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My recent review of the Creative ZiiSound D5 mentioned its apt-X credentials. However, I had no idea what apt-X was, so I’ve taken a look into it.
To manage the transfer of stereo audio, the Bluetooth Special Interest Group (SIG) ratified a system known as A2DP (Advanced Audio Distribution Profile). Now, Bluetooth stipulates the maximum available bandwidth for A2DP is 768kbps. So for high quality stereo music, it is necessary to use some form of audio coding to reduce the required data rates. This is where apt-X comes in.
Originally developed for use in the professional audio and broadcasting sectors, apt-X is a real-time digital audio data reduction system that compresses audio by a factor of 4:1 with no perceptible audible degradation and with negligible delay.
apt-X, though, is not just about compressing audio for Bluetooth purposes – it’s used for all sorts of hardware and software implementations, with different versions available for different tasks. For example, there is a lossless (where compression may occur but no data is lost) version of apt-X, as well as a hybrid-version which is “near lossless” and apt-X Live for digital wireless microphones.
The apt-X codec is handled by its parent company APTX who licence its use.
I have to say, the more I’ve read about apt-X, the more impressed I’ve been. It’s very easy with a new product to be blinded with lots of trademarked names and abbreviations without knowing exactly what they do and how important they are. From what I’ve read, certainly when it comes to Bluetooth audio, apt-X appears to be a must have.