FLV stands for "Flash Video". It is a format designed for web video playback that offers high rate of compression and produces video of high quality. FLV is becoming more and more popular on the web, because it can easily be embedded in a webpage and is supported by the main operating systems via the Adobe Flash Player and web-browser plugin. At present, FLV is the file format widely used by famous websites such as YouTube, Google Video, MySpace, etc.
FLV files are composed of a video bit stream and an audio bit stream. The commonly used video bit streamis is H.263 video standard which is also called Sorenson Spark. The audio bit stream that is found in most Flash files is encoded as MP3. It should also be noted that FLV files support other forms of audio such as AAC and ADPCM.