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Old October 10th, 2002, 04:51 PM   #1
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HD vs. DV

Can anyone explain:
what the difference between HD video and let's say mini-DV.

Bruce
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Old October 10th, 2002, 06:10 PM   #2
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Hi Bruce,

This is a great question and thanks for asking it. I can't provide a complete answer here, but I can start off what will hopefully be a very informative thread.

"DV" (or Mini-DV, which refers to a size of DV cassette) is known as Standard Definition video with a resolution of roughly 720x480 pixels in the American/Japanese flavor of video called NTSC, or 720x576 pixels in the European/Australian flavor of video called PAL.

"HD" is known as High Definition video with a resolution of at least 1280x720 pixels. There are a couple of different versions of HD.

Plain vanilla DV is usually referred to as DV25, meaning a DV format with a throughput of 25 megabits per second, whereas HD is -- somebody correct me if I'm wrong here -- referred to as DV100, with a throughput of 100 megabits per second.

Basically we're talking about the differences between Standard Definition digital video (good ol' Mini-DV) and High Definition digital video (which can cost some serious bucks). Hope this helps to get things started,
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Old October 10th, 2002, 07:24 PM   #3
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Is it the chip or the size of the tape? OR could there be (someday) a mini-dv that's HD.

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Old October 10th, 2002, 07:44 PM   #4
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Hi Bruce,

CCD size and cassette size do not make the determination between SD (standard definition) and HD (high definition) digital video.

It's strictly a question of signal, throughput and format. Right now, all of the HD aquisition tools that I'm aware of are using 2/3rd-inch native 16:9 chips, and are recording on HD cassettes, which come in different sizes (see http://www.pro-tape.com/sonybeta.html#hd for an example).

There are some DV cameras using 2/3rd-inch native 16:9 CCD's where are HD, and there are some others which are SD (not HD). The chip size doesn't affect the format.

Basically, digital video which has a throughput of 25 megabits per second is standard definition, and digital video which has a throughput of 100 megabits per second is high definition. That's where the determination is made between these two formats (SD and HD digital video).

Conceivably (maybe eventually) we'll see native 16:9 high-definition CCD's that are smaller than 2/3rd-inch, but it hasn't happened yet.

There could someday be an HD cassette that's the same size as Mini-DV, sure. But you wouldn't call it Mini-DV. Mini-DV itself is always SD (standard definition), not HD. Hope this helps,
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Old October 10th, 2002, 07:50 PM   #5
 
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It's not really related to the tape size, except for the tape's ability to record the data stream fast enough. Since HD has a higher data rate(aka data stream) the tape would need to move faster thru the transport to record at the same data density. I assume that the data density is pretty maxed out on DV tape at 25 mbps and current transport speeds.

As for chip size, it's not really related to chip size, either....rather to the number of pixels per unit area on the chip. The more pixels per unit area on the chip, the higher the resolution. I recently read that some Japanese firm has recently developed a 35mm chip...in order to dublicate the characteristics of 35mm film...I'd love to see those images, altho', I suspect it costs more than I'll make in my lifetime.

It follows that the more pixels a camera has, the faster the onboard processor needs to be able to stream the data bits thru the system on to the tape. A daunting problem once the number of pixels gets much over 1Meg(1, 000, 000).

Finally, the data format for HD is not the same as for DV. The data is recorded in a matrix of rows and columns, not in the traditional NTSC format of horizontal lines. Notice that your digital computer monitor shows no horizontal raster lines like an NTSC monitor.

Hope this helps.
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