video compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...

algorithms In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing c ...

a residual frame is formed by subtracting the

reference frame In physics and astronomy, a frame of reference (or reference frame) is an abstract coordinate system whose origin (mathematics), origin, orientation (geometry), orientation, and scale (geometry), scale are specified by a set of reference point ...

from the desired

frame A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (con ...

. This difference is known as the error or residual

. The residual frame normally has less

information entropy In information theory, the entropy of a random variable is the average level of "information", "surprise", or "uncertainty" inherent to the variable's possible outcomes. Given a discrete random variable X, which takes values in the alphabet \ ...

, due to nearby video frames having similarities, and therefore requires fewer

bit The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represente ...

s to compress. An encoder will use various algorithms such as

motion estimation Motion estimation is the process of determining ''motion vectors'' that describe the transformation from one 2D image to another; usually from adjacent frames in a video sequence. It is an ill-posed problem as the motion is in three dimensions b ...

to construct a frame that describes the differences. This allows a

decoder Decoder may refer to: Technology * Audio decoder converts digital audio to analog form * Binary decoder, digital circuits such as 1-of-N and seven-segment decoders * Decompress (compression decoder), converts compressed data (e.g., audio/video/im ...

to use the reference frame plus the differences to construct the desired frame.

References

Video compression {{Software-stub

See also

References