High Definition recorder

siranthony

Distinguished
Dec 8, 2001
326
0
18,780
Hey all,
I just purchased a high definition satalite reciever. The picture is very very nice. I work wierd hours and don't get to see all the movies and stuff I want. I am looking for a solution. I would like somthing like a TV tuner card that records high definition from an RGB connection in real time. Also being able to schedule record times and such. Is ther such a beast? And would it be cost effective versus a DVHS recorder that runs 500 to 700 USD.

Thanks

P4 2.4c @ 3.0 ASUS P4P800 dx Geil Golden Dragon PC4000 2.5,3,3,6 250FSB 1:1 Radeon 9800 non-pro 2 Maxtor 60gig 7200rpm 8mb cach in raid 0 SB Audigy 2 Antec True 480
 

Crashman

Polypheme
Former Staff
Most TV cards allow 720i recording, you'll still be stuck with an S-Video cable however.

I can't really see what the big deal with component video is anyway, aren't those signals carried by separate wires in the S-Video cable?

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>
 

siranthony

Distinguished
Dec 8, 2001
326
0
18,780
I can't say if they are or what. But I can tell you that on this satilite box there is no comparison between the s-video and the RGB connection. The box will only put out to one or the other. The s-video is defeintly not putting out high definition. The RGB puts out a very nice 1080I picture. Hard to explain until you have seen it on a high def big screen TV. It's better than even going to the movies. You see details like never before. I don't think the general public knows what they are missing.

P4 2.4c @ 3.0 ASUS P4P800 dx Geil Golden Dragon PC4000 2.5,3,3,6 250FSB 1:1 Radeon 9800 non-pro 2 Maxtor 60gig 7200rpm 8mb cach in raid 0 SB Audigy 2 Antec True 480
 

phsstpok

Splendid
Dec 31, 2007
5,600
1
25,780
The problem is bandwidth. 1080i (resolution 1920 x 1080) represents a lot of potential data. 1080i being interlaced means there is one field of 1920 x 540 pixels every 1/60th of second. Two fields make one frame so you get one 1920 x 1080 frame every 1/30th of second. If you wanted to record with 24-bit color you would need 1920 x 1080 x 3 (24 bits means 3 bytes) x 30 (frame per second) = 186,624,000 bytes/sec or roughly 187 MB/sec of uncompressed data. This is beyond the maximum bandwidth a PCI bus and way beyond the write capabilities of current hard drives, even in a RAID 0 configuration.

I don't know how you would get digital data from an RGB connection which is analog. You'd need A/D conversion and because of bandwidth limitations you'd also need real-time data compression.

Perhaps one of HDTV tuner cards can do what you want.

<b>56K, slow and steady does not win the race on internet!</b>
 

mattburklund

Distinguished
Mar 19, 2002
276
0
18,780
Hey crash your right, the problem is not the cable but the hardware at either end of the cable. S video with high quality components can be very competitive with component video. This is the opinion of the ceo of Rotel, I forgot his name but I can dig it up if you like
 
S-video and Component carry the signal differently.

S-video carries uses 2 wires (pins) for chromance and 2 for luminance channels.

Component uses 3 cables (2 wires each), and these cables are either RGB (red, green and blue) or colour difference channels: Y, Y-R and Y-B (yellow, yellow minus red and yellow minus blue) or Y,CB,CR or Y,I,Q, and for HDTV Y, PB and PR (although too many use that even for Super/Enhance-Def. signals); and the colour an intensity information is on seperate channels. Y usually carries the Luminance info in the non-RGB cases. This method uses less bandwidth than RGB because the hidh-def. info is carried just on the Y/luminance channel, whereas the RGB carries high-def. on all three signals. This method is also less likely to have 'off' colours as they are all related, while an error, interference or noise in an RGB set-up will give you one or two dominant colours making the picture look more/less blue/green/red. However this is nothing compared to the tons of issues you CAN have with composite and Svideo connections, chroma-crawl, busy edges, loss of detail, and cross-coloring just to name a few. Also component video is much more receptive to, and benifits more from, compression , especially time compression and time domain multiplexing on the colour diff. channels. Composite and S-video have alot of problems with compression and even encoding/decoding, the difference is quite noticeable, and it usually results in better picture quality and much less video noise (even in the RGB setup).
That's the main reasons why component is better at carrying the signal, but depending on what you're watching you may not notice.


- You need a licence to buy a gun, but they'll sell anyone a stamp <i>(or internet account)</i> ! <A HREF="http://www.redgreen.com" target="_new"><font color=green>RED</font color=green> <font color=red>GREEN</font color=red></A> GA to SK :evil:
 
Some of the Digital tuners now have DVI out so it would be a digital signal in that case.

And the PCI bus isn't the only method, the ATI's use the AGP bus and supposedly future versions will take advantage of that specifically for HD recording, as well as the future PCI-ex bandwidth. And some PCI-X SCSI raids can handle 600 MB/s and no I'm not meaning 600Mb/s, and it's quite doable like on my dual AMD video rig which I could scsi raid on my dual PCI-X slots (with 2 Adaptec controllers) should I have the need/desire/money :smile: . And who knows what SATA-300 will bring. The main reason compression would be good is because at even 100MB/s that doesn't allow you much recording time, even on a wide array 1 hr of recording would take up about 400gigs.

Anwyhoo, that is the future, the question is just how long it is before we can buy it for consumer clas products (not the Matrox Pro-sumer type stuff [whihc is VERY NICE, but a little expensive]).


- You need a licence to buy a gun, but they'll sell anyone a stamp <i>(or internet account)</i> ! <A HREF="http://www.redgreen.com" target="_new"><font color=green>RED</font color=green> <font color=red>GREEN</font color=red></A> GA to SK :evil:
 

phsstpok

Splendid
Dec 31, 2007
5,600
1
25,780
I have to admit I never even considered PCI-X (but then again I only claimed PCI).

I don't know much about it, PCI-X that is. I vaguely recall, that PCI-X 2.0 is a 64 bit, 66 Mhz bus with DDR technology providing 533 MB/sec. This sounds like PCI-X would have plenty of bandwith for HDTV. However, how many hard drives would you need to get the sustainable write speeds for uncompressed video. Are four striped "uber" SCSI drives enough? to cover the 180+ MB/sec of bandwidth of 1080i? I'm asking since I don't know.

One other thing, I negected some of the new desktop chipsets that don't put the hard drive interface on the Southbridge. Doesn't nForce2 have much high bandwidth available for HDs than HDs tied to at soutbridge and PCI bus?

Whatever the case, the hard drives themselves are the biggest bottleneck. I don't know the sustainable write speeds of all HDs but 7200 RPM IDE are in the 30 MB/sec range, I think. (I know the write speeds are lower than the read speads). I'm guessing 15K SCSI drives are twice as fast. Call it 60 MB/sec sustainable. How much realworld gains do get with RAID 0 for writes? I don't know but it's not 100% improvement per drive striped.

Anyway, you can see the issue. It's still quite a challenge to deal with the full bandwidth of HDTV.

It would be better to get the compressed MPEG2 stream instead.

Now the question is (for me), is the MPAA going prevent receiver manufacturers from making the HDTV digital stream available for recording here in the USA? I'll bet they don't want anyone doing digital recording.

The secondary question, as you hinted on, is what consumer products will we see and when? What's going to take the place of DVD? HDTV requires considerably more storage than DVD(sorry I don't feel like calculating it. That's if the modified MPEG2 compression is still used. Do you think they will use MPEG4 compression for the HDTV equivalent of DVD?

Would blue laser DVDs have enough space for HDTV movies with MPEG4 compression? Would the quality be good enough?

<b>56K, slow and steady does not win the race on internet!</b>
 
Well the Adaptec cards offer up to eight SCSI drives on my computer (4 per card), each having 80MB/S throughput max.

And yes you could cover it with a good scsi raid.

The nForce2 does have a higher speed hypertransport, but supposedly the nForce3's version is slower than VIA's solution (to which nV said 'ours is fast enough for most users' [perhaps, but we shall see])

SCSI drives often have 40MB/S speeds, bu the Voltage Differential drives are 80MB/S. And yeah you lose some performance, but 8X80MB/S = 640MB/S then multiply that by the loss factor and you'd have your answer. Maybe let's be conservative and say 50% loss, that means we still have320MB/S.

To me you'd run out of actual SPACE (especially with the tendancy for small SCSI drives) before you ran out of throughput bandwidth.

As for recording, you can already record a digital signal in compressed format on an RCA product I saw reviewed in Sight and Sound (IIRC). I can't remember the model (mainly because we don't have any over the air stuff yet in Canada). The review was in NYC and supposedly the recording results were very good. The review didn't really describe the technical aspects too much, like what kind of compression was used, but it was stored on a hard drive (it was an over the air broadcast card for your computer).

As for the consumer product, our first example will likely be the BlueRay DVD recorder/player from Sony as you elude to. I'm not sure if the version availible in Japan records HDTV or not (and have no idea of the/any compression technique used). The main problem is that those cost about $10K right now, so they aren't really for your average BestBuy customer.

As for the compression method, I'm not sure. MP4 has alot of potential since it supposedly maintains a higher level of video fidelity than MP2. There is MP5 that Samsung used for their Pro-Sumer camcorders last year, but I haven't see a serious review of the diff. between the two. And not each new Mpeg is geared for the same thing. I'm not sure if MP5 isn't some hybrid compression method. I know Mpeg7 is more content/composition andtexture based, and of little use in current video entertainment applications, however the content descriptors will likely be a part of future media. There's alot of them out there, like MPEG-21, which I can't remember what it does. And perhaps a better method comes out from an independant body. Like Vorbis did for music.

With more processing power we may be able to run higher and more complex compression/decompression real-time. However I wouldn't expect much within the next year or two, and especially in the states, where it seems regulating Mickey's Legacy is more important than giving the public products it wants/needs.


- You need a licence to buy a gun, but they'll sell anyone a stamp <i>(or internet account)</i> ! <A HREF="http://www.redgreen.com" target="_new"><font color=green>RED</font color=green> <font color=red>GREEN</font color=red></A> GA to SK :evil:
 

phsstpok

Splendid
Dec 31, 2007
5,600
1
25,780
OK, so it's possible but not practical to record uncompressed high definition video.

You provided some good leads to research regarding video compression. Thanks.


<b>56K, slow and steady does not win the race on internet!</b>
 

TRENDING THREADS