How to check if a FLAC file was made from MP3?

Question

Possible Duplicate:
Finding out if a FLAC or WAVPACK audio file is NOT originally encoded from a lossy source

Sometimes I doubt that FLAC files are made from original music, because of deaf-dumb-blind feelings typical to MP3's, or because turning the highest frequencies on equalizer give no effect on sound. I'm searching for a tool for a quick check of FLAC files, to simply throw away wrong files without having a long unpleasant listening. Do you know any tool which may help?

Solution

Thanks to the fact that mp3 compression has a perceptual element, mp3's exhibit certain characteristics that can exposed through visual frequency and spectral analysis. In particular, there will be a sharp roll above 16 khz. Note that in mp3's of a very high bit rate, such artifacts may not be at all obvious without an original reference file.

There is a nice run down of the wave analysis process here.

Tau Analyzer tries to automate the process but I can't vouch for how accurate it is in it's assessment.

Comments

[ChrisF]

If you only have the FLAC file then probably not. There's no connection between the output file and the input. There might be some meta data which indicates the source, but I'm not familiar with the FLAC format to be able to say for sure.

[Yaroslav]

Thank you very much for the spectrum analysis idea to identify the damages caused by MP3. However the Tau Analyzer cannot accept FLAC files, it accepts only CDs... :(