Lossless coding of MPEG-1 Layer III encoded audio streams

In this paper we describe a lossless coding scheme for the encoding of MPEG-1 Layer III encoded audio bitstreams. Commonly known as MP3, the MPEG-1 Layer III standard has proved widely popular for the transmission of encoded audio files (MP3's) over the Internet. However, the MPEG-1 Layer III standard has been designed with a wide range of applications in mind. As such, the frame sizes are kept small and redundancies between samples in neighboring frames are not exploited. We propose a design which uses a combination of linear predictive coding and arithmetic coding to exploit such redundancies. The proposed coder was tested on a number of Layer III encoded audio (MP3) files and shown to produce an average coding gain of 12.2% over the original Layer III encoded files.