 for interworking of H-Series multimedia terminals with H-Series multimedia terminals and voice/voiceband terminals on the PSTN (more accurately, GSTN, or General Switched Telephone Network) and ISDN. H.247 ITU recommendation to establish a method for multipoint extension for broadband audiovisual Video Communication: the Whole Picture communication systems and terminals. H.261 The ITU-T's Recommendation that allows dissimilar video codecs to interpret how a signal has been encoded and compressed, and to decode and decompress that signal. The standard, formally known as "Video Codec for Audiovisual Services at Px64 Kbps," it also identifies two picture formats: the Common Intermediate Format (CIF) and the Quarter Common Intermediate Format (QCIF). These two formats are compatible with all three television standards: NTSC, PAL and SECAM. H.262 ITU recommendation for using the MPEG-2 compression algorithm for compressing a videoconferencing transmission. H.263 H.263 is the ITU-T's "Video Coding for Low Bit Rate Communication." It refers to the compression techniques used in the H.324 Recommendation and in other ITU-T recommendations, too. H.263 is similar to H.261 but differs from it in several ways. Its advance negotiable options enable implementations of the Recommendation that employ them to achieve approximately the same resolution quality as H.261 at half the data rate. H.263 uses half-pixel increments for motion compensation (optional in both standards) while H.261 uses full-pixel precision and specifies a loop-filter. In H.263, portions of the data stream hierarchy have been rendered optional. This allows the codec to be configured for enhanced error recovery or, alternatively, for very low data rate transmission. There are, in H.263, four options designed to improve performance. They are advance prediction, forward and backward frame prediction, syntax-based arithmetic coding and Unrestricted Motion Vectors. H.263 supports not only H.261's optional CIF and mandatory QCIF resolutions but also SQCIF (128x96 p