A) Schemes for compressing high bit rate signals into 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 employed from arbitrary resampling to more complex processing with the objective of reducing the transmission of redundant information in the image and possibly eliminating 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.