mp3 SX (Stereo eXtended) is a program that allows users to upgrade mp3 stereo files to MP3 Surround files. mp3 SX analyzes the existing natural ambience of the stereo material and plays it back through the rear channels. The sound sources remain in the front channels, but are played back through the Left, Center and Right channel, providing a stable front image even for off-sweet-spot listening. mp3 SX preserves the original stereo sound stage, creating additional surround envelopment, with only 15 kB/s additional information.
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MP3 SX Wikipedia(Text) CC BY-SA