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A screenshot of FL Studio 10, a popular DAW by Image-Line.

A digital audio workstation (DAW) is an electronic system designed solely or primarily for recording, editing and playing back digital audio. DAWs were originally tape-less, microprocessor-based systems such as the Synclavier and Fairlight CMI. Modern DAWs are software running on computers with audio interface hardware.^[1]

Integrated DAW[link]

An integrated DAW consists of a mixing console, control surface, audio converter, and data storage in one device. Integrated DAWs were more popular before personal computers became powerful enough to run DAW software. As computer power increased and price decreased, the popularity of the costly integrated systems with console automation dropped. Systems such as the Orban Audicy once flourished at radio stations and television stations. Today, some systems still offer computer-less arranging and recording features with a full graphical user interface (GUI).

Software DAW[link]

A computer-based DAW has four basic components: a computer, a sound converter (also called a sound card or audio interface), a digital audio editor software, and at least one input device for adding or modifying musical note data. This could be as simple as a mouse, and as sophisticated as a MIDI controller keyboard, or an automated fader board for mixing track volumes. The computer acts as a host for the sound card and software and provides processing power for audio editing. The sound card (if used) or external audio interface typically converts analog audio signals into digital form, and for playback converting digital to analog audio; it may also assist in further processing the audio. The software controls all related hardware components and provides a user interface to allow for recording, editing, and playback. Most computer-based DAWs have extensive MIDI recording, editing, and playback capabilities, and some even have minor video-related features.

Simple smartphone-based DAWs, called Mobile Audio Workstation (MAWs), are also available, used for example by journalists for recording and editing on location.

Common functionality[link]

As software systems, DAWs could be designed with any user interface, but generally they are based on a multitrack tape recorder metaphor, making it easier for recording engineers and musicians already familiar with using tape recorders to become familiar with the new systems. Therefore, computer-based DAWs tend to have a standard layout which includes transport controls (play, rewind, record, etc.), track controls and/or a mixer, and a waveform display. In single-track DAWs, only one (mono or stereo form) sound is displayed at a time.

Multitrack DAWs support operations on multiple tracks at once. Like a mixing console, each track typically has controls that allow the user to adjust the overall volume and stereo balance (pan) of the sound on each track. In a traditional recording studio additional processing is physically plugged in to the audio signal path. However, a DAW can also route in software or use software plugins to process the sound on a track.

DAWs are capable of many of the same functions as a traditional tape-based studio setup, and in recent years have almost completely replaced them. Modern advanced recording studios may have multiple types of DAWs in them and it is not uncommon for a sound engineer and/or musician to travel with a portable laptop-based DAW, although interoperability between different DAWs is poor.

Perhaps the most significant feature available from a DAW that is not available in analogue recording is the ability to 'undo' a previous action. Undo makes it much easier to avoid accidentally permanently erasing or recording over a previous recording. If a mistake is made, the undo command is used to conveniently revert the changed data to a previous state. Cut, Copy, Paste, and Undo are familiar and common computer commands and usually available in DAWs in some form.

Commonly DAWs feature some form of automation, often performed through "envelopes". Envelopes are procedural line segment-based or curve-based interactive graphs. The lines and curves of the automation graph are joined by or comprise adjustable points. By creating and adjusting multiple points along a waveform or control events, the user can specify parameters of the output over time (e.g., volume or pan). Automation data may also be directly derived from human gestures recorded by a control surface or controller. MIDI is a common data protocol used for transferring such gestures to the DAW.

MIDI recording, editing, and playback is increasingly incorporated into modern DAWs of all types, as is Synchronization with other audio and/or video tools.

History[link]

The earliest attempts at creating digital audio workstations in the 1970s and 80s were limited by factors such as the high price of storage, vastly smaller slower processing and disk speeds available. But in the face of this, the company Soundstream (who previously came to prominence in the early days of digital audio by releasing one of the first commercially available digital audio tape recorders in 1977), built what could be considered the first digital audio workstation in 1978, using some of the most current computer hardware of the time. The Digital Editing System, as Soundstream called it, consisted of a DEC PDP-11/60 minicomputer running a custom software package called DAP (Digital Audio Processor), a Braegen 14"-platter hard disk drive, a storage oscilloscope to display audio waveforms to be edited, a video display terminal for controlling the system, and interface cards that plugged into the PDP-11's Unibus slots (the Digital Audio Interface, or DAI) that provided analog and digital audio input and output for interfacing to both Soundstream's digital recorders and conventional analog tape recorders as well. The DAP software could perform edits to the audio recorded on the system's hard disks, as well as provide effects such as crossfades.

By the late 1980s, a number of consumer level computers such as the Apple Macintosh, Atari ST and the Commodore Amiga began to have enough power to handle the task of digital audio editing. Macromedia's Soundedit, with Microdeal's Replay Professional and Digidesign's "Sound Tools" and "Sound Designer" were used to edit audio samples for sampling keyboards like the E-mu Emulator II and the Akai S900, and soon went on to be used for simple two track audio editing and CD mastering purposes. In 1994, a company in California called OSC produced a 4 track editing-recorder application called DECK that ran on Digidesign's hardware system, and which was employed in the production of The Residents' "Freakshow" LP; this combination of audio software and hardware was one of the earliest examples of what we today would call a DAW.

Many major recording studios finally "went digital" after Digidesign introduced its Pro Tools software, modelled after the traditional method and signal flow present in almost all analog recording devices. At this time, most of the DAWs were Apple Mac based (e.g. Pro Tools, Studer Dyaxis, Sonic Solutions). Around 1992, the first Windows based DAWs started to emerge from companies such as Soundscape Digital Technology (which was later acquired by Mackie then by SSL), SADiE, Echo Digital Audio and Spectral Synthesis. All the systems at this point used dedicated hardware for their audio processing.

In 1993, german company Steinberg released Cubase Audio on Atari Falcon 030. This version brings DSP built-in effects with 8-tracks audio recording & playback using only native hardware. It was an incredible solution for the price at this time.

The first Windows based software-only product, introduced in 1993, was Samplitude Studio (which already existed in 1992 as an audio editor for the Commodore Amiga).

In 1996, Steinberg introduced Cubase VST, which could record and play back up to 32 tracks of digital audio on an Apple Macintosh without need of any external DSP hardware. Cubase not only modelled a tape-like interface for recording and editing, but also modelled the entire mixing desk and effects rack common in analog studios. This revolutionised the DAW world, both in features and price tag, and was quickly imitated by most other contemporary DAW systems.

Free and open source software[link]

Qtractor screenshot

There are many free and open-source software programs that can facilitate a DAW. These are often designed to run on a variety of operating systems and are usually developed non-commercially.

The development of digital audio for Linux and BSD fostered technologies such as ALSA, which drives audio hardware, and JACK. JACK allows any JACK-aware audio software to connect to any other audio software running on the system, such as connecting an ALSA- or OSS-driven soundcard to a mixing and editing front-end, like Ardour or Rosegarden. In this way, JACK acts as a virtual audio patch bay, and it can be configured to use a computer's resources in real time, with dedicated memory, and with various options that minimize the DAW's latency. This kind of abstraction and configuration allows DJs to use multiple programs for editing and synthesizing audio streams, or multitasking and duplexing, without the need for analogue conversion, or asynchronous saving and reloading files, and ensures a high level of audio fidelity.

• Audacity is a free and open-source digital audio editor that can run on Mac OS X, Microsoft Windows, and Linux; it is particularly popular in the podcast community, and also has a large following among the visually impaired due to its keyboard interface.
• Macaw is a public domain source code music program that runs on Microsoft Windows. It features a large number of built in instrument synthesizers and effects, and it can load and play SoundFonts.
• Rosegarden is a multi-featured audio application that includes audio mixing plugins, a notation editor, and MIDI matrix editor. The MusE Sequencer is a similarly featured audio application that includes an audio mixer and a MIDI sequencer.

Other open-source programs include virtual synthesizers and MIDI controllers, such as those provided by FluidSynth and TiMidity. Both can load SoundFonts to expand the voices and instruments available for synthesis and expand the ports and channels available to synthesizers. Such virtualization allows users to expand the traditional limitations of ADC-DAC hardware.

The Linux Audio Development (LAD) mailing list is a major driving force in developing standards, such as the LADSPA, DSSI and LV2 plugin architectures. The Virtual Studio Technology (VST) plugin standard is supported as an option by some such programs but is generally implemented as a separate plugin, not a built-in option, due to Steinberg's licensing scheme. Among others, the creators of Audacity provide an optional, somewhat minimalist, VST-to-LADSPA bridge plugin for their software, but it is a separate download.

Commercial systems[link]

Free and open source systems[link]

• Ardour
• Audacity
• LMMS
• MusE
• Psycle
• Qtractor
• Rosegarden
• Traverso DAW

See also[link]

Computer Science portal

• Audio restoration
• Broadcast automation
• Comparison of digital audio editors
• Console automation
• Multitrack recording
• Multitrack recording software
• Music Workstation
• Radio software

References[link]

External links[link]

• Introduction to DAW
• WikiRecording's Guide to Digital Audio Workstations (DAWs)
• A list of software DAWs, Sequencers, Hosts, etc.
• A basic explanation of a DAW system.

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A sound wave, in gray, represented digitally, in red (after quantization and zero-order hold).

Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion (ADC), digital-to-analog conversion (DAC), digital storage, processing and transmission components. A primary benefit of digital audio is in its convenience of storage, transmission and retrieval.

Overview of digital audio[link]

Sampling and 4-bit quantization of an analog signal (red) using Pulse-code modulation

Digital audio is useful in the recording, manipulation, mass-production, and distribution of sound. Modern distribution of music across the Internet via on-line stores depends on digital recording and digital compression algorithms. Distribution of audio as data files rather than as physical objects has significantly reduced the cost of distribution.

In an analog audio system, sounds begin as physical waveforms in the air, are transformed into an electrical representation of the waveform, via a transducer (for example, a microphone), and are stored or transmitted. To be re-created into sound, the process is reversed, through amplification and then conversion back into physical waveforms via a loudspeaker. Although its nature may change, analog audio's fundamental wave-like characteristics remain the same during its storage, transformation, duplication, and amplification.

Analog audio signals are susceptible to noise and distortion, unavoidable due to the innate characteristics of electronic circuits and associated devices. In the case of purely analog recording and reproduction, numerous opportunities for the introduction of noise and distortion exist throughout the entire process. When audio is digitized, distortion and noise are introduced only by the stages that precede conversion to digital format, and by the stages that follow conversion back to analog.

The digital audio chain begins when an analog audio signal is first sampled, and then (for pulse-code modulation, the usual form of digital audio) it is converted into binary signals—‘on/off’ pulses—which are stored as binary electronic, magnetic, or optical signals, rather than as continuous time, continuous level electronic or electromechanical signals. This signal may then be further encoded to allow correction of any errors that might occur in the storage or transmission of the signal, however this encoding is for error correction, and is not strictly part of the digital audio process. This "channel coding" is essential to the ability of broadcast or recorded digital system to avoid loss of bit accuracy. The discrete time and level of the binary signal allow a decoder to recreate the analog signal upon replay. An example of a channel code is Eight to Fourteen Bit Modulation as used in the audio Compact Disc (CD).

Conversion process[link]

The lifecycle of sound from its source, through an ADC, digital processing, a DAC, and finally as sound again.

A digital audio system starts with an ADC that converts an analog signal to a digital signal.^{[note 1]} The ADC runs at a sampling rate and converts at a known bit resolution. For example, CD audio has a sampling rate of 44.1 kHz (44,100 samples per second) and 16-bit resolution for each channel. For stereo there are two channels: 'left' and 'right'. If the analog signal is not already bandlimited then an anti-aliasing filter is necessary before conversion, to prevent aliasing in the digital signal. (Aliasing occurs when frequencies above the Nyquist frequency have not been band limited, and instead appear as audible artifacts in the lower frequencies).

The digital audio signal may be stored or transmitted. Digital audio storage can be on a CD, a digital audio player, a hard drive, USB flash drive, CompactFlash, or any other digital data storage device. The digital signal may then be altered in a process which is called digital signal processing where it may be filtered or have effects applied. Audio data compression techniques — such as MP3, Advanced Audio Coding, Ogg Vorbis, or FLAC — are commonly employed to reduce the file size. Digital audio can be streamed to other devices.

The last step is for digital audio to be converted back to an analog signal with a DAC. Like ADCs, DACs run at a specific sampling rate and bit resolution but through the processes of oversampling, upsampling, and downsampling, this sampling rate may not be the same as the initial sampling rate.

History of digital audio use in commercial recording[link]

Pulse-code modulation was invented by British scientist Alec Reeves in 1937^[1] and was used in telecommunications applications long before its first use in commercial broadcast and recording. Commercial digital recording was pioneered in Japan by NHK, and Nippon Columbia (a.k.a. Denon) in the 1960s. The first commercial digital recordings were released in 1971.^[2]

The BBC also began experimenting with digital audio in the 1960s. By the early 1970s they had developed a 2-channel recorder and in 1972 they deployed a digital audio transmission system linking their broadcast center to their remote transmitters.^[2]

The first 16-bit PCM recording in the United States was made by Thomas Stockham at the Santa Fe Opera in 1976 on a Soundstream recorder. In 1978, an improved version of the Soundstream system was used by Telarc to produce several classical recordings. At the same time 3M was well along in development of their digital multitrack recorder based on BBC technology. The first all-digital album recorded on this machine was Ry Cooder's "Bop 'Til You Drop" which was released in 1979. In a crash program started in 1978, British record label Decca developed their own 2-track digital audio recorders. Decca released the first European digital recording in 1979.^[2]

Helped along by introduction of popular digital multitrack recorders from Sony and Mitsubishi in the early 1980s, digital recording was soon embraced by the major record companies. With the introduction of the CD by Sony and Philips in 1982, digital audio was embraced by consumers as well.^[2]

Digital audio technologies[link]

Digital audio broadcasting

• Digital Audio Broadcasting (DAB)
• HD Radio
• Digital Radio Mondiale (DRM)
• In-band on-channel (IBOC)

Storage technologies

• Digital audio player
• Digital Audio Tape (DAT)
• Compact Disc (CD)
• Hard disk recorder
• DVD Audio
• MiniDisc
• Super Audio CD
• Various audio file formats

Digital audio interfaces[link]

Audio-specific interfaces include:

• AC'97 (Audio Codec 1997) interface between Integrated circuits on PC motherboards
• Intel High Definition Audio A modern replacement for AC'97
• ADAT interface
• AES3 interface with XLR connectors
• AES47, Professional AES3-style digital audio over Asynchronous Transfer Mode networks
• I²S (Inter-IC sound) interface between Integrated circuits in consumer electronics
• MADI Multichannel Audio Digital Interface
• MIDI low-bandwidth interconnect for carrying instrument data; cannot carry sound but can carry digital sample data in non-realtime
• S/PDIF, either over coaxial cable or TOSLINK
• TDIF, TASCAM proprietary format with D-sub cable
• A2DP via Bluetooth

Naturally, any digital bus (e.g., USB, FireWire, and PCI) can carry digital audio. Also, several interfaces are engineered to carry digital video and audio together, including HDMI and DisplayPort.

In professional architectural or installation applications, many digital audio networking protocols and interfaces exist.

See also[link]

• Analog recording vs. digital recording
• Digital audio editor
• Digital audio workstation
• Digital signal processing
• Noise shaping
• Nyquist–Shannon sampling theorem
• Quantization (signal processing)
• HTML5 Audio
• Sampling (signal processing)

Notes[link]

1. ^ Some audio signals such as those created by digital synthesis originate entirely in the digital domain, in which case analog to digital conversion does not take place.

References[link]

Sources[link]

• Borwick, John, ed., 1994: Sound Recording Practice (Oxford: Oxford University Press)
• Bosi, Marina, and Goldberg, Richard E., 2003: Introduction to Digital Audio Coding and Standards (Springer)
• Ifeachor, Emmanuel C., and Jervis, Barrie W., 2002: Digital Signal Processing: A Practical Approach (Harlow, England: Pearson Education Limited)
• Rabiner, Lawrence R., and Gold, Bernard, 1975: Theory and Application of Digital Signal Processing (Englewood Cliffs, New Jersey: Prentice-Hall, Inc.)
• Watkinson, John, 1994: The Art of Digital Audio (Oxford: Focal Press)