A codec is an algorithm (OK can be simple – some kind of program!), Which is usually software installed on a server or software installed on hardware ( ATA , IP phone , etc.) that is used to convert voice (for VoIP) signals into digital data that is transmitted over VoIP during a call over the internet or another network.
The word “codec” comes from the words “coder-decoder” or “compressor-decompressor” entered. Codecs typically accomplish three tasks (very few do the latter):
- Encoding – decoding
- Compression – decompression
- Encryption – decryption
Encoding – decoding
If you are talking on a regular PSTN phone, your voice will be routed through the phone line in a similar way. However, with VoIP, you turn your voice into a digital signal. This conversion is technically coded and is achieved by a codec. When the digitized voice reaches its destination, it must be decoded back to the original analog signal so that it can be heard and understood by another correspondent.
Compression – decompression
Bandwidth is a scarce product. Therefore, if the data sent is lighter, you can send more over a period of time and thus improve performance. Making a digitized call is less, it’s compressed. Compression is a complex process that stores the same data but uses less space (digital bits). During compression, the data is limited to a structure suitable for the compression algorithm (packet). The assembled data is sent over the network and when it reaches its destination, it is decompressed back to its original state before it is decoded. In most cases, data recovery is not necessary because the compressed data is already in a consumable state.
Types of compression
When the data is compressed, it becomes lighter and thus performance improves. However, it tends to be that the best compression algorithms reduce the quality of the compressed data. There are two types of compression: lossless and lost. With a non-hazardous seal, you lose nothing, but you can’t compress so much. With harmful compaction, you achieve excellent reduction, but you lose quality. Usually, the compressed data cannot be lost in its original state to the compressor because the quality was sacrificed in size. But for the most part, this is not necessary.
A good example of damage compression is MP3 for audio. If you compile the sound, you will not get back the compactness, then MP3 audio is already very good to listen to, compared to huge pure audio files.
Encryption – decryption
Encryption is one of the best tools to achieve security. It is the process of transforming data into a state that no one can understand. In this way, the data will still remain confidential, even if the encrypted data is hidden by unauthorized persons. When the encrypted data reaches its destination, it is decrypted back to its original form. Once the data is compressed, it is already encrypted to some extent because it is changed from its original state.