A Research On Coding Techniques At Very Low Bitrate Of H.263

With the development of digital communication and multimedia technology ,the research on very low bitrate video coding technology is becoming more important.this thesis mainly studies the low bitrate video coding based on H.263 standard . a new bit rate control strategy with both global pre-allocation and local segmentation (GLAS) for low bit rate application is proposed.First,it allots bit date to every frame in advance according to possessive rate of buffer ,and then distribute different quantization parameters according conctete detail.By means of this method,buffer is controlled more particularly.and the quality of decoded image is improved, the traditional video image coding method,that is to say ,the intraframe coding based on DCT and the interframe prediction coding based on motion compensation ,is not suitable for low bit rate compression and aside from this ,the encoder is too complicated . The XYZ video image compression method based on 3-D DCT is discussed and realized ,we propose the 3-D "Z" scanning program of 3-D DCT coefficients, which greatly increasing the encoding efficiency .