An ADSR envelope, which stands for attack, decay, sustain and release, is an envelope used to shape synthesized sounds.
Attack time - This is how long it takes from the moment the synth is triggered until it reaches it's peak level.Decay time - This is...
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The Advanced Linux Sound Architecture is a audio framework, which is part of the Linux kernel. Both JACK and Pulse Audio use ALSA as their backend. Unless you are using a firewire device (see FFADO), it is ALSA that you will be looking at...
Soundcards have two main stages, preamp and an analog to digital conversion stage. The preamp boosts the signal and the A to D stage converts that usable signal into the digital domain, which the computer can then process. Some soundcards come with only analog to...
A common setting on compressors and various types of filters. In compressors, this determines how quickly the compressor effect will kick in/how long it takes to pull the gain down. This is measured in milliseconds. Setting a few milliseconds of an attack allows the initial attack to come...
A device that gets audio in and out of your computer. All computers and laptops will have a basic built in sound card that will handle inputs (mic/line in) and outputs (to speakers/headphones). For professional audio you will need an additional soundcard/interface. These comes in various forms,...
An audio server, or sound server, is software that manages the use of audio devices. Such software typically runs in the background. PulseAudio is the standard audio server for desktop audio on Linux, while JACK is the standard audio...
Automation is a system that memorizes and then plays back the position of faders, plugin controls, etc. Automation can be drawn/programmed in, or else inputted in realtime using a mouse or midi controller.
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Bit depth relates to how many bits of information there are per sample. In laymans terms this equates to how many levels of loudness a digital waveform can have. 16 bit has 65,536 possible levels of loudness while 24bit has 16,777,216 possible levels. 24bit is often used in recording as it has a...
BWF stands for Broadcast Wave Format. A BWF file is the same as a .wav file (including the .wav extension) except that it additionally includes timecode data.
Chorus is a popular modulation effect, often used on guitars. This effect is most often described as adding a 'lush' or 'dreamy' effect that thickens up the sound source. This effect is achieved by splitting the sound source in two and delaying the copy. It's delay time is then modulated/varied...
If a device is class compliant, it means that it does not need any special drivers and will work out of the box.
In practice, convolution is being able to apply the sound of speaker cabinets or reverb from real spaces to a dry sound source. This is done by creating an impulse response. These arecaptured by generating a known sound signal in an environment, eg. through a guitar speaker cabinet or in a...
A DAW, which stand for Digital Audio Workstation, is software used for the recording, editing and mixing of digital audio. DAW's started off as integrated hardware units but nowadays, a DAW most commonly refers to recording software.
DAW's follow many conventions from hardware recording...
Digital distortion is what happens when a signal goes above 0dBFS. Audio cannot be represented above this point and will distort. Digital distortion is particularly harsh sounding.
A digital to analog converter converts a digital signal to an audio signal. A simple example of this is the speaker out on your computers soundcard. A soundcard that has both A to D and D to A converters can be used to send audio to an outboard unit, eg. A reverb unit, and to send it back into...
DSSI (Disposable Soft Synth Interface) is a plugin format (pronounced “dizzy). This is an extension to the LADSPA plugin format. DSSI plugins can have their own GUI's and were designed specifically with virtual instruments in mind. DSSI has been superseded by the...
EQ, or equalizers, can manipulate the frequency response of audio material in various ways. There are 3 parameters that EQ's typically have, gain, frequency and Q. Gain relates to increasing or decreasing a specific frequency. Frequency relates to which frequency is being manipulated and Q, or...
FFADO stands for Free FireWire Audio Drivers. This is an open source device driver backend for JACK. If you want to use a firewire interface, check out the FFADO website to see which devices are supported....
FLAC is a free and open source audio compression format. It stands for Free Lossless Audio Codec. FLAC files use lossless compression, meaning that the file size is compressed while retaining full sound quality. FLAC encoded files can typically be compressed by up to 50%. More info can be found...
FLOSS stands for Free/Libre/Open Source Software and is applied to any software that is free for the user to study, modify and redistribute to anyone and for any purpose.
The Libre part is added to emphasize that it is referring to freedom of action, not just free as in no cost. FOSS is...
A high-pass filter (HPF) is a EQ filter that let's all high frequencies pass through unaffected, but cuts the low frequencies. For this reason, it is also sometimes referred to as a low cut filter.
On hardware mixers, a high pass filter set to a particular...
Inserts are found in both software and hardware mixers and allow external software and/or hardware to be inserted into the signal path. It does this through send and returns, where sends divert the channels signal to the device/software processor and the return takes the devices outgoing signal...
The Jack Audio Connection Kit is a professional sound server for low latency audio and MIDI connections. When running JACK you can interconnect audio and MIDI ports between any JACK aware programs. It is a very flexible system that can allow for very...
Any program that supports JACK is said to be JACK Aware. This means that it not only has support for JACK audio and MIDI ports, but that is also is capable of having it's timeline synced up via JACK.
The combination...
The kernel is the bottom most layer of your operating system. Every operating system has a kernel. The common factor in every Linux distribution is the Linux kernel itself. This deals with basic input and output, on top of which everything else is built. The Linux kernel is where device drivers...
Not a setting on every compressor but some compressors have this option. This is related to how the threshold takes affect. A soft knee will introduce the compression more gradually, whereas a hard knee setting will be more abrupt. Both have their place but soft...
LADSPA is a plugin format. It stands for Linux Audio Developers Simple Plugin API. LADSPA plugins come with no GUI's of their own, instead using their hosts generic GUI. Virtually every host supports LADSPA plugins. A popular collection of LADSPA plugins is the Caps suite of plugins.
LFO stands for Low-frequency oscillation. The name comes from the fact that it is an electronic signal with a low frequency, which oscillates to create a rhythmic pulse, or wobble. LFO's are common in synths and help vary their sound capabilities.
A number of popular effects are based...
LinuxVST's are VST plugins compiled specifically for Linux. Supported hosts include Ardour, Qtractor and Carla.
A low-pass filter (LPF) is a EQ filter that let's all low frequencies pass through unaffected, but cuts high frequencies. For this reason, it is also sometimes referred to as a high cut filter.
Most software EQ's will allow you to choose what frequency you want...
The LV2 plugin standard is the successor to LADSPA. LV2, which stands for LADSPA version 2, is intended to address the limitations of LADSPA. LV2 plugins can easily be extended and most LV2 plugins come with custom GUI's. Supported hosts include...
MIDI (Musical Instrument Digital Interface) is a protocol that allows various electronic instruments and MIDI software to communicate with each other. The standard MIDI connector (5 pin DIN cable) is used to connect MIDI hardware, although some devices can also send MIDI data via USB cables to...
A MIDI controller is any device that sends out MIDI data to control another MIDI device or program. Some MIDI controllers are also capable of recieving MIDI data. Two examples of a MIDI controller would be a MIDI keyboard which can...
A MIDI keyboard is a piano-style keyboard used for sending MIDI data to a computer, or other MIDI devices. MIDI keyboards are a type of MIDI controller. You can think of a MIDI keyboard as a dummy keyboard. They don't produce any...
Modular set ups are where more than one program is used in a set up. JACK allows you to connect and sync various audio programs together so you can benefit from the strengths of individual applications. Session management can be...
Monolithic set ups are where you do all your work in one program. This is the most common approach people using Windows and Mac audio software will be used to. In Linux, JACK allows for very modular set ups, although some applications are...
Your noise floor is the sum of all noise sources and unwanted signals within your system. This may include low level sound sources that a mic picks up as well as system induced noise that may be introduced, for example, your preamp may also add noise to your signal...
Ogg Vorbis is a free and open source lossy audio codec. Is similar to the MP3 codec although it's sound quality is better at lower bitrates when compared to MP3. That and it is a truly free alternative, whereas MP3 is a proprietary codec. OGG is maintained by the Xiph.Org Foundation. More info...
Parallel compression is a form of upward compression. It can add punch and energy, without sounding overly squashed. It does this while retaining some of the dynamics of the original signal. This is achieved by mixing a heavy compressed version of the track in with the original, uncompressed...
Phantom power is a 48v power supply used to power certain microphones (condenser), active DI boxes, etc. Most preamps/audio interfaces will include an on/off switch for this.
Phase is the offset of two waveforms expressed in degrees, where 360 degrees corresponds to a delay of one cycle. Waveforms that are 180 degrees out of phase will cancel each other out to complete silence.
Phase problems can occur when two similar sound sources are out of alignment with...
Post-fader means that something is active after the fader. This is most commonly used when talking about effects, plugins, sends and inserts. As the fader controls the volume of the channel or track, putting something before or after the fader can have drastic effects on the volume of...
A pre-delay setting is found on some reverbs. This setting allows you to set the length of time (in milliseconds) before the onset of the reverb, after the dry signal. This mimics how direct sound and sound reflections in a room arrive at our ears at different times. A short pre-delay will sound...
Pre-fader means that something is active before the fader. This is most commonly used when talking about effects, plugins, sends and inserts. As the fader controls the volume of the channel or track, putting something before or after the fader can have drastic effects on the volume of...
A preamp boosts the input signal, from a mic or instrument, to a usable level. Most audio interfaces include a preamp.
Pulse audio is a sound server that uses ALSA as it's backend. It is more geared towards general desktop audio. While it is useful for these purposes, pulse audio isn't used for any audio production software.
A common setting on compressors. This setting relates to a compressors threshold setting. The higher the ratio setting, the more compression will be applied to any audio that breaches the threshold. On lower settings, the compression affect will be more subtle....
A common setting on compressors. This is related to the attack setting. Where the attack setting tells the compressor when to kick in, the release tells the compressor when to stop compressing the signal. Release settings are measured in milliseconds.
Sample rate refers to how many samples per second are in an audio signal or file. CD quality uses a sample rate of 44.1kHz, or 44,100 samples per second. Audio interfaces use different sample rates but common ones are 44.1kHz, 48kHz and 96kHz.
Due to Linux audio's flexibility, very modular set ups are possible. Session management makes this easy by remembering software and their connections. You can launch various programs, connect them up and have you session manager remember, and later, relaunch the...
