Q, Quality Factor@Describes the slope of a filter. In audio filters specifically, Q is the ratio of the center frequency of a peaking filter to its bandwidth; so that for a fixed center frequency the Q will be inversely proportional to the bandwidth ("center frequency over bandwidth"). (Bandwidth is defined as the range between the points that high and low frequency levels are boosted or cut by 3dB, compared to the center frequency's level.) In simple terms: for a given Center Frequency and amount of boost/cut, higher Q values correspond to narrower bandwidths (steeper slopes); lower Q values to broader bandwidths. (In electronics, the Q Factor (acronym for Quality Factor) is the ratio of energy stored to energy lost in a coil or resonant circuit.) See also Center Frequency, Bandwidth, Peaking Filter.@Q10@Plug-in software products by Waves, very sophisticated 10--band parametric equalization. Q10 is available in many plug-in formats, including VST, TDM, AudioSuite, etc.@Quadra@A series of Apple Macintosh computers, the first Macs to use the Motorola 68040 processor. Some models, such as the 950, 900, 700, 840av, 800, and 650, featured NuBus slots where audio cards could be installed; others, such as the 610, 660av, and 605, did NOT accept full-size NuBus cards. Since the first part of 1995 Quadras were discontinued. They were replaced by the PowerMac series, based on the PowerPC processor. See PowerPC.@Quantization@1) The capture of any continuously varying value, using a limited number of discrete steps to represent that value's total range. Captured values are converted to a series of binary data, which can be stored or manipulated in the digital domain. The number of bits (binary digits) used in the number which represents each sample determines the total number of possible values that can be registered. Any input levels which fall between two of these discrete steps must be rounded up or down to the nearest step (quantum) provided by that system's resolution, or Bit-Depth.
Digital audio recorders may quantize the variations in the amplitude of an input waveform into a series of 8, 16, 20, or 24-bit data words, representing 256, 65,536, 1,048,576 or 16,777,216 possible levels. Each additional bit of Resolution reduces Quantization Error by approximately 6 dB (a rounding error producing a granular sort of distortion, sometimes called Quantization Noise). See also Signal/Error Ratio, Digital, Bit-Depth.
2) In MIDI sequencers, Quantization is a rhythmic function which adjusts the timing of note events, rounding them by "snapping" their beginning to the nearest 1/4 note, 1/8 note, triplet, etc. It is useful for fine-tuning the rhythmic feel of recorded MIDI tracks, or compensating for less-than-perfect keyboard technique! Professional MIDI sequencers offer ever-more sophisticated quantizing options: variable swing, groove quantize templates, match quantize, etc.@Quantization Noise or Error@Mispresentation (or distortion) of an analog waveform, when it is captured and reproduced in the digital domain. Related to the number of discrete numerical steps used to represent the continuously varying values present in the original waveform. When relatively smaller numbers of levels are available to decscribe the entire range of values (i.e., number of bits per sample, Bit-Depth is smaller), the capture and representation will be necessarily be more inaccurate. This introduces a granular type of audio distortion popularly known as quantization "noise", more properly referred to as quantization "error". When any given Bit-Depth used for recording audio, its inherent level of quantization error is described by the Signal-to-Error ratio. The practical Signal-to-Error ratio of a digital audio device will additionally depend on other hardware considerations. See also Quantization, S/N Ratio, Resolution.@QuickDraw@A set of programming routines for the Macintosh (developed originally by Bill Atkinson), which facilitate the display of all the text and graphics on the Macintosh screen. The use of a common method for controlling onscreen display of graphics was one of the key elements which made cut and paste operations so compatible between diverse Macintosh programs.@QuickPunch@Digidesign Pro Tools term. Refers to a capability of the Pro Tools software, where the operator (by reserving a Voice, can punch in recordings "on-the-fly"; that is, without previously designating the start and end points for recording. Individual tracks are record enabled, then the Record button on the Transport is used to activate and deactivate the recording mode during playback. Recordings in QuickPunch mode are always non-destructive; QuickPunch and Destructive Recording modes are mutually exclusive.@QuickTime@Apple Macintosh term. A format for digital video on computers, developed by Apple Computer and introduced in 1991. QuickTime "movie" files can also incorporate audio tracks at various resolutions, in AIFF format. QuickTime compatibility is implemented through an operating system Extension file on Macintosh computers, or corresponding drivers on Windows machines. One of the outstanding features of QuickTime is that frames will be skipped during playback, if the computer is unable to correctly reproduce all frames at the proper rate. In this way, proper durations are maintained for QuickTime movies, their images stay synchronized to the audio. The QuickTime "MooV" (or .MOV) file format doesn't impose limitations on the size or resolution (number of bits, frames per second, compression method, etc.) used for video or audio. Instead, the developer will make decisions based on speed and disk space considerations, and the type of computer that will be used by his audience. If the computer used to play back a QuickTime movie is too slow, the frame skipping will produce a jerking, or stepped movement during playback. See also AIFF.@QWERTY Keyboard@The standard American keyboard layout for computers, based on typewriter keyboards. The name QWERTY derives from the first letters in the top row of the alphabetical section of the keyboard.@
