Flash Video is a container file format used to deliver digital video content (e.g., TV shows, movies, etc.) over the Internet using Adobe Flash Player version 6 and newer. Flash Video content may also be embedded within SWF files. There are two different Flash Video file formats: FLV and F4V. The audio and video data within FLV files are encoded in the same way as SWF files. The F4V file format is based on the ISO base media file format, starting with Flash Player 9 update 3. Both formats are supported in Adobe Flash Player and developed by Adobe Systems. FLV was originally developed by Macromedia. In the early 2000s, Flash Video was the de facto standard for web-based streaming video (over RTMP). Users include Hulu, VEVO, Yahoo! Video, Metacafe, Reuters.com, and many other news providers.
Flash Video FLV files usually contain material encoded with codecs following the Sorenson Spark or VP6 video compression formats. As of 2010 public releases of Flash Player (a collaboration between Adobe Systems and MainConcept) also support H.264 video and HE-AAC audio. All of these compression formats are restricted by patents. Flash Video is viewable on most operating systems via the Adobe Flash Player and web browser plugin or one of several third-party programs. Apple's iOS devices, along with almost all other mobile devices, do not support the Flash Player plugin and so require other delivery methods such as provided by the Adobe Flash Media Server.
The 2002 release of Flash Player 6 added support for video in the SWF file format. The 2003 release of Flash Player 7 added direct support for the FLV file format. Because of restrictions in the FLV file format, Adobe Systems created new file formats in 2007, based on the ISO base media file format (MPEG-4 Part 12). In this way, the F4V format shares a common base with the MP4 format, which is why F4V is sometimes informally called "Flash MP4". Flash Player does not check the filename extension but instead examines the file to determine the format.
The new file formats are very different from the older FLV file format. For example, F4V does not support Screen video, Sorenson Spark, VP6 video compression formats and ADPCM, or Nellymoser audio compression formats. Authors of Flash Player strongly encourage use of the new standard file format F4V (ISO base media file format) because it overcomes functional limits with the FLV structure when streaming H.264 or AAC, which is one reason Adobe Systems is moving away from the older FLV file structure. Since 2002, the initial format is Flash Video and the file suffix is .flv with a MIME derived Internet media type of video/x-flv.
The Adobe-branded file suffix .f4v was extended from 2007 to support the ISO base media file format using the same MIME derived Internet media type of video/mp4 as the Apple file suffix of .m4v and the general file suffix of .mp4. Adobe-branded file suffixes exist for .f4p which relates to media encrypted with their Adobe Access DRM scheme; .f4a and .f4b relate respectively to .m4a and .m4b with the same MIME derived Internet media type of audio/mp4.
SWF files published for Flash Player 6 and later versions are able to exchange audio, video, and data over RTMP connections with the Adobe Flash Media Server. One way to feed data to Flash Media Server is from files in the FLV file format. Flash Player can play SWF files created for Flash Player 7 and later versions in FLV format directly (MIME type video/x-flv). Flash Player can also play the new F4V file format, beginning with SWF files created for Flash Player 9 Update 3.
Commonly, Flash Video FLV files contain video bitstreams which are a proprietary variant of the H.263 video standard, under the name of Sorenson Spark (FourCC FLV1). Sorenson Spark is an older codec for FLV files but it is also a widely available and compatible one, because it was the first video codec supported in Flash Player. It is the required video compression format for Flash Player 6 and 7. Flash Player 8 and newer revisions also support the playback of On2 TrueMotion VP6 video bitstreams (FourCC VP6F or FLV4). On2 VP6 is the preferred video compression format for use with Flash Player 8 and higher. On2 VP6 can provide higher visual quality than Sorenson Spark, especially when using lower bit rates. On the other hand, it is computationally more complex and therefore will not run as well on certain older system configurations.
The Flash Video FLV file format supports two versions of a so-called 'screen share' (Screen video) codec which is an encoding format designed for screencasts. Both these formats are bitmap tile based, can be lossy by reducing color depths and are compressed using zlib. The second version is only playable in Flash Player 8 and newer. Audio in Flash Video files is usually encoded as MP3. However, audio in Flash Video FLV files recorded from the user's microphone use the proprietary Nellymoser Asao Codec. (Flash Player 10 released in 2008 also supports the open-source Speex codec.) FLV files also support uncompressed audio or ADPCM format audio. Recent versions of Flash Player 9 support AAC (HE-AAC/AAC SBR, AAC Main Profile, and AAC-LC). Support for encoding Flash Video files is provided by an encoding tool included with Adobe's Flash Professional and Creative Suite products, On2's Flix encoding tools, Sorenson Squeeze, FFmpeg and other third-party tools.