Flash Video

Flash Video is a container file format used to deliver video over the Internet using Adobe Flash Player versions 6–11. Flash Video content may also be embedded within SWF files. There are two different video file formats known as Flash Video: FLV and F4V. The audio and video data within FLV files are encoded in the same manner as they are within SWF files. The latter F4V file format is based on the ISO base media file format and is starting with Flash Player 9 update 3. Both formats are supported in Adobe Flash Player and currently developed by Adobe Systems. FLV was originally developed by Macromedia.
Flash Video has been accepted as the default online video format by many sites. Notable users of it include YouTube, Hulu, VEVO, Yahoo! Video, metacafe, Reuters.com, and many other news providers.
The standards documentation for BBC Online states that the BBC now preferentially accepts Flash videos for submission, to the disadvantage of other formats previously in use on its sites such as RealVideo or WMV.
Flash Video FLV files usually contain material encoded with codecs following the Sorenson Spark or VP6 video compression formats. The most recent public releases of Flash Player (collaboration between Adobe Systems and MainConcept) also support H.264 video and HE-AAC audio. All of these compression formats are currently 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 do not support the Flash Player plugin and so require other delivery methods such as provided by the Adobe Flash Media Server.




Support for video in SWF file format was added in Flash Player 6, released in 2002. In 2003, Flash Player 7 added direct support for FLV file format. Because of restrictions in the FLV file format, Adobe Systems has created in 2007 new file formats listed below, based on the ISO base media file format (MPEG-4 Part 12). Flash Player does not check the extension of the file, but rather looks inside the file to detect which format it is. The new file formats are completely different from the older FLV file format. For example, F4V does not support Screen video, Sorenson Spark, VP6 video compression formats and ADPCM, Nellymoser audio compression formats. Authors of Flash Player strongly encourage everyone to embrace the new standard file format F4V (ISO base media file format). There are functional limits with the FLV structure when streaming H.264 or AAC which could not be overcome without a redesign of the file format. This is one reason why Adobe Systems is moving away from the traditional FLV file structure.


Encoding


Commonly, Flash Video FLV files contain video bit streams 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 bit streams (FourCC VP6F or FLV4). On2 VP6 is the preferred video compression format for use with Flash Player 8 and higher. On2 VP6 can provide a 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 'screenshare' (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.


Media type support
Supported media types in FLV file format:
Video: On2 VP6, Sorenson Spark (Sorenson H.263), Screen video, H.264
Audio: MP3, ADPCM, Linear PCM, Nellymoser, Speex, AAC, G.711 (reserved for internal use)
Supported media types in F4V file format:
Video: H.264
Images (still frame of video data): GIF, PNG, JPEG
Audio: AAC, HE-AAC, MP3


FLV converters
An FLV converter is a type of video conversion software that is used for turning videos from different formats into FLV. Below is a list of popular free video converters which supports conversion to FLV.
SUPER (freeware)
Free Studio (freeware)
Freemake Video Converter (freeware)
Format Factory (freeware)
HandBrake Video Converter (GPL-licensed free software)
These programs run under Windows7/Vista/XP. HandBrake also under Mac OS X and Linux.