FLV File

FLV file extension is used by files in Flash Video Format. This format was introduced in 2003 as an extension to the SWF file format. At some point FLV was the most popular format used for streaming over internet.

FLV files use similar encoding method as SWF (Shockwave Files). In 2007 Adobe introduced F4V which is based on ISO base media storage format and provides full support for H.264 and AAC content.

Original FLV files used a proprietary variation of H.263 for encoding under the name of Sorenson Spark. Starting from Adobe Flash Player 8 support for On2 TrueMotion VP6 video streams was added which can provide better video quality than Sorenson Spark on similar bit rates.

FLV file format also supports storing screencast content to store screen-based videos.

Audio in older versions of FLV files could be encoded using MP3, Nellymoser Asao or Speechex codecs. More recent versions typically use Advanced Audio Coding (AAC). Uncompressed audio and ADPCM (Adaptive differential pulse-code modulation) also could be used.

Flash Video files could be played using Adobe Flash Player, VLC media player, Winamp, Realplayer, Media Player Classic. Android and iOS devices could play FLV and F4V files but only with special apps like Skyfire web browser installed. On 29 June 2012 future Adobe Flash development was discontinued and no future versions of Adobe Flash Player were released after that. Android dropped support for Flash Player starting from Android 4.1.

Following alternative extensions could be used:

F4V is a replacement for FLV which overcomes certain FLV limits related to H.264 and AAC streaming.
F4P is used for FLV videos encrypted using DRM
F4A is used to store audio content
F4B is used to store bookmarks

To transfer FLV files over internet following Internet Media Types (formerly known as MIME types) are used: