View the world-what is the video format?

As the saying goes, things are clustered by groups. Video files are no exception. After careful calculation, video files can be divided into two categories: image files, for example, common VCD files. The second is streaming video files. This is a later video show after the development of the Internet. For example, online live broadcasting is built on the stream video technology. In daily life, image formats (video) come into contact with more animations in VCD and multimedia CD ...... These are all image files. Image files not only contain a large amount of image information, but also contain a large amount of Audio Information. Therefore, the "body" of image files is usually several MB or even dozens of MB. 1. If you are a player in AVI format, you should note that the first animation of many games is in AVI format. For example, in the legend of the legend that many people like to play, the animation of the First Section of the film, which is full of Traditional Chinese colors (Qingshan, green water, and egrets), uses the AVI format. Avi has a professional name called audio video interleaved format. It is a digital audio and video file format developed by Microsoft. It was originally only used in Microsoft's Windows video operating environment (VFW, Microsoft Video for Windows ), it is now directly supported by most operating systems. The AVI format allows video and audio to be played simultaneously in a staggered manner. However, the AVI file is not limited to compression standards, which makes Avi a "permanent heartache ", that is, the AVI file format is not compatible. Different compression standards generate AVI files, you must use the corresponding decompression algorithm to play it out. We can often find a trace of it on a multimedia CD, which is generally used to store film, TV, and other image information, and sometimes it also appears on the Internet, it is mainly used to let users enjoy the highlights of new films. Commonly used Avi playback drivers include Microsoft Video for Windows or Video 1 in Windows 95/98, and Intel's Indeo video. 2. You may not be familiar with mov format (QuickTime) because it is an audio and video file format developed by Apple. QuickTime is used to save audio and video information. It is now supported by all mainstream computer platforms, including Apple Mac OS and Microsoft Windows 95/98/NT. The quick time file format supports 25-bit color, supports advanced integrated compression technology, provides over 150 video effects, and is equipped with sound devices that are compatible with more than 200 MIDI audios and devices. The new version of QuickTime further extends the original features, including key features of Internet-based applications. To sum up, QuickTime has been widely recognized by the industry for its cross-platform and low storage requirements. It has become a de facto industrial standard in the digital media software field. 3. Are you familiar with the mpeg/MPG/DAT format on your computer? But do you know how to compress so much audio and video information into a CD? If you have opened a VCD file, you will find an MPEG folder. At this time, you will surely realize that the compression of the VCD is in the format of MPEG (refer to section 36, section 21 of this newspaper. This is the abbreviation of Moving Pictures Experts Group (dynamic image Expert Group). It was jointly established by the International Standardization Organization ISO (International Standards Organization) and IEC (International Electronic Committee) in 1988, it is dedicated to the standardization of motion images (MPEG videos) and audio companion codes (mPEG audios. MPEG is an international standard for Motion Image Compression Algorithms and is now supported by almost all computer platforms. Unlike some earlier video formats, MPEG uses lossy compression to reduce redundant information in motion images to achieve a high compression ratio. Of course, these operations are performed on the basis of ensuring image quality. The Mpeg Compression standard is designed for motion images. The basic method is to collect and save the first frame information within a unit of time, and then only store the changes of the remaining frames relative to the first frame, to achieve the goal of compression. The average compression ratio of MPEG is 50∶1, up to 200: 1. The compression efficiency is high. At the same time, the quality of images and audios is also very good, and there is a unified standard format on the microcomputer, the compatibility is quite good. The MPEG standard consists of three parts: MPEG Video, MPEG audio, and MPEG System (video and audio synchronization). MP3 audio files are a typical application of MPEG audio, while video CD (VCD) super VCD (SVCD) and digital versatile disk are all new consumer electronic products produced by fully adopting MPEG technology. Streaming video format (streaming video format) Currently, many video data must be transmitted in real time over the Internet. As we mentioned earlier, the size of video files is usually relatively large, however, the existing network bandwidth is often relatively "narrow", and thousands of troops and tens of thousands of horses have to go through the zhuqiao bridge. The result is certainly conceivable. Objective factors limit the real-time transmission and playback of video data. Therefore, a new stream video format emerged. This type of stream video adopts the "transmitting and broadcasting" method, that is, first downloading a part of the video file from the server to form a video stream buffer and then playing it in real time. At the same time, download continues, prepare for the next playback. This method avoids the disadvantage that users must wait for the entire file to be downloaded from the Internet. Up to now, most stream video formats have been used on the Internet: 1. RM (Real Media) the RM format is a new stream video file format developed by RealNetworks. It has three roles: RealAudio, realvideo, and realflash. RealAudio is used to transmit audio data close to the sound quality of Cd, while realvideo is used to transmit continuous video data. realflash is a highly compressed animation format recently developed by RealNetworks and Macromedia. RealMedia sets different compression ratios based on different network data transmission rates to enable real-time transmission and playback of image data on low-rate wide-area networks. Here we will mainly introduce realvideo, which can be used in addition to playing in the form of normal video files, but also with the RealServer server, realencoder is responsible for converting existing video files to the RealMedia format in real time, while RealServer is responsible for broadcasting RealMedia video files. During data transmission, you can play a video image by using RealPlayer while downloading it. Instead of downloading it like most video files, you must first download it before playing it. Currently, many websites on the Internet use realvideo technology to broadcast live events of major events. 2. mov file format (QuickTime) mov can also be used as a stream file format. QuickTime can provide real-time digital information flows, workflows, and file playback functions over the Internet. To adapt to this network multimedia application, quickTime provides the corresponding QuickTime Viewer plug-in (plug-in) for a variety of popular browser software, enabling real-time playback of multimedia data in the browser. The "fast start" function of this plug-in allows users to watch the first video screen when sending requests, this plug-in allows you to play video images while downloading video data. You do not need to wait until all the download is complete. In addition, QuickTime also provides the automatic rate selection function. When you call a plug-in to play a QuickTime Multimedia file, you can select a different connection rate to download and play the image. Of course, different rates correspond to different image quality. In addition, QuickTime uses a virtual reality technology called QuickTime VR. You only need to use the mouse or keyboard, you can observe the scene of 360 degrees around a location, or observe an object from any angle of space. 3. asf (Advanced Streaming Format) Advanced Streaming Format (ASF, advanced stream format) released by Microsoft is also a technical standard for transmitting multimedia in real time over the Internet, microsoft is ambitious and hopes to use ASF to replace technical standards such as QuickTime. The main advantages of ASF include local or network playback, extensible media types, part downloads, and scalability. The main components of the ASF application are the netshow server and the netshow player. An independent encoder compiles media information into an ASF stream and sends it to the netshow server. Then, the netshow server sends the ASF stream to all netshow players on the network, to achieve single-channel broadcast or multi-channel broadcast. This is similar to the real-time broadcast of the real system.