mp4 or MPEG-4 Part 14 is a multimedia container format with the extension .mp4.
MP4 is a set of compression coding standards for audio and video information, developed by the Moving Picture Experts Group under the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). , MPEG) was formulated, the first version was adopted in October 1998, and the second version was adopted in December 1999. The main uses of the MPEG-4 format are in online streaming, optical discs, voice transmission (video telephony), and television broadcasting.
MPEG-4 contains most of the functions of MPEG-1 and MPEG-2 and the advantages of other formats, and adds and expands support for Virtual Reality Modeling Language (VRML), targeting Composite files of objects (including sound effects, video and VRML objects), as well as digital rights management (DRM) and other interactive features. One of the features of MPEG-4 that is more advanced than MPEG-2 is that it no longer uses macro blocks for image analysis, but records changes on individuals in the image. Therefore, even if the image changes quickly and the bit rate is insufficient, it can No block screen will appear.
MPEG-4 consists of a series of sub-standards, called parts (sometimes translated as volumes), including the following parts:
Part (ISO/IEC 14496-1): System: Describes the control, synchronization and mixing methods of video and audio data streams (ie, Multiplexing, abbreviated as MUX).
Part 2 (ISO/IEC 14496-2): Video: Defines a codec for various visual information (including natural video, still textures, computer-generated graphics, etc.). (For example, XviD encoding belongs to MPEG-4 Part2)
Part 3 (ISO/IEC 14496-3): Audio: defines a set of codecs that encode various audio signals. Includes several variants of Advanced Audio Coding (AAC) and other audio/speech coding tools.
Part 4 (ISO/IEC 14496-4): Conformance: Defines the procedures for conformance testing of other parts of this standard.
Part 5 (ISO/IEC 14496-5): Reference software: Provides software for demonstrating functions and describing the functions of other parts of this standard.
Part 6 (ISO/IEC 14496-6): DMIF for Delivery Multimedia Integration Framework
Part 7 (ISO/IEC 14496-7): Optimized reference Software: Provides examples of optimized implementations (implementation here refers to Part 5).
Part 8 (ISO/IEC 14496-8): Transmission over IP networks: Defines the method for transmitting MPEG-4 content over IP networks.
Part 9 (ISO/IEC 14496-9): Reference Hardware: Provides a hardware design solution for demonstrating how to implement the functions of other parts of this standard on hardware.
Part 10 (ISO/IEC 14496-10): Advanced Video Coding or Advanced Video Coding (AVC): defines a video codec (codec). AVC and XviD both belong to MPEG-4 encoding, but because AVC belongs to MPEG-4 Part10, its technical characteristics are more advanced than XviD, which belongs to MPEG-4Part2. In addition, it is consistent with the ITU-T H.264 standard, so it is also called H.264.
Part 12 (ISO/IEC 14496-12): ISO-based media file format: defines a file format for storing media content.
Part 13 (ISO/IEC 14496-13): Expansion of intellectual property management and protection (IPMP for Intellectual Property Management andProtection).
Part 14 (ISO/IEC 14496-14): MPEG-4 file format: Defines the video file format for storing MPEG-4 content based on Part 12.
Part 15 (ISO/IEC 14496-15): AVC file format: Defines a file format based on Part 12 for storing Part 10 video content.
Part 16 (ISO/IEC 14496-16): Animation Framework Extension Function (AFX: Animation Framework eXtension).
Part 17 (ISO/IEC 14496-17): Synchronized text subtitle format.
Part 18 (ISO/IEC 14496-18): Font compression and streaming (for Open Font Format).
Part 19 (ISO/IEC 14496-19): Synthesized Texture Stream.
Part 20 (ISO/IEC 14496-20): Simple scene representation (LASeR for Lightweight Scene Representation.
Part 21 (ISO/IEC 14496-21): MPEG-J extension for rendering.
Part 22 (ISO/IEC 14496-22): Open Font Format.
Second Part 13 (ISO/IEC 14496-23): Symbolic Music Representation.
Part 24 (ISO/IEC 14496-24): Audio and system interaction (Audio and systems interaction).
Part 25 (ISO/IEC 14496-25): 3D GraphicsCompression Model.
Part 26 (ISO/IEC 14496 -26): Audio conformance check: defines the method for testing whether audio data is consistent with ISO/IEC 14496-3 (Audioconformance).
Part 27 (ISO/IEC 14496-27): 3D graphics conformance check: defines testing 3D graphics data with ISO/IEC14496-11:2005, ISO/IEC 14496-16:2006, ISO/IEC 14496-21:2006, is the method consistent with ISO/IEC14496-25:2009 (3D Graphics conformance).
Profiles are defined within each part, so an implementation of a certain part is usually not a complete implementation of that part.
MPEG-1, MPEG-2, MPEG-7 and MPEG-21 are other MPEG standards developed by MPEG.
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