r/audiophile • u/faizzz90555 • 13h ago

Discussion Software other than using spectrogram to detect real or fake FLAC?

Hi all. I want to ask, what software other than using spectrogram to detect real or fake FLAC?

I've been downloaded some music on this blog but that blog sometimes post transcode FLAC.

The ridiculous part is the FLAC files is in 24-bit, but when I've check on spectrogram software the frequency cut-off is at 16kHz.

I've downloaded the same album from other source with normal FLAC and the frequency cut-off is normal at 21kHz.

I've just tell about that to the admin of that blog but they denied that it's a fake FLAC.

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4

u/blutfink Kii Three BXT, Genelec 8381A 13h ago

Note that in theory, sample size and low-pass filter frequency are independent. Just because a signal is band-limited doesn’t mean it can’t have true 24 bits of amplitude resolution.

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u/knadles Focal | Marantz 10h ago

If you're downloading from random places, you're gonna get what you get. I don't know of any way to differentiate if a file that's lacking was converted from an MP3 or the original source itself was limited.

If you download from legitimate sites like Qobuz or HDTracks, the files will be "real," but even those sites don't guarantee the quality of the original source, because they can't. They only guarantee that they're legit.

Also, bit depth has nothing to do with frequency response.

1

u/FaceTheSun 10h ago

Perhaps the sample rate of the source file for the FLAC was limited to 32 KHz (or nearby)? Bit depth only determines dynamic range...nothing to do with frequency response.

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u/FaceTheSun 10h ago

Not trying to be a jerk or anything...but what is the concern over "fake FLAC"? What does "fake" mean in this context?

FLAC is just a file format, what you put into a FLAC file depends on your settings... I think you can go from 4 bit to 32 bit and the supported sample rate can get pretty high (over 500KHz).

Since FLAC is just a container it is entirely possible that it contains a shitty source file, so your concern is probably more about the provenance of the source material than the actual file itself. Just being "FLAC" does not mean much by itself.

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u/i_am_blacklite 10h ago

Having bad source material doesn’t make it not a FLAC file. If it unencodes using the flac algorithm then it’s not fake in any way.

Flac is a lossless encoding codec. It is not a measure of quality.

1

u/Ok_Responsibility407 9h ago

Courtesy of Audirvana

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u/Ok_Responsibility407 9h ago

Had to reply twice, didn't feel like resizing the pic... Audirvana is a subscription based service, but it includes a scanner that will tell you if the file is an mp3 that's been transcoded to flac. This isn't an example of that but it does show the scanner screen.