CD Quality Compared to MP3 Quality

[Workin']

<< What I'd like to see is a double blind study done with self-proclaimed audiophiles where the same track is played in MP3 format and CD format. >>

Sound and Vision Magazine did just such a study about 1.5 years ago, using the Fraunhofer encoder, and found that 128kbps mp3's were easily identified by every listener on the panel. 256kbps were consistently identified by only a few listeners and only on a few specific test tracks.

However, encoders like LAME have improved quite a bit in the last year, but I would still say that using mp3 for critical listening is not quite appropriate.

I can identify a 128kbps mp3 probably 85% of the time using my PC's Altec ACS295 speakers. Played through my stereo, I can always pick out a 128kbps file. EVERY time. Using LAME-encoded 256kbps files I can never tell the difference on my PC speakers, and on my stereo maybe 10% of the time.

<< Technically i from what i calculated from the book CD quality is 172kpbs >>

What calculations from what book? A CD data stream is 1.4+ Mbps, BTW.

 

[Zlash]

128kbps isn't a very good mp3 these days either. Have you encoded any at 320? I usually encode everything at 192 or 224 and wouldn't be able to tell the difference between the two.

This a+ book i have lists CD quality at 178,000 something kbytes, which is like 172KBps.

 

[CSFM]

After all has been said and done though, Mp3's are a great format. They do sound good, and they are small enough to keep on you PC's HDD in bulk. I also like the fact that NO ONE company has a patent for Mp3's... hence it's popularity.
No, CD's are not perfect, If you want perfect sounding music... go out and see a live act.

-CSFM-

 

[Zlash]

Ok here ya go

CD quality is = 16 bits * 44,100 samples/sec *2 = 1, 411, 200bits = 176,400 BYTES = 172.26 KBps

Which you can easily acheive with MP3's.

 

[Workin']

<< Ok here ya go

CD quality is = 16 bits * 44,100 samples/sec *2 = 1, 411, 200bits = 176,400 BYTES = 172.26 KBps

Which you can easily acheive with MP3's. >>

LOL! MP3 bitrates are in kiloBITS per second. Not kiloBYTES! You're only off by a factor of 8!

 

[Zlash]

Then you do the math, i got too many bits and bytes running through my head now =).

 

[CSFM]

Take a look at this link it should explain a few things for you.

Data sizes

Mp3 is not a good as CD in sound quality... end of story, no matter what bit rate you rip a disc down at... current Mp3's are not as good for sound quality

 

[Zlash]

Well that explained all of nothing for me, until you get some resources that actually i can buy that, everyone i know doesn't buy that and if sound quality is such a big thing for you audiophiles...why do you have mp3's if they aren't as good or better? =)

 

[Workin']

<< Well that explained all of nothing for me, until you get some resources that actually i can buy that, everyone i know doesn't buy that and if sound quality is such a big thing for you audiophiles...why do you have mp3's if they aren't as good or better? =) >>

Just what are you "not buying"? The difference between bits and bytes???? That CD audio isn't 1378.125 kbps?? Or that even mp3's at 320 kbps about 75% of the original data is being discarded. At 128 kbps nearly 90% of the original data is being tossed out. How can you even think that sound quality isn't affected?

The main advantage to mp3 is the ability to get *acceptable* sound quality from smaller files than a CD audio track. Which is handy for portable audio players and sharing music over the internet. NOT for audio fidelity. Sometimes "good enough" is good enough. Other times it's not. It's a simple concept.

 

[Oogle]

Not sure if there's a current study out there, but there is a "do-it-yourself" double blind test (ironic, huh?) called ABX that can do exactly what you described.

In fact, most audiophiles use this test to prove their "L33T" hearing. Check it out at the PCABX website. It's pretty straightforward to use. All you have to do is convert your test MP3 back to a WAV format (this is a lossless conversion) and compare that WAV with the WAV you extracted straight from your CD. ABX will allow you to run your own tests without any apprehensions of bias from either yourself or the computer tester (unless you think your PC is out to get you ).

So the next time people complain that 128, 160, 192, 256, etc. isn't good enough for CD quality, you can tell 'em to go ABX themselves.



<< What I'd like to see is a double blind study done with self-proclaimed audiophiles where the same track is played in MP3 format and CD format. One has to choose which is the CD and which is the MP3. Do it for 96, 128, 160, 192, etc. If any of those bit rates is able to get the group to pick the MP3 over the CD ~50% of the time, you can say it's CD-quality (to our ears). You have to make it so they have to pick one...no "they're both CD, or they're both MP3" choices. That way, at 50%, you reduce it to chance of guessing the correct format. >>

 

[Zlash]

Ok workin, now your just pulling numbers out of thin air.

 

[Workin']

<< Ok workin, now your just pulling numbers out of thin air. >>

Right. Now pay attention...

CD audio = 16 bits/sample x 44100 samples/second x 2 channels = 1,411,200 bits/second. 1024 bits/kilobit gives 1378.125 kilobits/second

Pulled out of the air? Hardly.

How much data is discarded? 1378.125 - 320 = 1058.125 kilobits/second is lost. 1058.125/1378.125 = 0.768 or 76.8% lost for 320kbps mp3. 1378.125 - 128 = 1250.125/1378.125 = 0.907 or 90.7% lost for 128 kbps mp3.

Pulled out of the air? I don't think so.

Obviously you are a troll (or just really stupid). You should talk to your teacher back there in 4th grade and maybe she can teach you some elementary math.

 

[CSFM]

I don't know how to please you Zlash. I have tried to explain it as simple as I could. OK... Let me get into details...
Mp3 is the file extension for MPEG, audio layer 3. Layer 3 is one of three coding schemes (layer 1, layer 2 and layer 3) for the compression of audio signals. Layer 3 uses perceptual audio coding and psychoacoustic compression to remove all superfluous information (more specifically, the redundant and irrelevant parts of a sound signal. The stuff the human ear doesn't hear a lot of). It also adds a MDCT (Modified Discrete Cosine Transform) that implements a filter bank, increasing the frequency resolution 18 times higher than that of layer 2.
The result in real terms is layer 3 shrinks the original sound data from a CD (with a *bitrate of 1411.2 kilobits per one second of stereo music) by a factor of 12 (down to 112-128kbps) without sacrificing too much sound quality.

*Bitrate denotes the average number of bits that one second of audio data will consume.*

You do loose sound quality. All be it not too much to make the songs incomprehensible. Keep in mind that you are taking away from the CD's native format and compressing it down. Whenever you compress something in this way (by discarding some of the information) you always loose some quality. Have a look at your DivX format compared to DVD... no surround sound and the picture quality is much poorer. But it is still acceptable quality to most who want to get the files onto there computer.

-CSFM-

 

[Zlash]

You guys are confusing fidelity, and quality. Workin, just because it's smaller doesn't mean your losing all that data.

 

[Zlash]

Done some more reading up, 256k is considered CD quality by audiophiles using a Lame or fraunhofer encoder. And my math was right, i just made the mistake of using KBs instead of kbs =).

CSFM, you can stop trying to explain these things to me that i already know...i'm just trying to show you that they can be the same quality.

 

[Workin']

<< Workin, just because it's smaller doesn't mean your losing all that data. >>

You are monumentally ignorant. Where does the data go?? You obviously have no idea whatsoever how the mp3 encoding algorithm works.

<< And my math was right, >>

If 172 is the same as 1380 then your math is right. If they are different then you are a moron. Here's a hint - you're a moron.

You go ahead an keep right on thinking whatever you want. That doesn't make it correct.

<< You guys are confusing fidelity, and quality >>

I think you are confusing reality with something else. Can't tell what, though. I understand the difference between fidelity and quality - and by definition, no lossy compression scheme can have quality comparable to the original - fidelity has nothing to do with it.

<< CSFM, you can stop trying to explain these things to me that i already know... >>

By your inane comments it is obvious you don't have a clue, and won't take one, either.

 

[CSFM]

>>>CSFM, you can stop trying to explain these things to me that i already know...i'm just trying to show you that they can be the same quality.<<<

No they can't... you simply cannot get the same sound quallity from Mp3's as you do from a CD. But I will agree to disagree with you.

In any case, it is a great format to store music and gerat for file sharing. I listen to 70% Mp3's at home and about 30% CD's... so I have a soft spot for Mp3's.

 

[CSFM]

>>>You are monumentally ignorant. Where does the data go?? You obviously have no idea whatsoever how the mp3 encoding algorithm works.<<<

Ha... that is the all time biggest question! Where does the Data go? LOL... LOL again.

Maybe it takes a vacation. Boy... I sure could use one of those after this thread. Dunk Island looks good this time of year.
The Dunk!

 

[Zlash]

Workin your not too bright at figuring a little math out on your own so, i said i made the mistake of using KBs and not kbs so genious what is 172*8? That's right ~1380.

"You are monumentally ignorant. Where does the data go?? You obviously have no idea whatsoever how the mp3 encoding algorithm works"

It's compressed, just because it is a lossless method doesn't mean it's cutting out so much data that it matters...it all depends on the bitrate. Omg a file is smaller when zipped but it's the exact same!


Just goto www.r3mix.net and look under Quality so you can finally stfu. And if you can read german you can go read the article that is linked there that did tests on the quality of mp3's. 256 is considered CD quality by audiophiles and if you can come up with some sources to refute it, be my guest.

 

[Zlash]

To get technical about the bitrate stuff, CD fidelity is the 1411kbps which your right MP3's aren't but in terms of quality, mp3's can be the same quality but at the lower bitrate. You can't really compare the bitrate of 2 different formats so our whole discussion here is moot =).

 

[CSFM]

Your make a valid point. We shouldn't compare bit rates, comparing formats is what we should be doing. I suggest you do some real listening... You will be able to hear a definate decrease in quality from WAV to MP3. End of story!

You can't really compare the bitrate of 2 different formats so our whole discussion here is moot =).

Then leave?????!!!!

 

[Zlash]

There is no end of story, go read the link and if ya don't believe it then i don't know what to tell ya. If you think you can tell the difference between a CD and a 256 mp3 then either your a dog or your imaging things.

 

[merlocka]

I think you are confusing reality with something else. Can't tell what, though.

LOL, I about pee'd myself.

This is a rehash of all the debates when Sony unveiled ATRAC for minidisc.

The basic concept of audio compression which is "inaudible" comes from the physics of hearing.

Basically, if there is a loud tone at some frequency X, the ear becomes less sensitive to frequencies above and below. The shape and steepness of this curve varies from person to person. There have been some generalities made like 256kbps is "CD quality", but the point is... almost 90% of the data can be discarded and it still sounds WAY better than FM. This is why mp3's are so popular.

These limits depend on many many many things, the individual, the compression amount and method, the decoding, and of course the audio reproduction.

Omg a file is smaller when zipped but it's the exact same!

OK, there is a big difference between lossy and loss-less compression. I'da though someone who knew about Lame or fraunhofer encoder's woulda figured that one out. Take a .bmp and compress it to .jpg, you get good compression (lossy, like mp3). Now run Winzip on that .jpg and see how small you can make it (hint, not much smaller).

You can't really compare the bitrate of 2 different formats so our whole discussion here is moot =).

Of course you can, that's the whole point of compressed audio! The two comparisons that matter are how much space it takes up on a HD, and how well it reproduces music.

Anyway, I think the general population which listens to Top-40 radio is more than happy with properly encoded 128kbps mp3.

I also think that Joe Stereophile with his Sumo front end and directional speaker wire would probably deny not being able to hear 256kbps Lame, but he'd fail a ABX.

 

[Zlash]

"OK, there is a big difference between lossy and loss-less compression. I'da though someone who knew about Lame or fraunhofer encoder's woulda figured that one out. Take a .bmp and compress it to .jpg, you get good compression (lossy, like mp3). Now run Winzip on that .jpg and see how small you can make it (hint, not much smaller)."

I was being sarcastic hehe...just sick of hearing because it's smaller and a mp3 it's losing all this "quality".

As for comparing the bitrates, applying it to this it's not a good way to compare the quality of the sound between a wav and a mp3 as for HD space now that's a different matter.

 

[merlocka]

I was being sarcastic hehe...just sick of hearing because it's smaller and a mp3 it's losing all this "quality".

Like you were being sarcastic when you said Cd quality is 44,100 Hertz and 128kbps encoding and you can acheive way over CD quality if you so choose =) ? Cause that one is obviously wrong also.

It is losing quality, but some amount of compression can be transparent depending on the reproduction and the ears of the person listening.

I believe that for most people 256kbps encoding is a threshold of audibility. That's based on what I've read, what I've learned about audio, and what I've heard. I also believe that some people can hear the difference at compression ratio's much lower than that.

The point about mulitple generations of encoding is also notable. Several passes of lossy compression will quickly cause audible artifacts.