The Motion Picture Experts Group MPEG officially announced the first version of the MPEG-4 (ISO/IEC 14496) standard in February 1999. At the end of the same year, the second edition of MPEG-4 also came to an end and officially became an international standard in early 2000.
MPEG-4 is very different from MPEG-1 and MPEG-2. MPEG-4 is not just a specific compression algorithm. It is an international standard developed for the needs of integration and compression technologies such as digital television, interactive graphics applications (audiovisual composite content), interactive multimedia (WWW, data retrieval, and decentralization). The MPEG-4 standard integrates a large number of multimedia applications into a complete framework that aims to provide standard algorithms and tools for multimedia communications and application environments, thereby establishing a universal application that can be used for multimedia transmission, storage, and retrieval. The unified data format.
MPEG-4 coding concept is: MPEG-4 standard is the most significant difference from the previous standard is that it is based on the concept of object-based coding, that is, in the coding of a scene is divided into a number of time and space in the interconnected video and audio After the objects are coded, they are multiplexed and transmitted to the receiver, and then they are decoded separately for different objects to be combined into the required video and audio. This not only facilitates us to use different encoding methods and representation methods for different objects, but also facilitates the integration of different data types, and it can also facilitate the operation and editing of various objects. For example, we can put a cartoon character in a real scene, or put a real person in a virtual studio, and also can easily interact on the Internet, and selectively combine various video and audio according to their own needs. Graphical text object.
The general framework of the MPEG-4 system is: the representation of natural or synthetic audiovisual content; the management of audiovisual content data streams, such as multipoint, synchronization, buffer management, etc.; support for flexibility and configuration of different parts of the system.
Compared with MPEG-1 and MPEG-2, MPEG-4 has the following unique advantages:
(1) Content-based interactivity MPEG-4 provides content-based multimedia data access tools such as indexing, hyperlinking, downloading, and deleting. With these tools, users can easily obtain their desired object-related content from multimedia databases, and provide content manipulation and bitstream editing capabilities that can be applied to interactive home shopping, digital fading in and out. Effect and so on. MPEG-4 provides efficient natural or synthetic multimedia data encoding methods. It can combine natural scenes or objects into composite multimedia data.
(2) Efficient compression MPEG-4 is based on higher coding efficiency. Compared with other existing or emerging standards, it is based on higher visual auditory quality at the same bit rate, which makes it possible to transmit video and audio over low-bandwidth channels. At the same time, MPEG-4 can also encode simultaneously occurring data streams. The multi-view or multi-channel data stream of a scene can be synthesized into the final data stream efficiently and synchronously. This can be used for virtual 3D games, 3D movies, flight simulation exercises, etc. (3) Universal accessibility MPEG-4 provides robustness to error-prone environments to ensure its use in many wireless and wired networks and storage media. In addition, MPEG-4 also supports content-based scalability, that is, the content, quality and complexity are divided into many small blocks to meet the different needs of different users, supporting transmission channels and receivers with different bandwidths and different storage capacities.
These features will undoubtedly accelerate the development of multimedia applications. Applications that benefit from this include: Internet multimedia applications; broadcast television; interactive video games; real-time visual communication; interactive storage media applications; studio technology and television post production; Virtual conferences of animation technology; multimedia mail; multimedia applications under mobile communication; remote video surveillance; remote database services through ATM networks, etc. The main application of MPEG-4 is as follows:
(1) Application to Internet Video and Audio Broadcasting As the number of people surfing the Internet increases, the number of viewers of traditional television broadcasting gradually decreases. As a result, advertising revenue decreases, so today's fixed TV broadcasting will eventually shift to the Internet based on TCP/IP. Broadcasting, viewers' viewing methods are also changed from simple remote control channels to online video on demand. The concept of video on demand is not to first download the program to the hard disk and then play it again, but to stream video (streaming video), click and watch it, play it while transmitting.
Currently playing video and audio in the Internet are: Real Networks' Real Media, Microsoft's Windows Media, and Apple's QuickTime. The video and audio formats defined by them are incompatible with each other and may cause confusion in the media stream that is difficult to control. MPEG The -4 provides a series of standard tools for Internet video applications, making video and audio code streams have a normative consistency. Therefore, using MPEG-4 for video and audio on the Internet is a safe choice.
(2) Applied to wireless communication MPEG-4 High-efficiency rate compression. The interaction and classification features are especially suitable for multimedia communication on narrow-band mobile networks. The future mobile phones will become multimedia mobile receivers, not only mobile TV phones and mobile phones. Internet, you can also receive mobile multimedia broadcasts and watch TV.
(3) Applied to still image compression Still images (pictures) are used extensively on the Internet. Nowadays, JPEG technology is used for picture compression on the Internet. The still image (texture) compression in MPEG-4 is based on wavelet transform. Under the same quality condition, the compressed file size is about one tenth of the JPEG compressed file. Converting JPEG pictures used on the Internet to MPEG-4 format can greatly increase the speed of pictures in the network.
(4) Compression coding standards applied to narrow-band videotelephone services traditionally used in videotelephony, such as H261, which uses intra-frame compression, inter-frame compression, reduced pixel and decimation to reduce the bit rate, but the coding efficiency and image quality It is unsatisfactory. Compression coding of MPEG-4 makes it possible to deliver audio-visual signals of acceptable quality at extremely low bit rates, enabling video-telephony services to be implemented on narrow-band public telephone networks.
(5) Applied to computer graphics, animation and simulation MPEG-4 special coding methods and powerful interaction capabilities, making MPEG-4 based computer graphics and animations available from a variety of sources of multimedia databases to capture material and real-time combination The desired result. As a result, the future of computer graphics can be infinitely developed in the desired direction within the range permitted by the MPEG-4 syntax, producing today's unimaginable animation and simulation effects.
(6) MPEG-4 can be used in electronic games to mix natural images and sounds with artificially synthesized images and sounds. It has unprecedented flexibility in coding methods, and can call materials from various sources of multimedia databases in time. . This can produce movie-like video games in the future, enabling extremely high-level interactive operation.
MPEG-4 is very different from MPEG-1 and MPEG-2. MPEG-4 is not just a specific compression algorithm. It is an international standard developed for the needs of integration and compression technologies such as digital television, interactive graphics applications (audiovisual composite content), interactive multimedia (WWW, data retrieval, and decentralization). The MPEG-4 standard integrates a large number of multimedia applications into a complete framework that aims to provide standard algorithms and tools for multimedia communications and application environments, thereby establishing a universal application that can be used for multimedia transmission, storage, and retrieval. The unified data format.
MPEG-4 coding concept is: MPEG-4 standard is the most significant difference from the previous standard is that it is based on the concept of object-based coding, that is, in the coding of a scene is divided into a number of time and space in the interconnected video and audio After the objects are coded, they are multiplexed and transmitted to the receiver, and then they are decoded separately for different objects to be combined into the required video and audio. This not only facilitates us to use different encoding methods and representation methods for different objects, but also facilitates the integration of different data types, and it can also facilitate the operation and editing of various objects. For example, we can put a cartoon character in a real scene, or put a real person in a virtual studio, and also can easily interact on the Internet, and selectively combine various video and audio according to their own needs. Graphical text object.
The general framework of the MPEG-4 system is: the representation of natural or synthetic audiovisual content; the management of audiovisual content data streams, such as multipoint, synchronization, buffer management, etc.; support for flexibility and configuration of different parts of the system.
Compared with MPEG-1 and MPEG-2, MPEG-4 has the following unique advantages:
(1) Content-based interactivity MPEG-4 provides content-based multimedia data access tools such as indexing, hyperlinking, downloading, and deleting. With these tools, users can easily obtain their desired object-related content from multimedia databases, and provide content manipulation and bitstream editing capabilities that can be applied to interactive home shopping, digital fading in and out. Effect and so on. MPEG-4 provides efficient natural or synthetic multimedia data encoding methods. It can combine natural scenes or objects into composite multimedia data.
(2) Efficient compression MPEG-4 is based on higher coding efficiency. Compared with other existing or emerging standards, it is based on higher visual auditory quality at the same bit rate, which makes it possible to transmit video and audio over low-bandwidth channels. At the same time, MPEG-4 can also encode simultaneously occurring data streams. The multi-view or multi-channel data stream of a scene can be synthesized into the final data stream efficiently and synchronously. This can be used for virtual 3D games, 3D movies, flight simulation exercises, etc. (3) Universal accessibility MPEG-4 provides robustness to error-prone environments to ensure its use in many wireless and wired networks and storage media. In addition, MPEG-4 also supports content-based scalability, that is, the content, quality and complexity are divided into many small blocks to meet the different needs of different users, supporting transmission channels and receivers with different bandwidths and different storage capacities.
These features will undoubtedly accelerate the development of multimedia applications. Applications that benefit from this include: Internet multimedia applications; broadcast television; interactive video games; real-time visual communication; interactive storage media applications; studio technology and television post production; Virtual conferences of animation technology; multimedia mail; multimedia applications under mobile communication; remote video surveillance; remote database services through ATM networks, etc. The main application of MPEG-4 is as follows:
(1) Application to Internet Video and Audio Broadcasting As the number of people surfing the Internet increases, the number of viewers of traditional television broadcasting gradually decreases. As a result, advertising revenue decreases, so today's fixed TV broadcasting will eventually shift to the Internet based on TCP/IP. Broadcasting, viewers' viewing methods are also changed from simple remote control channels to online video on demand. The concept of video on demand is not to first download the program to the hard disk and then play it again, but to stream video (streaming video), click and watch it, play it while transmitting.
Currently playing video and audio in the Internet are: Real Networks' Real Media, Microsoft's Windows Media, and Apple's QuickTime. The video and audio formats defined by them are incompatible with each other and may cause confusion in the media stream that is difficult to control. MPEG The -4 provides a series of standard tools for Internet video applications, making video and audio code streams have a normative consistency. Therefore, using MPEG-4 for video and audio on the Internet is a safe choice.
(2) Applied to wireless communication MPEG-4 High-efficiency rate compression. The interaction and classification features are especially suitable for multimedia communication on narrow-band mobile networks. The future mobile phones will become multimedia mobile receivers, not only mobile TV phones and mobile phones. Internet, you can also receive mobile multimedia broadcasts and watch TV.
(3) Applied to still image compression Still images (pictures) are used extensively on the Internet. Nowadays, JPEG technology is used for picture compression on the Internet. The still image (texture) compression in MPEG-4 is based on wavelet transform. Under the same quality condition, the compressed file size is about one tenth of the JPEG compressed file. Converting JPEG pictures used on the Internet to MPEG-4 format can greatly increase the speed of pictures in the network.
(4) Compression coding standards applied to narrow-band videotelephone services traditionally used in videotelephony, such as H261, which uses intra-frame compression, inter-frame compression, reduced pixel and decimation to reduce the bit rate, but the coding efficiency and image quality It is unsatisfactory. Compression coding of MPEG-4 makes it possible to deliver audio-visual signals of acceptable quality at extremely low bit rates, enabling video-telephony services to be implemented on narrow-band public telephone networks.
(5) Applied to computer graphics, animation and simulation MPEG-4 special coding methods and powerful interaction capabilities, making MPEG-4 based computer graphics and animations available from a variety of sources of multimedia databases to capture material and real-time combination The desired result. As a result, the future of computer graphics can be infinitely developed in the desired direction within the range permitted by the MPEG-4 syntax, producing today's unimaginable animation and simulation effects.
(6) MPEG-4 can be used in electronic games to mix natural images and sounds with artificially synthesized images and sounds. It has unprecedented flexibility in coding methods, and can call materials from various sources of multimedia databases in time. . This can produce movie-like video games in the future, enabling extremely high-level interactive operation.
Cable Cutter Stripper,Cable Wire Stripper,Coaxial Stripper
DisplayPort Cable Co., Ltd. , http://www.easycabling.cn