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EX1 codec question


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#1 Jason Outenreath

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Posted 22 March 2010 - 11:48 AM

I was importing footage from this camera for the first time the other day, and noticed that despite the files being 1920x1080 24p images, that supposedly record 35mbps, the files were unusually small. For example, a 2 minute scene would be about 700mb. I was wondering if it's just a really efficient codec? Or lossy one? Or I'm doing something wrong. Thanks.
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#2 Chris Millar

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Posted 22 March 2010 - 03:55 PM

Thats 4:2:0 for ya ...

Now try recording the same scene and duration in 720p and look at the file size - that's the real mind boggler
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#3 John Sprung

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Posted 22 March 2010 - 05:03 PM

Actually, 4:2:0 is only 25% better than 4:2:2. Most of the compression in this format comes from it being long GOP.

I haven't been able to find out if this camera is giving you 8 or 10 bits out, but assuming 8 since they don't say, your uncompressed two minutes would be about 72 Giga bits, or 9 Giga Bytes.

Long GOP gets you the best picture in the least bits, but it takes some extra effort to edit.




-- J.S.
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#4 Adrian Sierkowski

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Posted 22 March 2010 - 06:05 PM

sometimes it's just best to say well it works and I like the images. Just food for thought.
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#5 David Williams

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Posted 22 March 2010 - 07:58 PM

I've read Juan Martinez from Sony confirm 10bit from HD-SDI, full 10bit, not padded 8bit.

You also have to really try very hard to intentionally break the XDCAM EX mpeg2 codec in acquisition. Generational edits and heavy post will produce quantisation banding and build on the inherent mosquito noise though of course, so transcode to something more suitable.
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