FAKE: hard cutoff at 16 kHz — consistent with a lower-bitrate lossy source re-wrapped as FLAC.
Fake FLAC detector for macOS
Fake FLAC Detector for Mac
Not every FLAC file is genuinely lossless. Spectro detects FLAC files re-encoded from MP3 or AAC using spectral frequency analysis — automatically, in batch, fully offline.
In short
A fake FLAC is a FLAC file re-encoded from a lossy source — MP3, AAC, or similar. Spectro detects it by analyzing the frequency cutoff. Detection is backed by peer-reviewed research (ACM MM&Sec 2009) with 99% accuracy across 2,512 songs.
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Who this is for
- - DJs who buy or pool FLAC and want to verify the source, not just the extension.
- - Collectors building lossless archives from mixed download sources.
- - Anyone who was told “FLAC is always lossless” and wants a real check.
What Spectro does
- - Batch-scan folders of FLAC (and WAV, AIFF, MP3) with one verdict per file.
- - See FAKE, MEDIUM, or LOSSLESS with cutoff readout — no manual spectrogram reading.
- - Runs fully offline; nothing is uploaded.
- - Native Universal Binary for Apple Silicon and Intel.
How to check your FLAC files in under 2 minutes
- 1. Download Spectro and open it on your Mac.
- 2. Drag a folder of FLAC files into the Spectro window.
- 3. Spectro analyzes the frequency spectrum of each file and returns a LOSSLESS, FAKE, or MEDIUM verdict.
- 4. Filter by FAKE to see which FLAC files are actually re-encoded MP3s or AAC files.
What makes a FLAC file "fake"?
FLAC is a lossless container: it does not throw away audio when you store data in it. But the audio inside can still come from a lossy encode. Re-wrapping an MP3 or AAC as FLAC does not restore highs that were discarded — it only changes the file format. That is what people mean by a "fake" FLAC: valid FLAC on disk, lossy content underneath.
You cannot trust the extension alone. Spectro looks at the spectrum — where energy stops — not at the filename.
How Spectro detects fake FLAC
Spectro runs spectral analysis (FFT) on the decoded audio. A genuine lossless capture tends to show energy extending toward Nyquist. A file transcoded from MP3 or AAC shows a hard cutoff at the encoder's brick-wall frequency — the same pattern as a fake WAV, whether the container is FLAC or not.
LOSSLESS: energy extends naturally — what you want from a real lossless source.
Frequently asked questions
How does Spectro detect fake FLAC files?
Spectro analyzes the frequency spectrum of each FLAC file. A genuine lossless FLAC recording has energy extending cleanly to near Nyquist (around 22 kHz for 44.1 kHz files). A fake FLAC — a FLAC file re-encoded from a lossy source like MP3 or AAC — shows a hard cutoff at the original encoder's frequency limit, typically 16–20 kHz. Spectro reads this pattern and returns a FAKE verdict automatically.
Can a FLAC file be fake?
Yes. FLAC is a lossless container format, but the audio data inside it can come from a lossy source. A common case is re-encoding an MP3 to FLAC — the resulting file is a valid FLAC but contains lossy audio. Spectro detects this by analyzing the spectral content, not the file extension.
Is fake FLAC common in DJ libraries?
Yes. Many download stores and record pools distribute FLAC files that were derived from lossy masters. Beatport, Bandcamp, and promo pools have historically shipped fake lossless files — often without knowing. Spectro batch-scans your entire library and flags each file individually.
Does Spectro work on Apple Silicon?
Yes. Spectro is a native Universal Binary — it runs natively on both Apple Silicon (M1, M2, M3, M4) and Intel Macs. No Rosetta emulation required.