The difference between m-jpeg and MPEG-4 m-jpeg VS MPEG

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m-jpeg VS MPEG

http://blog.csdn.net/bluesky_sunshine/article/details/6182721

M-jpeg (Motion-join Photographic Experts Group) technology, motion still image (or frame-by-frames) compression technology, is widely used in non-linear editing fields for precise frame editing and multi-layer image processing. The motion video sequence as a continuous still image processing, this compression method to compress each frame separately, in the editing process can be randomly stored each frame, can be accurate to frame editing , in addition m-jpeg compression and decompression is symmetric, can be implemented by the same hardware and software. However, m-jpeg only compresses space redundancy within the frame. The time redundancy between frames is not compressed, so the compression efficiency is not high . The M-jpeg digital compression format provides a program equivalent to the Betecam SP quality image when the compression ratio is 7:1.

The JPEG standard based algorithm is based on DCT (discrete cosine transform) and variable length coding. The key technologies of JPEG are transform coding, quantization, differential coding, motion compensation, Huffman coding and run-length coding, etc.

The advantage of m-jpeg is that it can be easily made to edit the frame, the device is more mature. The disadvantage is that the compression efficiency is not high.

In addition, M-jpeg this compression method is not a completely unified compression standard, different manufacturers of codecs and storage methods do not have a unified format. This means that each model of the video server or coding board has its own version of the M-jpeg, so between the server data transmission, non-linear production network to the server data transfer is simply impossible.

MPEG Series Standard

An acronym for the active Image Expert group (moving Picture Exports Group), MPEG was established in 1988 as a group of experts on compression standards for digital AV/audio, with more than 300 members, including IBM, SUN, BBC, NEC, INTEL, at &t and other world-renowned companies. the initial authorization for the MPEG organization was to develop a variety of criteria for the "active image" encoding, which was then expanded to "and accompanying audio" and its combined encoding . Later, for different application needs, the "use of digital storage media" restrictions, become now the "active image and audio coding" standards of the organization. The various standards developed by MPEG organizations have different goals and applications, and the MPEG-1, MPEG-2, MPEG-4, MPEG-7 and MPEG-21 standards have been proposed.

1. MPEG-1 Standard

The MPEG-1 standard, published in August 1993, is a digital storage media motion image and its audio encoding for transmitting 1.5Mbps data transfer rates. The standard consists of five parts:

The first section describes how to encode audio and video in terms of the second part (video) and the third part (audio). The Forth part describes the process of verifying the output bit flow of the decoder or encoder in accordance with the first three parts. Part V is a full C language implementation of the encoding and decoding device.

The standard from the moment of promulgation, MPEG-1 achieved a series of successes, such as VCD and MP3 a large number of uses, Windows95 later versions have a MPEG-1 software decoder, portable MPEG-1 cameras and so on.

2. MPEG-2 Standard

The PEG organization introduced the MPEG-2 compression standard in 1994 to realize the possibility of interoperability between AV services and applications. The MPEG-2 standard is a detailed specification of the compression scheme and the system layer for standard digital TV and HDTV in a variety of applications, with code rates ranging from 3 megabits per second to ~100 megabits, standard formal specifications in iso/iec13818. MPEG-2 is not a simple upgrade of MPEG-1, MPEG-2 in the system and transmission aspects of more detailed provisions and further improvement. MPEG-2 is particularly suitable for the encoding and transmission of broadcast-grade digital TVs and is recognized as the encoding standard for SDTV and HDTV.

The principle of MPEG-2 image compression is to take advantage of two features in the image: spatial Correlation and temporal correlation . These two correlations make a large amount of redundant information available in the image. If we can remove these redundant information and only keep a small amount of non-related information for transmission, we can save the transmission band greatly. The receiver utilizes these non-related information, according to certain decoding algorithm, can restore the original image under the premise of guaranteeing certain image quality. A good compression coding scheme is the ability to maximize the removal of redundant information in the image.

MPEG-2 encoded images are divided into three categories, called I-frames, p-frames, and B-frames, respectively.

I-frame images are encoded in-frame, that is, using only spatial correlations within a single-frame image, rather than using temporal correlation. P-Frame and B-frame images use inter-frame encoding, i.e., the correlation between space and time is utilized simultaneously. The P-Frame image only uses forward-time prediction, which can improve the compression efficiency and image quality. The P-frame image can contain part of the intra-frame encoding, that is, each macro block in the P-frame can be forward-predicted or intra-frame encoded. B-Frame image adopts bidirectional time prediction, which can greatly improve the compression ratio.

MPEG-2 code stream is divided into six levels. To better represent coded data, MPEG-2 a hierarchical structure with syntax. It is divided into six layers, from top to bottom respectively: Image sequence layer, image Group (GOP), image, macro block, macro block, block.

3. MPEG-4 Standard

The motion Picture Expert Group MPEG formally released the first version of the MPEG-4 (iso/iec14496) standard in February 1999. The second edition of MPEG-4 was also finalized at the end of the same year and formally became an international standard in early 2000.

MPEG-4 differs greatly from MPEG-1 and MPEG-2. MPEG-4 is not only a specific compression algorithm, it is the international standard for digital TV, interactive mapping applications (audio and video synthesis content), interactive multimedia (WWW, data capture and dispersion) and other requirements of the integration and compression technology. The MPEG-4 standard integrates numerous multimedia applications into a complete framework designed to provide standard algorithms and tools for multimedia communication and application environments, thus establishing a unified data format that can be widely used in multimedia transmission, storage, retrieval and other applications.

MPEG-4 's coding philosophy is:The most significant difference between the MPEG-4 standard and the previous standard is that it uses an object-based coding concept, that is, at the time of encoding, a scene is divided into several video and audio objects which are connected with each other, encoded, then multiplexed to the receiving end, and then decoded separately for different objects, thus combining the required video and audio. It is convenient for us to use different coding methods and representations for different objects, and to facilitate the fusion 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, but also on the Internet to facilitate the implementation of interactive, according to their own needs have a choice of combination of various video audio and graphic text objects.

The general framework of the MPEG-4 system is: the representation of natural or synthetic audiovisual content, the management of audio-visual content data streams, such as multipoint, synchronization, buffer management, 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 indexes, hyperlinks, downloads, deletions, and more. Using these tools, users can easily obtain their desired object-related content from the multimedia database, and provide content manipulation and bit stream editing functions, which can be applied to interactive home shopping, fading and fading digital effects, etc. MPEG-4 provides efficient natural or synthetic multimedia data encoding methods. It can combine natural scenes or objects into synthetic multimedia data.

(2) Efficient compression

The MPEG-4 is based on higher coding efficiency. At the same bitrate, it is based on higher visual hearing quality, which makes it possible to transmit video and audio on low-bandwidth channels, compared to other standards that are or will be formed. At the same time, MPEG-4 can encode data streams that occur concurrently. Multi-view or multichannel data streams from one scene can be synthesized efficiently and synchronously into the final data stream. This can be used for virtual three-dimensional games, three-dimensional movies, flight simulation exercises, etc.

(3) Universal accessibility

MPEG-4 provides the robustness of the error-prone environment to ensure its application in many wireless and wired networks as well as storage media, and MPEG-4 supports content-based tiering, which divides content, quality, and complexity into small chunks to meet different user needs, supporting different bandwidths, Different storage capacity of the transmission channel and the receiving end.

These characteristics will undoubtedly accelerate the development of multimedia applications, which benefit from the application areas: Internet multimedia applications, radio and television, interactive video games, real-time visual communication, interactive storage media applications, studio technology and TV post-production, virtual conference using facial animation technology; multimedia mail , multimedia applications under mobile communication conditions, remote video surveillance, remote database services through ATM networks, etc. The main applications of MPEG-4 are as follows:

(1) applied to Internet AV Broadcasting

Due to the increasing number of Internet access, the traditional TV broadcasting audience gradually reduced, followed by the decline in advertising revenue, so the current fixed-line television broadcasting will eventually turn to TCP/IP-based Internet broadcasting, viewers to watch the way from the simple remote control channel to the online video-on-demand. The concept of video-on-demand is not to download the program to the hard disk, and then play, but streaming video (streaming), click-to-view, side transmission side play.

Now the Internet plays AV: Real Networks's real Media, Microsoft's Windows Media, Apple's QuickTime, their definition of video and audio format is incompatible, it may lead to difficult to control the media flow chaos, The MPEG-4 provides a series of standard tools for the Internet video application, which makes the visual audio stream have the canonical consistency. Therefore, it is a safe choice to use MPEG-4 on the internet to play AV audio.

(2) apply to wireless communication

MPEG-4 efficient bitrate compression, interaction and grading features are especially suitable for multimedia communication in narrowband mobile network, the future mobile phone will become a multimedia mobile receiver, not only can play mobile TV, mobile internet, but also can be mobile to receive multimedia broadcast and watch TV.

(3) Apply to still image compression

Still images (Pictures) are used extensively in the Internet, now the image compression on the Internet uses JPEG technology. 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 JPEG compressed file. Converting JPEG images used on the Internet to MPEG-4 format can greatly improve the transmission speed of images in the network.

(4) used in Videophone

Traditional compression coding standard used for narrowband video services, such as H261, adopts intra-frame compression, inter-frame compression, reduction of pixels and frame extraction to reduce the bitrate, but the coding efficiency and image quality are difficult to be satisfactory. MPEG-4 compression coding can be achieved at very low bit rate transmission quality acceptable audio and visual signals, so that the telephone service can be implemented in the narrow band of public telephones.

(5) Applied to computer graphics, animation and simulation

MPEG-4 's special coding and powerful interactivity enable MPEG-4-based computer graphics and animations to capture material from various sources of multimedia databases and to combine the desired results in real time. Thus, the future of computer graphics can be in the scope allowed by the MPEG-4 grammar to the desired direction of unlimited development, resulting in today's unimaginable animation and simulation results.

(6) Apply to video games

MPEG-4 can be used to encode natural images and sounds with synthetic images and sounds, with unprecedented flexibility in encoding, and to call footage from multimedia databases of various sources in a timely manner. This can produce video games like movies in the future, enabling interactive operations with very high degrees of freedom.

The difference between m-jpeg and MPEG-4 m-jpeg VS MPEG