Data element
An item of data as represented before encoding and after decoding.


DC coefficient
The DCT coefficient for which the frequency is zero in both dimensions.


DCT (Discrete Cosine Transform)
Either the forward discrete cosine transform or the inverse discrete cosine transform. The DCT is an invertible, discrete orthogonal transformation.


DCT coefficient
The amplitude of a specific cosine basis function.


De-emphasis
Filtering applied to an audio signal after storage or transmission to undo a linear distortion due to emphasis.


Decoded stream
The decoded reconstruction of a compressed bitstream.


Decoder
An embodiment of a decoding process.


Decoding (process)
The process that reads an input coded bitstream and produces decoded pictures or audio samples.


Dequantisation
The process of rescaling the quantised DCT coefficients after their representation in the bitstream has been decoded and before they are presented to the inverse DCT.


Dolby digital
See AC-3.


Downmix
A matrixing of n channels to obtain less than n channels.


DPCM (Differential Pulse Code Modulation)
Differential pulse code modulation (DPCM) is a source coding scheme that was developed for encoding sources with memory. The reason for using the DPCM structure is that for most sources of practical interest, the variance of the prediction error is substantially smaller than that of the source.


DSM (Digital Storage Media)
A digital storage or transmission device or system.


DVD (Digital Versatil Disc)
DVD is an high density media which looks like a CD-ROM. It can have one or two sides containing data, and each side can be single or double layer. Each layer have a 4.7 giga bytes maximum capacity, so the total maximum capacity of a DVD is 18.8 giga bytes.
    It uses the EFM storing scheme in order to increase reliability of data stored on it.