Macroblock level bits allocation for depth maps in 3-d video coding

For 3-D videos, one commonly used representation method is texture videos plus depth maps for several selected viewpoints, whereas the other viewpoints are synthesized based on the available texture videos and depth maps with the depth-image-based rendering (DIBR) technique. As both the quality of the texture videos and depth maps will affect the quality of the synthesized views, bits allocation for the depth maps become indispensable. The existing bits allocation approaches are either inaccurate or requiring pre-encoding and analyzing in temporal dimension, making them unsuitable for the real-time applications. Motivated by the fact that different regions of the depth maps have different impacts on the synthesized image quality, a real-time macroblock level bits allocation approach is proposed, where different macroblocks of the depth maps are encoded with different quantization parameters and coding modes. As the bits allocation granularity is fine, the R-D performance of the proposed approach outperforms other bits allocation approaches significantly, while no additional pre-encoding delay is caused. Specifically, it can save more than 10 % overall bit rate comparing with Morvan's full search approach, while maintaining the same synthesized view quality.