[barksdale]

Is there anyway to confirm a real FLAC file vs a fake?  People have suggested to use spectrogram software such as "Spek" but others have said this will still not give a definitive answer.
 
FLAC files are suppose to go past 22 kHz on the spectrum, while 320 kbps mp3 should be 20 kHz.  
 
Below is an image comparing FLAC, 320 kbps mp3, 192 kbps mp3, and 128 kbps mp3.  Notice that the FLAC files have "blank" areas marked in red?  The first FLAC has a tiny area marked in the top left.  The second file has a bunch of blank space in the middle, but the 22 kHz area is covered at the top.  The 128 kbps mp3 is 16 kHz for the most part, which is accurate with that bitrate, but 2 lines hit 22 kHz.

What can you deduce from this?
 
http://imgur.com/a/yaLFj

 

[MindsMirror]

The spectrogram is also an indication of the audio that was recorded. If for example you record a bass guitar that doesn't have much high frequency content, or you have a quiet section, that could also result in a blank area.
 
People can't hear past 20KHz, so to avoid wasting energy or risking distortion from sounds that you can't hear, someone producing a CD might filter those upper frequencies. But they won't do it with a hard limit like you see in the MP3s. There's usually not much useful information up there anyway.
 
The second file looks like it has had the 11KHz to 20KHz range filtered, but it does not look like a hard cut like you get in MP3s. There could be many reasons why someone would do that to the audio. Perhaps that frequency range was full of hiss, with no useful musical content, so they just removed it. Perhaps it was a recording that was slowed down, so the frequencies at 22KHz got halved, down to 11KHz, and the original recording did not capture anything above 22KHz so there was nothing to fill that space.
 
The MP3s all look like what you would expect of a lossy file. The blank space near the beginning of the first MP3 just indicates that it is a quiet part, or a recording of something without any high frequencies.
 
You will often see that hard cut like in the last MP3, where the encoder filtered most of the frequencies above the cut, but decided to keep some of the louder and more important high frequencies sounds.
 
The two spikes in the 4th file are probably clipping.

 

[sonitus mirus]

Unless you ripped the CD to FLAC yourself, there really isn't any way to know for certain what was done to the file.

My suggestion would be to use CueTools and compare the track to the AccurateRip database.

Start here:

http://www.cuetools.net/wiki/Main_Page