What is AVI?
The AVI format was invented by Microsoft over twenty years ago, yet AVI remains one of the most popular formats for storing video information in the world.
For the first time, the AVI format appeared in November 1992 together with the innovative Windows 3.1 operating system for those times, becoming the main one for storing video in Microsoft Windows operating systems. The abbreviation “AVI” stands for – Audio Video Interleave (interlaced audio and video).
Unlike common formats like MP3 or JPG, AVI is a container that can contain compressed video / audio data using different combinations of codecs. So if MP3 and JPG files are based on using only the main type of data compression (compression) (MPEG Audio Layer 3 and JPEG), an AVI file can contain several types of compressed data (for example, DivX – video + WMA – audio or Indeo – video + PCM – audio), depending on the codec used for encoding / decoding. All AVI files look the same “on the outside” (they have the extension .AVI), but they can be very different “on the inside”.
Recording in AVI format can be done with or with compression. To encode data in AVI, Motion JPEG is commonly used. Compression formats are also supported: Microsoft Video 1 (the format works only with 8 and 16 bit color), Microsoft RLE (8 bit color only), Indeo, Cinepak Editable MPEG, which uses only I-frames.
Most of the time, data in AVI container format is encoded and decoded using the DivX codec, which is a decrypted version of Microsoft’s MPEG-4 video codec.
All Windows operating system software players can understand and play AVI format.
Main disadvantages:
Lack of VBR support
Unfortunately, the AVI format does not support variable bit rate (VBR) audio streams. The developers of the AVI format managed to implement support for the variable bit rate of MP3 tracks, but it does not support sound in the Ogg Vorbis format.
Picture and sound out of sync The
Data in the AVI container is stored as sequences of recordings, each of which consists of a frame and the corresponding soundtrack. For video, the division into frames is completely natural, but the sound is a continuous stream, artificially divided into fragments corresponding to the frames. If a video capture device is used to record both video and sound, problems generally do not arise. However, if the sound is recorded via a sound card, there is no exact synchronization of the picture and sound, and the sound may “come out of the picture”.
AVI data can be exported to other formats.
AVI format: specifications and capabilities
There are several computer video formats, of which, until recently, AVI (Microsoft) was the most popular.
Most frame capture and non-linear editing systems deal with the AVI (Audio Video Interleave) format. This format allows you to store images and sound simultaneously. They are recorded alternately, so that after the frame, there is a sound recording.
Audio Video Interleave is abbreviated as AVI, which stands for “audio and video interleaving.” The .avi file format is known as a media container, developed by Microsoft in 1992. AVI is a file format like MP3 or JPG. But, unlike these formats, AVI is a container format. Meaning it can contain compressed video / audio data using different codec combinations, allowing video and sound to be played in sync. Therefore, if MP3 and JPG files are based on using only the main type of data compression (MPEG Audio Layer 3 and JPEG), an AVI file can contain several types of compressed data (for example, DivX – video + WMA – audio or Indeo – video + PCM – audio), depending on the codec used for encoding / decoding. Like a DVD AVI files support multi-streaming audio and video. AVI files can contain various types of compressed data, such as DivX for video and MP3 for audio.
In structure, the AVI format is a variant of the RIFF format. The file of this format consists of blocks (fragments) that, in turn, can contain other nested blocks. The “top” block – RIFF – contains the form identifier “avi_”, which actually means that we are dealing with an avi file. There are four characters for the identifier, but one of them is not used.
