seem logical that someone would have done this by now.

Not really actually. I don't know of anywhere in the world where 1080p is broadcast, simply because the cost of broadcasting a channel at such a resolution is very high. 1080i is very good, and takes only about half the bandwidth of 1080p (half bandwidth -> half cost). So there is that. I would agree that there are consumer video cameras that capture in 1080p these days, but you don't need to run the recordings through a capture card to get them onto your computer - you just copy the files across (or whatever...).

Out or curiosity, after the satellite STB tunes the signal and sends it out to the capture card (or the TV), is it encoded for protection in any way at that point?

Yes, but not all the time. I'd imagine the answer would almost certainly be "yes" with a provider like Directv. There are two main forms of protection that you'd see at that stage:
1. HDCP - high-bandwidth digital copy protection. This is used with HDMI. Apparently the Colossus' HDMI input does not support inputs that are protected with HDCP.
2. Macrovision - an analog copy protection technology.

There are ways of getting around both, but I'd ask you to respect our forum rules and not discuss anything further about such things here.

Finally, am I correct that in order to build a PC DVR I need a capture card, PC with sufficient speed and memory, video card with sufficient memory, a large enough power supply to power it all and a large HD to store all the video?

Yep, sounds about right, although you don't need the latest and greatest i7 system. I think an i3 would probably be more than enough. I'm not so up to date with my knowledge in this area as the last PC I bought was a first gen Core 2.

Sometimes they will specify a dual core processor to go with a particular card. Why is the processing speed not sufficient ie 3GHz?

Can you give an example of such a card?

mm

 

[David Abineri]

mm, From the Hauppage web site for Colossus card:

Note: when playing back video recordings made with the Colossus, a fast CPU and at least 256MB of graphics memory are needed.

Processor Requirements (minimum for HD playback): Dual core CPU 2.0GHz or faster
Windows 7 (32 and 64-bit), Windows Vista or Windows XP service pack 2 (32-bit).
Graphics with 256MB memory (or greater)
PCI Express x1 slot
Sound card for audio playback
CD-ROM drive for installing the Colossus software

Does one really need a dual core processor or is the 2GHz all that is required?

Thanks, Dave

 

[mm1352000]

Hi again Dave

Right, understood. The deal with that is that the Colossus re-encodes analog inputs with a hardware h.264 encoder. Both encoding and decoding h.264 *is* processor intensive. In other words, watching recordings from the Colossus would require a decent CPU and/or a decent GPU to enable the h.264 to be decoded smoothly. Note that I said "and/or". Most modern GPUs have dedicated hardware for accelerating the decoding h.264, and this dramatically reduces the load on the CPU.

Probably the best way to explain this is to use my own system as an example:
Intel Core 2 e6600 2.4 GHz (dual core) CPU
Sapphire HD 4670 512 MB video card
4 GB RAM
XP Pro SP3

Okay, so my video card supports decoding h.264 with hardware (AKA DxVA). When I view 1080i HD content (which is similar to what the Colossus would produce - 10-15 Mbps), I usually use a codec that enables that dedicated hardware to be used. My CPU usage sits at less than 10% the entire time. My GPU on the other hand is working at around 33%. If I use a codec that *doesn't* support DxVA, my CPU usage sits at around 40% and my GPU sits at around 20%. Note that I have a 24" 1920x1200 screen and these tests are only running at 1/4 resolution (meaning the numbers are lower that they would normally be) - I'm sorry I can't do any better because I can't view CPU and GPU usage while MP is full screen.

Anyhow, hopefully that gives you some idea. Older Pentium 4 or Pentium D dual cores would probably need to run at at least 2.8 or 3 GHz, but a Core 2 is much more efficient. Hauppauge have to (1) be conservative so they don't get customers that complain because they bought the bare minimum and it didn't work, and (2) be vague about the technical details because most people wouldn't know the difference between a Pentium 4 era dual core and a Core 2/i7 era dual core - they're more likely to base things on a Pentium 4 as a lowest common denominator.

mm

 

[David Abineri]

Sorry, mm, every answer (and they are very good) poses a new set of questions.

If I purchase a video card with h.264 decoding, how is that invoked or is it automatically recognized? I have never tweaked a video card before.

How do I invoke different codecs (this may be the same question)?

What are the key phrases to be sure I get a reasonable CPU? The one for your machine does not say Pentium 4 or Pentium D. Will any dual core 2Ghz be sufficient if it is not one of these two?

Sorry for taking up your time but I hope you understand where I am coming from. I am building my own PC system by the way.

Thanks, Dave

 

[mm1352000]

Sorry, mm, every answer (and they are very good) poses a new set of questions.

As much as I'm happy to answer, it *is* quite time consuming for me. Perhaps you could have a look at the wiki for this next set of questions? The codec page is pretty good. In fact the entire "preparing your system" section might be worth a read...

Brief answers before I go to bed (it is 7am here and I've been up all night):

If I purchase a video card with h.264 decoding, how is that invoked or is it automatically recognized? I have never tweaked a video card before.

It is all about the codecs. Codecs either do or don't support DxVA. If they do, then they often have configuration options (example - note the "use hardware accelerator" options) that allow you to turn DxVA on or off. So if your video card supports DxVA then there is usually nothing you have to do with the video card itself other than installing the appropriate drivers. You choose codecs that support DxVA in MediaPortal configuration, and enable DxVA if appropriate. Configuration for that is explained briefly -->here<--.

How do I invoke different codecs (this may be the same question)?

MediaPortal configuration as linked above. Note that if you're starting to ask these kinds of questions then I think it is about time you install it and have a bit of a fiddle.

What are the key phrases to be sure I get a reasonable CPU? The one for your machine does not say Pentium 4 or Pentium D. Will any dual core 2Ghz be sufficient if it is not one of these two?

I'd recommend you *don't* go for a Pentium 4 or Pentium D. That technology is now 5 years old at least and has been totally superseded. You might have to do some of your own research here based on what you've budgeted. On the Intel side, an i3 system would possibly be a good place to start. For AMD, maybe Brazos (Fusion)... not so sure.

Sorry for taking up your time but I hope you understand where I am coming from. I am building my own PC system by the way.

I do understand, but do expect to spend a fair amount of time reading as there is a point where you do need to do the research yourself to find what suits you. The information is laid out all over the internet already - you just have to know where to look. You may want to visit Anandtech to take a look at their HTPC related articles, and also have a read -->here<--.

Right, I'm off to bed. Happy reading!
mm

 

[mm1352000]

Hi again Dave

Just another brief comment about hardware requirements. You might want to read -->this<-- [short] thread. A guy there is able to run MP with 1080i streams and a 1680x1050 22" monitor (almost full HD) with the following setup:

Single core Athlon64 2GHz
2G RAM
Win XP SP3
HIS ATI 4670 AGP edition

Food for thought! As he says, if he didn't have the decent graphics card (and codecs that support DxVA) then it wouldn't work.

mm