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I have a number of audio tracks (in FLAC) and I would like to determine with some confidence if they all come from the same source (a CD) or if they were assembled and repackaged from multiple sources.

For example, is there a way to distinguish between a low-bitrate MP3 that was re-encoded into FLAC, and a FLAC that was encoded straight from the CD audio information?

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  • Do FLAC files carry metadata? I wonder if you could figure this out by opening them in a text editor. There must be some sort of metadata viewer for FLAC files out there somewhere. Mar 22, 2022 at 20:49
  • I can view the metadata, yes - but the metadata can be easily changed. What would I be looking for? I am asking about some kind of audio signature that is consistent across the tracks. For example, can one tell the difference between a low-quality MP3 that was re-encoded to FLAC, versus a FLAC that was ripped straight from CD? I will update my question to reflect this.
    – infojunkie
    Mar 22, 2022 at 20:59

1 Answer 1

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You can see the difference between a very low-bitrate mp3 & an unsullied file with a spectrograph; but you can also hear it.
By the time you're up in the decent file-types, high-Q mp3 & AAC, I very much doubt you'll ever be able to tell. An officially-purchased AAC from such as iTunes can often be quantitively better than an accurate rip from an old CD. There's a huge amount of 'wishful optimism' about FLAC files. People forget that a lossless version of a poor original is still poor.

See this QA on our sister site, Music Fans - Original recording of Traffic's The low spark of high heeled boys — good sound quality? for a more detailed explanation of why this might be.

Note:
If the tracks were ripped from CD, the metadata is just what was found as 'closest match' from a CDDB lookup* [either automatically or by user-selection if multiple matches were found]. It's not guaranteed accurate in the first place. Two people ripping the same CD on the same software could end up with dramatically different metadata.
This is also trivial to copy/paste between files.

*CDs do not contain any computer-readable metadata. CDDB & others use a fingerprinting method, which is not infallible.

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  • Thanks. The important part of my question is about SAME source or different sources. If all the tracks come from the same old CD, that's fine by me.
    – infojunkie
    Mar 23, 2022 at 18:31
  • No way to tell. Flac, almost by definition, makes it an unofficial 'release' - so what you see is definitely not what you get.
    – Tetsujin
    Mar 23, 2022 at 18:37
  • I have purchased FLAC files from "official" sources many times - for example, from 7digital.com and Bandcamp, so I'm not 100% in agreement with your characterization, or our definition of "official" is wildly different.
    – infojunkie
    Mar 23, 2022 at 21:56
  • OK, let's ignore the source of the flac for now. No, there's no way to be certain what its history was, other than in extreme cases - as mentioned in my answer. The closer to source, the more reliable. As mentioned in my linked answer, often with newer releases the high-res AAC will be the best commonly-available version; one conversion from 24-bit wav.
    – Tetsujin
    Mar 24, 2022 at 9:03

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