List of MP3 sources on CD

We have discussed this topic here before, but I thought it would be a good idea to start a list of CDs where one or more tracks are confirmed to have been mastered from an MP3 source. Because I just found out that this is the case with a very surprising title: Varese's "25 Rockin' Instrumentals."

Varese has a reputation for careful mastering, so I doubt if anyone on their end was aware of the situation. But it appears that the track "Honky Tonk (Parts 1 & 2)" by Bill Doggett, featured on this CD with both sides of the single edited together, was mastered from an MP3 source.

Look at the images below. This is the track "Honky Tonk (Part 1)" from Ace UK's "Teen Beat Vol. 5":



As you (barely) can see, the audio frequencies go all the way up to at least 22hz.

Now take a look at the same spectral view of "Part 1 & 2" from Varese's "25 Rockin' Instrumentals":



See how frequencies above 15hz are just cut out? That's exactly what you see in medium-bitrate MP3 (under 256kb). That's part of how MP3s compress the audio -- they just cut out frequencies that are above the range of most people's hearing.

I showed this to Aaron, and he agrees, with no doubt: that song was mastered from an MP3 on the Varese CD.

I'll add that I checked this on three different copies of the CD, and all are identical. I don't know what happened. Again, I doubt if the mastering engineers knew about this -- I think they were probably sent a digital master by King Records. But it makes me wonder if the other songs on this CD are like this. Or what other tracks out there might be...

EDIT: Let me add one more image. This is the Ace UK version of "Honky Tonk (Pt 1)" which I've ripped as a 128kb MP3 with iTunes. See how the spectral view now resembles the Varese CD:



Edited by Brian W.

I thought it would be a good idea to list the tracks, if we know what they are. "Hey There Delilah" was the first one to come to mind.

Edited by Brian W.

OMFG! NO WAY! Unbelievable. What a pain -- now I'm going to have to do spectral analysis on virtually every one of my CDs from about 2003 on.

Edited by Brian W.

Pat,

Not to create too much extra work for you, but does it make sense to add a parenthetical "mastered from MP3" note in the database for those tracks that we know are from lossy sources? It would certainly add value. I see it as no different than the "mastered from vinyl" comments that are in there now.

Props to Brian for figuring out the sonic signatures from
mp3 compression!

The views that he shows in the embedded pictures are from
a newer version of the old standby, Cool Edit Pro. (I
still use an ancient version of it for my editing, and
will likely never change to anything else.)

The default view in Cool Edit Pro is the "waveform view",
which we're all used to seeing. It's trivially easy to
switch to the spectral view that Brian shows - Go to View
> Spectral View.

I'd think that Audacity or the other editing programs
should have a similar view, but I can't confirm.

I played a little with mp3 encoding from the old CDex
program, just to see if the effects are visible even at
very high encoding rates. I took a wav file of one of my
needledrops, encoded to mp3, then converted back to wav
so I could view it in Cool Edit Pro. I mp3-encoded with
"preset insane" option on CDex, which encodes at 320
kbps. The wav-to-320 kbps mp3-to wav file shows the hard
cutoff effect that Brian shows, but at 21 kHz. The
source file has frequencies that extend to the max scale
and don't show a hard cutoff.

Edited by crapfromthepast