KAR is the original format of audio files for creating karaoke, which are formed in a variety of software systems. It has the ability to save not only MIDI file data, but also lyrics. The KAR format is part of the .midi extension. In most cases, they are used as a source for adding special text to regular MIDI files, and they also differ from the Karaoke file. After all, there is no additional track with words that are synchronized with the main melody according to certain algorithms. As a rule, in order to realize the vocal part, you must apply the first track. For a stream of words, a second track is used. This file extension can be obtained using specialized software. But not only. It can also be created using MIDI keyboards that are connected to computer hardware. If there are appropriate plugins, then you can open the KAR file using the Media Player traditional for the Windows operating system. Anyone using the Mac OS platform can play KAR files in the Mireth Technology Music Man karaoke application. But the universal option for this pair of systems is PG Music Band-in-a-Box. This software is the most popular among analogues. Together with the .KAR extension, they sometimes provide reference data on where audio catalogs and item metadata associated with audio tracks are located. It is also possible that there is information about the artist and about the albums.
AU is an audio file format created in Audacity. This is a free cross-platform program designed to edit audio files. AU format (Audio Units) was developed by Sun Microsystems. This format greatly simplifies the task of reliable storage of audio files. An AU file consists of 3 parts: a header (max. 24 bytes), a description block of various sizes, and audio data. The file format is used on computers running the Sun or Unix operating system. However, it opens with other audio players. The AU format uses the logarithmic encoding method, previously very popular on computers running the Sun SPARCstation operating system. Previous sound file formats, in order to reduce the size, used the logarithmic scale of recording samples. Among the representatives of such formats, the Sun AU group of formats, which are still in action, gained great fame. Problems with opening the AU file usually manifest themselves when there are no corresponding applications that would be installed on the PC. Applications that use .AU files are Apple QuickTime Player, Microsoft Windows Media Player, Real Player, Winamp, and other widely used audio players. And this is the vast majority of professional audio editors.