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IDProjectCategoryView StatusDate SubmittedLast Update
0001088DCP-o-maticClean-uppublic2017-06-16 16:002017-06-21 04:41
Reportermanuelac Assigned Tocarl  
PrioritynoneSeverityfeatureReproducibilityN/A
Status closedResolutionnot fixable 
Summary0001088: Calculate hash before writing to disk
Description

Disk access is a bottleneck in many systems. Doing the hash after encoding but while the frame is still on memory could help.

Some thoughts:
-Is it compatible with the hardlink trickery?
-Need to store the incomplete chunk (512 bits?) to prepend it to the next frame
-Conform the size of the frame to a hash-friendly size (up to 64 bytes? more per frame) (compatible with distributed encoding and hashing?)
-Maybe a filesystem function or library already do something similar

Most probably sound processing would need too big of a modification to accommodate this strategy.

It does't look like an easy task, and not sure how big of a difference will it make to the final encoding time.

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carl

2017-06-19 23:55

administrator   ~0001721

I have thought about this before, and sadly i think it is impossible. If the MXF was written linearly it would be fine but right at the end of the MXF write we have to go back to the beginning of the file and fill in some stuff in the header. I don't know of a way to compute the hash for the main body of the MXF and then modify it to account for the new header, and I suspect it may be impossible.

manuelac

2017-06-21 04:40

developer   ~0001722

I see. Of course you thought about it before! :) I was hoping that this will give you some new ideas.

Bug History

Date Modified Username Field Change
2017-06-16 16:00 manuelac New Bug
2017-06-19 23:55 carl Assigned To => carl
2017-06-19 23:55 carl Status new => feedback
2017-06-19 23:55 carl Note Added: 0001721
2017-06-21 04:40 manuelac Note Added: 0001722
2017-06-21 04:40 manuelac Status feedback => assigned
2017-06-21 04:41 manuelac Status assigned => closed
2017-06-21 04:41 manuelac Resolution open => not fixable