Efficient quantization step selection scheme for I-frame in rate-constrained video coding

Quantization step (QS) selection for I-frame has an obvious impact on rate-distortion performance in rate-constrained video coding. An efficient QS selection scheme for I-frame is presented which is based on a balanced bits allocation scheme between I and P frames and a new experimental rate-quantization step (R-Q) model. In the balanced bits allocation scheme, firstly a model on the ratio of bits allocation between I and P frame is derived under the constraint of certain target bit rate; then based on the model, a feasible bits allocation algorithm is proposed by experimental analysis among different target bit rates. The analysis and final simulation results show that compared to the existing methods, the proposed algorithm improves PSNR performance significantly (up to 1.2 dB).