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Neil Sadwelkar
Arri RAW data rate
on Aug 25, 2010 at 4:04:04 am

I did search for 'data rate' for ArriRAW files on this forum and came up with no results.

Anyone here has experience shooting ArriRAW with the Alexa or maybe even with the D-20/21. Exactly what is the data storage requirement for shooting ArriRAW? I remember reading somewhere that it is 15 GBytes/min.

Any real world figures?

-----------------------------------
Neil Sadwelkar
neilsadwelkar.blogspot.com
twitter: fcpguru
FCP Editor, Edit systems consultant
Mumbai India


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gary adcock
Re: Arri RAW data rate
on Aug 25, 2010 at 2:02:05 pm

[Neil Sadwelkar] " did search for 'data rate' for ArriRAW files on this forum and came up with no results. "

Does not surprise me Neil, I don't believe the question has come up before.

There are 2 main issues when working with ArriRaw, first is that it cannot be recorded as compressed content so ArriT-Link certifications are limited to Uncompressed recording devices from companies like Stwo, KG and Codex.

the D21:
2880 x 2160 RAW 12 bit Bayer data @ 23.976p, 24p, 25p
2880 x 1620 RAW 12 bit Bayer data @ 29.97p, 30p

Alexa:
2880 x 1620 RAW 12 bit Bayer data @ 23.976, 24, 25, 29.97, 30, 50, 59.94,60 PsF requires a recorder with Variframe support. Recording ARRIRAW requires an ARRIRAW T-Link certifed recorder

So for standard production frame rates (24 & 25) you are looking at roughly 250MB -300 MB per second for the ArriRaw data rate when recorded via Arri's T-link (a modified

Since ArriRaw is a true LOG format, that 12 bit sensor data actually holds the same amount of data as a 16bit RGB linear that would require a data rate OVER 460MB per second to playback.


This is why everyone is so excited over working in ProRes4444 in LogC, as a 12bit Log recording- especially a compressed one - offers users far beyond what has ever been possible in post, as data streams this rich have been as rare as unicorns in production, everyone knows they exist but no one has ever seen one.

gary adcock
Studio37

Post and Production Workflow Consultant
Production and Post Stereographer
Chicago, IL

http://blogs.creativecow.net/24640



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Neil Sadwelkar
Re: Arri RAW data rate
on Aug 25, 2010 at 7:11:11 pm

I went over to the Arri site and read the description for the OB-1 recorder from S.two. It has a cartridge of 500 Gb which is good for 30 mins of Arri Raw. Which makes it about 1 hr per Tb of Arri Raw. Pretty much like 2k DPX scans.

So, shooting Arri Raw for an entire feature of about 20 hrs of Arri Raw rushes will need storage of about 20 Tb and/or LTO backups worth that much. s.two make a dock that reads the memory cartridges and backs them up to 2 LTOs so one can keep them at different locations for backup.

So, the cost of the recorder (which would translate into higher rentals) and cartridges and/or disk storage, is likely to discourage many productions from shooting Raw and preferring ProRes4444 instead.

-----------------------------------
Neil Sadwelkar
neilsadwelkar.blogspot.com
twitter: fcpguru
FCP Editor, Edit systems consultant
Mumbai India


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Michael Aranyshev
Re: Arri RAW data rate
on Aug 27, 2010 at 6:30:17 am

2880 x 2160 D21 footage recorded on s.two (RAW wrapped in DPX) is about 11 MB per frame. That makes current Alexa model 8 MB per frame I think.

The ecosystem s.two tries to built around Arri digital cameras looks good on paper but in real life it doesn't work as advertised yet. Their a.dock can back up to LTO just fine but I would like to see a real person who managed to pull selects back from storage with an EDL.


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gary adcock
Re: Arri RAW data rate
on Aug 27, 2010 at 2:49:55 pm

[Michael Aranyshev] "2880 x 2160 D21 footage recorded on s.two (RAW wrapped in DPX) is about 11 MB per frame. That makes current Alexa model 8 MB per frame I think."

there are 2 sizes to ArriRaw in the D21-
2880 x 2160 is for 23.98, 24.0 and 25 fps
2880 x1620 is used for all other frame rates.

Alexa uses the 2880x 1620 frame size and I do not see how a couple of hundred pixels can make 3 MBs difference per frame.

Alexa's 2880 x 1620 raster size will keep the size of Arriraw imagery around that 11MB per frame.

gary adcock
Studio37

Post and Production Workflow Consultant
Production and Post Stereographer
Chicago, IL

http://blogs.creativecow.net/24640



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Michael Aranyshev
Re: Arri RAW data rate
on Aug 27, 2010 at 6:52:37 pm

It's actually a 1.5 megapixel difference. At 12 bits per pixel.


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