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Technical Info Digital audio file formats explained.

Technical Info Digital audio file formats explained.

Recording file formats

DSS Transcription

Digital Speech Standard. Highly compressed file format enabling files to be recorded, downloaded and emailed. DSS is currently the industry standard for digital dictation. DSS can be converted to WAV format but the file will be much larger so therefore not recommended. DSS files are usually only 1/12th – 1/20th the size of a WAV file and there is no reduction in playback quality. DSS compression occurs at the time of recording so other files cannot be converted to DSS.

WAV Transcription

Uncompressed audio file format originally developed and built into Windows 95. These files are large due to being uncompressed.

It’s a standard that was developed by Microsoft and IBM back in 1991.

A lot of people assume that all WAV files are uncompressed audio files, but that’s not exactly true. WAV is a Windows container for different audio formats. This means that a WAV file could potentially contain compressed audio, but it’s rarely used for that.

MP3 Transcription

MP3 files are compressed and filter out sounds the human ear cannot hear, reducing the file size. Can be played by most portable digital audio players and many DVD players. About 1/12th the size of conventional WAV format.

Nearly every digital device in the world with audio playback can read and play MP3 files, whether we’re talking PCs, Macs, Androids, iPhones, Smart TVs, or whatever else. When you need universal, MP3 will never let you down, which is why it’s one of the world’s most popular audio file formats.


An MP2 file is an audio file compressed using MPEG-1 Audio Layer II compression. The .MP3 format has largely replaced the MP2 format. However, MP2 is still used for digital radio and television broadcasts.

Windows Media Audio Transcription (WMA)

Similar to MP3. Supported on fewer devices and DVDS than MP3, but noticeably better quality. It was first released in 1999 and has undergone several evolutions since then, all while keeping the same WMA name and extension. It’s a proprietary format created by Microsoft.

Not unlike AAC and OGG, WMA was meant to address some of the flaws in the MP3 compression method—and it turns out that WMA’s approach to compression is pretty similar to AAC and OGG. So yes, in terms of objective compression quality, WMA is actually the better audio file type than MP3.

AMI Files

AIFF stands for Audio Interchange File Format. Similar to how Microsoft and IBM developed WAV for Windows, AIFF is an audio file format developed by Apple for Mac systems back in 1988.


AAC stands for Advanced Audio Coding. It was developed in 1997 as the successor to MP3, and while it did catch on as a popular audio format, it never really overtook MP3 as the most popular.

The compression algorithm used by AAC is much more advanced and technical than MP3, so when you compare the same recording in MP3 and AAC formats at the same bitrates, the AAC one will generally have better sound quality.

Even though MP3 is more of a household format, AAC is still widely used today. In fact, it’s the standard audio compression method used by YouTube, Android, iOS, iTunes, later Nintendo portables, and later PlayStations.


Audio file saved in the 3GPP format, which was developed by the 3rd Generation Partnership Project; most commonly used on cell phones for capturing, playing, and transmitting audio data.


AIFF stands for Audio Interchange File Format. Similar to how Microsoft and IBM developed WAV for Windows, AIFF is an audio file format developed by Apple for Mac systems back in 1988.

Also similar to WAV files, AIFF files can contain multiple kinds of audio formats. For example, there is a compressed version called AIFF-C and another version called Apple Loops used by GarageBand and Logic Audio. They both use the same AIFF extension.


An OGG file is an audio file, similar to an .MP3 file, that typically stores music. It contains audio data saved in the Ogg container format and compressed with Vorbis audio compression. OGG files may also include song metadata, such as artist information and track data.


An AMR file is an audio file saved in a compressed audio format developed by Ericsson. It is optimized for storing spoken audio and is used by many 3G cell phones to store voice recordings, which include MMS messages.


An ASF file is a multimedia file stored in the Advanced Systems Format (ASF), a proprietary video and audio container format. It may store only audio data or video and audio data, along with optional metadata, such as title, author, and bibliographic copyright data. Microsoft developed ASF files primarily for streaming media online.


MP4(short for MPEG-4 Part 14) is a file format based on ISO/IEC 14496-12:2004 that is based on QuickTime File Format but formally specifies support for Initial Object Descriptors (IOD) and other MPEG features. It is mostly used to store video and audio but can also be used to store subtitles and still images.


An M4A file is an audio file that may store various types of audio content, such as songs, podcasts, and audiobooks. It is saved in the MPEG-4 format and encoded with either the Advanced Audio Coding (AAC) codec or the Apple Lossless Audio Codec (ALAC).


Audio format developed by the Nippon Telegraph and Telephone Corporation (NNT Labs); uses transform-domain weighted interleaved vector quantization to compress audio data; can be encoded in 80, 96, 112, 128, 160, and 192 kbps bitrates.


An AC3 file is an audio file saved in the AC-3 (Dolby Digital) audio format. It can include up to six channels of audio (DD 5.1 surround sound with subwoofer output). Cinema movies, DVDs, Blu-rays, and video games often use audio saved as AC3 files.


A MIDI file contains electronic music data saved in the Musical Instrument Digital Interface (MIDI) format. The MIDI format defines notes that are played, when they are played, how long they are held, and their velocities (how hard they are pressed). Many music applications can load MIDI files, along with MIDI hardware devices.

Technical helplines

Olympus European: 00800 67 10 83 00
Ndeava: 01769 560 620
Speak-It: 0870 700 9080
Sanyo: 0800 328 7060
Philips: 01206 755903
Grundig: 01277 725129
Dictaphone: 0121 433 4848

Standard Play and Long Play with Philips Recorders

The DSS Standard Play (SP) mode is the compatible format for professional mobile dictation devices. The Long Play (LP) modes are not a mandatory format and are implemented differently by different manufacturers. The achieve best sound quality, Philips recommends the use of SP recording mode only. The LP mode recording format is recommended to extend the recording time if needed.

Voice Activated Recording

Avoid using this if your recorder has this feature as the recorder takes a split second to wind up and the beginnings of sentences are generally cut off.

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