This should play if your Web browser has WebAssembly enabled (most do). Most examples will play unless they need to load files. The first time you click Play, Csound will spend a few seconds loading, then play. You can edit this code and replay it.
<CsoundSynthesizer> <CsOptions> ; Select audio/midi flags here according to platform -odac -m0 --midi-key=4 --midi-velocity-amp=5 ; treat p4 and p5 as midi data ; For Non-realtime ouput leave only the line below: ; -o madsr-2.wav -W ;;; for file output any platform </CsOptions> <CsInstruments> ; Required settings for WebAudio: sr = 48000 ksmps = 128 nchnls = 2 nchnls_i = 1 ; sr = 44100 ; ksmps = 32 ; nchnls = 2 0dbfs = 1 ; by Menno Knevel - 2021 instr 1 ; use score and treat p4 and p5 as midi data icps = cpsmidinn(p4) ; take midi note (p4) from score iveloc ampmidid p5, 92 ; take velocity (p5) from score ; att, dec, lvl, release kenv madsr .001, .2, 1, p6 prints "duration of note (%ds) + release (%2.1fs)\\n", p3, p6 ; asig vco2 iveloc, icps asig butlp asig, 2000 outs asig*kenv, asig*kenv endin </CsInstruments> <CsScore> ; note vel release s i 1 0 1 62 60 0 i 1 2 1 62 80 0 i 1 4 1 62 100 0 i 1 6 1 58 50 0 s i 1 1 1 62 60 0 i 1 3 1 62 80 .5 i 1 5 1 62 100 1.5 i 1 7 1 58 50 3 e </CsScore> </CsoundSynthesizer>