What are the formats of movies?
VCD, animation in multimedia CD … these are all image files. Image files contain not only a lot of image information, but also a lot of audio information. Therefore, the "figure" of image files is often not to be underestimated, often several MB or even dozens of MB.
1, AVI format
If you are a gamer, you should notice that the opening animations of many games are in AVI format. For example, many people like to play "The Legend of the Sword and the Chivalrous Man". The animation with traditional Chinese colors (egrets in green mountains and green waters) at the beginning of the film is AVI format. AVI has a professional name called audio-video interlaced format. Its background should not be underestimated. It is a digital audio and video file format developed by Microsoft. It was originally used only in Microsoft's Windows operating environment (VFW), and now it has been directly supported by most operating systems. AVI format allows video and audio to be played alternately and synchronously, but there is no limited compression standard for AVI files, which has caused an "eternal heartache" for AVI, that is, AVI file formats are incompatible. AVI files generated by different compression standards must use the corresponding decompression algorithm to play. We can often find traces of it on the multimedia CD-ROM, which is generally used to save various image information such as movies and TV, and sometimes appears on the network, mainly for users to enjoy the wonderful clips of new movies. Commonly used AVI playback drivers mainly include Microsoft Video for Windows or Video 1 in Windows 95/98, and Intel's Indeo Video, etc.
2.MOV format (QuickTime)
You may not be familiar with QuickTime format, because it is an audio and video file format developed by Apple. QuickTime is used to save audio and video information, and now it is supported by all major computer platforms, including Apple Mac OS and Microsoft Windows 95/98/NT. The QuickTime file format supports 25-bit color and advanced integrated compression technology, providing video effects over 150, and is equipped with sound equipment, providing more than 200 MIDI-compatible audio and equipment. The new version of QuickTime further expands the original functions and includes the main functions of Internet-based applications. To sum up, QuickTime has been widely recognized by the industry because of its cross-platform and small storage space requirements, and has now become the de facto industry standard in the field of digital media software technology.
3.MPEG/MPG/DAT format
Everyone is used to watching VCD on the computer, right? But do you know how to compress so much audio and video information into one CD? If you have ever opened a VCD file, you will find an MPEG folder in it. At this time, you are smart enough to realize that MPEG is used for VCD disc compression (please refer to the content in 2 1 edition of this newspaper, issue 36). It is the abbreviation of Moving Pictures Experts Group, which was jointly established by ISO (International Organization for Standards) and IEC (International Electronic Commission) on 1988, and is dedicated to the standardization of moving pictures (MPEG video) and their audio coding (MPEG audio). MPEG is an international standard for moving image compression algorithm, which is supported by almost all computer platforms. Different from some previous video formats, MPEG uses lossy compression to reduce redundant information in moving images, thus achieving the goal of high compression ratio. Of course, these are all carried out on the basis of ensuring image quality. MPEG compression standard is designed for moving images. The basic method is to collect and save the information of the first frame in unit time, and then only store the changes of the rest frames relative to the first frame, so as to achieve the purpose of compression. The average compression ratio of MPEG is 50∶ 1, and the highest compression ratio can reach 200∶ 1, which shows high compression efficiency. At the same time, the quality of images and sounds is also very good, and there is a unified standard format on the microcomputer, and the compatibility is quite good. MPEG standard includes three parts: MPEG video, MPEG audio and MPEG system (synchronization of video and audio). MP3 audio file is a typical application of MPEG audio, and Video Disc (VCD), Super VCD (SVCD) and DVD (Digital Versatile Disc) are new consumer electronic products produced by MPEG technology.
Streaming video format (streaming video format)
At present, a large number of video data need to be transmitted in real time through the Internet. As we mentioned earlier, the volume of video files is often large, while the existing network bandwidth is often "narrow", and the result can of course be imagined. Objective factors limit the real-time transmission and playback of video data, so a new streaming video format came into being. This kind of streaming video adopts the way of "broadcasting while transmitting", that is, downloading a part of video files from the server, forming a video stream buffer and playing it in real time, and continuing to download it to prepare for the next play. This method of "broadcasting while transmitting" avoids users