In
video compression algorithms a residual frame is formed by subtracting the
reference frame from the desired
frame. This difference is known as the error or residual
frame. 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 ...
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/i ...
to use the reference frame plus the differences to construct the desired frame.
See also
*
Motion compensation
Motion compensation in computing, is an algorithmic technique used to predict a frame in a video, given the previous and/or future frames by accounting for motion of the camera and/or objects in the video. It is employed in the encoding of video d ...
References
Video compression
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