[to3m]

I wondered what my favourite test tracks would sound like, so I made a (somewhat stupid, and a bit slow...) program to produce the difference between an MP3 and a WAV: https://github.com/tom-seddon/bin/blob/master/find_mp3_resid...

(Dependencies: python 2.7, lame, GNU make, mpg123, and (if you use FLAC files as input) flac. Tested on my Linux PC with LAME 64bits version 3.99.5 and mpg123 1.14.4 from the debian stable package repository. Run with -h to get some "help".)

It uses lame to compress and mpg123 to decompress, and I don't know if there's something special going on but the output WAVs always seem to have the same number of samples as the original. And they seem to be aligned - if you use this program you'll find that the difference between WAV and 128kbps MP3 is somewhat noisy, but WAV vs 320kbps MP3 is pretty much silent.

(Or maybe you'll find something totally different! Who knows. I only tested this on my system.)

[mdisraeli]

Neat, thanks for running the experiment to see how differing MP3 encoder settings affect the lost portion. This explains why 320kbps is generally accepted amongst DJs, as any loss is significantly less than that caused by the club sound system :P

[to3m]

I did a blind test when I was in my 20s, and while on a couple of tracks I could actually tell the difference between 320kbps and the original, I did have to concentrate. And I couldn't really have said that one was necessarily better than the other; the effect was as if one type of noise-y sound was being replaced with a subtly different type of sound with the same noise-y quality. Different, but overall the same.

Listening to the diff of one of those tracks today was interesting! All I can hear is the drums... and where the sound I'm thinking of plays, it sounds like rather quiet interference! But the drums as I recall sounded absolutely identical. Interesting that the ears can detect one thing but not the other.

(I didn't bother to re-run the full comparison, as I'm no longer in my 20s. One good (?) thing about getting old is that your hearing deteriorates, and issues such as this become moot. You can also afford the disk space to just compress everything at 320kbps. Then you don't have to worry about it, and it fits OK on your phone too.)