Rate control for low-bit-rate video via variable-encoding frame rates

A novel rate-control algorithm with a variable-encoding frame-rate method is proposed in this work for low-bit-rate video coding. Most existing rate-control algorithms for low-bit-rate video focus on bit allocation at the macroblock level under a constant frame-rate assumption. The proposed rate-control algorithm is able to adjust the encoding frame rate at the expense of tolerable time-delay. The new rate-control algorithm attempts to achieve a good balance between spatial quality and temporal quality to enhance the overall human perceptual quality at low bit rates. It is demonstrated that the rate-control algorithm achieves higher coding efficiency at low bit rates, with a low additional computational cost. The proposed variable-encoding frame-rate method is compatible with the bit-stream structure of H.263+.