Endec
Encyclopedia
An endec is a device which acts as both an encoder and a decoder
on a signal
or data stream
, either with the same or separate circuitry or algorithm. The combining of these names is a portmanteau.
(compressor / decompressor) is that hardware
is usually considered to be an endec, while software is considered to be the codec. Similarly, the word "encoding" is usually used for hardware, while "coding
" is usually used in regard to software.
A device or program which uses a compression
algorithm to create MPEG audio
and/or video
is often called an encoder, and one which plays back such files is a decoder. However, this is technically a codec, especially if performed in software.
Decoding
Decoding is the reverse of encoding, which is the process of transforming information from one format into another. Information about decoding can be found in the following:* Digital-to-analog converter, the use of analog circuit for decoding operations...
on a signal
Signal (computing)
A signal is a limited form of inter-process communication used in Unix, Unix-like, and other POSIX-compliant operating systems. Essentially it is an asynchronous notification sent to a process in order to notify it of an event that occurred. When a signal is sent to a process, the operating system...
or data stream
Data stream
In telecommunications and computing, a data stream is a sequence of digitally encoded coherent signals used to transmit or receive information that is in the process of being transmitted....
, either with the same or separate circuitry or algorithm. The combining of these names is a portmanteau.
Definition
The general difference between an endec and a codecCodec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
(compressor / decompressor) is that hardware
Hardware
Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....
is usually considered to be an endec, while software is considered to be the codec. Similarly, the word "encoding" is usually used for hardware, while "coding
Coding
Coding may refer to:* Channel coding in coding theory* Line coding* Computer programming, the process of designing, writing, testing, debugging / troubleshooting, and maintaining the source code of computer programs...
" is usually used in regard to software.
A device or program which uses a compression
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
algorithm to create MPEG audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
and/or video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
is often called an encoder, and one which plays back such files is a decoder. However, this is technically a codec, especially if performed in software.
Examples
Examples of encoders, decoders, and endecs include:- A modemModemA modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
is an endec, likewise a modulator is an encoder and a demodulator is a decoder - An Emergency Alert SystemEmergency Alert SystemThe Emergency Alert System is a national warning system in the United States put into place on January 1, 1997, when it superseded the Emergency Broadcast System , which itself had superseded the CONELRAD System...
unit is usually an endec, but sometimes just a decoder - A stereo generator used in broadcastingBroadcastingBroadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...
is an encoder - A combination ADCAnalog-to-digital converterAn analog-to-digital converter is a device that converts a continuous quantity to a discrete time digital representation. An ADC may also provide an isolated measurement...
and DACDigital-to-analog converterIn electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...
would technically be an endec, though they are usually called CODECs - Hardware that encodes data bits to a run length limitedRun Length LimitedRun length limited or RLL coding is a line coding technique that is used to send arbitrary data over a communications channel with bandwidth limits. This is used in both telecommunication and storage systems which move a medium past a fixed head. Specifically, RLL bounds the length of stretches ...
line codeLine codeIn telecommunication, a line code is a code chosen for use within a communications system for baseband transmission purposes...
, and decodes the line code back to data bits, is an endec. - When implementing the Infrared Data AssociationInfrared Data AssociationThe Infrared Data Association defines physical specifications communications protocol standards for the short-range exchange of data over infrared light, for uses such as personal area networks ....
(IrDA) protocol, often an endec is used between the UART and the optoelectronics.