Detecting whether a 24-bit file has been upconverted from 16-bit? Options

[vincefalks]

I downloaded a FLAC album from online web store and it appears that the files I've downloaded are 24-bit. it's not a hd web store like hdtracks, it's generally a CD 16-bit 44.1kHz store with either FLAC or MP3 to choose from in its offerings.

I'm wondering whether the 24-bit files are real and were supplied as 24-bit from the label and they just didn't label it correctly on the download page, or whether there was an encoding error or just somehow it made its way from 16-bit files to 24-bit FLACs.

Is there a way I can definitively tell or analyze it (looking at spectral maybe) to see if it's been upconverted? Are there certain algorithms and 'good jobs' that can be done to make its 16->24 upconversion undetectable?

happy to upload a sample if it helps.

thanks
vince

[nu774]

Try something like the following to see if wasted bits is equal to or greater than 8 for each FLAC sub-frames.

CODE

flac -ac foo.flac | findstr wasted_bits (for windows)
flac -ac foo.flac | grep wasted_bits (for Unix like OS)