Arri Alexa - Filesize discrepency

March 15, 2011

Hi all,

Hoping someone can help shed some light on this conundrum:

An Alexa 'take' that appears as 4.3gb in size, on a SxS card mounted on Mac OS X is coming up at just under 4gb in size when transfered to another device, in this case a G-Tech 500gb drive, Mac OS X Journaled).

Is this an issue with .xml file paths being disrupted, or symptomatic of the transfer across media formatting i.e SxS and UDF -> G-Tech, Mac OS X Journaled?

There appears to be no 'loss' within picture and sound. Camera used has current firmware.

John Sprung · March 16, 2011

It sounds like the difference between the binary and decimal interpretations of Giga- about 7.4%. If so, it's nothing to worry about.

-- J.S.

Phil Rhodes · March 16, 2011

Seconded. If it works, don't worry.

March 16, 2011

Thank you both for your advice - number of bytes match also, which eased my concern.

Today however, I noticed that after turning over for 2 seconds at ProRes 4444, the camera displayed a codec error, and ceased recording. (I wrote a log file and it was sent to Munich).

Comparing what was on SxS and on the target drive I had set up, the file on card was roughly 100 megabytes, and after transfer - 2.5 megabytes.... I wonder if there is something else at work here - such as after the recent firmware update enabling playback on camera, is some kind of header/encapsulation generated and tacked onto files whilst on camera?

andrew kuepper · June 11, 2012

I recently had this same issue. SxS cards were not giving me copies that had the same byte length on original files in both desktop copies and copies to one or more external drives.

I used Al3xa Data manager, with md5 verififcations that came back positive for verification, but did NOT have the same byte length as original clips. Manual copies to desktop exhibited the same issue. I Could find no problems with the copied files, they scrubbed and played back as the originals. This was all extemely frustrating and disconcerting.

Adrian Sierkowski · June 11, 2012

Differant OS'es (and programs therein) may be rounding differently. Instead of 1024 they go off of 1000 to the mega, hence you'll have file-size discrepancies. normally they should be pretty small--relatively-- a 100 to 2.5 mb difference would be a big concern, but then again, if checksums, check, the stuff should all be there.