What Is the MPEG 4 Standard?

The MPEG-4 standard is a group of international specifications for the coding of audio-visual objects, published as ISO/IEC 14496 by the Moving Picture Experts Group. First introduced in late 1998, MPEG-4 extended the earlier MPEG framework by moving from frame-based video compression to an object-based model, enabling separate encoding and manipulation of video objects, still textures, synthetic graphics, and audio within a single multimedia scene. The standard encompasses a broad suite of parts covering systems multiplexing, video and audio codecs, a scene description language, intellectual property management, and container file formats.

The standard draws on work from MPEG-1 and MPEG-2 for its basic compression tools and introduces concepts from computer graphics and synthetic media to support interactive and scalable audiovisual presentations. Its most commercially influential component, Part 10 (Advanced Video Coding, jointly standardized with ITU-T as H.264), became the dominant video codec for internet streaming, Blu-ray disc, and mobile video worldwide.

Video Coding

Part 2 of ISO/IEC 14496 specifies object-based video coding, where individual foreground objects can be encoded separately from the background, allowing a decoder to composite or manipulate the scene. It defines profiles including Simple Profile for low-complexity mobile applications and Advanced Simple Profile for improved quality at similar bit rates through B-frame support and quarter-pixel motion compensation. Part 10, Advanced Video Coding (AVC), supersedes Part 2 for most applications, delivering roughly twice the compression of MPEG-2 at equivalent quality through intra-prediction, 4-by-4 integer DCT, context-adaptive binary arithmetic coding (CABAC), and flexible reference frame selection. The Library of Congress format description for MPEG-4 AVC documents the profile hierarchy and deployment context. High Efficiency Video Coding (HEVC, H.265) later succeeded AVC for high-resolution delivery, but AVC remains broadly deployed.

Audio Coding

Part 3 specifies Advanced Audio Coding (AAC), the audio component that became MPEG-4's primary audio format and is also used in MPEG-2 as a non-backward-compatible extension. AAC supports sampling rates from 8 kHz to 96 kHz and up to 48 channels, using a filterbank based on the modified discrete cosine transform (MDCT), temporal noise shaping, and perceptual noise substitution to achieve higher quality than MPEG-1 Layer III (MP3) at equivalent bit rates. Extensions within Part 3 include High Efficiency AAC (HE-AAC), which applies spectral band replication to reconstruct high-frequency content from a low-bitrate base layer, enabling acceptable audio quality at 24 kbit/s and lower.

Systems, Scene Description, and File Formats

Part 1 defines the systems layer, specifying how elementary streams are synchronized and multiplexed. The scene description framework uses BIFS (Binary Format for Scene), an extension of VRML that describes spatial relationships among audio and visual objects and supports interactivity. Part 14 defines the MP4 file format, an extensible container derived from Apple's QuickTime format, which stores multiplexed audio and video tracks along with metadata and is now the basis for the ISO Base Media File Format used by modern adaptive streaming standards. The ISO specification for the MP4 file format documents the container's box-based structure. Vector quantization is one of the optional coding tools supported in the visual profile for texture coding of synthetic content.

Applications

The MPEG-4 standard has been applied across a range of fields, including:

• Internet video streaming, including platforms using H.264/AVC as the baseline codec
• Digital multimedia broadcasting for mobile television (DMB, DVB-H)
• Blu-ray and HD-DVD disc authoring using AVC video
• Video telephony and conferencing via mobile and broadband networks
• Video surveillance and IP camera systems
• Interactive multimedia and game content with object-based scene composition