Indeo Video (commonly known now simply as "Indeo") is a video codec developed by Intel in 1992. It was sold to Ligos Corporation in 2000. While its original version was related to Intel's DVI video stream format, a hardware-only codec for the compression of television-quality video onto compact discs, Indeo was distinguished by being one of the first codecs allowing full-speed video playback without using hardware acceleration.
During the development of what became the P5 Pentium microprocessor, the Intel Architecture Labs implemented one of the first, and at the time highest-quality, software-only video codecs, which was marketed as "Indeo Video". At its public introduction, it was the only video codec supported in both the Microsoft (Video for Windows) and Apple Computer's QuickTime software environments, as well as by IBM's software systems of the day.
The original Indeo codec was highly asymmetrical, meaning that it took much more computation to encode a video stream than to decode it. Intel's ProShare video conferencing system took advantage of this, using hardware acceleration to encode the stream (and thus requiring an add-in card), but allowing the stream to be displayed on any personal computer.
Intel produced several different versions of the codec between 1993 and 2000, when it was sold to Ligos, based on very different underlying mathematics and having different features. Indeo Video Interactive, a wavelet-based codec that included novel features such as chroma-keyed transparency and hot spot support, was aimed at video game developers.
Though Indeo saw significant usage in the mid-1990s, it remained proprietary. Intel slowed development and stopped active marketing, and it was quickly surpassed in popularity by the rise of MPEG codecs and others, as processors became more powerful and its optimization for Intel's chips less important. Indeo still saw some use in video game cutscene videos.
Official Indeo 5 decoders exist for Microsoft Windows, Mac OS Classic, BeOS R5 and the XAnim player on Unix. Versions 2, 3, 4 and 5 have reverse-engineered decoders in FFmpeg. Indeo version 3 (IV31 and IV32), 4 (IV41) and 5 (IV50) are supported by MPlayer and XAnim. Version 5.11 is freeware and may be used on all 32-bit versions of Windows prior to Vista. Version 5.2 has been created for XP and is available to buy from the official website for use only with Windows 95, 98, ME, NT, 2000 and XP. This includes support for Indeo Video 4.5 and Indeo Audio 2.5 codecs but the version 3.2 video codec has been removed since the original release of Indeo XP for Windows. Although Indeo video is not officially supported by Windows Vista and Windows 7, simply entering the following into the command prompt might enable the playback of Indeo encoded video:
regsvr32 ir50_32.dll
Security advisory 
The Microsoft Windows implementation of the Indeo codec contains several security vulnerabilities and one should not play Indeo videos from untrusted sources. On fully patched systems the Indeo codec is partially disabled in most circumstances; there are no plans to fix the vulnerabilities as the codec is third party code.
See also