Definition - What does Frame Synchronization mean?
The term frame synchronization is used in two different contexts. In the case of video, it refers to the process of synchronizing display pixel scanning to a synchronization source. In the case of telecommunication, it is the process by which incoming framed data are extracted for decoding with the help of frame alignment signals. This process is called as such because framing and synchronization must be carried out whenever a bit slip event occurs during data transmission.
Techopedia explains Frame Synchronization
Frame synchronization can be defined as the process of identifying valid data from a framed data transmission. When data frames are transmitted to a receiver from the sender but get interrupted, the receiver must resynchronize. The process used for the synchronization between the sender and the receiver is known as frame synchronization.
Some of the common frame synchronization schemes are as follows:
- Framing bit
- Syncword framing
- Cyclic redundancy check-based framing
The following are the four major methods of frame synchronization:
- Time based -- Uses a specific period of time between frames for the synchronization.
- Character counting -- Uses the count of the remaining characters in the frame header.
- Byte stuffing -- Uses special byte sequences like DLE (data link escape), STX (start of text) and ETX (end of text).
- Bit stuffing -- Uses special bit patterns to denote the start and the end of a frame.
The system that carries out the frame synchronization process is known as the frame synchronizer. A frame synchronizer aligns the frames of a pulse code modulation binary stream. Cross-correlation, self-referential synchronization or any similar methods can be used in the frame synchronization process.
The media access control sublayer of the data link layer usually takes care of the frame synchronization process, which determines where one frame of data ends and the next one starts.
In the case of video playback, frame synchronization refers to the process of matching the timing of an incoming video source to the timing of an existing video system. The frame synchronizer used in television production matches the time base of each frame in a video to a professional video system. It also makes use of a common gunlock signal to make sure that all the equipment works with a common time base. This type of frame synchronizer is used to correct the glitches that may arise in video playbacks.