The International Telecommunications Union (ITU) have published a number of standards aimed at coding video for real time applications, such as video conferencing. In such a case it is not possible to spend several hours preparing the material prior to transmission or to have a high latency when beginning coding, otherwise conversation is not possible. As both parties in the conference will have full coder/decoders then the workload of the coding can be split between them.
The standards organizations ISO and IEC joined together to make MPEG standards for viewing movies and television. In this case it is possible to spend more time on the preparation phase; however we expect that the decoder will be in some common domestic appliance (e.g. a DVD player) and therefore the complexity must be kept low as to keep the cost low.
The latest video coding standard from ITU, H.264 is combined with MPEG-4 part 10 under a process run by a Joint Video Team (JVT).
Ideas for navigation are encapsulated in concepts such as Intra (I) coded frames. A predictive video coder regularly incorporates an image that does not require any previous frames for decompression. This makes it easy for the user to navigate to any part of the sequence and decode an image, without having to decode the whole sequence.
It is important to recognise that most video coding standards do not specify the algorithm used for generating the coding, they only specify the decoder. This gives more scope to the person implementing the standard to choose a method appropriate to their application, it could be that their available computing power is very small so they choose a simple method or perhaps a new method is discovered that gives better performance. This is the reason why we do not say "MPEG coding algorithm" etc.