Developing Software Synthesizers

1. Developing Software Synthesizers By: Dan Bogucki

2. Overview • What is Sound? • What is a Sound Synthesizer? • History of the Synthesizer • Hardware vs. Software • Why turn to Software Synthesizer? • Types of Synthesizers Methodology • The Makeup of a Synthesizer • Developing a Software Synthesizer

3. What is Sound? • Sound is moving energy that travels as a pattern of changing pressure • Sound is the perceived vibration (oscillation) of air resulting from the vibration of a sound source • Sound source can be anything • Guitar sound board, speaker cone, hair dryer, vocal cord, etc

4. Sound Waves • As your sound source expands and contracts a pattern of changing air pressure energy moves away from the source Ottewill, Matt. "What Is Sound?" Planet Of Tunes. N.p., n.d. Web. 13 Mar. 2013.

5. Sound Waves • Four Types of basic waveforms • Sine • Square • Sawtooth • Triangle

6. Sound Waves

7. What is a Sound Synthesizer? • An electronic instrument capable of producing sound • Generate electric signals (waveforms) which are converted to sound through speakers or headphones

8. History of the Synthesizer • 1860 – Hermann von Helmholtz built an electro-mechanical oscillator • 1906 – Lee de Forest invented a vacuum-triode amplifier valve • 1950s – Transistors became available • 1961 – Harald Bode invented the Melochord, the first voltage controlled synthesizer • 1964 – Robert Moog constructed a transistor voltage-controlled oscillator and amplifier • 1966 – Moog launched the first commercial version of the Moog Synthesizer

9. History Continued • 1950s – Max Mathews of Bell Telephone Lab began exploring the use of using digital computers as a means to generate sounds. • 1960 - Mathews produced MUSIC III • 1962 – MUSIC IV • 1968 – MUSIC V • 1968 – Barry Vercoe developed MUSIC 360 • 1973 – Vercoe developed MUSIC11 • 1979 – Australian Fairlight CMI synthesizer was introduced

10. Hardware vs. Software • Software synthesizers use digital processors • Hardware synthesizers use analog circuitry • Computer technology is advancing faster than hardware synthesizer technology • For example, wavetable and additive synthesis is not feasible with hardware synthesizers • Musicians preference between hardware sounds and character vs. software sounds

11. Why Turn to Software Synthesizers? • Popularity of personal computers • More flexibility and invention for both the end user as well as the software itself • Cost

12. Software Synthesizer Example https://www.youtube.com/watch?v=6FgKeGUZKiE

13. Synthesizer Methodology • Additive Synthesis • Subtractive Synthesis • FM Synthesis • Wavetable Synthesis

14. Additive Synthesis • Most fundamental method of sound synthesis • Based on the Fourier Theory • Produces sound by adding different sine waveforms together • This technique can potentially generate sounds similar to acoustic musical instruments

15. Subtractive Synthesis • Basically the reverse of additive synthesis • Produces sounds by generating a waveform that contains more harmonic content than a sine wave • The waveform is passed through filters which subtract harmonics

16. FM Synthesis • Uses FM sidebands as harmonics for synthesized waveforms. • Applied digitally through FM operators • Digital sine waveform and an envelope • Output is then used to modulate the frequency of another operator • Modulation of one sine wave by another produces more complex sounds • Used widely in radio transmission

17. Wavetable Synthesis • Also known as sampling • Most widespread and popular method • Recorded or synthesized musical events are stored in the internal memory and are played back on demand • Provides a set of playback tools • Pitch Shifting • Looping • Enveloping

18. General Makeup of a Synthesizer Today • Oscillators • Envelopes • Filters • Frequency Modulators • Samplers (in some synthesizers) • Functionality and options are endless

19. Oscillators • Control to repeat a waveform with a fundamental frequency and peak amplitude

20. Envelopes • The synthesizer’s time varying gain function • Simple analogy: A sequence of events that occurs every time you press a key • Attack • Decay • Sustain • Release

21. Filters • Subtract frequency content • Behave like an equalizer • Four basic types • Low-pass • High-pass • Band-pass • Band-reject

22. Developing a Software Synthesizer • To create sound we need to move an object. In this case a speaker or headphones • Formula for generating a sine wave is • Y = sin(x) Simple right?

23. Developing a Software Synthesizer • Many programming languages have standard mathematics libraries with many of the trigonometric functions represented • Most basic computer synthesis methods follow this same general scheme: a formula or function is defined that accepts a sequence of values as input

24. Developing a Software Synthesizer • Computer soundcards have digital-to-analog converters • They are able to generate an electrical signal from a digital number that is given to it

25. Producing a Simple Sine Wave • A cycle of a sine wave is 2π radians long • Sine waves have a peak amplitude of +/- 1 • A sample rate would be 44100 cycles per second – range of the entire human ear

26. Producing a Simple Sine Wave • Input: Peak amplitude (A), Frequency (f) Output: Amplitude value (y) y = A * sin(phase) phase = phase + ((2 * pi * f) / samplerate) if phase > (2 * pi) then phase = phase - (2 * pi)

27. Producing a Square Wave • Input: Peak amplitude (A), Frequency (f) Output: Amplitude value (y) if phase < pi then y = A else y = -A phase = phase + ((2 * pi * f) / samplerate) if phase > (2 * pi) then phase = phase - (2 * pi)

28. Virtual Studio Technology (VST) • Interface for integrating software audio synthesizer and effect plugins with audio editors • Use digital signal processing • VST is supported by a large number of audio applications

29. Virtual Studio Technology (VST) • Run within your Digital Audio Workstation (DAW) • Classified as instruments or effects • VST instruments include synthesizers and samplers • VST effects include effects like reverb and phaser • First released in 1996

30. Virtual Studio Technology (VST) • VST is the plugin standard for DAWs • Allows any third party developer to create a VST plugin for use within DAWs • Steinberg’s VST SDK is a set of C++ classes based around an underlying C API. • You can download the SDK from their website • Steinberg also developed the VST GUI (another set of C++ classes) which is also available to add graphical interface to your VST

31. Virtual Studio Technology (VST) • There are several third party ports available • jVSTwRapper – Java version • Python ctypes-based VST wrapper • Noise and VST.NET – two .NET versions • LADSPA – Linux Audio Developers Simple Plugin API • JRUBY • And many more!

32. Virtual Studio Technology (VST) • LADSPA Header File • http://www.ladspa.org/ladspa_sdk/ladspa.h.txt

33. Questions / Comments?

34. References • Alles, Harold G. "Music Synthesis Using Real Time Digital Techniques." Proceedings of the IEEE 68.4 (1980): 436-49. Web. 10 Mar. 2013. <http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1455942>. • Crombie, D.; Lenoir, R.; McKenzie, N., "Producing accessible multimedia music," Web Delivering of Music, 2003. 2003 WEDELMUSIC. Proceedings. Third International Conference on , vol., no., pp.45,48, 15-17 Sept. 2003 <http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1233872&isnumber=27650> • Echeverria, U.G.; Castro, F.E.G.; Lopez, J.M.D.B., "Comparison between a Hardware and a software synthesizer," Electronics, Communications and Computer (CONIELECOMP), 2010 20th International Conference on , vol., no., pp.311,314, 22-24 Feb. 2010doi: 10.1109/CONIELECOMP.2010.5440747 <http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=5440747&isnumber=544074 6> • "electronic music." Encyclopædia Britannica. Encyclopædia Britannica Online Academic Edition. Encyclopædia Britannica Inc., 2013. Web. 10 Mar. 2013. <http://www.britannica.com/EBchecked/topic/183823/electronic-music>. • Gibbons, J. A.; Howard, D.M.; Tyrrell, A.M., "FPGA implementation of 1D wave equation for real-time audio synthesis," Computers and Digital Techniques, IEE Proceedings - , vol.152, no.5, pp.619,631, 9 Sept. 2005 doi: 10.1049/ip-cdt:20045178 <http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1532084&isnumber=32679>

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