Accounting for Companding Nonlinearities in Lossless Audio Compression

This paper introduces a novel prediction structure for improving the lossless compression ratio, by accounting for companding nonlinearities of different sample-based audio formats. This applies to a wide class of formats including a-law, μ-law, DAT-LP (digital audio tape recorders), DV-LP (digital video camcorders), and HDCD (high definition compatible digital). The proposed prediction structure obtains significant compression improvements (8-12%) over traditional linear prediction for a-law, μ-law, DAT-LP, DV-LP and also small compression improvements for HDCD. The improvement in compression can also be used for the detection of nonlinearities in HDCD format, making possible to play HDCD CDs at improved audio resolution in ordinary public domain players.