MP1/2/3/4

MPEG-1

History

Developments in video conferencing techniques and standards such as H.261 in the late 1980s formed the basis of the MPEG-1 standard in the early 1990s. The Moving Picture Experts Group (MPEG) investigated how to store compressed video on a CD-ROM, which led to the development of the MPEG-1 standard.

MPEG-2

MPEG-2 is used in Digital Video Broadcast and Digital Versatile Discs. The transport stream, TS, and program stream, PS, are container formats.

MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio compression (audio data compression) methods which permit storage and transmission of movies using currently available storage media and transmission bandwidth.

MP3

MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a digital audio encoding format using a form of lossy data compression.

It is a common audio format for consumer audio storage, as well as a de facto standard encoding for the transfer and playback of music on digital audio players.

MP3 (1989) - Motion Picture Experts Group Audio Level III

MP3 is actually a software compression/de-compression (codec) algorithm rather than a piece of hardware. MP3 stands for Motion Picture Experts Group, Audio Layer III which defines the codec.

Prior to MP3, audio wav and wma files were huge, and transferring a wav file over the net could be better described as more of an "endurance test" rather than that of a file transfer.

MP3 changed all that ! ....... It typically compresses these huge files down anywhere's from 1/6 to 1/12th their normal size, making file exchange of great sounding audio across the net, viable. MP3 has also effectively changed the way that people now listen to their music, and has cemented the marriage between the computer and the home entertainment center. A typical CD can store typically 74 minutes of audio in CD audio format. Compare that to approximately 14 hours of MP3 audio on a single CD !

The compression technique has led to a plethora of MP3 based products. Portable MP3/AAC players such as Apple's highly successful iPod ® have all but replaced the bulky portable standard CD players. http://www.videointerchange.com/audio_history.htm

MPEG-4

MPEG-4 is a collection of methods defining compression of audio and visual (AV) digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal standard ISO/IEC 14496. Uses of MPEG-4 include compression of AV data for web (streaming media) and CD distribution, voice (telephone, videophone) and broadcast television applications.

MPEG-4 absorbs many of the features of MPEG-1 and MPEG-2 and other related standards, adding new features such as (extended) VRML support for 3D rendering, object-oriented composite files (including audio, video and VRML objects), support for externally-specified Digital Rights Management and various types of interactivity. AAC (Advanced Audio Codec) was standardized as an adjunct to MPEG-2 (as Part 7) before MPEG-4 was issued.

MPEG-4 is still a developing standard and is divided into a number of parts. The companies promoting MPEG -4 compatibility do not always clearly state whi ch "part" level compatibility. The key parts to be aware of are MPEG-4 part 2 (MPEG-4 SP/ASP, used by codecs such as DivX , Xvid, Nero Digital and 3ivx and by Quicktim 6) and MPEG-4 part 10 (MPEG-4 A VC/H.264, used by the x264 codec, by Nero Digital AVC, by Quicktime 7, and by next -gen DVD formats like HD DVD and Blu-ray Disc).

Most of the features included in MPEG-4 are left to individual developers to decide whether to implement them. This means that there are probably no complete implementations of the entire MPEG-4 set of standards. To deal with this, the standard includes the concept of "profiles" and "levels", allowing a specific set of capabilities to be defined in a manner appropriate for a subset of applications.

Initially, MPEG-4 was aimed primarily at low bit-rate video communications; however, its scope was later expanded to be much more of a multimedia coding standa rd. MPEG-4 is efficient across a variety o f bit-rates ranging from a few kilobits per second to tens of megabits per second. MPEG -4 provides the following functionalities:

· Improved coding efficieency

· Ability to encode mixe d media data (video, audio, speech)

· Error resilience to enab le robust transmission

· Ability to interact with the audio-visual scene generated at the receiver