a) Schemes for compressing high bit rate signals to channels with much lower bit rates.

b) A reduction in the real-time transmission rate in digital format, usually to facilitate recording, transmission, broadcast, display, etc., or even to comply with fixed limitations.

Various algorithms appropriate for video signals may be applied from arbitrary sampling to more complex process with the objective of reducing the transmission of redundant information to the image and possibly eliminate image content that will not be obvious in the final specified display. Bit rate reduction is also appropriate and employed in audio records, either associated with video or standing alone.