Audio Source Checker
A FLAC file can contain audio that was previously compressed with a lossy codec. This tool looks for high-frequency cutoffs that may hint at that history. It cannot confirm the source, and your file stays in your browser.
Key features
- Local processing
- No upload required
- High-frequency rolloff reference
- Detected cutoff frequency
- Spectrum visualization
How detection works
The tool decodes the audio locally and checks where high-frequency energy falls away. A sharp cutoff may suggest prior lossy encoding, but recordings and mastering choices can produce similar patterns.
Understanding the verdict
The result is based on the highest frequency with measurable energy. It describes the spectrum only; it cannot certify that the audio came from a lossless source.
Limitations
Frequency analysis is a heuristic. Some legitimate recordings have natural high-frequency rolloff. Some lossy sources may not trigger this check. Always use this as one data point, not a definitive verdict.
Common use cases
Inspect a FLAC file before adding it to your library
Look for a sharp high-frequency cutoff that may warrant a closer look at the file’s source.
Review files with unknown origins
Compare suspicious files with known sources. A cutoff is a starting point for investigation, not a final answer.
Check a rip before archiving
Inspect the spectrum of a rip alongside its source information before you archive it.
Frequently asked questions
Can this tool definitively prove a file is fake lossless?
No. This is a heuristic indicator based on frequency content — not proof. Frequency analysis is a strong clue but not definitive. Some recordings naturally lack high-frequency content. Some encoders apply transparent high-frequency limiting. Treat the result as a reference hint, not a final verdict.
What cutoff is typical for MP3?
There is no universal cutoff for a given MP3 bitrate. It depends on the encoder, its settings, and the source audio.
Is my audio uploaded?
No. Everything runs locally in your browser.