A codec (coder-decoder or compressor-decompressor) is a program used to convert voice signals into the digital bit stream and back to be conveyed over the Internet or any network during a VoIP call. The codecs for VoIP are also termed “vocoders,” meaning voice encoders.
Codecs typically perform encoding-decoding, compression-decompression, and least often, encryption-decryption.
Encoding – Decoding
When you use a conventional public switched telephone network (PSTN) phone, the produced voice is carried in an analog manner over the phone line. When VoIP technology is used, the voice is converted into digital signals. This conversion is the process of encoding. When this digital signal reaches its end point, it has to be decoded back to its original analog state so the other party can perceive sound and understand it.
Compression – Decompression
Bandwidth is a limited article of trade so if the data to be transmitted is less bulky, you can transmit more in a given time, hence enhancing its function. To make the digitized data (the voice) lighter, it is compressed by the codec.
Compression is an intricate course of action whereby the same data is saved but there is less digital space used. During this process, the digitized data is restrained to a packet to the compression algorithm.
The lighter data is transmitted over the IP network. Once it arrives at its end point, it is decompressed back to its previous form before it becomes decoded. Most of the time, the data is not decompressed back since the compressed data is already in a consumable state.
Encryption – Decryption
Encryption is one of the best ways to provide security. In encryption, the data is converted into a state which no one can understand. This way, even if the encrypted data is interrupted by illicit individuals, the data would still be confidential. When the encrypted data gets to its end point, it is decrypted back to its previous state. Sometimes, data is already somehow encrypted when it is compressed, since it is changed from its original form.
There are many codecs for video, audio, text, and fax. As a user, you may deem it unnecessary for you to study what these are. However, it is always good to know even a little of these codecs, since you might have to relate codecs concerning VoIP in your business in the future.
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