Video format classification and introduction
At present, video formats can be divided into two categories: local video video suitable for local playback and network streaming video video suitable for playback on the network. It is worth mentioning here: although the latter is stable in playback and playback screen quality The former may not be as good as the former, but the widespread dissemination of online video streaming video makes it widely used in Internet information services such as video-on-demand, web presentations, distance education, online video advertising and so on.
With the rapid development of computer hardware and software technology and broadband Internet technology, various video and video recording and post-production technologies have also developed by leaps and bounds. Traditional video and video (such as .AVI and .MPEG formats, etc.) are generally large and have poor resolution, such as the VCD format played on a computer. But now, the same video and video, not only can be reduced in volume several times than the original, but also make people feel like immersive ultra-high definition even makes us have to sigh and thank the ever-changing technology for our lives. Benefits! The reality is far more than that, we usually use broadband Internet technology and a multimedia technology called "Streaming Video (Streaming Video)" can be very convenient and quick access to any video and video materials they need and users do not even need to download the entire Or the entire video can preview any specified segment of the video material!
The development and changes of video and video can be analyzed from two aspects: the ultra-high definition of video and video is of course the result of continuous updating of video recording equipment, and the substantial reduction in the size of video and video and the transfer performance of video files like streaming Thanks to the continuous innovation and improvement of video compression technology and video editing processing technology, the macro performance of this innovation and improvement of video technology is the video format.
1. Local Video
â— AVI format: its English name is Audio Video Interleaved, that is, audio and video interleaved format. It was launched by Microsoft in 1992 and is known and known by people along with Windows 3.1. The so-called "audio and video interleaving" means that video and audio can be interwoven together for simultaneous playback. The advantage of this video format is that the image quality is good, and it can be used across multiple platforms. The disadvantage is that it is too bulky, and the worse is that the compression standard is not uniform. The most common phenomenon is that the high version of the Windows media player cannot be played early. Encoded and edited AVI format video, and the lower version of Windows Media Player can not play the latest encoded and edited AVI format video, so when we play some AVI format video playback, it often occurs that the video cannot be played due to video encoding problems or Even if it can be played, there are some inexplicable problems such as the inability to adjust the playback progress and only the sound and no image during playback. If the user encounters these problems when playing the AVI format video, you can solve it by downloading the corresponding decoder.
â— nAVI format: nAVI is the abbreviation of newAVI. It is a new video format developed by an underground organization called ShadowRealm (not much related to the AVI format we mentioned above). It is a modification of the Microsoft ASF compression algorithm, but it is different from the ASF video format in the network video video introduced below. It sacrifices the original ASF video file video "streaming" at the cost of adding frames To greatly improve the clarity of ASF video files.
â— DV-AVI format: DV's English name is Digital Video Format, which is a home digital video format jointly proposed by Sony, Panasonic, JVC and other manufacturers. Currently very popular digital video cameras use this format to record video data. It can transfer video data to the computer through the computer's IEEE 1394 port, and can also record the video data edited in the computer to the digital video camera. The file extension of this video format is generally .avi, so it is also called DV-AVI format.
â— MPEG format: Its English name is Moving Picture Expert Group, which is the format of the Moving Picture Expert Group. This format is commonly used at home for VCD, SVCD, and DVD. The MPEG file format is an international standard for moving image compression algorithms. It uses a lossy compression method to reduce redundant information in moving images. What is more clear is that the compression method of MPEG is based on the fact that most of the two adjacent pictures are the same , The redundant part of the subsequent image and the previous image is removed, so as to achieve the purpose of compression (its maximum compression ratio can reach 200: 1). There are currently three compression standards for MPEG format, namely MPEG-1, MPEG-2, and MPEG-4. In addition, MPEG-7 and MPEG-21 are still in the research and development stage.
MPEG-1: Established in 1992, it is an international standard designed for digital storage media moving images and their accompanying audio coding with a data transmission rate below 1.5Mbps. This is the VCD production format that we usually see. Using the MPEG-1 compression algorithm, a 120-minute movie can be compressed to about 1.2GB. The file extensions of this video format include .mpg, .mlv, .mpe, .mpeg and .dat files on VCD discs.
MPEG-2: Established in 1994, the design goal is the image quality of higher industry standards and a higher transmission rate. This format is mainly used in the production (compression) of DVD / SVCD, and also has considerable applications in some HDTV (high-definition television broadcasting) and some high-demand video editing and processing. Using the MPEG-2 compression algorithm, a 120-minute movie can be compressed to a size of 4 to 8GB. File extensions for this video format include .mpg, .mpe, .mpeg, .m2v, and .vob files on DVD discs.
MPEG-4: Developed in 1998, MPEG-4 is specially designed for playing high-quality videos of streaming media. It can utilize a very narrow band and compress and transmit data through frame reconstruction technology to minimize the use of Data to get the best image quality. The most attractive aspect of MPEG-4 at present is that it can save small-sized video files close to the quality of DVDs. In addition, this file format also includes some special features such as bit rate scalability, animation sprites, interactivity, and even copyright protection that were not available in the previous MPEG compression standard. The file extensions of this video format include .asf, .mov, and DivX AVI.
Tip: Careful users must have noticed, why is there no MPEG-3 encoding in between? In fact, the familiar MP3 is the MPEG-3 (MPEG Layeur3) encoding.
â— RMVB format: This is a new video format that is extended and extended from the RM video format. Its advanced point is that the RMVB video format breaks the original average compression sampling method of the RM format, on the basis of ensuring the average compression ratio. Reasonable use of bit rate resources means that picture scenes with few still and motion scenes use a lower coding rate, so that more bandwidth space can be reserved, and these bandwidths will be used when fast-moving picture scenes appear. In this way, on the premise of ensuring the quality of the still picture, the picture quality of the moving image is greatly improved, so that a delicate balance is reached between the image quality and the file size. In addition, compared to the DVDrip format, RMVB video also has obvious advantages. If a DVD movie with a size of about 700MB is transcribed into the RMVB format with the same audio-visual quality, its maximum size is about 400MB. Not only that, this video format also has unique advantages such as built-in subtitles and no need for plug-in support. If you want to play this video format, you can use RealOne Player2.0 or RealPlayer8.0 plus RealVideo9.0 or later decoder to play.
â— DivX format: This is another video encoding (compression) standard derived from MPEG-4, also known as the DVDrip format, which uses the MPEG4 compression algorithm while integrating MPEG-4 and MP3 In terms of technology, to put it bluntly is to use DivX compression technology to compress high-quality video images on DVD discs, and at the same time use MP3 or AC3 to compress audio, and then combine the video and audio and add the corresponding external subtitle file to form Video format. The picture quality is close to DVD and the volume is only a fraction of DVD. This kind of encoding does not have high requirements on the machine, so DivX video encoding technology can be said to be a new-generation video compression format that poses the greatest threat to DVD, known as DVD killer or DVD terminator.
◠MOV format: A video format developed by Apple Inc. in the United States. The default player is Apple ’s QuickTImePlayer. It has the characteristics of high compression ratio and perfect video clarity, but its biggest feature is its cross-platform nature, that is, it can support not only MacOS, but also Windows series.
2. Network Video
â— ASF format: its English name is Advanced Streaming format, which is a video format launched by Microsoft to compete with the current Real Player. Users can directly use Windows Media Player that comes with Windows to play it. Because it uses the MPEG-4 compression algorithm, the compression rate and image quality are very good (high compression rate is conducive to the transmission of video streams, but the image quality will definitely be lost, so sometimes the picture quality of ASF format is not as good as VCD is normal).
â— WMV format: Its English name is Windows Media Video, which is also a file compression format introduced by Microsoft that adopts independent encoding and can directly watch video programs on the Internet in real time. The main advantages of the WMV format include: local or network playback, scalable media types, component downloads, scalable media types, stream prioritization, multi-language support, environmental independence, rich inter-stream relationships, and scalability, etc. .
â— RM format: The audio and video compression specifications developed by Real Networks are called Real Media. Users can use RealPlayer or RealOne Player to live broadcast network audio / video resources that meet RealMedia technical specifications and RealMedia can be formulated according to different network transmission rates. Different compression ratios are provided to achieve real-time transmission and playback of image data on low-rate networks. Another feature of this format is that users can use RealPlayer or RealOne Player to play online without downloading audio / video content. In addition, as the current mainstream network video format, RM can also convert other formats of video to RM video through its Real Server server, and the Real Server server is responsible for external publishing and playback. The RM and ASF formats can be said to have their own advantages. Generally, the RM video is softer, while the ASF video is relatively clear.
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