advanced video coding

Video Coding Experts Group

The Video Coding Experts Group or VCEG is the informal name of Question 6 (Video coding) of Working Party 3 (Media coding) of Study Group 16 (Multimedia terminals, systems and applications) of the ITU-T. It is responsible for standardization of the "H.26x" line of video coding standards and related technologies.

As of late 2006, VCEG has also become responsible for the ITU-T work on still image coding standards including JPEG (ITU-T T.81, T.83, T.84, and T.86), JBIG-1 (ITU-T T.82), JBIG-2 (ITU-T T.88), JPEG-LS (ITU-T T.87 and T.870), JPEG 2000 (ITU-T T.801 through T.812), and the JPEG-like ITU-T T.851.

Study Group 16 is responsible for studies relating to multimedia service capabilities, and application capabilities (including those supported for NGN). This encompasses multimedia terminals, systems (e.g., network signal processing equipment, multipoint conference units, gateways, gatekeepers, modems, and facsimile), protocols and signal processing (media coding).

The goal of Question 6 is to produce Recommendations (international standards) for video coding methods appropriate for conversational (e.g. videoconferencing and video telephony) and non-conversational (e.g., streaming, broadcast, file download, media storage/playback, or digital cinema) audio/visual services. This Question will focus on the maintenance and extension of existing video coding Recommendations, and laying the ground for new Recommendations using advanced techniques to significantly improve the trade-offs between bit rate, quality, delay, and algorithm complexity. Video coding standards will be developed with sufficient flexibility to accommodate a diverse number of transport types (Internet, LAN, Mobile, ISDN, GSTN, H.222.0, NGN, etc.).


VCEG was preceded in the ITU-T (which was called the CCITT at the time) by the "Specialists Group on Coding for Visual Telephony" chaired by Sakae Okubo (NTT) which developed H.261. The first meeting of this group was held Dec. 11-14, 1984 in Tokyo, Japan. In 1994, Richard Shaphorst (Delta Information Systems) took over new video codec development in ITU-T with the launch of the project for developing H.324. Schaphorst appointed Karel Rijkse (KPN Research) to chair the development of the H.263 codec standard as part of that project. In 1996, Schaphorst then appointed Gary Sullivan (PictureTel, since 1999 Microsoft) to launch the subsequent "H.263+" enhancement project, which was completed in 1998. In 1998, Sullivan was made rapporteur (chairman) of the question (group) for video coding in the ITU-T that is now called VCEG. After the H.263+ project, the group then completed an "H.263++" effort, produced H.263 Appendix III and H.263 Annex X, and then launched the "H.26L" project in early 2000. In 2000, Thomas Wiegand (Fraunhofer HHI) was appointed as an associated rapporteur (vice-chairman) of VCEG. Sullivan and Wiegand led the H.26L project as it progressed to eventually become the H.264 standard after formation of a Joint Video Team (JVT) with MPEG for the completion of the work in 2003. (In MPEG, the H.264 standard is known as MPEG-4 part 10.) Since 2003, VCEG and the JVT have developed extensions of H.264, produced H.271, and conducted exploration work toward the potential creation of a future new "H.265".

In July of 2006, the video coding work of the ITU-T led by VCEG was voted as the most influential area of the standardization work of the CCITT and ITU-T in their 50-year history.


The organization now known as VCEG has standardized (and is responsible for the maintenance of) the following video compression formats and ancillary standards:

  • H.120: the first digital video coding standard. v1 (1984) featured conditional replenishment, differential PCM, scalar quantization, variable-length coding and a switch for quincunx sampling. v2 (1988) added motion compensation and background prediction. This standard was little-used and no codecs exist.
  • H.261: was the first practical digital video coding standard (late 1990). This design was a pioneering effort, and all subsequent international video coding standards have been based closely on its design.
  • H.262: it is identical in content to the video part of the ISO/IEC MPEG-2 standard (ISO/IEC 13818-2). This standard was developed in a joint partnership between VCEG and MPEG, and thus it became published as a standard of both organizations. ITU-T Recommendation H.262 and ISO/IEC 13818-2 were developed and published as "common text" international standards. As a result, the two documents are completely identical in all aspects.
  • H.263: was developed as an evolutionary improvement based on experience from H.261, and the MPEG-1 and MPEG-2 standards. Its first version was completed in 1995 and provided a suitable replacement for H.261 at all bitrates.
  • H.263v2: also known as H.263+ or as the 1998 version of H.263, is the informal name of the second edition of the H.263international video coding standard. It retains the entire technical content of the original version of the standard, but enhances H.263 capabilities by adding several annexes which substantially improve encoding efficiency and provide other capabilities (such as enhanced robustness against data loss in the transmission channel). The H.263+ project was completed in late 1997 or early 1998, and was then followed by an "H.263++" project that added a few more enhancements in late 2000.
  • H.264: Advanced Video Coding (AVC) is the newest entry in the series of international video coding standards. It is currently the most powerful and state-of-the-art standard, and was developed by a Joint Video Team (JVT) consisting of experts from ITU-T’s Video Coding Experts Group (VCEG) and ISO/IEC’s Moving Picture Experts Group (MPEG) created in 2001. The ITU-T H.264 standard and the ISO/IEC MPEG-4 Part 10 standard (formally, ISO/IEC 14496-10) are technically identical. The final drafting work on the first version of the standard was completed in May 2003. As has been the case with past standards, its design provides the most current balance between the coding efficiency, implementation complexity, and cost based on state of VLSI design technology (CPUs, DSPs, ASICs, FPGAs, etc).
  • H.265: Not yet developed; expected 2010 or later.
  • H.271: Video back channel messages for conveyance of status information and requests from a video receiver to a video sender

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