Open file formats are published specifications for storing digital data which can be used and implemented by anyone. These are maintained by a standard organization. An open format can be implemented by both proprietary and free and open source software with the help of typical licenses used by each. Open file formats are published specifications for storing digital data, and open formats are not encumbered by any copyrights, patents, trademarks or other restrictions are known as free file formats.
The different types of open file formats include:
- gsm - It was the first digital speech coding standard that was used in the GSM digital mobile phone system. Also known as Full Rate or FR or GSM-FR or GSM 06.10, it has a bit rate of 13.2 kbit/s or 1.65 bits/audio sample. Wav files can also be encoded with the gsm codec and this makes a great compromise between file size and quantity.
- dct – These variable codec audio file formats were designed for dictation by NCH Software. The dictation header information can be encrypted.
- vox – It is an audio file format that has been optimized for storing digitized voice data at a low sampling rate. Also known as Dialogic ADPCM, VOX files are commonly found in telephony applications and an occasional arcade redemption game. The format uses the Dialogic ADPCM codec and compresses to 4-bits.
- aac – Advanced Audio Coding is a lossy compression and encoding scheme for digital audio, designed to be the successor of the MP3 format. It achieves better sound quality than MP3 albeit at similar bit rates. The format is based on the MPEG2 and MPEG4 standards. These files are generally ADTS or ADIF containers. It is the standard or default audio format for Apple’s iPhone, iPod, iTunes.
- mp4/m4a – MPEG-4 Part 14 or MP4 file format is a multimedia container format standard that has been specified as a part of MPEG-4. The format is commonly used to store digital video and digital audio streams. They can also be used to store subtitles and still images.
- mmf – This is a Samsung audio format used in ringtones.