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19.7 Mbps for HD100u? less than DVCAM (25Mbps)!!


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#1 Tomas Koolhaas

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Posted 17 February 2006 - 01:24 AM

Hi,
I was surprised to see that on the JVC website it says the HD100u has a 19.7 Mbps data rate in 720/24p HDV mode. This is less than the 25Mbps of DVCAM! How does everyone else think this will affect the compression artifacts/image quality of the camera in general.
Cheers.
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#2 Phil Rhodes

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Posted 17 February 2006 - 09:08 AM

Hi,

Yes, bit sick isn't it. You'd have hoped the MPEG-2 algorithm would be scalable to fill the tape space at any frame rate.

I'm writing a picture-quality article for Showreel magazine which will cover and compare the current JVC, Sony and Canon cameras; if there's anything in particular you'd like to read about, please say.

Phil
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#3 Tim J Durham

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Posted 17 February 2006 - 09:21 AM

Hi,

Yes, bit sick isn't it. You'd have hoped the MPEG-2 algorithm would be scalable to fill the tape space at any frame rate.

I'm writing a picture-quality article for Showreel magazine which will cover and compare the current JVC, Sony and Canon cameras; if there's anything in particular you'd like to read about, please say.

Phil


I'd like it if you could sort out all the potential data rates available on the Sony XDCams and their new HD cameras. There are several different selectable data rates, apparently, IMX in 3 or 4 flavors as well as DVCam and I'll be shooting with one in about two weeks and for several months thereafter.

At this point it looks like it will fall to me to figure out which data rate to use for broadcast. Shooting in NTSC (rental cams) and uprezzing to HD AND converting all to PAL for broadcast. Edit will happen in Avid Xpress XP and I need to figure out how I can convince them to let me edit on a Powerbook in the field.

How's that sound, Phil? I'm not exactly a master technologist.
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#4 Phil Rhodes

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Posted 17 February 2006 - 06:34 PM

Hi,

It's not that easy. You've got multiple codecs involved, including DV and variants, MPEG-2 intra and non-intra, VBR and CBR, so comparing numbers doesn't tell you much. An intra-compressed MPEG-2 will look better at the same bitrate than DV, at the expense of inter-frame smearing.

Phil
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