Multimedia video—coding method—H.263

H.263 is a draft standard of ITU-T, designed for low-stream communication. But in fact, this standard can be used in a wide range of code streams, not just for low code stream applications. It can be considered as a replacement for H.261 in many applications. H.263's coding algorithm is the same as H.261, but some improvements and changes have been made to improve performance and error correction capabilities. The .263 standard can provide better image effects than H.261 at low bit rates. The differences between the two are: (1) H.263 motion compensation uses half-pixel accuracy, while H.261 uses full pixels Precision and loop filtering; (2) Certain parts of the data stream hierarchy are optional in H.263, so that the codec can be configured to a lower data rate or better error correction capabilities; (3) H. 263 contains four negotiable options to improve performance; (4) H.263 uses unrestricted motion vectors and syntax-based arithmetic coding; (5) adopts the frame prediction method that is the same as the PB frame in MPEG in advance prediction; (6) H.263 supports 5 resolutions, that is, in addition to the QCIF and CIF supported in H.261, it also supports SQCIF, 4CIF and 16CIF. SQCIF is equivalent to half the resolution of QCIF, while 4CIF and 16CIF are 4 times and 16 times of CIF.

H.263 + introduced by IUT-T in 1998 is the second version of H.263 recommendation. It provides 12 new negotiable modes and other features to further improve the compression coding performance. For example, H.263 only has 5 video source formats, H.263 + allows more source formats to be used, and there are many options for the image clock frequency to widen the scope of application. Another important improvement is scalability, which allows multiple display Multi-rate and multi-resolution enhance the transmission of video information in a heterogeneous network environment that is prone to bit errors and packet loss. In addition, H.263 + has improved the unrestricted motion vector mode in H.263, plus 12 newly added optional modes, which not only improve the coding performance, but also enhance the flexibility of application. H.263 has basically replaced H.261.