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mp3PRO basics: technology


Why mp3PRO Technology?
Listening to music compressed with mp3 at 128 kbps sounds great. But if you go to lower bit rates the great sound starts lacking the high frequency components. At bit rates of 64 kbps and below the music may begin to sound dull. The reason is that mp3 at these bit rates runs out of bits to compress the music in full audio bandwidth and with significant detail. In this situation the developers of mp3 had to decide whether their codec should produce mp3 music with distortion (so called "coding artefacts") or with limited bandwidth. They opted for limited bandwidth. And as a result, you experience lower bit rate mp3 as band-limited music with just a few distortions.

What is mp3PRO Technology?
To improve the sound quality of mp3 at lower bit rates, Coding Technologies has developed an enhancement technology that gives back the sound the high frequency components. The technology is called "Spectral Band Replication" (SBR). SBR is a very efficient method to generate the high frequency components of an audio signal.

More Details
Combining mp3 with the SBR enhancement technology generates an audio signal with high bandwidth at low bit rates. mp3PRO, the resulting audio format is composed out of two components, the mp3 part for the low frequencies and the SBR or "PRO" part for the high frequencies. Since the "PRO" part requires only a few kbps, the format could be done in a way that it is still compatible with the original mp3 format. This fact allows existing mp3 players to play mp3PRO files. They simply ignore the PRO part. The only requirement is that they also have to support sampling rates of 16, 22.5 and 24 kHz along with 32, 44.1 and 48 kHz. While all (mp3 standard compliant) software players fulfil this requirement, not all portable and CD/DVD players do. To learn whether your mp3 player is capable to play mp3PRO files, please check with its manual or manufacturer.

mp3PRO Players
New players supporting mp3PRO technology will of course utilize both parts of the mp3PRO format to take full advantage of the "PRO" enhancement. mp3PRO players will still fully support mp3 since this is an important part of the new mp3PRO format. Thus you can continue to use your vast collection of mp3 files when upgrading to mp3PRO technology.

Demo Player
mp3PRO technology produces great sound quality at lower bit rates. The free Thomson Demo mp3PRO Player/Encoder software you can download, lets you experience the sound quality of mp3PRO technology at 64 kbps. The feedback we received from first listeners was that the quality of 64 kbps mp3PRO technology was in the range between 96 and 128 kbps mp3. This means that you can get nearly twice the amount of music on a portable and CD player with mp3PRO technology. For example, traditional audio CDs hold about 15 songs. An mp3 CD can hold 150 or more songs encoded at 128 kbps. In the near future, when mp3 CD players incorporate the mp3PRO decoder, you will be able to store over 300 songs on an mp3PRO encoded Compact Disc.

Supported Bitrates
mp3PRO technology can support more bit rates than just 64 kbps. At lower bit rates mp3PRO technology is ideal for web casting and Internet radio. At higher bit rates, mp3PRO technology is perfect for high quality audio transmission and storage. The following bit rates are supported by mp3PRO:
Mono: 18, 20, 24, 32, 40, 48, 56 kbps
LC-stereo: 18, 20, 24, 32, 40, 48, 56 kbps
Stereo: 32, 40, 48, 56, 64, 80, 96 kbps

For more background information about SBR and mp3PRO technology please visit www.CodingTechnologies.com/products/sbr.htm

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