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Ucompressed data?


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#1 Krstic Zoran

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Posted 04 April 2010 - 09:52 AM

How many bites was made if all of data from CCD is digitalized first...of course before MPEG4 compression in case of F23 or F35!?

3 x 74.25 MHz x 14 bits = 3118.5 Mbps /4:4:4

or

3 x (1920 x 1080) x 14 bits = 87.0912 Mb x 25 fps => 2177 Mbps

I think that first equation is right...but in book "High definition cinematography" Paul Wheeler (second edition) was explained second equation (for HDW-F900,but same story... :) ).

My second question...
RED ONE has CMOS sensor at 4096 x 2304/12 bits.
Uncompressed RAW => 4096 x 2304 x 12 bits = 113.24 Mb x 25 fps = 2831.15 Mbps
How much bytes would be made for RGB 4K (uncomressed)? There : http://www.redoneafrica.com/redone.htm, was written that RGB 4K uncompressed made 1313 MB/s, how?

Sorry for too much maths ;)
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#2 John Sprung

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Posted 05 April 2010 - 02:26 AM

The 74.25 MHz thing is from old time analog HDTV. The right answer on uncompressed bit rate is to multiply out colors, pixels, bits, and frame rates:

For 4:4:4 RGB you have three color channels, 1920 x 1080 pixels, 14 bit depth, and 25 frames per second:

3 x (1920 x 1080) x 14 bits x 25 fps = 87.0912 Mb x 25 fps = 2177 Mbps

For the Red, with its Bayer mask, you have one color per location, 4096 x 2304 photosites, and again 25 frames per second:

1 x (4096 x 2304) x 12 bits x 25 fps = 113.24 Mb x 25 fps = 2831 Mbps

RGB 4K, given the same height, bit depth, and frame rate would be 3 x 2831 Mbps = 8493 Mbps

1313 sounds like it's compressed.



-- J.S.
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#3 Harrison Hui

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Posted 22 April 2010 - 04:17 AM

Hello, er 1313MB/s is correct as 8 bits = 1 byte. So 8493Mb/s = 1061.625MB/s.

Rather massive file sizes if you think about it. Per minute of footage is around 60GB.
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#4 John Sprung

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Posted 22 April 2010 - 01:01 PM

Ah, yes, thanks -- you're right. It's the old bits vs. Bytes thing.

At 60 GBytes per minute, you can easily get half an hour on a two TeraByte drive. So, it's within the range of practicality now. S.Two and Codex are doing it -- uncompressed raw -- with the new Arri Alexa.




-- J.S.
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