About MPEG 2

MPEG 2 is another video standard developed by MPEG Group, but it is not a successor of MPEG1. Both MPEG 1 and MPEG 2 have their own functions: MPEG 1 is for low band width purposes and MPEG 2 for high bandwidth/broadband purposes. The international standard number of MPEG 2 is ISO 13818.

MPEG 2 is commonly used in Digital TVs, DVD Videos, SVCDs etc. Some Blu-ray disks also uses it.

The maximum bit rate available for MPEG-2 streams are 10.08 Mbit/s and the minimum are 300 kbit/s.

Resolutions that video streams can use, are:

720x480 (NTSC, only with MPEG-2)
720x576 (PAL, only with MPEG-2)
704x480 (NTSC, only with MPEG-2)
704x576 (PAL, only with MPEG-2)
352x480 (NTSC, MPEG-2 & MPEG-1)
352x576 (PAL, MPEG-2 & MPEG-1)
352x240 (NTSC, MPEG-2 & MPEG-1)
352x288 (PAL, MPEG-2 & MPEG-1)

The technical title for MPEG 2 is: "Generic coding of moving pictures and associated audio information".

MPEG-2 is a standard currently in 9 parts.

Part 1 of MPEG-2 addresses combining of one or more elementary streams of video and audio, as well as, other data into single or multiple streams which are suitable for storage or transmission. This is specified in two forms: the Program Stream and the Transport Stream. Each is optimized for a different set of applications. A model is given in Figure 1 below.

The Program Stream is similar to MPEG-1 Systems Multiplex. It results from combining one or more Packetised Elementary Streams (PES), which have a common time base, into a single stream. The Program Stream is designed for use in relatively error-free environments and is suitable for applications which may involve software processing. Program stream packets may be of variable and relatively great length.

The Transport Stream combines one or more Packetized Elementary Streams (PES) with one or more independent time bases into a single stream. Elementary streams sharing a common timebase form a program. The Transport Stream is designed for use in environments where errors are likely, such as storage or transmission in lossy or noisy media. Transport stream packets are 188 bytes long.

Part 2 of MPEG-2 builds on the powerful video compression capabilities of the MPEG-1 standard to offer a wide range of coding tools. These have been grouped in profiles to offer different functionalities. Only the combinations marked with an "X" are recognised by the standard.

Part 3 of MPEG-2 is a backwards-compatible multichannel extension of the MPEG-1 Audio standard. The figure below gives the structure of an MPEG-2 Audio block of data showing this property.

Part 4 and 5 of MPEG-2 correspond to part 4 and 5 of MPEG-1.

Part 6 of MPEG-2 - Digital Storage Media Command and Control (DSM-CC) is the specification of a set of protocols which provides the control functions and operations specific to managing MPEG-1 and MPEG-2 bitstreams. These protocols may be used to support applications in both stand-alone and heterogeneous network environments. In the DSM-CC model, a stream is sourced by a Server and delivered to a Client. Both the Server and the Client are considered to be Users of the DSM-CC network. DSM-CC defines a logical entity called the Session and Resource Manager (SRM) which provides a (logically) centralized management of the DSM-CC Sessions and Resources.

Part 7 of MPEG-2 will be the specification of a multichannel audio coding algorithm not constrained to be backwards-compatible with MPEG-1 Audio.

Part 8 of MPEG-2 was originally planned to be coding of video when input samples are 10 bits.

Part 9 of MPEG-2 is the specification of the Real-time Interface (RTI) to Transport Stream decoders which may be utilized for adaptation to all appropriate networks carrying Transport Streams.

Part 10 is the conformance testing part of DSM-CC.


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