Method and apparatus for lossless encoding of a source signal, using a lossy encoded data stream and a lossless extension data stream

摘要

In lossy based lossless coding a PCM audio signal passes through a lossy encoder (101) to a lossy decoder (102). The lossy encoder provides a lossy bit stream (111). The lossy decoder also provides side information (115) that is used to control (105) the coefficients (118) of a prediction filter (106) that de-correlates the difference signal (104) between the PCM signal and the lossy decoder output. The de-correlated difference signal is lossless encoded (108), providing an extension bit stream (121). The lossy encoded bit stream together with the lossless encoded extension bit stream form a lossless encoded bitstream. The invention facilitates enhancing a lossy perceptual audio encoding/decoding by an extension that enables mathematically exact reproduction of the original waveform, and provides additional data for reconstructing at decoder site an intermediate-quality audio signal. The lossless extension can be used to extend the widely used mp3 encoding/decoding to lossless encoding/decoding and superior quality mp3 encoding/decoding.