Copyright 2004 Ken Greenebaum Introduction to Interactive Sound Synthesis Lecture 14: Envelopes Ken Greenebaum
Copyright 2004 Ken Greenebaum Midterm Was shooting for Was shooting for Straightforward exam (material out of notes) Straightforward exam (material out of notes) Make you think a little Make you think a little Feel good as you leave Feel good as you leave
Copyright 2004 Ken Greenebaum Midterm questions Questions on specific problems? Questions on specific problems?
Copyright 2004 Ken Greenebaum Amplitude Envelope Controls amplitude over time Controls amplitude over time Consists of a series of segments: Consists of a series of segments: Initial (time, amplitude) pair Initial (time, amplitude) pair Final (time, amplitude) pair Final (time, amplitude) pair
Copyright 2004 Ken Greenebaum Amplitude rules Segments usually continuous Segments usually continuous Envelopes usually end at zero gain Envelopes usually end at zero gain Envelopes may consist of 1 or more segments Envelopes may consist of 1 or more segments Three usual segments encode: Three usual segments encode: Attack, sustain, decay Attack, sustain, decay More segments provide more complicated envelope More segments provide more complicated envelope
Copyright 2004 Ken Greenebaum Enveloping Example envelope: Example envelope:
Copyright 2004 Ken Greenebaum Envelope use Shape the sound: Shape the sound: How rapid is the onset How rapid is the onset How long is the sustain How long is the sustain How sharp is the decay How sharp is the decay
Copyright 2004 Ken Greenebaum Envelopes Objects have characteristic envelopes: Objects have characteristic envelopes: Collisions (fast attack) but: Collisions (fast attack) but: Damped objects (fast decay) Damped objects (fast decay) Hollow objects (slower decay) Hollow objects (slower decay) Bells (long sustain) Bells (long sustain)
Copyright 2004 Ken Greenebaum Envelopes and FM Synthesis Adding enveloping to FM synth transforms Adding enveloping to FM synth transforms Cool sounds we were generating Cool sounds we were generating To something resembling actual objects To something resembling actual objects
Copyright 2004 Ken Greenebaum FM Synthesis Enveloping Both oscillators may be enveloped Both oscillators may be enveloped Enveloping the modulator Enveloping the modulator Changes depth of modulation over time Changes depth of modulation over time Consider guitar Consider guitar Fuzzy when plucked Fuzzy when plucked Smoothes over time as the note rings Smoothes over time as the note rings Enveloping the carrier Enveloping the carrier Shapes the sound itself Shapes the sound itself
Copyright 2004 Ken Greenebaum Enveloping Challenges For high quality For high quality Envelope gain calculated on each sample Envelope gain calculated on each sample Shouldn’t solve line eq. for each sample Shouldn’t solve line eq. for each sample Use Bressenham’s line algorithm Use Bressenham’s line algorithm Pre-calculate and add delta x,y values Pre-calculate and add delta x,y values
Copyright 2004 Ken Greenebaum FM Experimentation with JSYN FM synthesis can make interesting FM synthesis can make interesting If not realistic sounds If not realistic sounds
Copyright 2004 Ken Greenebaum Assignment 5: FM Synthesizer Straightforward application Straightforward application No new software engineering required No new software engineering required Should be accomplished in your groups Should be accomplished in your groups Due Tuesday March 9th Due Tuesday March 9th
Copyright 2004 Ken Greenebaum Assignment 5: FM Synthesizer Synth to support Mixer’s synth interface Synth to support Mixer’s synth interface But turned in as called from simple main.c But turned in as called from simple main.c Input from stdin Input from stdin Output via PABLIO Output via PABLIO 48000Hz, mono 48000Hz, mono
Copyright 2004 Ken Greenebaum Assignment 5: FM Synthesizer Input format (all floats): Input format (all floats): Two lines: Two lines: Line 1 Line 1 Carrier frequency, list of time, attenuation pairs Carrier frequency, list of time, attenuation pairs Line 2 Line 2 Modulation frequency, list of time, attenuation pairs Modulation frequency, list of time, attenuation pairs Example: Example: , , , , , , , , , ,0.0
Copyright 2004 Ken Greenebaum Assignment 5: FM Sythesizer Deliverables: Deliverables: fm.c fm.c main.c (calls synth and plays samples) main.c (calls synth and plays samples) makefile makefile Data files: Data files: BassDrum.fm BassDrum.fm WindInstrument.fm WindInstrument.fm Cymbal.fm Cymbal.fm OuterSpace.fm OuterSpace.fm
Copyright 2004 Ken Greenebaum Optional 5b: Monophonic sequencer For those wanting a post midterm boost For those wanting a post midterm boost Control FM synth to play simple tunes: Control FM synth to play simple tunes: From stdin: From stdin: 2 line synth description followed by tune 2 line synth description followed by tune Cap A-G (note) or R(est) Cap A-G (note) or R(est) w(hole), h(alf), q(uarter), e(ight), s(ixteenth) w(hole), h(alf), q(uarter), e(ight), s(ixteenth)
Copyright 2004 Ken Greenebaum 5b: Monophonic sequencer Note should override carrier frequency Note should override carrier frequency A should be 440Hz A should be 440Hz Remember: Remember: 12 notes to an Octave 12 notes to an Octave Octaves represent a doubling of Frequency Octaves represent a doubling of Frequency
Copyright 2004 Ken Greenebaum 5b: Monophonic sequencer Note duration should ‘scale’ envelope length Note duration should ‘scale’ envelope length w – duration * 1.0 w – duration * 1.0 h - duration * 0.5 h - duration * 0.5 etc. etc.
Copyright 2004 Ken Greenebaum 5b: Monophonic sequencer Deliverables: Deliverables: monoseq.c (should call synth.c) monoseq.c (should call synth.c) Makefile Makefile Datafiles: Datafiles: mary.seq (mary had a little lamb) mary.seq (mary had a little lamb) Pick an appropriate ‘instrument’ Pick an appropriate ‘instrument’ Impressive.seq Impressive.seq Something to impress the class Something to impress the class
Copyright 2004 Ken Greenebaum Reading Audio Anecdotes Audio Anecdotes What we can learn from 1980’s Era Synthesis What we can learn from 1980’s Era Synthesis
Copyright 2004 Ken Greenebaum Next class: Guest Lecture: David Thiel (Voice of Q*bert) Guest Lecture: David Thiel (Voice of Q*bert) 1980’s Era Sound Synthesis 1980’s Era Sound Synthesis