View Full Version : MP3 Scourced???

2005-03-12, 05:52 PM
I am attaching a few screens shots. They only reason why I want some views because I do remember that recordings from FM broadcast can have drop offs similiar to mp3 scourced material.

2005-03-12, 05:52 PM
Frequency Analysis #1

2005-03-12, 06:07 PM
Frequency Analysis 2

2005-03-12, 06:08 PM

2005-03-12, 06:08 PM
This is Tales of the Who which if I remembered downloaded from STG last summer

New Homebrew
2005-03-12, 06:48 PM
mp3. Wish i could see the numbers a little better, but even without that, it looks bad.

2005-03-12, 06:51 PM
It doesn't look good, but I can't post anything conclusive yet...

can you show the spectral view zoomed in to 1.5-2 seconds? also, another SA with the FFT size set to max would help a little.

check the link in my sig for detecting mp3-sourced stuff, EAC is a bit hard to read.

2005-03-12, 07:29 PM
That looks like FM

2005-03-12, 08:25 PM

how about Adobe Audition Spectral view, zoomed in on 2 seconds and also showing a full song?

This doesn't look good to me so far.

2005-03-12, 09:38 PM
FM radio rolls off hard at around 15kHz. (The response is 15kHz wide and starts at 50Hz or so).

2005-03-14, 07:29 AM
I think it looks like non-mp3. The fact that the right and left channels each roll off at a different spot would be a dead giveaway.

2005-03-14, 07:51 PM
I wouldn't say so. mp3 encoders are not forced to use the same lowpass for both channels.

2005-03-14, 08:19 PM
FM radio rolls off hard at around 15kHz. (The response is 15kHz wide and starts at 50Hz or so).


Actually, there is no lower frequency limit to FM broadcasting, only the 15kHz upper range (as you mentioned). Looking through the FCC Part 73 specs, I don't see anything addressing highpass filtering.

Also, see:
for a pretty nice explanation of FM mux/demux.

I guess I should add that the individual FM receiver will probably be the limiting factor, not the broadcast.

2005-03-15, 01:03 AM
I still wanna see Audition Spectral Analysis zoomed in on 2 seconds. I don't think we can draw any conclusions from what we see here.