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Uncompressed Raw/RGB file sizes...


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#1 Cesar Rubio

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Posted 27 September 2011 - 03:00 PM

I want to start saying that all video must be compressed for final delivery.

But if you start capturing video in the best quality possible, it will show also in your final compressed video. That's why many prime time TV productions still shoot film.

Film is the equivalent to Uncompressed Raw in Digital Capture.

Some will argue that there is “no difference” in quality recording Compressed Raw or Uncompressed Raw. But it is.

When you are compressing video in capture, you are taking away color information (making the video more “pale” in comparison and with less contrast or dynamic range) , add “blockiness” to the images or take away complete frames!

That's why some codecs “break” in high movement shots (either form the camera or subjects in the frame).

Also, compression adds more “mosquito noise” into the video.

Don't believe me? Make your OWN tests.

Basically the “defendants” of compression is because they cannot offer that recording on camera.

Uncompressed Raw requires HUGE file sizes and FAST recording media.

Lets go back in history a little.

When the Silicon Image 2K camera was released, they only offered Cineform Raw recording, mainly because the laptop hard drives back then were slow and Cineform Raw did not require faster drives due to the high compression. Later they went with less compression with Cineform Raw. Now they offer Uncompressed Raw as well.

The Red One camera when it was released also had to use a lot of compression to deal with those huge 4K resolution files recording into CF cards and slow mechanical laptop drives. I remember that people were requesting the possibility to record Uncompressed Raw with that camera, but the Red team were not very fond with such idea. They even went to the extreme to compare the Redcode compression with “Uncompressed Raw” projected in a big screen at NAB. People saw that there was “no difference”...

I don't know how they recorded the Uncompressed Raw version since the camera doesn't offer outputs for that. I have made Uncompressed RGB recordings with my Panasonic DVX-100 camera (via the firewire output) and there is indeed no visual difference with that and the DV compression on camera.

So when looking for a camcorder you have to make sure that the HD-SDI outputs are indeed outputting truly Uncompressed RGB before ANY compression in camera.

In the past the Andromeda solution permitted to record truly Uncompressed RGB from the Panasonic DVX-100 camera, but you had to send it for “surgery” and use an external laptop for recordings. People when saw the huge image quality difference immediately were in love with it. I wanted to send mine as well, but somebody in the industry “bought” the Andromeda project....mainly to get rid of them. Now they are history.

Lets go back to the Red One camera, if that is true that there is no difference between Compressed Raw and Uncompressed Raw ,WHY then now they offer less compression in the camera and up to 3:1 compression on Epic-M/X?

Easy, now there are super fast SSD's (Solid State Drives) in the market.

Mark my words, the day is coming when they will offer totally Uncompressed Raw recordings for the Red Cameras.

Now, the drawback of working with Uncompressed Raw material is HUGE file sizes and the need for Raid Hard Drive setups in post production.

What are the sizes?

8 bit-1080/24p is 3GB per minute. 50MB/s -Media speed needed for capture: (minimum write speed NOT sustained).

12 bit-1080/24p is 4.5 GB per minute. 75MB/s

8 bit- 1080/60p is 7.5 GB per minute. 125MB/s

Make those numbers TRIPLE when you de-bayer to Uncompressed RGB!

And then DOUBLE that for Stereo 3D! ;-)

The Alexa-M camera recording Arriraw (Uncompressed Raw), requires like 9 GB per minute at 2880x1620 pxs. 24 fps. at 12 bit. And requires media capable of writing 150MB/s.

There are many SSD's in the market that can easily write such speeds now, and if you make a Raid configuration you can write larger frame rates or even larger resolutions.

I have made comparison recordings between Uncompressed Raw/RGB at 8,12 and 16 bit and saw no visual difference at all. I have also scanned 35mm film at 8 and 16 bit (Uncompressed TIFF). And the same, there is no visual difference. Probably because my monitors are 8 bits...(24 RGB).

That's why I prefer Uncompressed Raw/RGB 8 bit, for its smaller file sizes and superb image quality.

That's the price you have to pay working with Uncompressed video, but I can tell you this; IT'S WORTH IT!

Thanks,
Cesar Rubio.
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#2 Cesar Rubio

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Posted 29 September 2011 - 01:19 PM

I just want to add that for a final Digital Cinema delivery I prefer the Cineform HD codec, it preserves the best image quality of Uncompressed RGB that I ever seen with any video codec.

And its' faster to encode than jpeg-2000, and you can do it in any modern fast speed computer. jpeg-2000 is super slow and requires especial and expensive hardware to encode in a way that doesn't drive you crazy or have your computer running for days encoding....

I think in India Cineform HD is the standard for Digital Cinema delivery, and I wish other countries would follow that too.

CR.
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