Synchronization(redirected from Video synching)
Also found in: Dictionary, Thesaurus, Medical.
the bringing of two or several processes into a state of synchrony, that is, into a state such that identical or corresponding elements of the processes occur at a fixed phase difference relative to one another (for example, the words of a speaker and a translator during simultaneous translation) or simultaneously (for example, the movement of dancers in a corps de ballet). The synchronization of periodic processes is achieved by bringing the periods, or frequencies, of the processes into mutual correspondence (for example, to equality or some integral multiple value) and by establishing a constant relationship between the initial phases (constant mutual phase difference). Processes that satisfy the conditions of synchrony are called synchronous or synchronized processes, and the property which they possess is called synchronism. Nonsyn-chronous processes are called asynchronous.
The synchronization of processes is extremely important in technology. For example, in power engineering, the operation of generators in an electric power system is synchronized, and the generator voltages are equalized. In television engineering, the line scanning and frame scanning in television transmitters and receivers are synchronized. In motion-picture technology, the filmed image is synchronized with the sound track.
in cinematography, achieving an exact correspondence in time between visual images and a sound recording during projection of a motion-picture film or parts of a film produced by recording the visual image (picture) and the sound on two separate carriers— a motion-picture film and a magnetic tape. Synchronization is achieved by beginning projection of the picture and playback of the corresponding sound at the same moment, using the synchronization marks imprinted on the carriers when filming is begun. The projection and playback speeds are then matched exactly with the original filming and recording speeds.
Synchronized speeds for perforated carriers can be achieved if the tape and film traction mechanisms used in filming and in projection and playback are equipped with gear drums driven by synchronous electric motors. If nonperforated magnetic tape is used to record the sound, synchronizing signals must be used to achieve an exact correspondence between the speed of the film and that of the sound track. Such signals are marked on the sound track during filming and have a frequency that is equal to or is a multiple of the frequency or speed of the film. They can thus be used to correct the speed of the carriers during projection of the film or a retranscription of the sound track. If the visual image and the sound are recorded on the same carrier during the filming, synchronized reproduction is automatically achieved.
in physiology, changes in an electroencephalogram manifested by regular, time-ordered, and high-amplitude (50–100 microvolts) alpha, theta, and beta waves. The oscillations of the alpha waves range from eight to 13 per second, the theta waves, from four to seven per second, and the beta waves, from 14 to 25 per second. Sleep spindles, induced rhythms, and paroxysmal discharges are special forms of synchronized bioelectric potentials. The opposite of synchronization is desynchronization, which is associated with the influence of such structures as the mesencephalon, diencephalon, and nuclei of the hypothalamus and limbic system on the cortex of the cerebral hemispheres.
synchronization(1) See synchronous and synchronous transmission.
(2) Ensuring that the same photo, video or document is in two or more devices all the time. See data synchronization.
(3) Keeping time-of-day clocks in two devices set to the same time. See NTP.
(4) Keeping the clocks of two devices beating at the same rate. See synchronous transmission.
(5) Sending identical electronic signals from two transmitters. See MediaFLO.