Some general HD questions

[K. Forman]

With the awesome capabilities these new cameras are showing, I feel it is a shame to take a great 4:2:2 image, and save it on DV tape at 4:1:1. Dragging a small studio into the field is also not something I want to think about. All that said, with something like the bonsaiDrivehttp://bonsaidrive.com/bonsai.html, light, portable 4:2:2 capture is available.

IF I go with the HD100, is there a way to get 4:2:2 out of the composite out, and into the BNC inputs? Also, I haven't seen mention of it, but does the HD100 have Timecode and Genlock?

IF I went with an XL-H1, does the BNC offer 4:2:2 out, and still offer timecode?

By the way, the going price for a bonsaiDrive is around $2,200, and has a DC powered option.

[K. Forman]

Anybody? Bueller?

[David Heath]

Originally Posted by Keith Forman

I feel it is a shame to take a great 4:2:2 image, and save it on DV tape at 4:1:1.

IF I go with the HD100, is there a way to get 4:2:2 out of the composite out, and into the BNC inputs? Also, I haven't seen mention of it, but does the HD100 have Timecode and Genlock?

Keith, I think you have a few misconceptions. Firstly (AFAIK) NO HD system is 4:1:1 - top end is 4:4:4, more compressed systems 4:2:2 or 4:2:0, with HDCAM 3:1:1. But don't get too hung up on the numbers, they are ratios, not absolutes. For example, the "1" in the HDCAM colour space represents 480 horizontal samples....... exactly the same number as represented by "2" in DVCProHD! Why? Because in HDCAM "3" is referenced to 1920, in DVCProHD "4" is referenced to 960.

Equally, having twice as many chroma pixels sounds a great idea (as indeed it may well be) but not if bandwidth restrictions then force far higher degrees of compression on chroma in general.

Secondly, a composite output is by definition analogue, with the colour information carried on a subcarrier, and such only exists at SD. Equally, terms such as "4:2:2" have no meaning in the analogue domain. They represent the ratio of chroma (digital) samples to luminance.

Being able to boast the biggest numbers is always good from a marketing perspective. Unless you're absolutely clear about the underlying fundamentals be very, very wary. Sometimes a product with average scores across the board will be far better than one with one high score and a number of below average ones. (But guess which the advertising men will flag up.......!?)

4:1:1 is normal for colour space in NTSC SD DV25 formats, but in PAL, DV and DVCAM are both 4:2:0 (Only DVCPro is 4:1:1). My understanding is that 4:1:1 was initially seen as preferable when digital devices were islands in an analogue sea, as it supposedly withstood analogue-digital conversions better than 4:2:0. That day is long past.

[Douglas Spotted Eagle]

If you wanna get real technical about it, color sampling referenced with a "4" in front isn't accurate for HD anyway, it's an SD referencing display based on the frequency of the sample. What often is referred to as "4:2:2" is really 22:11:11, but that doesn't roll off the tongue as nicely, and it doesn't print as well. 22:22:22 is the full signal with no chroma subsampling.
22:11:11, which is what the composite outputs of the HD100 would be about 1.4Gbps (per second) that would need some kind of compression in a portable hardware device.
David's comment about looking at only numbers being a fallacy is a HUGE truth. While the sampling might indeed be say...4:2:2, what about the information FEEDING the sample? If you connect a VHS deck to an HDCAM deck and record it, the recorded information truly is 4:2:2. But the picture sure isn't an HDCAM-quality image.
Can get really fun, eh?

[K. Forman]

Hey David, thanks for responding. The way I understand it, these two new HD cameras are capable of getting higher quality images than the older DV cameras. This is because of better sensors, and better compression, right? But when you record to tape, you lose half of the chroma information, and half of the luminance info. This is, as you said, because the tape format is 4:1:1.

So, the common fix for this, is to capture the signal live, before it gets compressed to tape. The XL-H1 has BNC terminals, but the HD100 only has RCA composite and componant jacks. Is there an adaptor from RCA to BNC?

[Douglas Spotted Eagle]

There are RCA to BNC adapters that can be purchased for a couple dollars each, female RCA to male BNC. You can also very easily modify the factory cable to BNC male-only. I wouldn't, because most consumer displays are RCA only, in the event you want to monitor something live on an inexpensive monitor.

[K. Forman]

Thanks! That helps a bit.

[Chris Hocking]

Please excuse me if this is slightly off-topic. After reading this thread, I just had a quick look at the Rosendahl website and their "bonsaiDRIVE". I'm not quite sure I understood what I read. Is it possible to hook up a Sony Z1P (for example) via the "component out" sockets into the bonsaiDRIVE, and record uncompressed high-definition footage? If so, that's really, really cool! I was under the impression that there was nothing on the market that could do such a thing.

Can you take out the hard drive in the bonsaiDRIVE unit? Is the codex compatible with most NLEs? I guess what I'm getting at is, can I record my Z1P footage uncompressed onto this device, take out the hard drive, hook it up to my Mac (maybe using an IDE to Firewire interface?), and start editing? If I could that would be incredible.

Maybe I'm just missing something obvious and wasting my time day dreaming...

Chris!

[K. Forman]

I'm not sure if you can swap drives in it or not. But, if you have componant out, you should be able to capture uncompressed footage.

[David Heath]

Originally Posted by Keith Forman

But when you record to tape, you lose half of the chroma information, and half of the luminance info. This is, as you said, because the tape format is 4:1:1.

There's much more to it than that, and if you are in Melbourne, chances are you may never come across 4:1:1 anyway - the only thing you may come across that uses it is DVCPRO. In Standard Definition and PAL, DV and DVCAM are 4:2:0, unlike the States and NTSC where they are both 4:1:1.

But the real significant point about all these new HD cameras is that the pixel matrix they record is far more detailed than for Standard Definition. For PAL, SD is a frame matrix of 720x576 (for luminance), and the three corresponding figures for the HVX, HD100, Z1 are 960x720, 1280x720 and 1440x1080. In none of these cases is the colour sampled 4:1:1, it's either 4:2:2 or 4:2:0, and don't draw any conclusions from the different sizes of the three matrices other than they are ALL significantly better than SD.

In practical terms, the HD100 is 4:2:0, not 4:1:1. Coming out of the RCA outputs will be analogue, and any A-D conversion may cause more problems than 4:2:0. Personally, I'd feel the HD100 recording only 25p, not 50p, was far more of a drawback than any colour space issues. Any four 1/3" cameras are outstandingly good for the money, but all have their foibles and none matches any 2/3" camera.

[K. Forman]

My whole bottom line here, is that I want better footage before the edit. If you are starting out with regular 4:1:1 off of a tape, then edit, add some transitions, do some compositing, RECOMPRESS... you have stuff that isn't very clean. And if you want to do some keying? Sure, it can be done with any software, any footage, right? But it will be a lot cleaner if you start with more color and chroma info... which is what I would like.

You can't put back what isn't there.