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Thread: CRC embed new tag in previously ripped FLAC

  1. #1

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    CRC embed new tag in previously ripped FLAC

    I am running dbpa 17.4. I suspect some FLAC files in my library are becoming corrupt. to check this, I would like to add crc tags to the flacs.

    The FLACs are purchased downloads from Prestoclassical and Qobuz, etc.

    I would like to embed CRC tags in the FLACs. However, the codec Calculate CRC seems only to produce a text file of the CRC values. Is there a way to use the batch converter + CRC calculator + Edit tags codecs to do this?

  2. #2
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    Re: CRC embed new tag in previously ripped FLAC

    Quote Originally Posted by mtreloar View Post
    I am running dbpa 17.4. I suspect some FLAC files in my library are becoming corrupt. to check this, I would like to add crc tags to the flacs.

    The FLACs are purchased downloads from Prestoclassical and Qobuz, etc.

    I would like to embed CRC tags in the FLACs. However, the codec Calculate CRC seems only to produce a text file of the CRC values. Is there a way to use the batch converter + CRC calculator + Edit tags codecs to do this?

    I'm a bit confused with your question. FLAC files already have CRC embedded in file. You can run dbpa batch converter, converting to "TEST CONVERSION" to have dbpa compare calculated CRC to the already embedded CRC to ensure the file is not corrupt.

  3. #3

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    Re: CRC embed new tag in previously ripped FLAC

    @Garym, when I rip a CD using dbpa, I do have a CRC tag embedded in the FLAC. However, in downloaded FLAC files from commercial providers (e.g. Qobuz, Prestoclassical, etc), I do not find a CRC tag in the FLAC.

    1. My question is whether there is a way to create a CRC tag in a FLAC file using the Calculate CRC codec of dbpa Coverter.

    2. And now, since you mentioned using the Test Conversion to to ensure the file is not corrupt, what are the steps to show the result of the test? I ran Test Conversion on a FLAC that I had ripped and that had a CRC tag. However, I do not see any output from the Test Conversion.

  4. #4
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    Re: CRC embed new tag in previously ripped FLAC

    Only if the flac file has a corruption will an error be shown at the end.

  5. #5
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    Re: CRC embed new tag in previously ripped FLAC

    Quote Originally Posted by mtreloar View Post
    @Garym, when I rip a CD using dbpa, I do have a CRC tag embedded in the FLAC. However, in downloaded FLAC files from commercial providers (e.g. Qobuz, Prestoclassical, etc), I do not find a CRC tag in the FLAC.

    1. My question is whether there is a way to create a CRC tag in a FLAC file using the Calculate CRC codec of dbpa Coverter.

    2. And now, since you mentioned using the Test Conversion to to ensure the file is not corrupt, what are the steps to show the result of the test? I ran Test Conversion on a FLAC that I had ripped and that had a CRC tag. However, I do not see any output from the Test Conversion.
    The CRC in a tag (from ripping) is one thing. But all FLAC files have an embedded CRC in the file itself (not necessarily in a tag) that is used to test for corruption (such as the TEST CONVERSION with dbpa).

  6. #6
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    Re: CRC embed new tag in previously ripped FLAC

    Quote Originally Posted by garym View Post
    The CRC in a tag (from ripping) is one thing. But all FLAC files have an embedded CRC in the file itself (not necessarily in a tag) that is used to test for corruption (such as the TEST CONVERSION with dbpa).

    For example, see this. This saved CRC info is in the header/frames (not the tag....that is just something extra that dbpa does so you can actually see the CRC if you need to).

    https://xiph.org/flac/features.html

    Each frame contains a 16-bit CRC of the frame data for detecting transmission errors. The integrity of the audio data is further insured by storing an MD5 signature of the original unencoded audio data in the file header, which can be compared against later during decoding or testing.

  7. #7

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    Re: CRC embed new tag in previously ripped FLAC

    Thanks @Spoon and @Garym
    Confirming my understanding and some related questions:

    1. My original question was, "how can I find out if a downloaded flac is corrupted?"
    Q - Can I assume that the Test Conversion codec will do this, by comparing the original CRC embedded in the flac header to a calculated parameter and exiting with an error if corruption exists?

    2. dbpa does not have a feature that can write a CRC Tag to an existing FLAC. It does have this feature for a FLAC ripped from a CD using dbpa.
    Q - What is the use intended for the visible CRC Tag?

    4. The dbpa utility codec "Calculate Audio CRC" displays a CRC generated from audio data and this can be saved as a text file.
    Q- how would one use the CRC displayed value from this codec? (Test Conversion seems to do what is needed to confirm flac integrity without actually seeing the CRC value)

  8. #8
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    Re: CRC embed new tag in previously ripped FLAC

    1. Yes, test conversion will show if a flac file is corrupted.

    2. Correct there is no option to do this

    4. It is not needed for flac files.

  9. #9

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    Re: CRC embed new tag in previously ripped FLAC

    Thanks again!

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