AVI files are in fact a lot more complicated than they seem. Regarded by many as ‘the video file format’ the truth is, they’re not so much as a form of video as they are in fact a container. This video container format, invented by Microsoft in the early nineties has today become the most common type of video file around. Our website provides info on Digital Integration
AVI files are essentially containers that start with a block of information, followed by a block of video or audio and ends with a special block that serves as the index of the file. Containing both video and audio – the audio / video block is encoded using various standards such as DIVX, XVID, MP3 and the likes.
The Audio Video Interleave (AVI) format is known as such because of the way it encodes video and audio in blocks next to each other. To make this possible, each block is prepended with a four character identifier that identifies the codec used. An example would be DIVX for DIV3 or DIV4 for DIVX encoded video, or RAW for uuencoded (raw) video, and 0055 for MP3 (Mpeg) audio.
AVI is the oldest container file format and it does have some shortcomings, such as the fact that unlike DVD format which supports chapters, menus and the likes – AVI doesn’t. The other major disadvantage of AVI files today is that the index chunk which is the second most important is at the end of the file, making previewing content as it downloads a somewhat painful affair.
However, nonetheless for a format that’s almost 20 years old, AVI files are still going strong. The fact that AVI is pretty much intertwined in windows and that it’s a relatively lightweight and portable format that’s also been adopted widely in media players, phones and the likes mean that it’s likely to be popular for some time yet. While competing formats offer more flexibility supporting the likes of VBR (variable bit rate) audio and more advanced formats such as OGG Vorbis, AVI offers a lot of flexibility.
Today, there are many successors such as Windows Media (WMA & WMV) which have been popularized by many organizations, but it’s the fact that AVI is so old that it remains still popular. This container format will most probably remain the standard for most standard definition content that is to be played on computers.
However, when looking at what are AVI files, the Internet has changed the way we use video a lot, as it used to be the case that streaming video was highly resource intensive. Thanks to high speed internet connections – AVI files are being used less and in their place is real time streaming media in the form FLV video and the likes.
The only drawback to streaming media is that it’s only viewable over the web. When it comes downloading content and saving it to disk, AVI is still the popular file format of choice due to the fact it’ll play back on just about any player that has the required codecs.