Video encoding with the original picture as the reference picture

Inter-picture prediction uses a local decoded picture for the reference, in order to avoid a mismatch between encoding and decoding. However, this scheme does not necessarily result in optimal coding efficiency since it requires encoding the processing altogether. Therefore, we study the use of the original picture as the reference. In this case, although the mismatch causes degradation of the picture quality, the bit amount is reduced. If optimal encoding is used at each macroblock, the overall performance may be improved. Therefore, we propose an adaptive method based on rate distortion optimization. The original picture is used only in the macroblock, if it is lower cost than the local decoded picture is used. Experimental results show a 0.1 to 1.0 dB gain in PSNR in each sequence. The adaptive method is shown to work successfully and the coding performance is improved without side effects.