How do you tell if a cd is actually cd quality?

[Sovelin]

I recently purchased the deluxe version of Kid Cudi's Man on the Moon. The deluxe edition had an issue and most copies are missing the bonus tracks. When I called the distributor, they said that they could either give me a code so I could download the songs online, or they could send me a cd with just the three missing songs. I opted for the cd (I bought the cd, I obviously want the cd quality). I found out that the online download was encoded at 160kbps, which is terrible.

I will get the cd with the three songs in 2 weeks. Once I get it, I want to make sure that the songs are actually cd quality, and not just low quality mp3's that they burned to a cd. Is there a way to test the quality (without just listening to it)? I want to be able to back up my claim with numbers or some solid proof.

 

[Uncle Erik]

I'd think that a music CD has to conform to the Red Book standard. Try playing it in a CD player that doesn't support MP3s, etc. If it plays, it will be a regular Red Book disc.

 

[gevorg]

There are some programs that can detect (by percentage chance) if a CD is genuine or a rip from mp3. They do it by analyzing the spectrum (or something) of the CD.

Don't remember their names, someone here will probably post a link soon.

 

[Ham Sandwich]

Here's three programs that can analyze the audio and calculate a guess whether the audio was previously lossy encoded. The analysis isn't perfect. They do make false positives (saying a file was once lossy encoded when it never was).

Spectro
Audiochecker
Tau Analyzer

Visually looking at the spectrogram for a song can also give you a clue as to whether it was ever lossy encoded. High frequencies will be cut off by typical lossy encodes.

 

[Sovelin]

Thank you everyone! I'm on a waiting list for the tracks so they said it'll actually be two weeks, but I'll be ready for it.

 

[fjf]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif I'd think that a music CD has to conform to the Red Book standard. Try playing it in a CD player that doesn't support MP3s, etc. If it plays, it will be a regular Red Book disc.

You can burn a regular CD from mp3 files (with nero or other software, like K3B). It will play in normal CD players but it wont have all the data on it, lost before in the MP3 conversion.

 

[insyte]

You can try looking at the spectrum using foobar

 

[pdupiano]

Theres a quick way if you have "Full" CD

First determine the length of playtime for the cd. Divide the number by 80 and you should get a rough approximation of how much of the cd was actually used. Now flip the cd around and you'll see two different "colors" on the flipside of your cd. Theres a light foil and a foil with a different shade. The darker shade indicates that some info was imprinted on the cd, the remaining parts mean it wasn't used. If you have a cd that has 60 min but only 50% of the cd is imprinted with music then you have less than cd quality. Additionally, if you have any of those old remaster cds that have runtimes well above 80 min, eg, old van morison cds you'll notice that they can somehow fit 100+min of music on a single cd, that would be a clear indication that some of the tracks are not true cd quality. And its pretty easy to hear the differences.

If you happen to have Five for Fighting's "America Town" cd you can see what I'm talking about with regards to the amount of cd used versus the run time of the cd.

 

[Sovelin]

That's actually a really good way of looking at it. Although with only 3 songs on the cd, there is such a low percentage of music on there that I probably wouldn't be able to use this method this time. Otherwise, you do have a very interesting idea

 

[AdamWysokinski]

Quote:

Originally Posted by Sovelin /img/forum/go_quote.gif Is there a way to test the quality (without just listening to it)? I want to be able to back up my claim with numbers or some solid proof.

Use Audacity: Analyze -> Plot spectrum.

For example, this one is an original Apple Lossless file:

And this is a 160 kbps MP3 copy:

 

[TheOtus]

Quote:

Originally Posted by pdupiano /img/forum/go_quote.gif Additionally, if you have any of those old remaster cds that have runtimes well above 80 min, eg, old van morison cds you'll notice that they can somehow fit 100+min of music on a single cd, that would be a clear indication that some of the tracks are not true cd quality. And its pretty easy to hear the differences.

This got me very interested... How is this possible? Well, more precisely, how can a normal CD-player play that? I mean doesn´t the CD-player read the disc with a standard speed? I really don´t get this... The audio has to be compressed somehow, but how would a normal CD-player be able to get a clue of it?

To the topic, as said the analyzer or spectrum are only ways, beside listening. A CD burned of mp3-files takes the same amounf of space than a direct copy of the actual CD.

 

[Sovelin]

Quote:

Originally Posted by AdamWysokinski /img/forum/go_quote.gif Use Audacity: Analyze -> Plot spectrum. For example, this one is an original Apple Lossless file: And this is a 160 kbps MP3 copy:

So in this case the only thing cut out from the original song was above 15.25kHz? Well, I'm sure if we looked at it below the 1kHz mark we would see how the 160 kbps copy is lacking, probably cut off at ~100Hz

 

[TheOtus]

Just to point out a mistake, above 16 kHz.

How did you assume the cut off at 100 Hz?

 

[Sovelin]

lol, I definitely read the graph wrong. There's a very good chance I'm wrong on the 100Hz thing. It is probably closer to 50 or below. When I had my home theater system, I had the crossover on my sub set to 80Hz. When I played a song through my iPod that was at 160kbps, the bass response would be very weak. When I played the same song on the cd, the sub would knock me off my chair. I know the 160kbps is going to cut off the bass at some frequency, just not sure where.

 

[watchluvr4ever]

Quote:

Originally Posted by TheOtus /img/forum/go_quote.gif ...A CD burned of mp3-files takes the same amount of space than a direct copy of the actual CD.

I'm not sure I understand what you are saying. If I were to burn a CD in MP3 format it will take up less space.