ITU standardisation of very low bitrate video coding algorithms

摘要

The ITU near term standard for very low bitrate video coding, H.263 (ITU-T SG 15/1 Rapporteurs Group for Very Low Bitrate Visual Telephony, 1995), is described. Both QCIF and a sub-QCIF format (128 × 96) are mandatory picture formats for the decoder; the CIF picture format is optional. The H.263 algorithm consists of a mandatory core algorithm and four negotiable options. With H.263 a significantly better picture quality than with H.261 can be achieved, depending on the content of the video scene and the coding parameters. Also, the cost of the H.263 video codec can be kept low if only the minimum required is implemented. The negotiable options of H.263 increase the complexity of the video codec, but also significantly improve the picture quality. H.263 is part of a set of recommendations for a very low bitrate audio visual terminal that was frozen in January 1995 and is based on existing technology. A long term activity is planned by ITU for the development of a new video coding algorithm (H.263/L) with a considerable better picture quality than H.263. This standard will be developed in joint co-operation with MPEG4.