Audio video sync (audio to video synchronization) refers to the relative timing of audio (sound) and video (image) portions of a television program, movie or similar program. Commonly referred to as A/V sync or lip sync, audio to video synchronization errors occur when the relative timing of the audio and video parts of a program becomes upset. In film movies these timing errors are most commonly caused by worn films skipping over the movie projector sprockets because the film has torn sprocket holes. Errors can also be caused by the projectionist misthreading the film in the projector, although this is rare with competent projectionists. Image File history File links Please see the file description page for further information. ... Image File history File links Please see the file description page for further information. ... Audio can mean: Sounding that can be heard. ... Video (Latin for I see, first person singular present, indicative of videre, to see) is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion. ... Lip synchronization is the synchronization of audio signals (sometimes with corresponding video signals) so that there is no noticeable lack of simultaneity between them. ... 35 mm Kinoton movie projector in operation. ... A movie projector is an opto-mechanical device for displaying moving pictures. ...

In the television field, audio video sync problems are commonly caused when significant amounts of video processing is performed on the video part of the television program. The video processing causes video delays which can range from a few microseconds to tens of seconds. If a corresponding delay is not added to the companion audio signal the presentation of the video portion of the program to the viewer will lag the presentation of the audio. The resulting audio video sync error can be annoying to the viewer and even lead to detrimental effects on the viewer's enjoyment of the program and the program's effectiveness. The lack of effectiveness problems are of particularly concern when product commercials and political candidates are viewed. See the report "Effects of Audio-Video Asynchrony on Viewer's Memory, Evaluation of Content and Detection Ability" by Reeves and Voelker for more information(a non-copyrighted PDF is available at [1]). Television industry standards organizations have become involved in setting standards for audio video sync errors. See for example ATSC Document IS-191 ([2]). Video processing techniques are used in video codecs, video players and other devices. ...

Typical sources of significant video delays in the television field include video synchronizers and video compression encoders and decoders. Particularly troublesome encoders and decoders are used in MPEG compression systems utilized for broadcasting digital television and storing television programs on consumer and professional recording and playback devices. Another source of significant video delay is found in pixelated television displays (LCD, Plasma display, DLP)which utilize complex video signal processing to convert the resolution of the incoming video signal to the native resolution of the pixelated display, for example converting standard definition video to be displayed on a high definition display. The Moving Picture Experts Group or MPEG is a working group of ISO/IEC charged with the development of video and audio encoding standards. ... Digital television (DTV) is a telecommunication system for broadcasting and receiving moving pictures and sound by means of digital signals, in contrast to analog signals used by analog (traditional) TV. DTV uses digital modulation data, which is digitally compressed and requires decoding by a specially designed television set, or a... An internet image or digital picture of low quality that appears with unattractive blurry squares. ... LCD redirects here. ... Planar Systems plasma display Composition of plasma display panel A plasma display panel (PDP) is a type of flat panel display now commonly used for large TV displays (typically above 32). Many tiny cells located between two panels of glass hold an inert mixture of noble gases (neon and xenon). ... The DLP Logo Digital Light Processing (DLP) is a technology used in projectors and video projectors. ...

A tracking, variable audio delays called an audio synchronizer can be utilized to correct or maintain proper audio video sync. These devices operate by receiving a DDO (Digital Delay Output) signal carrying video delay information from a video processing device and in response to the DDO delaying the audio. Video delays can frequently and rapidly change by large amounts, requiring the audio synchronizer to achieve corresponding changes in the audio delay without introducing objectional artifacts such as pops, clicks, gaps or pitch errors in the audio. The audio signal processing necessary to achieve this level of performance is complex and expensive, limiting the use of audio synchronizers in consumer products.

See also

Dubbing (filmmaking) In filmmaking, dubbing or looping is the process of recording or replacing voices for a motion picture. ...