February 13

MIDI window: one or more tracks sharing a window
Controllers: Viewing and editing in "Continuous Data area" of track.
Serial nature of controllers: not really continuous, discrete events.
Points and Bars view shows this. Lines view leaves out intermediate events if transitions are smooth. Repeating a controller event at the same value usually does nothing.
Left tool: what to show and what will be affected by selection
Right tool: pencil and reshape tools will affect this data.

Draw a curve, or use reshape, or set to free.
Reshape tool can be used with other curves, and is periodic. Period depends on grid setting.

Make sure to: Initialize all controllers that you’re using, especially volume and pitchbend, at the beginning of the sequence, or you may be left with hanging controllers, meaning tracks that are out of tune or that have been faded out!

Insert measures: puts blank space on all tracks. To insert blank space on individual tracks, use Shift command.
Snip=cut & close up gap Splice=paste & push to the right

Region menu: Transpose, Transpose by key or scale interval, harmonize, change within a key or mode.
Also globally change velocity and duration (add, substract, scale, set, limit) in region menu.

Mixing console automtation: Changing volume and pan, recording motion. Put track into “auto record”, but do not click on Record in Transport window! Click on play. (Whether track is record-enabled or not doesn’t matter.) All movements of fader and pan knob will be recorded, can then be edited in sequence or MIDI window.

Sonivox SoundStage: First create an instrument track (Soundstage) and assign its outputs to the Mbox (Analog Outputs 1-2), Create a MIDI track to play it. It looks like you can assign 16 channels on each instrument, but actually there is only one, so just select the first channel.

Includes expanded General MIDI set. Each module is one channel/one patch, and must have its own Instrument track. You can use “Default patch” in the Tracks window but you won’t be able to access all of the sounds available.

February 8

Tracks vs. channels. More than one track can be assigned to a channel. All tracks going to the same channel have to have the same patch/sound!

Double-click selection in Tracks window opens MIDI window
Magnification: vertical, horizontal.
Grid on/off: sets cursor movement, not (necessarily) note placement. (Temporarily defeat it with Apple key.)

MIDI window can show one or several tracks at the same time. Use show/hide pane to set these up. To differentiate between tracks, reset the colors for the tracks in the Tracks window. Track with pencil icon can be added to.

Changing velocities in Continuous Data area. Difference between velocity and volume: playing the instrument softer or louder vs. moving a fader on a mixing console. For individual note velocity change, use arrow. Group select and change, use marquee and arrow (same tool). Make sure in View Filter note-off velocity is disabled.

Toolbox: Shift-O. Default tool is arrow. Use pencil for adding events. Use Reshape tool (S-curve) to reshape events (like velocity). Select "flavor" to determine how Reshape tool operates.

Add notes or controllers with pencil. edit with arrow, or group edit with marquee and arrow. Reshape periodic flavors: timing resolution dependent on grid setting (even if grid is off).

In Mixer window: Setting volume and pan for each track, statically. Is saved with sequence. But if you want to change volume or pan during sequence, make sure "automation play" is turned on in mixer window or they won't work!

Conductor track: Tempo slider vs. Tempo map. Event List: initial tempo, time signature (meter).
Create a tempo map: in Tracks window, double-click on conductor. Can magnify vertically with option key and left edge dragging. Also click on E (or shift-E), opens event list, select conductor.

Sequence window: one or more tracks in separate lines
Change size, select controllers to work on in left panel. Only controllers that are already in the track will show up on the drop-down--so you have to add them with the pencil or by recording them “live”.

February 6

The software MIDI studio: Virtual MIDI cables: connecting applications with both MIDI and audio using different protocols like Rewire, VST, Apple AU and IAC, MAS, RTAS, TDM. In the software studio, MIDI speed limit doesn't have to be adhered to. Only real-world input is keyboard (over USB); only output is analog stereo out to speakers.

General MIDI
Common configuration for MIDI program changes. Used for multimedia, file exchange, like .txt
Sound set (128 programs), Arranged in families of 8.
Percussion (47 sounds) on ch 10.
http://www.midi.org/about-midi/gm/gm1sound.shtml
Fixed controller meanings: volume 7, pan 10, expression=volume 11, mod wheel 1, PB range
Purity, a virtual instrument, has 16 channels, each one can have any of 128 sounds, except drums on Channel 10. Follows GM protocol.

Recording MIDI into a sequencer (Digital Performer)
Open DP: New, put folder in Documents folder on local computer.
Naming the project: the folder is named automatically
Setting up the audio output in DP
Configuring the keyboard
Instrument track: for Purity's audio output. Output is automatically analog 1-2. Inputs will show up on MIDI tracks.
Setting metronome: audio, choose sounds
Record-arming a track. Selecting Default patch: select from list
Countoff
Replace/overdub mode.
Double-click selection in Tracks window opens MIDI window.
Tempo setting: select "Tempo Slider", move slider.

Editing: moving and changing notes. Grid on and off for selecting and moving events. Sets cursor movement, not (necessarily) note placement.
Copy, paste to duplicate events. Cut, paste, to replace. Option-drag to duplicate. Click on end of note to change duration.

Save often!
Use server and thumb drive for backups.
NEVER OPEN A SEQUENCE from the server or a thumb drive.

February 1

Input devices for electronic music
Keyboards, drum pads, guitars, wind controllers, pitch convertors, marimbas, maracas, positional indicators, ribbons, game controllers
Because physical characteristics of device are not linked with acoustic characteristcs, you have total freedom.

MIDI: What is it?
MIDI is not music, not audio, but it is a representation of a musical performance, like a score, or a player piano roll. Every performance nuance is communicated, without the actual music. Notes, sliders, knobs, pedals, patch changes, other parameters.

Cannot be stored on tape, must be stored digitally — a sequencer: a list of instructions (commands) with their timings. Sequencer can be a computer, and the sequence is a computer file. Stored on disk, you can move it around between studios, or over a network. Usually quite small.

On stage, one keyboard could act as master and play all the others. In studio, a central controlling sequencer could control an entire orchestra of synths.
Central controller has performance data, while the actual sound is produced by the remote devices.

Initially this was all done using discrete hardware modules connected by MIDI cables. Now we can do it all in software.

Since performance data is broken down into gesture parameters, can isolate individual performance parameters: change key velocity, or note number, or pitchbend setting, or instrument, or rhythm without changing other performance parameters

Prepare an entire performance, change any parameter, singly or globally, at any time.

Who owns it
Public domain. A specification, not a standard, no legal or official standing. The industry agreed to support it, market forces keep it in line. If someone strays, users and reviewers will report the violation.
A living language: many holes in the spec for future development. Participation from all corners of the industry: hardware mfrs, software mfrs, systems designers
A compromise: performance vs. cost, initial hardware cost c.$10/unit. Seems slow by today's standards, but is still effective for its purpose.

Electrical and digital protocol
Originally used cables, binary on/off 5-volts DC. Each MIDI byte or word consisted of eight data bits, plus two “framing” bits. Speed is 31,250 bits per second, or 3,125 bytes/sec (8 data bits + two buffer bits= 10 bits/byte). Now mostly virtual.
Travels in one direction only: from MIDI Out jack to MIDI In jack. If you want bi-directional, you need two cables.
A universal standard: if an instrument has MIDI, it must be able to talk to any other MIDI instrument without restrictions.

MIDI over USB, etc.
Now MIDI can be piggybacked on other cables, like USB, Firewire, and Ethernet. But there are no standards for these, so manufacturers have to make software
drivers which are installed on receiving devices (computers) so that they can
understand what's coming in. Our keyboards are made by CME, and we have
to install special drivers on each computer so they can be recognized.
Advantage: can specify faster than MIDI speeds!

Message set
An eight-bit number has a decimal range of 0 (00000000) to 255 (11111111)
MIDI has two types of bytes:
Status or Command byte (>127, first bit is 1) is instruction
Data byte (≤127, first bit is zero) is value.

Some commands are defined as having 2 data bytes, some have 1 data byte.
Receiving device knows what to expect. Incomplete command is usually ignored.

Channel messages
First four bits of command byte is the type of instruction. Second four bits is the channel number. Early MIDI devices only read one channel at a time, ignored data on other channels (some, like drum synths, still do). Means you can use different devices on the same MIDI cable.
Modern synths, called "multitimbral", sort out data by channel, assign to different sounds in the instrument.
Channel number = 0000 (zero) to 1111 (15). But we call them 1 to 16.

Note on: Command byte (144-159) followed by two data bytes (0-127: note number, key velocity=how fast the key moves from top to bottom)

Note off: Command byte (128-143) + note number + velocity. Why note-off velocity?

Continuous Controllers: (176-191) + controller number (mod wheel, volume, pan, sustain) + value
127 possible controllers per channel.
Many controllers defined, some as transmitters (mod wheel=1), some as receivers (volume=7), some as both (sustain pedal=64).
Others that are defined: Stereo pan=10, Foot pedal=4, Data slider=6
Many others loosely or not defined.

Volume vs. velocity
Important to note the difference between velocity byte in note-on command
(which affects onset of note only) and volume controller (#7) (can affect sound continuously). Velocity=how loud the instrument is played. Volume=how high
the fader is.

Program change: (192-207) (Cn) + single data byte=value. Program change numbers are 0-127, often but not always called 1-128. Calls up a register in the synth's memory.

Pitchbend: (224-239) + two data bytes: Most significant byte (MSB) + Least Significant Byte (LSB). Designers wanted “double precision” so that when [tich wheel was moved you didn’t hear discrete pitches. So possible values are 0 to (128*128)-1=65,383. Turns out it wasn’t necessary: LSB is almost always ignored. But it must be there anyway.

"Zero pitch bend" is actually a value of 64 (MSB). Many sequencing programs describe pitchbend as +/-64, but in reality the values are 0-127.

Channel pressure/aftertouch: (208-223) + single data byte=value. Amount of pressure on keys after the note is played. Used for vibrato, filters, pitch change, etc.

Key pressure/polyphonic aftertouch: (160-175) + note number + value. Individual pressure values for each key. Quite rarely used: expensive to implement, complex to program, uses a lot of bandwidth

MIDI Sequencer: Program for receiving MIDI data, assigning it to multiple tracks, editing it, and playing it back to real or vitrual MIDI instruments.

Equipment response to command set:
Up to the manufacturer: as much or as little, must ignore what it doesn’t understand. Data sent and responded to is specified on MIDI implementation page of documentation.

January 30

Synthesizer Parts
Oscillator: simple or complex waveform
Filter/Equalizer: static or dynamic
Envelopes: volume, filter, pitch. Attack/Decay/Sustain/Release: approximation of natural envelopes, invented by Moog. Invertable for filter use.
LFO: volume, filter, pitch. Variable depth and rate, selectable waveform. random segments/random levels (sample+hold)

Types of synthesis
Additive or Fourier: building up from individual harmonics, with separate levels and envelopes for each. Impossible to do analog, hard to do digitally because hard to make interactive: so many computations per second. Used in Kawai synths, Kurzweil 150, some experimental synths. Hammond organ.

Subtractive: Start with complex waveforms like noise, sawtooth, square, and filter out harmonics — high, low, or bandpass. Filter envelopes much easier to deal with than individual harmonic envelopes. Analog synthesis is subtractive, also can be done digitally, digital simulations of analog synths now very popular. Also digitally controlled analog synths. “Real analog” synthesis has drift problems. Can be very complex (Thor)

FM: uses 2-6 sine waves or more complex waves ("operators") modulating each other, each with an envelope. Modulator, instead of filter, determines harmonic content, which can be very complex. Lends itself well to real-time control, not hard to compute. However, programming is not at all intuitive. Describe Sound Blaster chip: awful 2-op FM.

Physical modeling: digital models of instrument parts exist in software, interact in real time. Also called "waveguide". Might have excitation of a flute, resonance of a saxophone, bell of a trumpet. Can include elements like breath, embouchure pressure, tonguing, change in tube resonance as you cover "holes". Very powerful, difficult to do -- lots of computation. Yamaha mostly. Instruments can generally play only one or two voices at a time.

Granular: breaks up files (like samples) into tiny pieces, plays them back and reassembles them at different speeds and pitches, in real time. Adds processing.

Samplers
RAM: make recordings in a digital audio program, load them in. Also called (incorrectly) "wavetable".
Disc streaming: can use longer samples; headers of samples are in RAM, the rest streams from disc. Very resource heavy! Limitations on how many notes can sound at once. Some composers use multiple computers in their studio for large orchestrations.
Sample + Filters + DSP: Digital samples stored in ROM or RAM, played back under control of MIDI.
Multisampling prevents munchkinization. Formants—spectral areas that remain constant despite pitch; if you transpose them, you change the characteristic of the sound.

January 25

Timbre = complexity of waveform
Harmonic series = break down waveforms into harmonics or partials. Fourier transform/analysis.
Sine, saw, triangle, square, noise
Saw: each harmonic at level 1/n. Square, only odd harmonics at 1/n. Triangle, odd harmonics at 1/n2

In an electronic system, the ability to reproduce those high harmonic frequencies is called frequency response or fidelity.

Using filters to change timbral characteristics. Hipass, lowpass, bandpass

Audio electronics principles and components:
Transducer = converts one type of energy to another

Microphone = converts sound waves in air to Alternating Current (AC) voltages. Microphone has a magnetic metal diaphragm mounted inside a coil of wire. Diaphragm vibrates with sound waves, induces current into coil, which is analog of sound wave. This travels down a wire as an alternating current: positive voltage with compression, negative voltage with rarefaction.
Dynamic vs. Condensor/capacitor mics, Condensor mics can use phantom power, battery, or be “permanently” (electret) charged.
Pickup patterns: Omni, figure-8, cardioid, hypercardioid, boundary

Speaker, headphones = transducer, converts AC voltages to sound waves in air. Speaker has a wire coil that receives alternating current from amplifier, paper cone is attached to a magnet inside the coil. As the current alternates, the magnet moves in and out, and makes the paper cone move in and out, producing compression and rarefaction.

Human Ear:
converts sound waves to nerve impulses. Each hair or cilium responds to a certain frequency. The brain interpolates sounds between those frequencies. As we get older, hairs stiffen, break off, and high-frequency sensitivity goes down. Also can be broken by prolonged or repeated exposure to loud sound.

Cables and Connectors:
Balanced: XLR, ¼-inch TRS. Less noise (differential amplifier cancels noise picked up on line), better frequency response, longer distance.
Unbalanced: ¼-inch TS, RCA, mini. More prone to interference, high-frequency roll-off.
Stereo unbalanced: ¼-inch TRS, mini TRS.

January 23

Characteristics of a sound:
Sound is vibration of a medium, such as air. Travels in waves: compression, rarefaction. = changes in air pressure.

Frequency = pitch
Number of changes in pressure that go past your ear per unit time.
Expressed in cycles per second, or Hertz (Hz).
      The mathematical basis of the musical scale: go up an octave = 2x the frequency.
      Each half-step is the twelfth root of 2 higher than the one below it. = approx. 1.063     
The limits of human hearing = approximately 20 Hz to 20,000 Hz or 20 k(ilo)Hz.
Fundamentals vs. harmonics = fundamental pitch is predominant pitch, harmonics are multiples (sometimes not exactly even) of the fundamental, that give the sound character, or timbre. http://www.psbspeakers.com/Images/Audiotopics/fChart.gif

Loudness (volume, amplitude) Difference between maximum and minimum pressure
measured in decibels (dB). The decibel is actually a ratio, not an absolute.
      A minimum perceptible change in loudness is about 1 dB. Something we hear as being twice as loud is about 10 dB. So we talk about “3 dB higher level on the drums” in a mix, or a “96 dB signal-to noise-ratio” as being the difference between the highest volume a system is capable of and the residual noise it generates.
“dB SPL” is referenced to something: 0 dB SPL (Sound Pressure Level) =  the perception threshold of human hearing. Obviously subjective, so set at  0.0002 dyne/cm2
      The total volume or “dynamic” range of human hearing, from the threshold of perception to the threshold of pain, is about 130 dB, so the threshold of pain is about 130 dB SPL. Chart: http://harada-sound.com/sound/handbook/soundspl.gif

Timbre = complexity of waveform, number and strength of harmonics

Location = L/R, F/B, U/D

Envelope  = Change over time, applicable to any of the above

Vibrato = periodic change in any of the above = "Low Frequency Oscillator"

assignments

©2012 Paul D. Lehrman, all rights reserved