Codecs are crucial to the quality and efficiency of data encoding. In this practical tip we explain exactly what a codec is.
What is a codec? – 10 facts
The following information will help you understand what a codec is. The following example shows the differences between format, encoder, and decoder and shows how quality and efficiency depend on the codec.
-A codec is a combination of encoder and decoder.
-The objective of a codec is usually to reduce the amount of data for transmission or storage.
-Codecs are used in particular for audio, video and image data, as well as for text compression and encryption.
-In the audio sector there are special codecs for voice or music. -Video and graphics codecs are specially designed for comics / cartoons and real pictures / movies.
Lossy data reduction primarily uses psychophysical tricks to inaccurately encode those parts of image and sound that humans can barely or barely perceive.
-The most popular audio codecs are FLAC and MP3, where FLAC specifies both the format and the codec. MP3 is a codec for audio in MPEG I or MPEG II format.
-The MP3 decoder side is standardized by Fraunhofer and can be obtained without a license. However, the encoder is paid. Therefore, many use the free LAME encoder.
-G.722.2 and Full Rate (FR) voice codecs are used especially in telephony.
-The most popular video codecs are H.265 for UHD TV, DivX and XviD in MPEG-4 Part 2 and H.264 for QuickTime.
-Often various encoded formats like MP3 and JPG are combined into one container file, for example in AVI, MKV, MP4 and FLV.
A simple codec example
The principle of a codec is clarified with an example. An abbreviation codec reduces typed text to abbreviated text and uses it to generate typed text:
-Format: Your digital font format might dictate how all the letters and characters you use are encoded in binary.
-You define the type of encoding in a specification, for example, the rule that each character consists of 8 bits. To do this, write a table showing which bit sequence is assigned to which letter or character.
-Codec: You can now create an abbreviation codec to convert typed text into font formatted abbreviated text.
-To do this, your codec must specify which words will be abbreviated and how, for example, through a set of rules, a large list of abbreviations or a combination.
Encoder – An encoder can now convert typed text to abbreviation format using the rules and directory.
Decoder: a decoder can convert it to written text.
-The efficiency of data reduction is highly dependent on your codec.
-If you only created a directory with three abbreviations, most of the texts will not be noticeably shorter. Compression is low.
-If your list of abbreviations is huge, the device that is going to encode and / or decode the text must have a large memory and a high reading speed.
-However, if you set up a smart set of rules for encoding, your codec is ideally small and the end device doesn’t have to do a lot of computing or reading work.
-If a word can be abbreviated in more than one way, that’s fine. A good encoder would use the most efficient abbreviation.
-However, if an abbreviation can have multiple meanings, you have lost information. This will probably render your codec unusable.
-However, if only the words that you know you are omitting were abbreviated ambiguously, you would have invented a lossy psychophysical encoding. This takes advantage of the fact that you do not visually perceive every existing word optically.
-This idea is not entirely false. Because, as this example shows, we don’t necessarily read exactly what is written.
