Cauchy-Density-Based Basic Unit Layer Rate Controller for H.264/AVC

The rate control problem has been extensively studied in parallel to the development of the different video coding standards. The bit allocation via Cauchy-density-based rate-distortion modeling of the discrete cosine transform coefficients has proved to be one of the most accurate solutions at picture level. Nevertheless, in some specific applications operating in real-time low-delay environments, a basic unit (BU) layer is recommended in order to provide a good tradeoff between picture quality and delay control. In this letter, a novel BU bit allocation for H.264/advanced video coding is proposed based on a simplified Cauchy probability density function source modeling. The experimental results are twofold: 1) the proposed rate control algorithm (RCA) achieves an average peak signal-to-noise ratio improvement of 0.28 dB respect to a well-known BU layer RCA, while maintaining a similar buffer occupancy evolution, and 2) it achieves to notably reduce the buffer occupancy fluctuations respect to a well-known picture layer RCA, while maintaining similar quality levels.