This paper describes a compressed audio bitstream buffer implementation in an audio coprocessor, for handling MPEG-1 Layer 3 (MP3) bitstreams. The paper discusses hardware and firmware partitioning of bitstream buffers to address low power and low gate count requirements in audio coprocessors, as well as the capability of decoding different types of compressed audio streams, such as MP3 and MPEG-2/4 Advanced Audio Coding (AAC).