Jump to content


Photo

Ucompressed data?


  • Please log in to reply
3 replies to this topic

#1 Krstic Zoran

Krstic Zoran

    New

  • Basic Members
  • Pip
  • 6 posts
  • Digital Image Technician
  • Belgrade

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 ;)
  • 0

#2 John Sprung

John Sprung
  • Sustaining Members
  • 4635 posts
  • Other

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.
  • 0

#3 Harrison Hui

Harrison Hui

    New

  • Basic Members
  • Pip
  • 1 posts
  • Other

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.
  • 0

#4 John Sprung

John Sprung
  • Sustaining Members
  • 4635 posts
  • Other

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.
  • 0


Rig Wheels Passport

FJS International, LLC

Paralinx LLC

Opal

The Slider

rebotnix Technologies

Technodolly

CineTape

Broadcast Solutions Inc

Media Blackout - Custom Cables and AKS

Gamma Ray Digital Inc

Wooden Camera

Glidecam

Visual Products

CineLab

Abel Cine

Ritter Battery

Willys Widgets

Aerial Filmworks

Metropolis Post

Tai Audio

The Slider

Paralinx LLC

Aerial Filmworks

FJS International, LLC

Wooden Camera

Rig Wheels Passport

Tai Audio

Opal

Media Blackout - Custom Cables and AKS

Ritter Battery

Willys Widgets

Technodolly

Gamma Ray Digital Inc

CineTape

Broadcast Solutions Inc

Visual Products

Metropolis Post

CineLab

rebotnix Technologies

Abel Cine

Glidecam