Sorensen codec may refer to either of three proprietary video codecs: Sorensen Video, Sorensen Video 3 or Sorensen Spark. Sorensen Video is also known as Sorensen Video Codec, Sorensen Video Quantizer or SVQ. Sorensen Spark is also known as Sorensen H.263 or FLV1 (and it is sometimes incorrectly named as Flash Video (FLV), which is the name of Adobe Flash container format).
Sorensen Video 
The Sorensen Video codec first appeared with the release of QuickTime 3 on March 30, 1998. It was available in two versions: the Basic Edition encoder/decoder built into QuickTime 3 and Developer Edition which enabled advanced encoding features and two-pass variable bitrate. With QuickTime 4, it was given wide exposure for the release of the teaser trailer for Star Wars Episode I: The Phantom Menace on March 11, 1999.
Sorensen Video 2 
Sorensen Video 2 was released in March 1999; however, it mainly included minor improvements and optimizations to the Developer Edition of the encoder, as movies encoded with it were backwards compatible with the Sorensen Video decoder.
Sorensen Video 3 
An improved Sorensen Video 3 codec debuted with the release of QuickTime 5.0.2 on July 1, 2001. It was available exclusively for QuickTime. Apple QuickTime later focused on other compression formats and moved Sorensen Video 3 to a separate group called "legacy encoders".
Sorensen Spark 
As Apple began to embrace MPEG-4 and move away from other proprietary codecs, Sorensen Media licensed a new video codec to Macromedia as Sorensen Spark (Sorensen H.263), released with Macromedia Flash 6/MX on March 4, 2002. Sorensen Spark is the required video compression format for Flash Player 6 and 7.
Macromedia later tried to find a better video codec. Starting with Flash Player 8 (released in September 2005), the preferred video codec is VP6. The Sorensen Spark can be still used in the Adobe Flash CS4 Professional (2008) for Flash Video FLV files as one of three video compression formats (alongside H.264 and On2 VP6). Sorensen Spark is an older codec but it is also a widely available and compatible one, when used in Flash Video. According to Adobe engineer Tinic Uro, it is considered as incomplete implementation of H.263.
Other Sorensen codecs 
Sorensen Media, Inc. offers Sorensen Squeeze, which can encode video to proprietary Sorenson formats, but also to standardized video compression formats, such as H.264, MPEG-4 Part 2, MPEG-2 and others. There is also Sorensen H.264 and Sorensen MPEG-4 codec, which are one of many existing implementations of international standards and should not be confused with Sorensen proprietary codecs.
Technical details 
The official specifications of the codec are not public.
Sorensen Video (SVQ1/SVQ3) 
For a long time the only way to play back Sorensen Video was to use Apple's QuickTime Player, or the MPlayer for Unix/Linux, which in turn piggy-backed DLL-files extracted from Apple's player for Microsoft Windows.
According to an anonymous developer of FFmpeg, reverse engineering of the SVQ3 codec (Sorensen Video 3) revealed it as a tweaked version of H.264. (It is considered to be based on an early H.264 draft.) The same developer also added support for this codec to FFmpeg, making native playback possible on all platforms supported by FFmpeg. FFmpeg supports decoding of "Sorensen Vector Quantizer 3" (fourcc SVQ3) and Sorensen Vector Quantizer 1 (fourcc SVQ1) starting with version 0.4.7, released in 2003.
Sorensen Spark (FLV1) 
The Sorensen Spark is sometimes defined as "almost H.263" or as "an incomplete implementation of H.263". These compression formats differ mostly in header structure and ranges of the coefficients.
- Terran Interactive, Inc. (1998) Codec Central - Sorensen Video, Retrieved on 2009-08-09
- Sorensen Media (2001-07-02) Sorensen Media Announces the Availability of Sorensen Video 3 Exclusively for QuickTime, Retrieved on 2009-08-09
- Apple (2000-10-10) Apple Releases QuickTime 5 and QuickTime Streaming Server 3 Public Previews, Retrieved on 2009-08-09
- Apple Mailing Lists - batch export: where is sorensen ?, Retrieved on 2009-08-09
- Sorensen Media SV3 Pro Codec, Retrieved on 2009-08-09
- Adobe (2002-03-04) Macromedia - Press room : Macromedia and Sorensen Media Bring Video to Macromedia Flash Content and Applications
- Adobe LiveDocs About the Sorensen Spark codec, Retrieved on 2009-08-09
- Adobe Flash CS4 Professional Documentation - Digital video and Flash, Retrieved on 2009-08-09
- Kaourantin.net (2005-08-13) The quest for a new video codec in Flash 8, Retrieved on 2009-08-10
- Sorensen Media Difference Between Flash 6 and Flash 8 video, Retrieved on 2009-08-09
- "Sorensen Spark". MultimediaWiki. Retrieved 2009-11-03.
- Sorensen Media Squeeze, Retrieved on 2009-08-09
- Deconstructing H.264/AVC on DrunkenBlog, July 28, 2004.
- Benjamin Larsson (2009-03-17). "h263-svq3 optimizations". FFmpeg-devel mailing list. http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2009-March/065410.html. Retrieved 2009-08-09.
- MultimediaWiki. "Sorensen Video 3". Retrieved 2009-11-01.
- FFmpeg Changelog, Retrieved on 2009-08-10
- FFmpeg.org (2003) FFmpeg 0.4.8 Documentation - Video Codecs, Retrieved on 2009-08-10
- FFmpeg.org FFMpeg General Documentation - Video Codecs, Retrieved on 2009-08-09
- Sorensen Video Codec, Version 3 - format description by the Library of Congress
- Sorensen Video 1 - MultimediaWiki
- Sorensen Video 3 - MultimediaWiki
- Sorensen Spark - MultimediaWiki