Issue with Encrypted Files on ALEXA Mini - Playback Glitches & Export Failure

[erikaglert]

Skärmavbild 2024-10-01 kl. 14.21.38.png

Hi everyone,

I’ve encountered a strange issue with some of the files from an ALEXA Mini shoot. It seems that certain files on one specific card have become encrypted in some way. These files can still be played back, but the video glitches heavily during playback. Additionally, I’m unable to export them, receiving the error message: “Media’s data could not be decoded.”

It’s important to note that this issue only affects some files on the card, while the others are functioning perfectly fine. I’ve attached an image to show an example of the problem.

Has anyone experienced something similar or know how to resolve this issue? Any help would be appreciated!

Thanks in advance!

[Oliver Temmler]

Hi Erik,

this could be an issue introduced by bad blocks or something on the internal buffer of the camera. Is the artifact present on all clips starting from a certain number (which might point towards the camera) or do you have normal and buggy clips in no particular order (which points towards a card issue)?

I assume these are ProRes files? In some cases the ProRes decoder gets confused if there is a block of data it cannot read at the beginning of the clip. Cutting off a bit (just a second or so) from the beginning of the file and exporting it to a new ProRes clip might resolve the issue. You can also try exporting to new ProRes clips with different software.

If the error still does not go away, you could try to read the file directly from the camera card and export from there.

If that does not work, you can try to create a block copy of the original clip rather than a regular file copy:

Code: Select all

dd if=/Volumes/A0001ABCD/A0001ABCD/A0001C001_YYMMDD_ABCD.mxf of=/Users/YOURUSER/Desktop/A0001C001_YYMMDD_ABCD.mxf

In any case, you should do a health check on the CFast card and, if in doubt, replace it. You also can send the latest camera log file to service@arri.de so and let them know which Reel/Clip Numbers show the problem, so we can check if the camera logged an error.

Hope this helps
Oliver