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Digital audio formats

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Digital audio formats

Below is a non-exhaustive list of the most widely used digital audio formats.

AIFF – Audio Exchange File Format

Apple uses a standard audio format. This can be considered the wav equivalent of a mac environment. Audio data is organized according to PCM encoding and is not compressed. There is also a condensed option defined as AIFF-C or AIFC.

AAC – Advanced Audio Encoding

This format is based on MPEG2 and MPEG4 lossy compression standards. It was created as a successor to the mp3 format, which uses a slightly better algorithm. This allows you to get slightly better quality for the same speed.

ALAC – Apple Lossless Audio Codec

This is Apple’s lossless audio format. Also called ALE (Apple Lossless Encoder).

ATRAC (.mp3) – acoustic coding of adaptive transformation

Old Sony audio format with ATRAC compression. Files always have a .mp3 extension, but you need the ATRAC3 driver to open them. MiniDisc was a commercial advertising product that took advantage of this type of format. The codec was later improved by subsequent enhancements such as ATRAC3 (1999), ATRAC3plus (2002), and ATRAC Advanced Lossless (2006).

AS

This is the standard audio format used by Sun, Unix, and Java operating systems. Data encoding can be PCM (uncompressed) or compressed with μ-law, a-law G729 codecs. The Au audio format was introduced by Sun Microsystems. It was a format used on NeXT systems and early websites. Initially, the file did not have a header (the original data from the file) because the encoding was unique: 8 bits with µ-law compression and a sampling rate of 8000 Hz. The latest version of this format contains a header consisting of six blocks. 32 bits, an optional block of information, and finally audio data.

FLAC is a free lossless audio codec

It is an audio codec with lossy compression (without losing information). Data compression can reach 50-60% without losing quality.

M4P

It is a patented version of the MP4 AAC format with a DRM (Digital Rights Management) system developed by Apple to download music from the iTunes Music Store.

MPEG-4 Part 14 or MP4 (formerly ISO / IEC 14496-14: 2003) is a storage medium for multimedia data. It is mainly used to store audio / video data, but can also be used to store other types of data, such as still images and subtitles. Like all modern formats, this format allows data to be sent over the Internet in real time: this feature is implemented by adding a data path for transmission control. The only extension for files that use this codec is .mp4.

MP3 – MPEG layer III audio recording

It is currently the most widely used audio format. The MPEG-1 or MPEG-2 III audio layer, commonly referred to as MP3, is a patented lossy format. It is used for digital music use at the user (non-professional) level.

OGG

It is an open source container that supports a variety of formats, the best known being the Vorbis audio format. This format offers MP3-like audio compression, but is less common. The big difference with mp3 is the absolute free format. In terms of performance, with the same parameters, Vorbis is slightly more efficient than MP3.

The Ogg cache can handle multiple independent streams at the same time: audio, video, text (such as subtitles), and additional data (metadata).

RA and RM

This is a format developed by Real Audio to transmit audio over the Internet. The .Ra format allows you to store all the audio files you want to transfer in one file. The codec enables transmission from very low quality to high accuracy.

RAW

A RAW file can contain any type of data, but in reality it is mainly used for PCM-encoded (uncompressed) audio data. Thus, unlike the uncompressed audio format (wav, aiff), a flat file does not contain headers with information about the data itself (usually the header contains information about: sampling rate, quantitative bits, channels, type of markup used for the ideas). A typical file extension for this type is: .raw, .pcm, without the extension.

Vox

This audio format uses Dialogic ADPCM (Adaptive Differential Pulse Code Modulation). This performs 4. compression. Vox files are similar to wave files, except that they do not have a header, so you need to specify frequency information.

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Digital audio: a simple but deep explanation about digital audio. Part 1

Sound is a phenomenon that implies a propagation of waves generally produced by a vibratory movement of a body. The propagation of sound implies a transport of energy without carrying out a transport of matter.

As the sound is produced by a wave movement when applying the Fourier transform we can express it by a sum of sinusoidal curves that correspond to pure tones that can be characterized by the magnitudes of any wave such as:

-Period It is the time elapsed between two equivalent points of a wave.
– Wavelength It is the real distance a wave travels from its highest point to the next equivalent point.
-Frequency It is the magnitude that measures the number of repetitions in a space of time.
-Amplitude It is the distance between the furthest point of the wave with the equilibrium point.

These magnitudes give the sound a series of characteristics such as:

-Duration: Determines the length or short of the sound due to the time, measured in seconds, it occupies.
-Intensity: Determines the high or low sound due to what we know in relative terms as volume, which is measured in decibels (it is a logarithmic scale).
-Timbre: Determines the proper nuance of each instrument or sound source due to the different harmonics that compose it.
– Hue: Determines the acute or serious sound due to the frequency it has. The frequency is measured in hertz (Hz).

If we carefully consider it, we will see that the initial concept of Mp3Gain was intensity, which is measured in decibels and represents the loudness we perceive.

Digital audio

Digital audio is the digital coding of an electrical signal that represents any sound wave. This electrical signal is picked up for example by a microphone, which takes the sound whose nature is analog and transforms it into electricity that still has the same type of analog nature, then through the necessary hardware and software it can be transformed into binary information, turning Something continuous in discreet. This process involves two tasks: sampling and digital quantification of the electrical signal.

Within the digital audio there are different types of formats to represent the audio:

-PCM: They contain all the information received from the analog to digital converter, without any omission of data. This makes the type of formats that have the best quality in the digital world. WAV is an example of this type of format in question.

-Compressed: It is similar to the previous one, but specific compression techniques are used in which “non-essential” information can be lost to reduce the size of the final file. They usually have good quality in relation to the weight of the file, but as noted above, information is lost, so those with sufficiently developed / trained ears might perceive that there is something strange in a song for example. On the one hand we have formats such as MP3 and OGG that compress with loss, compared to FLAC that compresses without loss. Obviously between one format and the other there is a notable difference in the size of the final file.

-Descriptive: They are used primarily to make music and contain mainly a description of what would be the “score” of the song. With this description, the algorithm, which reproduces the song, can take a sound source with samples of the instruments that the composition needs, to synthesize the final sound based on the indications of the “score”. Examples of this format are MIDI and tracker formats (MOD, XM, IT, etc.). The difference between MIDI and tracker formats is that the latter bring built-in sound sources into the file, so the final file weighs more than using MIDI. However, with MIDI we will need to obtain a sound source on our own or use the one that brings the default sound card (which is not usually too good).