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.

spx

An audio file with recorded voice messages

This format extension is one of the Speex Audio formats. It is an open-source codec developed by Xiph.Org. Used for creating voice messages and transmitting voice over packet-based networks with a low level of security. It is an audio file with recorded voice messages that are packaged in an OGG file. Only certain media players can open it.