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720p 19mbps HDV vs 40mbps DVCPROHD both at 24fps


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#1 Jonathan Bryant

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Posted 13 July 2005 - 05:14 AM

Some people say that with the Varicam when you record 24fps you are only using 40mbps as opposed to using 100mbps for 60fps. It is also known that the 24fps 19mbps HDV 720 compression is more efficient than the 25mbps 1080i HDV codec for obvious reasons. So besides being descreet frames of video how much better is the 40 mbps codec for the hdx200 or varicam at 720p and 24fps over the more efficient 19mbps 720p 24fps HDV codec?
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#2 David Mullen ASC

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Posted 13 July 2005 - 10:56 AM

Well it sounds like almost half the compression and twice the color information with DVCPROHD versus HDV (4:2:2 color-subsampling instead of 4:1:1.)

But someone else can do the math for figuring out the compression ratio...
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#3 Michael Most

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Posted 13 July 2005 - 11:38 AM

Some people say that with the Varicam when you record 24fps you are only using 40mbps as opposed to using 100mbps for 60fps. It is also known that the 24fps 19mbps HDV 720 compression is more efficient than the 25mbps 1080i HDV codec for obvious reasons. So besides being descreet frames of video how much better is the 40 mbps codec for the hdx200 or varicam at 720p and 24fps over the more efficient 19mbps 720p 24fps HDV codec?


uhhhhh.. "this" much.

First of all, there is no 720p/24fps HDV format. Not to mention that HDV is an interframe codec, MPEG based. The DVCProHD codec is intraframe (each frame is discreetly processed) and thus able to better replicate original material, even given the same compression ratio (which is not the case). It is also far better for motion, and far better for editing, in that with HDV, the non-existent "P" frames must be reconstructed from the MPEG stream. I realize you're referring to the current product the Varicam, but in upcoming Panasonic products, such as the HVX200, the codec will be more efficiently used with lower frame rates such as 24fps, because the recording system won't require a 60fps stream - thus, at least in theory, providing lower compression ratios at lower frame rates.

Even though you and a lot of other people would like to think there's a simple answer here, and a clear "winner" and "loser," this is not the case. You are, to some degree, comparing apples and oranges.
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#4 Kai.w

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Posted 13 July 2005 - 12:20 PM

OT:

I do love this topics title... :lol:




-k (sorry for lack of content)
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#5 Robert Sanders

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Posted 13 July 2005 - 06:30 PM

The GY-HD100 uses JVC's ProHDV is 720P 24P.

True 24PA 2:3:3:2 720p record capability.
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#6 Michael Most

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Posted 13 July 2005 - 07:54 PM

The GY-HD100 uses JVC's ProHDV is 720P 24P.

True 24PA 2:3:3:2 720p record capability.


That makes it a 60i recorder, just as I pointed out. The HDV spec does not contain any provision for 24p. If you asked me about the Panasonic DVX100, I would have said the same thing - there's no such thing as a 24p DV recording, either. The only current videotape formats that allow 24 frame video recording are HDCam and HDCam SR. In the future, the Panasonic P2 cards will allow direct recording of 720/24p without the pulldown frames, making it a true 24p system as well. I wish people would actually understand this. Unfortunately, few do.
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#7 Mike Brennan

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Posted 14 July 2005 - 02:38 AM

That makes it a 60i recorder, just as I pointed out. The HDV spec does not contain any provision for 24p. If you asked me about the Panasonic DVX100, I would have said the same thing - there's no such thing as a 24p DV recording, either. The only current videotape formats that allow 24 frame video recording are HDCam and HDCam SR. In the future, the Panasonic P2 cards will allow direct recording of 720/24p without the pulldown frames, making it a true 24p system as well. I wish people would actually understand this. Unfortunately, few do.

<{POST_SNAPBACK}>


There are three DVCPROHD codecs that can be used on location
One for 720/60p standard (That varicam comacorder uses)
One that works at 25/50i AJ-HDX400? camcorder does 1440x 1080 4:2:2
One that works at 29.97p/59.94i AJ-HDX400 camcorder 1280 x 108 4:2:2


Note that the HDX400 camera uses a 1280x720 pixel ccd which is upconverted to 1080i then sampled to 1440 x 1080 or 1280 x 720. It also has a 12bit head so it is better than Varicam in these respects.


Mike Brennan
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