Optimal bit allocation under multiple rate constraints

We present a new Lagrangian-based iterative technique for rate-distortion optimization under multiple rate constraints. We show how for sets of "linear" constraints this technique can be proven to be optimal up to a convex hull approximation. As an application we consider the problem of optimal buffer-constrained bit allocation. Our technique can be used to find an excellent approximation to the solutions achieved using dynamic programming. In cases where the buffer size is relatively large our approach shows a significant reduction in complexity as compared to dynamic programming.