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ascmitc / mhl

ASC Media Hash List
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Handling intentional changes to files #134

Open OlliTee opened 1 year ago

OlliTee commented 1 year ago

To cover my bases, I’d like to present my particular use case that is not reflected in the examples/scenarios. Imagine a source folder containing an ascmhl file and a tool that will transcode only a particular type of file and copy everything else. The file name of the transcoded output is changed to identify files with the new codec.

For all transcoded files, a verification with ascmhl tool would result in an Error: Files referenced in the ASC MHL history are missing, and a new original hash for the newly created output. The verbose output of ascmhl create -h xxh64 -v /Volumes/PRO-BLADE1/HDE_HDET_asc-verify/A_0001_12NR would be:

Creating new generation for folder at path: /Volumes/PRO-BLADE1/HDE_HDET_asc-verify/A_0001_12NR ...
  verified                      A_0001_12NR_AVID.ale  xxh64: OK
  verified                      A_0001_12NR_BIN.bin  xxh64: OK
  created original hash for     A_0001C001_230202_052359_h12NR.mxf  xxh64: 831634f910e235ac
  created original hash for     A_0001C002_230202_052419_h12NR.mxf  xxh64: d07e0727d0934ba0
  created original hash for     A_0001C003_230202_052434_h12NR.mxf  xxh64: d3a52efeb7f20374
  created original hash for     A_0001C004_230202_052442_h12NR.mxf  xxh64: 25240d1fce0973a5
  created original hash for     A_0001C005_230202_052515_h12NR.mxf  xxh64: a04dfa3627d7c388
  created original hash for     A_0001C006_230202_052533_h12NR.mxf  xxh64: 0ed10f15dc9bfed7
  created original hash for     A_0001C007_230202_052647_h12NR.mxf  xxh64: 36d57baffa34b7a8
  created original hash for     A_0001C008_230202_052708_h12NR.mxf  xxh64: b7ee8d900446b429
  calculated root hash  xxh64: 6c1753e87fbd0b4e (content), b86f699d4b3d60b2 (structure)
Created new generation ascmhl/230207_A_0001_12NR_2023-02-06_173319.mhl
ERROR: 8 missing file(s):
  A_0001C001_230202_052359_a12NR.mxf
  A_0001C008_230202_052708_a12NR.mxf
  A_0001C004_230202_052442_a12NR.mxf
  A_0001C002_230202_052419_a12NR.mxf
  A_0001C007_230202_052647_a12NR.mxf
  A_0001C003_230202_052434_a12NR.mxf
  A_0001C006_230202_052533_a12NR.mxf
  A_0001C005_230202_052708_a12NR.mxf

And the output ascmhl would show <xxh64 action="verified"… for the two verified files and <xxh64 action="original"… for the newly created files.

Does this implementation look alright for you or should I handle it differently?

akda5id commented 1 year ago

And, there needs to be a way (added to the spec) to "accept" changes to the MHL. A flag for the create command that creates a new generation without any errors for missing files or changed hashes. Ideally with some info logging in the MHL that notes what was changed, but future generations wouldn't include.