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GY-HD 100 & 200 series ProHD HDV camcorders & decks.

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Old December 1st, 2006, 04:33 PM   #31
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Quote:
Originally Posted by Thomas Smet
HDV is basically like the DVD version of HD. It floats somewhere around like what a DVD would look like with a bitrate of 5-6 mbits. 720p HDV seems to be around what a DVD would look like with a bitrate around 7 mbits.
Exactly my point, but you have got the numbers wrong. As I said an 8 Mbps MPEG2 has small but certain differences from an original DV25, but with half the datarate (12 to 13 Mbps) the difference would only be marginal.

720p has 2.5x the pixels of DV, so a comparable datarate for HD would be around 60 Mbps for an encoder for each frame by itself. HDV giving you 19.7 is just at 1/3, but the frames are progressive, so the MPEG2 codec does a far better job and not every other group of pixels has a different complex pattern (it isn't chaos, is it) - which also helps...

All this means that HDV 720p at about 20 Mbps would be a better trade-off then 8 Mbps would be to original DV. A far better trade-off. The difference will be marginal in most cases.

Will there be cases where the codec will underperform? sure (It can't choose the place of the I frames for one...)

Is it perfect? Of course not, no one says it is...

At the end of the day: Anthony is right in stressing my point and adding another one. The lenses and everything are in balance for the price point. Some people want to have a Ferrari-engine in a Smart - but I suppose anyone would agree that's hardly a 'balanced package'. You want to have a $1k camerahead and record it uncompressed? That's like the engine of a Smart in a gigantic road truck... The extra loading space such a truck gives you won't do you any good if your engine won't support any more load than the load that can be fitted in the original car...


I'm talking about the footage of the GY-HD101 (that I'm quite familiar with). I can't say anything about the HC1 (I haven't seen it), but it makes me wonder if you have ever seen footage of the GY-HD101? Progressive is far, far better for MPEG2 (because that uses no higher order corrections for the relationships between 2 fields) - and don't take my word for it, you should see it with your own eyes.

Will uncompressed be even better? of course. But at what cost? Not being mobile anymore for one. No easy and fluid editing anymore either. And is the difference in quality that much to justify it? No, because the format and the head and the lens are all quite very nicely balanced...
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Old December 1st, 2006, 07:11 PM   #32
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I have seen HDV footage from every camera out there right now. I am a huge fan of progressive video and if you search you will find some heated arguments between me and a few others on here that I will not mention about how progressive is better then interlaced. In fact I keep trying to point out how much better progressive 4:2:0 is compared to interlaced 4:2:0 due to the fact that the chroma has to alternate every other line. Anyways.

The way I always figured it out was that HDV1 is 2.5 larger so I divide 19 mbits by 2.5 to get somewhere around 7-8 mbits.

HDV2 on the other hand which is the first number I gave you is 4.5 larger then DV so I divide 25 mbits by 4.5 which gives about 5.5 mbits. In my opinion that is a little low considering it is interlaced.

As for uncompressed I never use uncompressed. I prefer to use an in between format that trades off between performance and quality. For example with Liquid I like to use a I frame based mpeg2 codec that uses 50 mbits for SD. This thing is 4:2:2 and looks almost exactly like the uncompressed source but is only double the size of a DV file. In fact mpeg2 I frame at 25 mbits looks a lot better then DV at 25 mbits. For me capturing through an uncompressed feed into a high quality codec is the key. There are many codecs such as Cineform Prospect that will fit on a single drive and have quality that is good enough for even Hollywood. As much as I would love to work with uncompressed HD I do think it is a waste. A great codec can give you 98% of the quality for a fraction of the bandwidth and that is good enough for me. Heck it sure beats raw HDV. I don't even mind HDV or 4:2:0 (progressive please), It is the blocky banding that kills me during keying. I use a component/SDI/hdmi source to a light compressed file mainly just to avoid that sort of a thing.
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Old December 2nd, 2006, 06:09 AM   #33
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Quote:
Originally Posted by Thomas Smet
The way I always figured it out was that HDV1 is 2.5 larger so I divide 19 mbits by 2.5 to get somewhere around 7-8 mbits.

HDV2 on the other hand which is the first number I gave you is 4.5 larger then DV so I divide 25 mbits by 4.5 which gives about 5.5 mbits. In my opinion that is a little low considering it is interlaced.
19.7 divided by 2.5 gives you 8. 8 Mbps MPEG2 is pretty fine - too bad we hardly ever see it (movies are usually encoded 4-5 Mbps). Also, this 8 Mbps we'll use to encode progressive footage, which suits MPEG2 so much better, so the result is better.

Once again: 8 Mbps interlaced is fine, 12-13 Mbps interlaced is probably overkill. The sweet spot could arguably be around 10 Mbps for interlaced. I doubt 8 Mbps progressive will do any worse then 10 Mbps interlaced - you should try this with a good encoder (CCE or something).
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Old December 3rd, 2006, 12:30 PM   #34
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All good things to consider.

But in answer to the second part of the threads main question...

Quote:
Originally Posted by Tyson Perkins
How does this camera or the HD250 scale against these other cameras in its range? In terms of image quality, low light performance, etc?
For the 250 there is no comparison, simply because no one has produced a better camera that can do as much or as well. Again remember he was saying "for the money". Show me another camera for 10k-16K (with a good lens) that does everything the 250 can do.

As for the HD200, XL-H1 or HVX-200, it's all arguable as to how you use the camera anyway.
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