Function difference between encoder and decoder

In terms of multimedia, the encoder mainly compresses analog video and audio signals into data-encoded files, and the decoder converts the data-encoded files into analog video and audio signals. Generally speaking, one is used for encoding and the other is used for decoding.

The decoder is a hardware/software device that can decode and restore digital video and audio data streams into analog video and audio signals. Encoders such as mpeg4 for video, mp3 for audio, ac3, dts, etc. can compress and store the original data, but these are also commonly used encoding formats, and there are also some professional encoding formats that are basically not used by ordinary families. In order to replay these videos and audios on home devices or computers, you need to use decoding software, which is generally called a plug-in. Such as mpeg4 decoding plug-in ffdshow, ac3 decoding plug-in ac3fliter and so on. Only your computer with various decoding plug-ins can play these images and sounds. In terms of multimedia, the encoder mainly compresses analog video and audio signals into data-encoded files, and the decoder converts the data-encoded files into analog video and audio signals.

The decoder classification is as follows:

According to the PTZ power supply voltage, it is divided into AC decoder and DC decoder.

According to the communication mode, it is divided into one-way communication Shanghai decoder and two-way communication decoder.

According to the transmission mode of communication signals, it can be divided into coaxial transmission and twisted pair transmission.

The circuit of the decoder is based on the single-chip microcomputer, and is composed of power circuit, communication interface circuit, self-check and address input circuit, output drive circuit, alarm input interface and other circuits. The decoder can control the up, down, left and right rotation of the pan/tilt, the zoom, focus, aperture of the zoom lens and the control of the protective cover wiper, camera power supply, lighting and other equipment. It can also provide several auxiliary function switches to Meet the actual needs of different users. High-end decoders also have preset positions and cruise functions.

The output of absolute encoder is multi-digit digital (Gray code or pure binary code). Parallel output means that there are multiple high and low level outputs on the interface to represent digital 1 or 0. For absolute encoders with low digits , Generally, the digital output is directly in this form, which can directly enter the I/O interface of the PLC or the upper computer, the output is instant, and the connection is simple.

The main function of the codec is to compress and decompress the video signal. The compression ratio of the codec ranges from the general 2:1 to 100:1, making it possible to process a large amount of video data. There are differences between the three but also related aspects.