Design of the coupling schemes for the AC-3 coder in stereo coding

Abstract

When applying the Dolby AC-3 coder for the stereo music compression, the coupling scheme that combines the two channels stereo audio signals in high frequency into one channel is the key technology for the Dolby AC-3 to achieve the bit rates lower than 96x2 kbits/sec while preserving high stereo audio quality. This paper proposes four coupling methods for the AC-3 encoder. These four methods vary with the complexity and performance. These four methods are compared through both subjective and objective tests. These four coupling methods are also combined with the dithering scheme and examined through subjective and objective tests. The result shows that the dithering scheme can effectively ease the coupling artifacts and enhance the audio quality.