decoder
A decoder is a device which does the reverse of an encoder, undoing the encoding so that the original information can be retrieved. The same method used to encode is usually just reversed in order to decode.
In digital electronics, a decoder can take the form of a multiple-input, multiple-output logic circuit that converts coded inputs into coded outputs, where the input and output codes are different. e.g. n-to-2n, binary-coded decimal decoders. Enable inputs must be on for the decoder to function, otherwise its outputs assume a single "disabled" output code word. Decoding is necessary in applications such as data multiplexing, 7 segment display and memory address decoding.
The example decoder circuit would be an AND gate because the output of an AND gate is "High" only when all its inputs are "High." Such output is called as "active High output". If instead of AND gate, the NAND gate is connected the output will be "Low" only when all its inputs are "High". Such output is called as "active low output".
Example: A 2-to-4 Line Single Bit decoderA slightly more complex decoder would be the n-to-2n type binary decoders. These type of decoders are combinational circuits that convert binary information from 'n' coded inputs to a maximum of 2n unique outputs. We say a maximum of 2n outputs because in case the 'n' bit coded information has unused bit combinations, the decoder may have less than 2n outputs. We can have 2-to-4 decoder, 3-to-8 decoder or 4-to-16 decoder. We can form a 3-to-8 decoder from two 2-to-4 decoders (with enable signals).
Similarly, we can also form a 4-to-16 decoder by combining two 3-to-8 decoders. In this type of circuit design, the enable inputs of both 3-to-8 decoders originate from a 4th input, which acts as a selector between the two 3-to-8 decoders. This allows the 4th input to enable either the top or bottom decoder, which produces outputs of through for the first decoder, and through for the second decoder.
A decoder that contains enable inputs is also known as a decoder-demultiplexer. Thus, we have a 4-to-16 decoder produced by adding a 4th input shared among both decoders, producing 16 outputs.
Founded in 2000, decoder + is a trusted translation company, located strategically in Hong Kong, the gateway to Greater China and Asia.
We owe our success to our specialization in Asian languages and our wide application of international standards.
FFDShow could say it is all-powerful decoding, encoder. Initially FFDShow just mpeg video decoder, but now he can do much more than that. It can decode the video format has far exceeded the scope of mepg4, including the indeo video, WMV, mpeg2 and so on. Meanwhile, it also provides a wealth of processing options, you can sharpen images, adjust the screen brightness and so on. not just video, FFDShow now also can decode the audio, AC3, MP3 and other audio formats can be supported. and you can plug-in winamp plug-in DSP to improve hearing results. FFDShow can say now is the windows-platform multimedia player has been a very good tool.
