Bitrate quality of MP3's

Here are 2 articles showing the difference's in the 128 bit and 256 bit variables.
1 showing the performance increase, and 1 showing the waste.
I thought these 2 would be interesting to compare, and there is a video to make the decision yourself.

Sound To Blow Your Mind
Comparing iTunes' old and new audio formats.
Posted Friday, June 1, 2007, at 12:49 PM ET
This week, Apple's iTunes Music Store began selling some songs in a new audio format that the company says has two advantages over its previous offerings: The tracks are free of digital rights management (DRM) restrictions, meaning you can play them on devices other than an iPod, and they have higher audio quality. The new iTunes Plus tracks also come at a premium: $1.29 compared with $0.99 for the old format.

The excitement of the anti-DRM crowd was dampened when it came out that Apple is embedding personal information about the buyer, including name and e-mail address, in each purchased song. But the question we wanted to consider is this: Can you really hear a difference between tracks encoded at 128 kbps (Apple's old format) and 256 kbps (the new format)? Back in April, the Explainer said probably not. For a different verdict, we offer this video by Scott Blaszak:

Go to this link to compare the differences.

Are iTunes' Premium Downloads Worth It?
Do compressed music files sound any different at 256 kbps?
By Christopher Beam
Posted Thursday, April 5, 2007, at 4:24 PM ET

Record label EMI and Apple announced Monday that iTunes will soon offer premium music files, which come without copy protection and have a bitrate of 256 kbps instead of the usual 128 kbps. The luxury tracks will cost 30 cents more than the standard downloads. Will people be able to hear the difference?

Related in Slate
Confused by all this newfangled tech speak? Back in 1999, Bruce Gottlieb explained how they get audio and video onto the Internet. Evan Cornog tested out the best MP3 players around. Peter Rojas explored ways to play MP3s in your car. Paul Boutin hailed the new compression format that will replace MP3s. In 2003, Boutin welcomed the iTunes Music Store. Jack Shafer tweaked the press for its love affair with Apple.In any case, doubling the bitrate from 128 kbps to 256 kbps won't make music sound twice as good, because the smaller file already has the most important information. Codecs like MP3 and iTunes' AAC chop up music from a CD into little time frames and, for each one, determine which frequencies to keep and which to discard. As a result, about 90 percent of an audio CD's original data gets thrown away in the MP3 compression process. (This type of compression is called "lossy," as opposed to "lossless." You lose data during "lossy" compression, whereas "lossless"—think ZIP files—allows you to reassemble the whole thing later.) Listeners don't need all the data on a CD, since much of it is imperceptible to the human ear. Sound compression takes advantage of this fact by removing all that extra information. For starters, codecs throw out frequencies outside the range of human hearing—roughly 20Hz to 20,000 Hz. But that only accounts for a small amount of savings. To save even more space, the codecs also scrap frequencies that would be audible on their own but become virtually imperceptible in the presence of other sounds, like a booming bass. A well-designed codec will only get rid of stuff you wouldn't notice in the original record; that's why the codec you use to compress a file can be more important than its bitrate.

But all else being equal, a song's bitrate provides a reasonable indicator for sound quality. In general, the more bits, the better. That said, each extra bit you add when expanding a compressed file will be less essential than the last. (Going from 64 kbps to 128 kbps adds more important data than going from 128 kbps to 192 kbps.) So, as you compare higher and higher bitrates, sound quality becomes harder to distinguish—the musical equivalent of diminishing returns.


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