Lip synchronization is the synchronization of audio signals (sometimes with corresponding video signals) so that there is no noticeable lack of simultaneity between them. The term lip sync is an abbreviation of lip synchronization, and describes two similar forms of vocal pantomime.

One is a form of musical pantomime in which a performer moves his/her lips to the words of a played musical recording, creating the illusion of the performer singing in the recorded singer's voice. The hobby reached its greatest popularity in the 1980s, hitting its peak with the syndicated television game show, Puttin' On The Hits. Professional performers sometimes use this method in live performances, especially in dance numbers that require too much exertion to perform as well as sing. It was once common in the Hong Kong music scene. It can also be used fraudulently to misrepresent a musical act with the group, Milli Vanilli being the most notorious.

The other is the art of making a character appear to speak in a pre-recorded track of dialogue. The lip sync technique to animate a character in 3D involves figuring out the timings of the speech (breakdown) as well as the actual animating of the lips/mouth. Computer-animated movies such as Shrek and Toy Story use the lip sync technique, putting well-known voices on their 3D characters. Lip synching is also used in comedies such as This Hour Has 22 Minutes and political satire, changing totally or just partially the original wording. It has been used in conjunction with translation of films from one language to another, for example, Spirited Away.

An example of a lip synchronization problem is the case in which television video and audio signals are transported via different facilities (e.g., a geosynchronous satellite radio link and a landline) that have significantly differently delay times, respectively. In such cases it is necessary to delay the audio electronically to allow for the difference in propagation times.

See also

1. Federal Standard 1037C
2. List of electronics topics
3. Half Life 2 and Source Engine, the first FPS engine to do lip sync on the fly.

External links

• Lip Sync - Making Characters Speak in 3D http://www.comet-cartoons.com/toons/3ddocs/lipsync/lipsync.html
• Lip Sync Videos of old pop songs http://www.drivenbyboredom.com/lipmovies.htm
• Bush and Blair's "Endless Love" (satirical music video) http://politicalhumor.about.com/library/multimedia/bushblair_endlesslove.mov - Quicktime format