Developed by Apple in 2004, M4A is an audio file created in a multimedia format. It is used to store compressed video and audio files. Worth noting, M4A files can also store images. Using different codecs, you can compress the file with or without losses. M4A is an improved version of the mp3 format. You can convert it to other formats without any loss of quality and size. Playable on devices powered by any Apple platform.

amr

AMR (Adaptive Multi Rate): adaptive encoding with variable bitrate

This information compression format allows for optimizing speech encoding. Files in the Adaptive Multi Rate format can be created using phones and smartphones. AMR files are mostly used for voice recordings. The main advantages of the format are the large number of encoding and decoding rates, as well as the small size of the resulting content. With the help of appropriate software, an Adaptive Multi Rate file can be converted into any other audio format.