Implement MP4 moov atom validation

[mzur]

If the moov atom is at the wrong location, the video may not be displayed correctly. Add a validation step to the ProcessNewVideo job that checks the atom location. If the atom is at the wrong position, set an error state for the video (like "too large", "not found") and abort processing. Then display the error message in the UI.

Also create a manual page for how a video should be created/converted so it works with BIIGLE. The error message of the video should link to this page.

[dlangenk]

Is this moov atom set correctly in most videos or is that some very rare thing. If it is rare I would rather just show a warning and possibly a "do you want to continue?" and a link to the manual how to reformat the video correctly. If this is set in most cases anyway showing an error is fine (and a link how to fix it).
Does setting the atom involve re-encoding the video? If not what about just setting the atom after uploading the video?

[mzur]

Is this moov atom set correctly in most videos or is that some very rare thing.

It was the cause of incorrect annotations in multiple occasions now. I guess most people don't see this because everything looks correct for them in the video annotation tool. The error only becomes visible if you compare the annotations with Largo.

Does setting the atom involve re-encoding the video? If not what about just setting the atom after uploading the video?

It's not re-encoding exactly but you still have to modify the video file. Currently, BIIGLE never modifies any files and I'd like to keep it this way until we implement a general video transcoding service (like Tator, this was an idea at some point). This also wouldn't work with any non-uploaded videos.

[dlangenk]

It would probably be nice to have a good documentation or means to fix this before implementing the validation leading to an error.