Digital Audio Signal Processing, 3rd Edition

Chapter 9Audio Coding

U. Zölzer and P. Bhattacharya

For transmission and storage of audio signals, different methods for compressing data have been investigated in addition to the pulse‐code modulation (PCM) representation. The requirements of different applications have resulted in a variety of audio coding methods which have become international standards. In this chapter, the basic principles of audio coding will be introduced and then the most important audio coding standards will be discussed. Audio coding can be divided into two types: lossless and lossy audio coding. Lossless audio coding is based on a statistical model of the signal amplitudes and coding of the audio signal (audio coder). The reconstruction of the audio signal at the receiver allows a lossless resynthesis of the signal amplitudes of the original audio signal (audio decoder). Alternatively, lossy audio coding makes use of a psychoacoustic model of the human acoustic perception for quantizing and coding the audio signal. In this case, only the acoustic relevant parts of the signal are coded and reconstructed at the receiver. The samples of the original audio signal are not exactly reconstructed. The objective of both audio coding methods is a data rate reduction or data compression for transmission or storage compared with the original PCM signal.

9.1 Lossless Audio Coding

Lossless audio coding is based on linear prediction followed by entropy coding [Jay84], as shown in Fig. 9.1.

• Linear Prediction. ...