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Thread: Verify that FLAC file is still an accurate rip a year later

  1. #1

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    Jan 2021
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    Question Verify that FLAC file is still an accurate rip a year later

    Hi

    I am hoping to verify that my FLAC file is the same as it was when I ripped it a year ago (using XLD). From the log file of my RIP I know:

    CRC32 hash : FA5DDF0A
    CRC32 hash (skip zero) : 5E8732E4
    AccurateRip v1 signature : 8C0BCA19
    AccurateRip v2 signature : E6EE3E8E

    Is it possible to calculate any of these from my FLAC to ensure that no bitrot has set in?

    Many thanks

    Andrew

  2. #2
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    Re: Verify that FLAC file is still an accurate rip a year later

    Quote Originally Posted by arohl View Post
    Hi

    I am hoping to verify that my FLAC file is the same as it was when I ripped it a year ago (using XLD). From the log file of my RIP I know:

    CRC32 hash : FA5DDF0A
    CRC32 hash (skip zero) : 5E8732E4
    AccurateRip v1 signature : 8C0BCA19
    AccurateRip v2 signature : E6EE3E8E

    Is it possible to calculate any of these from my FLAC to ensure that no bitrot has set in?

    Many thanks

    Andrew
    Edit: of course to make sure the FLAC file is not corrupted, you can simply use dbpa CONVERTER and "convert to" [TEST CONVERSION]

    yes, the dbpa related program PerfectTunes can do an AccurateRip database match check post-ripping. That's the main reason I purchased PerfectTunes.
    https://www.dbpoweramp.com/perfecttunes.htm


  3. #3

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    Re: Verify that FLAC file is still an accurate rip a year later

    Quote Originally Posted by garym View Post
    Edit: of course to make sure the FLAC file is not corrupted, you can simply use dbpa CONVERTER and "convert to" [TEST CONVERSION]

    yes, the dbpa related program PerfectTunes can do an AccurateRip database match check post-ripping. That's the main reason I purchased PerfectTunes.
    https://www.dbpoweramp.com/perfecttunes.htm

    I was hoping to write some code to do it myself :-) I am not sure what file the CRC32 checksum has been done on - obviously not the flac file - do you know?

    Many thanks

    Andrew

  4. #4
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    Re: Verify that FLAC file is still an accurate rip a year later

    Flac internally has an MD5 hash of the audio, this is compared each time FLAC is decoded in dBpoweramp, any miss-match and dBpoweramp would inform you. All CRCs are on the decoded audio data.

  5. #5
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    Re: Verify that FLAC file is still an accurate rip a year later

    Quote Originally Posted by arohl View Post
    I was hoping to write some code to do it myself :-) I am not sure what file the CRC32 checksum has been done on - obviously not the flac file - do you know?

    Many thanks

    Andrew

    when you convert a FLAC to [TEST CONVERSION] it is decoding the FLAC file and comparing the embedded checksum with the calculated checksum. So you know the FLAC file is the same as originally encoded. And this can be done in an automatic batch. After moving my collection to a new backup drive, I often run batch convert to [TEST CONVERSION] on the library on the new drive to make sure nothing went wrong in the transfer. This seems to easily do what you desire with only a couple of mouse clicks, so not sure of the reason to write code to do the same thing.

  6. #6

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    Re: Verify that FLAC file is still an accurate rip a year later

    Many thanks both - I have learned something about the flac format now! I can simply use flac --test on all my files.

    Andrew

  7. #7
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    Re: Verify that FLAC file is still an accurate rip a year later

    Quote Originally Posted by arohl View Post
    Many thanks both - I have learned something about the flac format now! I can simply use flac --test on all my files.

    Andrew
    And this built in ability to do the checksum test is one of the most important aspects of FLAC. I often have to try to explain this to people who think using WAV or AIFF format is "better" (it's not for any sound quality reason by the way). They say, "disk space is cheap, so why not use WAV/AIFF?" But when I point out that I can confirm with a few mouse clicks in a batch manner whether any of my 116,000 flac files are corrupted, but with WAV files, one would have to check each file one at a time, this gives them pause at least.

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