Music Check

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Contains adsIn-app purchases

About this app

You download a 24-bit FLAC file. Is it truly lossless?

Many "lossless" files floating around online are actually MP3 or AAC files that have been decompressed and repackaged as FLAC/WAV. The file size remains large, the file extension is still good, but the lost audio cannot be recovered. It's very difficult for the human ear to hear the difference. The frequency spectrum, however, is immediately apparent.

Music Check decodes the music file directly on your computer, analyzes the frequency spectrum using FFT, and tells you the result straight away.

━ WHAT IT MEASURES

• Cutoff frequency — where the sound stops abruptly, traces left by lossy encoding

• Brick-wall — what distinguishes a compressed file from a file that is inherently low in high frequencies
• True bit depth — a file declared as 24-bit but actually only uses 16
• Noise floor, spectral holes, mid/side ratio in the high frequency range
• MD5 comparison recorded in FLAC

• Spectrum map over time

━ FOUR ANSWERS, NONE AMBIGUOUS

PASS · DOUBT · FAIL · NOT MEASURED

"NOT MEASURED" is the most important answer. When the data is insufficient to conclude, the app directly states that it has not been measured — instead of making wild guesses and wrongly accusing a real file.

━ TWO MODES

Fast — a few seconds. Take a section from the middle of the track, separate left/right channels.

In-depth — scan the entire track. Add absolute noise floor, true bit depth, MD5 comparison, time-series spectrum map.

━ INCLUDES MUSIC PLAYER

Scan your device's library, play music, playlists, favorites, view information and cover art. Free, unlimited.

━ FAIR DISCLAIMER

This is an estimate based on the frequency spectrum, not an absolute assertion. A genuine recording with low high frequencies can still be wrongly suspected. And there are encoders — for example, AAC at high bitrate — that leave almost no trace on the frequency spectrum; in those cases, the app reports "NOT MEASURED" rather than making up a conclusion.

━ FREE AND PAID

Free: unlimited quick assessment, 3 in-depth scans, full music player. Contains ads.
One-time unlock: unlimited in-depth access, multi-track appraisal by pack, full score, ad-free. Buy once, use forever, no subscription.

━ PRIVACY

No account, no login. Music and appraisal results remain on your device.

What’s new

First release.

• Verify music files: reads the frequency spectrum to tell whether a FLAC/WAV is genuinely lossless or a disguised MP3
• Two modes: Fast (seconds) and Deep (whole track)
• Four plain verdicts: PASS, SUSPECT, FAIL, and NOT MEASURED when the data cannot support a conclusion
• Music player: library, playlists, favourites, background playback
• Your music and your results never leave your device