in-depth introductory audio engineering and digital signal processing
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2 x 1 hr with one hour lunch break in between.
(aimed at people new to home recording and/or digital audio with little theoretical background but some practical experience)
presented by steve harris (the dsp side of things) and
jörn nettingsmeier (the analog domain :)
each of the sections introduces their basic concepts by looking at and explaining the working of analog gear.
we then proceed to its digital counterpart.
at the end of each section, we offer some usage tricks for practical work.
(1) the nature of sound and analog audio signals and their digital representation
analog:
* pressure waves in air, from source to microphone
* ac signals
* some terms [oscilloscope visualization in the _time_domain_]:
* frequency
* amplitude
* phase (practical example: symmetric cables)
/* should we show an actual synthesizer and meterbridge here? */
* sine waves as "building blocks", overtones (i)
* example: adding two sine waves -> additive synthesis
* example: saw wave, rectangular wave [spectrogram visualization in the _freq_domain_], taylor series /* is that the term for how you build them out of sines? */
* problems:
* noise
* distortion (clipping amplifier spectrum, mention fourier transform here)
* tradeoff noise vs. fidelity: s/n ratio, dynamic range
* frequency range and its limiting factors (microphone inertia, tape speed)
* cumulative errors (increasing loss of high end, noise)
digital:
* sampling
* continous vs. discrete signals
* nyquist theorem and aliasing
* problems:
* aliasing
* quantization noise
* distortion (show wrapping int samples on scope, compare to analog distortion)
* cumulative rounding errors and maintaining precision
* float and int representation, dithering (katz explanation), noise shaping
* sample rate conversion, _interpolation_
* d/a conversion by lp filtering, _interpolation_ by reconstruction filter
practical stuff:
* practical considerations of digital audio: aliasing
[steve might cover dither in his mastering talk]
(2) controlling spectrum: equalization
* frequency-selective electronic components (example: a simple analog filter circuit)
* the analog equalizer: f,gain and q
* simple digital frequency-selective operations
* digital parametric eqs
* some tricks for setting the eq: sweeping, "the best eq is no eq"
(3) controlling dynamics (compressors/expanders)
* the importance of dynamics as a musical parameter, micro-/macrodynamics
* faders (variable resistors), the vca
* measuring loudness (rms, peak)
* the analog compressor: threshold, ratio, attack, release, knee, makeup gain
* the analog expander
* digital compressors/expanders: implementation and specialties (look-ahead)
* compressor usage tips (don't squash the sound!, pumping)
* side chaining, de-essing
* noise reduction with expanders (stuttering)
(4) controlling timing
* the importance of timing and time-feel
* analog delays
* digital delays
* the haas effect, practical example: delayed p.a. loudspeakers and sound localization
* comb filtering
* using track delay
(5) space and spatialisation
* aural perception of space
* head-related stereo
* standard stereo reproduction
* x-y (m-s), a-b, and "pan-pot" stereo
* caveats w/ stereo signals (polarity, stereo compression, mono compatibility)
* natural reverb
* analog "convolution": the reverb chamber
* digital convolution reverb
* reverb parameters: duration, early reflections, pre-delay, room size, damping
* artificial digital algorithmic reverb
* using reverb in mixes, z-axis "panning"
(6) q & a
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test signals needed:
sine waves
some dynamic music
pink noise
[some noisy percussive music]
[a frequency sweep]
equipment needed:
a parametric eq
a compressor
[an expander]
a simple reverb unit
a delay
two speakers, not too wide apart