Hybrid DCT/wavelet I-frame coding for efficient H.263+ rate control at low bit rates
At low bit rates, the bit budget for I-frame coding in H.263+ can be too high to be practical. A hybrid DCT/wavelet transform based I-frame coding is proposed in this work as a solution to the rate control problem. This new coder is compatible with the H.263+ bit stream syntax, and aims at an R-D optimized performance with a reasonable amount of computational complexity. By employing fast estimation of the coding efficiency with a rate-distortion model and performing an R-D based rate allocation, the hybrid coding scheme achieves higher coding gain at low bit rates.