1

When I export an Adobe Premiere project to video twice with the same export settings, why does it yield videos with different file hashes?

Shouldn't the files be identical and have matching hashes? Where is the source of randomness coming into the encoding process?

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The encoding settings

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These two files were encoded using identical settings a few seconds apart, note that the files are not actually identical.

2

Yes, your observation is correct and everything works fine. Even if settings are identitcal, the file hashes will always be different.

The reason is quite simple: XMP metadata which is embedded in the files.

Such metadata entries which are often different are:

  • time stamps (not only the date but the time too)
    • creation date
    • modified date
    • metadata date
  • IDs
    • document ID
    • instance ID
    • original document ID

A bit of binary data in the header is different too. All the rest, meaning the actual video and audio data is the same. The encoding algorithms are working deterministic - that means, given the same input they produce the same output. At least those I've tried for my example. This doesn't have to be true in other cases.

1
  • wow, now that you mention it, its obvious. thanks – Joseph Feb 8 at 18:06

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