For what purposes and how are codecs used?

Let’s start with the analysis of the name that is the result of the union of two words CODer and DECoder. In fact, through the codecs it should be possible both to decode multimedia, audio or video files, as well as to create them.
In reality, codecs do not always allow file creation and the reason is often legal or commercial in nature.

Its internal functioning is usually very complex, due to
to the nature of the processing they must perform. While the
The purpose is to allow the expansion capacity of the different players, so that they can see or let us listen to the content of the files written in a format that they did not understand at the time of their launch.

Regardless of the file format, the content is always the same, that is, a movie or audio, intended to be played.
So it was decided to introduce an additional software layer between the file and the player, which filters access to the file itself and that
always makes the player “see” the same type of object even if the file format varies.

In order to use codecs, you first need to know
its existence, which is why in Windows systems there are
parts of the log file, which collect information
on the different multimedia filters installed. Generally, your
Interaction with players is done through COM interfaces.
Simply put, when we tell our favorite player to open a media file, it will do nothing more than retrieve the list of installed codecs and try to open the file with
each. If one of the codecs is successful, the player will use it
to show us or listen to the file.

As we have seen, its use is completely transparent for the user and is completely managed by the player. Some players even manage the installation of the necessary codecs. However, it is also possible to install them manually. On Windows systems, codecs that use COM technology are generally in the form of DLLs that must be registered, a procedure that involves entering all public interfaces of the codec in the registry file.
To do this, you need to run the command
“Regsvr32 <dll name>” while uninstalling it
just add the “/ u” option to the first command.

Other operating systems use some interprocess communication mechanism other than COM, but the structure does not change. That is, it is always a filter to access the file.

The existence of different formats and related CODECs arises for technical and commercial reasons. Different multimedia companies usually prefer to define their own encoding formats, to optimize their use by their applications.
And in addition to this, by defining their own format, they are not obliged to pay user licenses
. This mainly applies to file generation; in fact, many codecs are simply decoders.

In this way, companies can add read support for various formats to their applications at no additional cost, while using their proprietary format for saving.