wav The Waveform Audio file format associated with the .wav filename extension was a format developed through collaboration between Microsoft and IBM. It is an extension of the RIFF and was first released in 1991. It is one of the earliest standards used for encoding audio bit streams on personal computers. It is typically used for storing uncompressed raw audio files on the Microsoft Windows platform, however it enjoys cross platform support on Macintosh and Linux and does have support for compressed audio. Because of the relatively large file sizes of uncompressed .wav files, the WAVE format in unpopular for file distribution over limited bandwidth computer networks including the internet.
amr The .amr filename extension refers to the adaptive multi-rate audio codec initially released in 1999. The format is typically used to encode speech audio and is optimized for this purpose. It can encode speech into one of two file version, either AMR-NB (narrow Band) or AMR-WB (Wide Band) which supports a broader frequency. Because of its optimization for speech audio, the format has been widely adopted as the standard speech codec for GSM and UMTS mobile phone networks by the 3rd Generation Partnership Project ' a collaborative group of organizations in the telecommunications industry.