Difference in Data Rate Alexa LF and Mini LF

Tue Aug 11, 2020 11:45 am

Hello,

I am currently calculating storage for an upcoming project and since we did not yet decide if it is going to be LF or Mini LF I have to look at both. Normally I would expect that the LF and Mini LF have the same data rates but they do not.
Not in ARRIRAW nor in ProRes. Could you please explain why

as attachment you can find one example.

Thanks
Markus Kreuzwirth
 
Posts: 2
Joined: Thu Nov 03, 2016 8:16 pm

Re: Difference in Data Rate Alexa LF and Mini LF

Mon Aug 17, 2020 11:56 am

Dear Markus,

for ARRIRAW you have a minor difference of just some seconds of run time.
For ProRes you can only use half the size of a 1TB SXR capture drive because the drives inside runs as a mirrored raid configuration. So that's half the capacity of a Compact Drive.

Cheers,
Jan
Jan Heugel
Application Engineer
Jan Heugel
 
Posts: 399
Joined: Wed Aug 13, 2014 3:15 pm
Location: Munich, Germany

Re: Difference in Data Rate Alexa LF and Mini LF

Wed Aug 19, 2020 9:24 am

Dear Jan,

Thank you for your reply. My question points more to the differences in Gb/h or Mbit/s for final storage.
Since the only difference in is the wrapper (mov/mxf) there should not be differences of for example 794 Gb/h on MINI LF to 924 Gb/h on the LF in PR444, or at least not so huge. It makes quite a difference for Storage or LTO.

If the codec, resolution and frame rate are the same why does the ProRes data rate differ so much?

thanks for your help....

Markus
Markus Kreuzwirth
 
Posts: 2
Joined: Thu Nov 03, 2016 8:16 pm

Re: Difference in Data Rate Alexa LF and Mini LF

Wed Sep 02, 2020 7:11 am

Dear Markus,

that's the nature of ProRes. In the Classic ALEXA's we allocated a certain size for every frame (CBR) and therefore could predict the runtime very precisely. That's convenient for almost ervery entity - but not all.

So for AMIRA, Mini and Mini LF, which use a different "core", we decided to go with the flow and change to VBR. This makes it harder to pinpoint to a certain runtime, makes it harder to predict the datarate and leaves everyone digging into that confused - but in the end: gives you more runtime - which e.g. wildlife cinematographers, documentarists and everyone who needs just that little bit more appreciates.

For calculation purposes a typical datarate has been picked.

Kind regards,
Jan
Jan Heugel
Application Engineer
Jan Heugel
 
Posts: 399
Joined: Wed Aug 13, 2014 3:15 pm
Location: Munich, Germany

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