FAST TIME-FREQUENCY TRANSFORM ALGORITHMS AND THEIR APPLICATIONS TO REAL-TIME SOFTWARE IMPLEMENTATION OF AC-3 AUDIO CODEC

AC-3 audio coding technology is a kind of Perceptual Audio Coder (PAC) developed by the Dolby Company. Up to 5 full-bandwidth channels and o ne subwoofer channel (cutoff at 120Hz) are available in AC-3 to provid e multi-channel, low bit rate, and high perceptual quality of audio. T his explains why AC-3 has become the audio standard of many internatio nal standards. In this paper, we focus on the real-time software imple mentation issues of AC-3, Two fast algorithms of the time-frequency tr ansform, one for memory economization and the other is for time domain subsampling, are presented. Meanwhile, we will state the current perf ormance status of our AC-3 decoder.