of the design. Indeed, blocking artifacts are probably a familiar phenomenon to almost everyone who has watched digital video. Deblocking filtering has since become an integral part of the more recent standards H.264 and HEVC (although even when using these newer standards, additional post-processing is still allowed and can enhance visual quality if performed well). Design refinements introduced in later standardization efforts have resulted in significant improvements in compression capability relative to the H.261 design. This has resulted in H.261 becoming essentially obsolete, although it is still used as a backward-compatibility mode in some video-conferencing systems (such as H.323) and for some types of internet video. However, H.261 remains a major historical milestone in the field of video coding development. Software implementations The LGPL-licensed libavcodec includes a H.261 encoder and decoder. It is supported by the free VLC media player and MPlayer multimedia players, and in ffdshow and FFmpeg decoders projects. Patent holders The following companies contributed patents towards the development of the H.261 format: Hitachi PictureTel Corp. Graphics Communication Technologies, Ltd. Nippon Telegraph and Telephone (NTT) BT Group Toshiba KDDI Alcatel Compression Labs, Inc. AT&T Corporation GPT Data Systems (GEC) Philips Sony Sharp Corporation Oki Electric Industry Matsushita Communication Industrial Co., Ltd. Mitsubishi Electric Fujitsu Orange S.A. NEC Electronics and Telecommunications Research Institute See also Video compression CIF – Common Intermediate Format References External links H.261 (03/93): Video codec for audiovisual services at p x 64 kbit/s (ITU) Video codecs ITU-T recommendations ITU-T H Series Recommendations H.26x 1988 introductions