Are you confused by different digital audio file extensions?
The Monkey's Audio and other confusions
You have downloaded some music from the Internet, started your favourite media player and sit back to enjoy the soothing sounds. Nothing happens. You have just crossed the threshold where the only digital music you knew about was Mp3. Do not despair. You will be able to play your music - eventually.
In the last decade, many different audio formats and codecs have seen the light. Some of these have become very popular and any music lover should become familiar with the terminology. With the different formats, different media players were also created, as were ways to convert files and ways to adapt current media players to play some of these file formats.
Basic terms and formats
Basic terms
- digital audio format: the format of the digital audio data
- codec: a computer algorithm used to compress and decompress digital audio data in a particular audio format
The different formats can be divided in three categories:
- uncompressed audio file formats
- lossless compression audio formats
- lossy compression audio file formats
Different file formats permit diverse file sizes and qualities.
Uncompressed audio file formats
The original sound recording is usually stored as a WAV file (or AIFF in MAC) from PCM (Pulse Code Modulation) format. These are usually quite large (about 10MB for every minute) . Other formats are BWF (Broadcast Wave Format) which allows metadata to be stored in the file.
Uncompressed audio formats encode both sound and silence with the same number of bits per unit of time.
Lossless compressed audio formats
A lossless compressed format eliminates unnecessary data and thus stores data in less space. It requires a lot of processing power both to compress the data and then to uncompress to play the sound.. In a lossless compressed format the music itself would occupy a small space than in uncompressed formats, and silence will take up almost no space at all. The original uncompressed data can be recreated exactly.
These include, Flac (.flac), WavPack (wv), Monkey's Audio (.ape) , ALAC/Apple Lossless (m4a).
Development in lossless compression formats aims to reduce processing time while maintaining a good compression ratio.
Lossy compressed audio formats
Lossy compression reduces file size even more by removing some of the data with as little as possible reduction in the quality of the sound. These files can be from 25% to 3% of the original data size (the smaller the percentage kept the lower the quality of the data).
The most well-known of these formats is the MP3 with .mp3 extension. Others are Advanced Audio Coding (AAC) with extensions such as aac, mp4, and m4a (Apple).
Proprietary formats include Windows Media Audio (extensions .wma and .asf); RealAudio (extensions .ram and .ra) and QuickTime (extension .mov). There are both lossy and lossless codecs available for WMA.
Open formats include Ogg Vorbis (.ogg) and AIFC (extension .aifc)
So what to choose?
What you select as your music format depends on your lifestyle.
At home on your sophisticated music system, you can show off your original CDs or play lossless music in FLAC format. In your car or while jogging you will probably play your m4a’s on your IPod or Mp3 on your car radio. With some research on the internet, you will be able to convert different formats or download players to play your favourite music.
http://en.wikipedia.org/wiki/Audio_file_format
http://richardgriscom.com/da/node18.html
