Efficient codebook allocation for an arbitrary set of vector quantizers

Traditional solutions to the bit allocation problem assume nicely behaved quantizers whose distortion versus rate characteristic is a standard exponentially decreasing function. This model is often inadequate and leads to suboptimal bit allocations for actual quantizer characteristics. This inadequacy prevails particularly in coding systems based on vector quantization (VQ). The distortion-rate characteristic for VQ suffers from irregularities because of suboptimality of the codebook and of the codebook search method. We propose a new algorithm which efficiently allocates a given quota of bits, based on the actually measured quantizer performance, without any prior assumptions on its behavior. The algorithm can enhance the performance-of traditional scalar coders as well as any modern coder which employs dynamic bit allocation.