This document discusses different types of audio file compression formats including lossy formats like MP3 and AAC that sacrifice quality for size, lossless formats like FLAC and ALAC that compress without quality loss, and uncompressed formats like AIFF and WAV. It provides details on popular lossy formats that remove imperceptible audio data, lossless formats that eliminate unnecessary data while retaining full quality, and uncompressed formats designed for archiving original recordings when storage space allows.

1. Uncompressed
Lossy & Lossless
audio

2. Lossy & Lossless
• Lossy Codec: refers to a codec that sacrifices
file quality for the sake of compression.
• Lossless Codec: does not destroy any data,
regardless of whether or not the data is
necessary for the file’s integrity.

3. Uncompressed audio files
• Uncompressed audio files are large, original studio-quality
digital-audio files. They are flexible file formats designed to
store more or less any combination of sampling rates or
bitrates. This makes them suitable file formats for storing and
archiving an original recording if storage space is no concern.

4. Uncompressed audio files
• AIFF (Audio Interchange File Format) - An audio file format standard used
for storing sound data for personal computers and other electronic audio
devices. The format was co-developed by Apple Computer and is most
commonly used on Apple Macintosh computer systems. Standard AIFF is a
leading format used by professional-level audio and video applications,
and unlike the better-known lossy MP3 format, it is non-compressed
(which aids rapid streaming of multiple audio files from disk to the
application), and lossless. Like any non-compressed, lossless format, it
uses much more disk space than MP3—about 10MB for one minute of
stereo audio at a sample rate of 44.1 kHz and a sample size of 16 bits.
• WAV (Waveform Audio File Format) - A Microsoft audio file format
standard for storing audio on PCs. It is the main format used on Windows
systems for raw and typically uncompressed audio. shortcoming identified
in WAV is its inability to hold any metadata describing its audio contents.
File size is also limited to 4Gb.

5. Lossless audio files
• Lossless audio files are another form of studio-quality digital-
audio format, but they are compressed. A lossless
compressed format stores data in less space by eliminating
unnecessary data. Lossless compression still retains low-level
resolution of a standard CD. The advantage is that it takes up
less room on your computer than an uncompressed format,
and unlike lossy codecs, it does not remove any information
from the audio stream and is suitable both for everyday
playback and for archiving audio collections.
• Development in lossless compression formats aims to reduce
processing time while maintaining a good compression ratio.

6. Lossless audio files
• FLAC (Free Lossless Audio Codec) – The FLAC format is
currently well supported by many software audio products,
and is the only free lossless audio compression format that
has any hardware support.
• ALAC (Apple Lossless compression) – ALAC is an audio codec
developed by Apple for lossless data compression of digital
music. After initially keeping it proprietary for many years
from its inception in 2004, in late 2011 Apple made the codec
available open source and royalty-free.

7. Lossy compression
• Lossy compression enables even greater reductions in file
size by removing some of the data. Lossy compression
typically achieves far greater compression than lossless
compression by simplifying the complexities of the data.
This of course results in a reduction in audio quality, but a
variety of techniques are used, mainly by exploiting
psychoacoustics, to remove the data that has least effect on
perceived quality.
• For many everyday listening situations, the loss in data (and
thus quality) is imperceptible. Most formats offer a range of
degrees of compression, generally measured in bit rate.
The lower the rate, the smaller the file and the more
significant the quality loss.

8. Lossy compression
• AAC (Advanced Audio Coding) – AAC was designed as an improved-performance
codec relative to MP3. File format is typically .mp4 or .m4a (audio only). AAC is the
format used by iTunes
• ATRAC (Adaptive TRansform Acoustic Coding) – Sony’s audio compression
algorithm used to store information on MiniDisc and other Sony-branded audio
players.
• MP3 (MPEG Audio Layer-3) – One of the most popular music formats, due to it
being able to be played or nearly all portable music players.
• MP3 is a lossy format, designed to remove parts of the music that the human ear
find hard to hear. A number of techniques are used to allow ~10:1 compression
compared with uncompressed audio. MP3′s allow encoding at a range of ‘bit
rates’, these are typically between 128 and 320 kilobits per second. Variable Bit
Rate (VBR) is now also commonly used, here the bit rate alters through the music
depending on the demands of the music.

9. Lossy compression
• OGG Vorbis – Vorbis is an open and free audio compression which
normally goes under the name format of OGG. Due to the free
nature, Ogg Vorbis format has proved popular among the open
source communities, along with its claimed best quality lossy audio
codec (at certain bitrates).
• WMA (Windows Media Audio) – WMA is Microsoft’s audio file
format. A WMA file is almost always encapsulated in an Advanced
Systems Format file. The resulting file may have the Filename
extension .wma or .asf (.wma being used being used if audio only).
Windows Media Audio supports DRM which has led to itself as a
competitor to the AAC format used by iTunes.
•