III Standards-Based Codecs

International Telecommunication Union (ITU) and International Organization for Standardization (ISO) worked together to establish a joint international standard for the compression of multilevel still images.
This effort has been know as Joint Photographic Experts Group, or JPEG (ISO/IEC international standard 10918-1, Digital Compression and Coding of Continuous-Tone Still Images, or ITU-T Recommendation T.81)
For digital video, ISO established the Moving Pictures Expert Group (MPEG) to develop standards for coding moving pictures and associated audio information.

MPEG-1 (ISO standard 11172, Coding of Moving Pictures and Associated Audio-for Digital Storage Media at up to about 1.5 Mbit/s.)
MPEG-2 (ISO standard 13818, or ITU-T Recommendation H.262, Generic Coding of Moving Pictures and Associated Audio)
MPEG-4 (ISO/IEC standard 14496)
MPEG-7, etc.

For video conference in ISDN environment, ITU developed H.320 standard (H.261 for video). H.261 is also called P x 64 standard because it describes the coding and decoding methods at the rate of p x 64 kbits/s, where integer p = [1,30]. For the general switched telephone network (GSTN), ITU developed the H.324 suite for real-time voice, data, and video over V.34 modems. The video component is known as H.263 which will provide coded video around 26 kbits/s compare to the 64 kbits/s for H.261.