• mp3 - the MPEG Layer-3 format is the most popular format for downloading and storing music. By eliminating portions of the audio file that are essentially inaudible, mp3 files are compressed to roughly one-tenth the size of an equivalent PCM file while maintaining good audio quality. The mp3 format is recommended for music storage. It is not that good for voice storage.
• gsm - designed for telphony use in Europe, gsm is a very practical format for telephone quality voice. It makes a good compromise between file size and quality. Note that wav files can also be encoded with the gsm codec.
• dct - A variable codec format designed for dictation. It has dictation header information and can be encrypted (often required by medical confidentiality laws).
• vox - the vox format most commonly uses the Dialogic ADPCM (Adaptive Differential Pulse Code Modulation) codec. Similar to other ADPCM formats, it compresses to 4-bits. Vox format files are similar to wave files except that the vox files contain no information about the file itself so the codec sample rate and number of channels must first be specified in order to play a vox file.
• [[|Advanced Audio Coding|aac]] - the Advanced Audio Coding format is based on the MPEG2 and MPEG4 standards. aac files are usually ADTS or ADIF containers.
• mp4/m4a - MPEG-4 audio most often AAC but sometimes MP2/MP3

Proprietary Formats

• wma - the popular Windows Media Audio format owned by Microsoft. Designed with Digital Rights Management (DRM) abilities for copy protection.
• atrac (.wav) - the older style Sony ATRAC format. It always has a .wav file extension. To open these files simply install the ATRAC3 drivers.
• ra - a Real Audio format designed for streaming audio over the Internet. The .ra format allows files to be stored in a self-contained fashion on a computer, with all of the audio data contained inside the file itself.
• ram - a text file that contains a link to the Internet address where the Real Audio file is stored. The .ram file contains no audio data itself.
• dss - Digital Speech Standard files are an Olympus proprietary format. It is a fairly old and poor codec. Prefer gsm or mp3 where the recorder allows.
• msv - a Sony proprietary format for Memory Stick compressed voice files.
• dvf - a Sony proprietary format for compressed voice files; commonly used by Sony dictation recorders.
• m4p - A proprietary version of AAC in MP4 with Digital Rights Management developed by Apple for use in music downloaded from their iTunes Music Store.