Lossy and Lossy Digital Audio Formats: Audio Codec Guide
In recent years, the way we listen to music has changed a lot, also thanks to the Internet, which has allowed a great diffusion of digital audio files. In a short time we went from vinyl to CD, to online music transmitted in high resolution.
An analog sound to be handled by a computer must become digital. To maintain the exact fidelity of the original audio, you must write a lot of information, thus producing heavy files that take up a lot of disk space. Hence the need to reduce the size of the audio file to save space on various storage media, such as hard drives, but also to take better advantage of the available bandwidth for transferring and listening to files.
Digital audio formats
Every day we use multimedia content such as YouTube, online radio or music streaming services, with a quality that is sometimes enough, other times excellent. This is because the files are the result of a data compression process through the use of codecs.
What is an audio codec?
A codec is an algorithm for encoding and decoding the audio (but also video) data stream.
It is used both to compress a file and to convert, for example, an analog to digital file. The difference in digital audio formats lies in the type of compression that determines their quality and, consequently, their size according to the type of codec used.
Types of digital audio formats.
Audio formats can be of three types:
-Loss (with data loss)
-No loss (no data loss)
-Uncompressed
Lossy digital audio formats
Lossy audio formats are compressed files with lost data and information. They allow you to significantly reduce the size of the original file, even up to 90%. The sound quality is lower than the CD-Audio standard because the compression algorithm “cuts” certain frequencies that the human ear has more difficulty perceiving and, therefore, are less relevant, generally the highest (more than 16 -17,000 Hz).
The Lossy audio format is widely used for listening to digital audio, such as streaming (Spotify, Deezer, Apple Music, etc.). Depending on the type of codec used, compression can vary significantly, as does the quality of the listening. The most popular and popular format is MP3 and WMA.
MP3
The most famous and well-known digital audio format. In its entirety, Motion Picture Expert Group-1/2 Audio Layer, 3, developed by MPEG, offers good compression and discrete audio quality, in particular with a bit rate of 192 kbit / s and 320 kbit / s. Although still widely used, better compression algorithms can be found.
OGG Vorbis
The open source format without lossy audio compression offers an excellent alternative to MP3. With the same perceived quality, it allows for greater compression. The high frequencies (above 16 kHz) are wider and wider, offering greater spatiality of sound. Also used in computer games, it is also often used for audio streaming. Spotify music, for example, uses the Ogg Vorbis digital audio format from 96 kbit / s to 320 kbit / s in addition to the AAC codec.
WMA
Windows Media Audio is Microsoft’s proprietary digital audio format. Encrypted WMA offers excellent compression and good audio quality at high bit rates, but at the same time little compatibility. Precisely for this feature it is now little used. WMA consists of four different codecs: WMA codec, lossless WMA (lossless), WMA Pro, or WMA Voice.
AAC
The Advanced Audio Coding Format (AAC) is part of the MPEG consortium and was born as MP3’s successor. It became famous thanks to Apple that uses it with iTunes, but also thanks to several radios (DABè) that use it to transmit audio. It is the excellent quality and good compression digital audio format used by YouTube, iPhone, Android smartphones and many other devices such as Nintendo and Playstation. The AAC supports 48 audio channels with sampling up to 96 kHz and uses constant bit rate (CBR – Constant Bit Rate) or variable (VBR – Variable Bit Rate) compression encoding. AAC is one of the best lossy codecs, the encoding speed is not among the best.
MPC
Musepack (or MPC) together with AAC vies for the podium as the best lossy digital audio format. The quality is very high, thanks to the VBR encoding that guarantees a good distribution of the bit rate. The peculiarity of this codec, in terms of AAC, is the clarity of the sound, which is very wide and spacious. Good encoding speed, it is ideal for those looking for quality while keeping a small audio file size.
ATTRAC
ATRAC (Adaptive Transform Acoustic Coding) is a lossy audio compression algorithm developed by Sony. Born for MiniDisc (MD) whose production ended in 2013, this codec has not been very successful and is no longer used today.
mP3Pro
Derived from MP3, its peculiarity lies in the fact that it maintains the same quality as an MP3 at 128 kbps but with lower bit rates, from 64 kbps to a maximum of 96 kbps. Compression of the higher frequencies, a painful note from lossy files, occurs through the Spectral Band Replication (SBR) algorithm. The result is space savings at lower bit rates, but also less dynamic and unclear sound.
Dolby Digital
Dolby Digital is a multi-channel audio encoding system, used primarily in DVD, film, and digital television. Contrary to what one might think, it is a lossy audio format, therefore compressed with loss of information. Known as Dolby Digitale 5.1, it works with a minimum bit rate of 96 kbit / s up to a maximum of 640 kbit / s. On DVD, it maintains an average of 192 kbit / s in stereo audio and up to 448 kbit / s in 5.1 signals
Lossless digital audio formats
Lossless audio formats are compressed but lossless files. They maintain the original audio quality, without degrading its characteristics in any way, while managing to compress certain information up to 40-50%. The most popular and widely used Lossless Codec format is the FLAC (Free Lossless Audio Codec) file. Apple has produced its own lossless format called ALAC (Apple’s Lossless Audio Codec) that iTunes uses.
Lossless files offer the quality of a CD (reported as standard), but to maintain fidelity, the dimensions will be larger and take up more disk space than Lossy, but still half the original file.
FLAC
FLAC (Free Lossless Audio Codec) is a codec released under a free software license with lossless data compression. Extended and compatible with most audio devices, the FLAC codec compresses data from a minimum of 30% to 50%, compared to the original file, while maintaining the perceived quality unchanged.
A Flac file can be 8, 16, or 24-bit deep and has a sample rate of up to 192 kHz (Flac Hi-Res).
Various music audio streaming services like Deezer Music, QoBuz, Tidal offer high quality music equal to or higher than the CD standard using this format.
Lossless wma
WMA Lossless is the lossless version of Microsoft’s WMA Lossy codec. It offers good and fast compression. Although it is proprietary, it can also be played by VLC Media Player, WinaAmp, RealPlayer and others.
A THE C
ALAC (Apple Lossless Audio Codec), also known as ALE (Apple Lossless Encoder) is an audio codec developed by Apple in 2004. In 2011, the source code was made available under an open source license. Primarily used by iTunes, other online music services have also used it in recent years. Excellent audio quality and fast decoding, but slightly less compression than FLAC files.
