What is a Constant Bit Rate vs. a Variable Bit Rate?
When encoding a video program, different bit rates can be used. The bit rate refers to how much information is represented per second of video. A video file encoded at a constant bit rate will show the exact same amount of digital information from one time segment to the next, for the entire length of the video file. When a variable bit rate is used, the amount of information displayed varies from one time segment to another. Using a variable bit rate allows for more efficient use of storage space on the medium which is carrying the encoded file. To illustrate, when scenes vary significantly from one another in a given program (such as in a movie where action scenes are interwoven with slower scenes), a variable bit rate is used to accommodate the higher encoding needs of the action shots (a high bit rate is used for those) and the slower scenes (where the bit rate is reduced since there is less action to show). By contrast, a constant bit rate is used for programs with consistent amou
