H.263 is a backwards-compatible update to H.261, and uses a pixel motion-estimation process, predicted frames, and a Huffman coding table to improve picture quality. It is designed for low bit rate communication, and is being used to replace H.261 in many applications. It supports five standard picture formats: QCIF, CIF, SQCIF, 4CIF, and 16IF.

A standard for variable low bit rate coding of video. H.263 is better than MPEG-1/MPEG-2 for low resolutions and low bit rates. H.263 is less flexible than MPEG, but therefore requires much less overhead. HD-0: A set of formats based partially on the ATSC Table 3, suggested by The DTV Team as the initial stage of the digital television rollout. Pixel values represent full aperture for ITU-R 601. The DTV Team's HD0 Compression Format Constraints.

An old codec (see Codec) developed by Apple for video conferencing. Supports video resolutions (sharpness and clarity of an image) of 1408 x 1152, 704 x 576, 352 x 288, 176 x 144, and 128 x 96 at up to 29.97 frames per second.

ITU standard for low bit-rate for video encoding. Used as a basis for video conferencing over the Internet.

The second encoding algorithm for videoconferencing (better for motion and more tolerant of packet loss).

ITU-T Recommendation, Video Coding for Low Bitrate Communication; regarding a video codec for audiovisual services. Considerably broadens H.261 capabilities, extending from low- resolution, credit card-size images, to high-quality, exceptional detail images, for applications such as telemedicine. Backward compatibility to H.320 QCIF(Quarter Common Intermediate Format) and, optionally, to CIF and SQCIF (Sub-QCIF) is provided.

"Video Coding for Low Bit Rate Communication" is the coding method designed for H.324, using the techniques of H.261 plus significant enhancements.

Refers to the compression techniques for low data rate transmission used in H.324 video. A more sophisticated codec than H.261 which uses half-pixel increments.

An ITU-T standard for video coding, specifically designed for operating at low data rates, i.e. 64 to 128 kbit/s.

This video compression standard is an upgrade to H.261. It was originally developed to try and get reasonable quality video telephony over the existing (analogue) phone line, using say 28.8 kbps modems. However, in the course of the development of the algorithm, it was found that the algorithm gave better quality than H.261 over the entire range of bit-rates and can now be used in any applications that H.261 might be used in. However, since it is a more sophisticated algorithm than H.261, it is generally more expensive to implement at equivalent bit-rates.

ITU-T recommendation regarding a video codec for audio-visual services, video coding for low bit rate communication. Considerably broadens H.261 capabilities, extending from low- resolution, credit card-size images, to high-quality, exceptionally detailed images for applications such as telemedicine. Backward compatibility is provided with H.320 QCIF (Quarter Common Intermediate Format) and optionally to CIF and SQCIF (Sub-QCIF).   The following table compares H.320 and H.324 video capabilities:  Picture Format Luminance Pixels Video Modes H.320/H.261 H.324/H.263 SQCIF 128H x 96V QCIF 176H x 144V CIF 352H x 288V 4CIF 704H x 576V- 16CIF 1408H x 1152V- Where: S = Sub, Q = Quarter, H = Horizontal pixels, V = Vertical pixels, R = Required, O = Optional and, - = Not Defined.

ITU standard for video compression

A new standard that has better motion handling at lower bandwidth than H.261. All sites must be capable of supporting this standard to use this option.

A video compression scheme defined by the ITU, originally for use in video telephony and related systems; particularly suited to operation at very low rates (e.g. over a modem).

H.263 is a video codec originally designed by the ITU-T in 1995/1996 as a low-bitrate compressed encoding solution for videoconferencing.