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Topic: Comparing two CDs for authenticity and audio quality (Read 837 times) previous topic - next topic
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Comparing two CDs for authenticity and audio quality

I have two different CDs of Backless by Eric Clapton. They both have the same 1978 year on the back, and the track list and CD artwork are quite different. What is the industry history about seemingly same releases but different artwork?

Are there common audio CD tools that can display the CD's detailed metadata and possible compression info? One way I can think of comparing the two is to rip each CD and then compare track frequency spectrum.

Re: Comparing two CDs for authenticity and audio quality

Reply #1
I have two different CDs of Backless by Eric Clapton. They both have the same 1978 year on the back, and the track list and CD artwork are quite different. What is the industry history about seemingly same releases but different artwork?

Are there common audio CD tools that can display the CD's detailed metadata and possible compression info? One way I can think of comparing the two is to rip each CD and then compare track frequency spectrum.

The simplest way of figuring out what you might have is to go online and look.  Usually there's a serial number or catalog number somewhere on the case that can help you pin down what release you might have.  It isn't fool proof.  Sometimes you can have the same album and mastering but different artwork but other times you can have the same album, different mastering and different artwork.

There were no CD releases in 1978.  The format didn't debut until 1982.

Re: Comparing two CDs for authenticity and audio quality

Reply #2
If they don't sound obviously different, why worry about it?

The spectrum might give you a clue.

In Audacity you can Measure the RMS level.

You can also "trick" Audacity into giving you the peak level - Run the Amplify effect and it will default to whatever change is needed for normalized/maximized 0dB peaks.   i.e. If it defaults to +3dB, your current peaks are -3dB. (You can cancel the effect after making note of the peak.)  But many (if vnot most) tracks are 0dB normalized so that might not tell you anything.

There is also the YouLean online loudness checker that can give you LUFS loudness.

Re: Comparing two CDs for authenticity and audio quality

Reply #3
If they don't sound obviously different, why worry about it?

The spectrum might give you a clue.

In Audacity you can Measure the RMS level.

You can also "trick" Audacity into giving you the peak level - Run the Amplify effect and it will default to whatever change is needed for normalized/maximized 0dB peaks.   i.e. If it defaults to +3dB, your current peaks are -3dB. (You can cancel the effect after making note of the peak.)  But many (if vnot most) tracks are 0dB normalized so that might not tell you anything.

There is also the YouLean online loudness checker that can give you LUFS loudness.

You do a complete "bit-compare" with Audacity.

Import both into Audacity.
Apply the “Invert” effect to one of the tracks.
Select both tracks, then from the “Tracks menu > Mix and Render”.
If the tracks were identical, the result will be silence.
To check that it is absolute silence, select the full (mix) track, and open the “Amplify” effect.
If the Amplify effect says that the “New Peak Amplitude” is “-infinity”, then the mix track is totally silent and the two imported files have identical audio.

Re: Comparing two CDs for authenticity and audio quality

Reply #4
What is the industry history about seemingly same releases but different artwork?

That is very common. See Discogs, which lists 43 different CD pressings for this particular album, with several album cover variations.
Music: sounds arranged such that they construct feelings.

Re: Comparing two CDs for authenticity and audio quality

Reply #5
What counts as a different pressing?

As I understand it, very much like vinyl a CD is pressed from a stamp, and the stamp is prepared from a master.  The stamps wear out, so is a new stamp from the same master a different pressing?  In this case the CDs should be bit-identical.

If the master has to be rewritten from a master tape, then if the master tape is digital the master stamp should be bit-identical except perhaps the number of lead and tail zeros.  If the master tape is analogue then digitising to rewrite the master stamp is likely to result in significant differences.

I can understand the question about comparing pressings: if they can be verified as bit-identical, there is no need to go to the effort of auditioning them.
It's your privilege to disagree, but that doesn't make you right and me wrong.

Re: Comparing two CDs for authenticity and audio quality

Reply #6
Are there common audio CD tools that can display the CD's detailed metadata and possible compression info? One way I can think of comparing the two is to rip each CD and then compare track frequency spectrum.

Perhaps this old software provides some of the information you are looking for. It still seems to run on current versions of Windows.
http://tausoft.org/wiki/True_Audio_Checker_Downloads

I found another good (better) alternative in my personal archive, but couldn't find it anywhere on the web (not even in the Wayback Machine).
It is called CD-Inspektor by Claus Müller and was once available on the website of the University of Jena. The interface and PDF manual are in German,
but that shouldn't be much of a limitation. Also, I'm not sure about the licenses. So I'm concerned if I should publish it here.

Re: Comparing two CDs for authenticity and audio quality

Reply #7
With regards to different versions/editions/pressings of the same release, then it has already been mentioned Discogs and MusicBrainz should be investigated.

If you're unable to identify the exact version, then rip both CDs and paste the EAC/XLD log file into http://eac-log-lookup.blogspot.com/ and it'll give you the MusicBrainz disc ID from the MusicBrainz database (if it's already in there).

If you want to preform some sort of audio comparison, then this page has a great example (there are other comparisons on his website) of what he's done to find the "best version of xyz". You could follow how he's done it.

Cover variations is extremely common in the music industry, especially with older releases that get re-released/remastered etc. And it can also vary as to what source they use to create the new version. Sometimes only old vinyl versions exist for them to copy! Not ideal obviously.


 

Re: Comparing two CDs for authenticity and audio quality

Reply #8
The bit-comparison feature of FB2K is also of value for doing the initial comparisons. If you already have securely ripped versions of both CD's it's very easy to do the comparison this way.