Coverter fidelity

[haihayho]

So according to this reply, and theoretically, same "source" files should be the same and have identical hash. I get that and personally, I agree that uncompressed data should always be the same.

However, when I convert a blank WAV (no metadata) to WAV and uncompressed FLAC, all 3 of them show different hash. Does it mean they are different? If anyone can explain this to me I'm much appreciated.

[Spoon]

Re: Coverter fidelity

If using windows install the utility codec 'Calculate Audio CRC':

https://www.dbpoweramp.com/codec-central-utility.htm

Then convert all 3 files to this codec and a notepad will appear showing the audio CRC for the decoded data, if it matches all 3, then they are identical.

[garym]

Re: Coverter fidelity

As @spoon notes it is important to compare *audio* CRCs. You are likely comparing total file CRCs, and these can differ because of the metadata (non-audio) information in each file.

[haihayho]

Re: Coverter fidelity

Thank you, I was looking for something like this. The results are the same.

However, it's pretty strange cause what might cause my problem in the first place is metadata, but I deleted all of them, so all files are "blank".

[Spoon]

Re: Coverter fidelity

There are headers also in the files.

[simbun]

Re: Coverter fidelity

Expecting the hash of the WAV and FLAC to match is like expecting the hash of a word document and a LibreOffice document to match; even though they may have the same user content they're two completely different formats.

I don't know enough about the wav format to know why your original wav and the converted wav didn't match, but if you used the same tool and options they should. I converted from a single wav multiple times to wav and flac formats, and all the wav's matched as did all the flac's.

Flac stores the hash of the decoded audio content internally, so even if you'd made lots of tag changes, or even changed the flac compression level itself, it's trivial to compare/validate that the audio is still the same (by storing the original value somewhere).

To display the MD5 of the decoded audio data:

metaflac --show-md5sum <filename>

To verify that the actual audio data still matches the stored hash (to highlight data corruption):

flac -t <filename>