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Test conversion to check integrity of flac files--where is the log file?

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  • randym
    • Jan 2007
    • 36

    Test conversion to check integrity of flac files--where is the log file?

    I wish to do a test conversion of my entire music library to check that the md5sum of each file matches the metadata info. Years ago I did this; I believe it was possible to configure the program so that files for which the check sum does not match are listed in a log file. How do I do this, and where is the log file located?

    Thanks in advance for your help.
  • randym
    • Jan 2007
    • 36

    #2
    Re: Test conversion to check integrity of flac files--where is the log file?

    I did find this post:

    Hi all, Long time user of dbpoweramp but only just joined the forums. Sorry if this has been asked before but what does the test conversion on db music converter do & when would one need to used it? Thanks in advance Gary


    that explains that test conversion only reports errors, and that by default md5sum errors are checked for and reported.

    But I'd still like to know where in my computer's file structure the log file is located.

    Thanks

    Comment

    • garym
      dBpoweramp Guru
      • Nov 2007
      • 5743

      #3
      Re: Test conversion to check integrity of flac files--where is the log file?

      Originally posted by randym
      I wish to do a test conversion of my entire music library to check that the md5sum of each file matches the metadata info. Years ago I did this; I believe it was possible to configure the program so that files for which the check sum does not match are listed in a log file. How do I do this, and where is the log file located?

      Thanks in advance for your help.
      When I run this, I don't get any output UNLESS there is a mismatch. And I recall then, the popup allows me to save the output to a file.

      Comment

      • randym
        • Jan 2007
        • 36

        #4
        Re: Test conversion to check integrity of flac files--where is the log file?

        Thanks garym.

        I dug a bit deeper to be sure I understand the md5sum checking. I used a hex editor to corrupt a file. The test conversion reported that there was an error as follows:

        Error converting to Test Conversion, 'E:\SS Music\10,000 Maniacs\(1993) Mtv Unplugged\corrupted flac file for test.flac' to 'E:\SS Music\10,000 Maniacs\(1993) Mtv Unplugged\corrupted flac file for test.IGNORE'
        Encountered 'FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC' in FLAC File 'E:\SS Music\10,000 Maniacs\(1993) Mtv Unplugged\corrupted flac file for test.flac'

        Note that there is no mention of a md5sum in the error reporting. The message 'FLAC__STREAM_DECODER_SEARCH_FOR_FRAME_SYNC' means the "decoder state" is "The decoder is ready to or is in the process of searching for the frame sync code" . I presume this is the decoder state at the time the error occurred.

        Wanting more assurance it was the md5sum that triggered the error, I extracted the tag md5sum for the corrupted file (file "bad") and for it's uncorrupted version (file "good", which a test conversion verifies is good) using the program metaflac, and I also computed the md5sum's directly using the program md5sums (http://www.pc-tools.net/win32/md5sums/). The tag md5sums are the same as expected, and the computed md5sum's are different as expected. But the tag md5sum for file "good" is not the same as the computed md5sum for "good".

        Does this have something to do with tags? The tags for "good" have changed since the file was first converted to flac. I'm assuming that the tag value for md5sum is computed ignoring all the bytes associated with tags (header bytes?), but that the md5sum computed by the program md5sums takes into account header bytes. Is that correct?

        Thanks.

        Comment

        • Spoon
          Administrator
          • Apr 2002
          • 43902

          #5
          Re: Test conversion to check integrity of flac files--where is the log file?

          Your corruption made the file so it would not read completely, MD5 can only be compared if all the file can be read.
          Spoon
          www.dbpoweramp.com

          Comment

          • randym
            • Jan 2007
            • 36

            #6
            Re: Test conversion to check integrity of flac files--where is the log file?

            Originally posted by Spoon
            Your corruption made the file so it would not read completely, MD5 can only be compared if all the file can be read.
            Thanks. Do you know what the error message would say if the file was readable but the md5sum was off? I would like to search the log file for a keyword that would be output in that case.

            Also, am I correct that the program md5sums will not compute the same md5sum as the flac encoder does because of how the metadata is treated?

            Comment

            • Spoon
              Administrator
              • Apr 2002
              • 43902

              #7
              Re: Test conversion to check integrity of flac files--where is the log file?

              Information converting to Test Conversion, 'Z:\a.flac' to 'Z:\a.IGNORE'
              1 errors / information messages whilst decoding:
              md5 did not match decoded data, file is corrupt.

              You cannot use md5sum.
              Spoon
              www.dbpoweramp.com

              Comment

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