The difference between synchronous video recording and continuous video recording.

Internal synchronization is completed by the synchronization signal of the camera internal synchronization signal generating circuit. "Internal synchronization" working mode: refers to the working mode that the camera is only locked by the line and field synchronization signals generated by its own crystal oscillator circuit. External synchronous input (SYNC) On the backboard of most high-end CCD color cameras, besides the video output port, there is generally a port marked with the word SYNC in the same shape, and there is also a toggle switch nearby, which is the external synchronous input port. When using the camera alone, it is generally not necessary to connect this port. Just connect the video output port to a video device such as a monitor or a video recorder through a video cable, and a stable image can be obtained. However, when multiple cameras are used at the same time and share the back-end video equipment, sometimes multiple pictures will be out of SYNC, so an external synchronous input (SYNC) port is needed.