├── .gitignore ├── .babelrc ├── .travis.yml ├── package.json ├── readme.md ├── index.js ├── envelope-generator.js ├── test.js └── LICENSE.MD /.gitignore: -------------------------------------------------------------------------------- 1 | node_modules 2 | .* 3 | -------------------------------------------------------------------------------- /.babelrc: -------------------------------------------------------------------------------- 1 | { 2 | "presets": ["es2015"] 3 | } 4 | -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: node_js 2 | node_js: 3 | - "5" 4 | -------------------------------------------------------------------------------- /package.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "envelope-generator", 3 | "version": "3.0.0", 4 | "description": "An envelope generator for web audio", 5 | "main": "envelope-generator.js", 6 | "scripts": { 7 | "test": "./node_modules/.bin/mocha --compilers js:babel-register", 8 | "build": "./node_modules/.bin/babel index.js --presets babel-preset-es2015 > ./envelope-generator.js", 9 | "prepublish": "npm run build" 10 | }, 11 | "keywords": [ 12 | "web audio", 13 | "envelope", 14 | "envelope generator", 15 | "adsr", 16 | "attack", 17 | "decay", 18 | "sustain", 19 | "release" 20 | ], 21 | "author": "itsjoesullivan", 22 | "license": "ISC", 23 | "devDependencies": { 24 | "babel": "^6.5.2", 25 | "babel-cli": "^6.7.5", 26 | "babel-preset-es2015": "^6.6.0", 27 | "babel-register": "^6.7.2", 28 | "chai": "^3.5.0", 29 | "istanbul": "^0.4.3", 30 | "mocha": "^2.4.5", 31 | "sinon": "^1.17.3" 32 | }, 33 | "dependencies": {} 34 | } 35 | -------------------------------------------------------------------------------- /readme.md: -------------------------------------------------------------------------------- 1 | ## Envelope Generator ![Test status](https://api.travis-ci.org/itsjoesullivan/envelope-generator.svg) 2 | 3 | Basic ADSR envelope generator for web audio. A demo is running [here](http://joesul.li/van/envelope-generator/). 4 | 5 | - The release stage exists as a separate `GainNode`, so the envelope doesn't need to keep track of its output gain internally. 6 | - Uses the [voltage](https://github.com/mmckegg/adsr/blob/master/index.js#L126) idea from [mmckegg/adsr](https://github.com/mmckegg/adsr). 7 | 8 | ### Example 9 | 10 | ```bash 11 | npm install --save envelope-generator 12 | ``` 13 | 14 | ```javascript 15 | import Envelope from 'envelope-generator'; 16 | 17 | let context = new AudioContext(); 18 | let osc = context.createOscillator(); 19 | 20 | let gain = context.createGain(); 21 | 22 | let env = new Envelope(context, { 23 | attackTime: 0.1, 24 | decayTime: 3, 25 | sustainLevel: 0.4, 26 | releaseTime: 0.1 27 | }); 28 | 29 | env.connect(gain.gain); 30 | 31 | var startAt = context.currentTime; 32 | 33 | var releaseAt = startAt + 0.5; 34 | 35 | osc.start(startAt); 36 | env.start(startAt); 37 | 38 | env.release(releaseAt); 39 | 40 | let stopAt = env.getReleaseCompleteTime(); 41 | osc.stop(stopAt); 42 | env.stop(stopAt); 43 | ``` 44 | 45 | ### Usage 46 | 47 | #### Constructor 48 | 49 | The constructor accepts two arguments: an AudioContext and a settings object. All settings are optional, but you will probably want to set at least `attackTime`, `decayTime`, `sustainLevel`, and `releaseTime`. 50 | 51 | - All `...Time` properties are in seconds 52 | - All `curve`, `attackCurve`, `decayCurve`, and `releaseCurve` properties default to `"linear"`, with `"exponential"` the alternative. 53 | - attackCurve, decayCurve, and releaseCurve override their respective curves 54 | - Passing an `initialValueCurve` will determine the shape of the curve usually covered by the attack and decay sections of an envelope, overriding any other curve values. 55 | - Passing a `releaseValueCurve` will determine the shape of the release, overriding any other release curve value. 56 | - Both initialValueCurve and releaseValueCurve are expected to be normalized, i.e. not extending outside of the bounds [0, 1]. This is relatively intuitive for the `initialValueCurve`, but ensure that your `releaseValueCurve` also starts at a value of 1 to avoid any jumps in the sound. The reason for this is that these two curves are applied in series. 57 | - The sampleRate property applies to initialValueCurve and releaseValueCurve, allowing them to be expressed in a sampleRate different from that of the context. 58 | 59 | ```javascript 60 | let context = new AudioContext(); 61 | let settings = { 62 | curve: "linear", 63 | attackCurve: "linear", 64 | decayCurve: "linear", 65 | releaseCurve: "linear", 66 | initialValueCurve: Float32Array, 67 | releaseValueCurve: Float32Array, 68 | sampleRate: 44100, 69 | delayTime: 0, 70 | startLevel: 0, 71 | maxLevel: 1, 72 | attackTime: 0.1, 73 | holdTime: 0, 74 | decayTime: 0, 75 | sustainLevel: 0.5, 76 | releaseTime: 1 77 | }; 78 | let env = new Envelope(context, settings) 79 | ``` 80 | 81 | #### connect 82 | 83 | The `connect` method should be attached directly to `AudioParam`s: 84 | 85 | ```javascript 86 | let osc = context.createOscillator(); 87 | let gainNode = context.createGain(); 88 | let env = new Envelope(context, settings); 89 | env.connect(gainNode.gain); 90 | ``` 91 | 92 | #### start 93 | 94 | The `start` method triggers the attack and decay stages of the envelope: 95 | 96 | ```javascript 97 | let osc = context.createOscillator(); 98 | let gainNode = context.createGain(); 99 | let env = new Envelope(context, settings); 100 | env.connect(gainNode.gain); 101 | 102 | osc.start(context.currentTime); 103 | env.start(context.currentTime); 104 | ``` 105 | 106 | #### release 107 | 108 | The `release` method triggers the release stage of the envelope: 109 | 110 | ```javascript 111 | let osc = context.createOscillator(); 112 | let gainNode = context.createGain(); 113 | let env = new Envelope(context, settings); 114 | env.connect(gainNode.gain); 115 | 116 | osc.start(context.currentTime); 117 | env.start(context.currentTime); 118 | 119 | // Release the envelope after 1 second 120 | env.release(context.currentTime + 1); 121 | ``` 122 | 123 | #### getReleaseCompleteTime 124 | 125 | Releasing the envelope isn't the same as stopping the sound source. Once release has been called, `getReleaseCompleteTime()` will return the time that the envelope finishes its release stage. If this is an amp envelope, and the startLevel (i.e., where the envelope will release to) is 0, `getReleaseCompleteTime()` is when your sound source is guaranteed to be silent and can be stopped: 126 | 127 | ```javascript 128 | let osc = context.createOscillator(); 129 | let gainNode = context.createGain(); 130 | let env = new Envelope(context, settings); 131 | env.connect(gainNode.gain); 132 | 133 | osc.start(context.currentTime); 134 | env.start(context.currentTime); 135 | 136 | env.release(context.currentTime + 1); 137 | 138 | // Stop the oscillator once the envelope has completed. 139 | osc.stop(env.getReleaseCompleteTime()); 140 | ``` 141 | 142 | #### stop 143 | 144 | Because they are generating a signal, envelopes need to be stopped as well as released. This should coincide with when the actual sound source is stopped. 145 | 146 | ```javascript 147 | let osc = context.createOscillator(); 148 | let gainNode = context.createGain(); 149 | let env = new Envelope(context, settings); 150 | env.connect(gainNode.gain); 151 | 152 | osc.start(context.currentTime); 153 | env.start(context.currentTime); 154 | 155 | env.release(context.currentTime + 1); 156 | 157 | // Stop the oscillator once the envelope has completed. 158 | let stopAt = env.getReleaseCompleteTime(); 159 | osc.stop(stopAt); 160 | env.stop(stopAt); 161 | ``` 162 | -------------------------------------------------------------------------------- /index.js: -------------------------------------------------------------------------------- 1 | /** 2 | * Create an envelope generator that 3 | * can be attached to an AudioParam 4 | */ 5 | class Envelope { 6 | constructor(context, settings) { 7 | // Hold on to these 8 | this.context = context; 9 | this.settings = settings; 10 | 11 | this._setDefaults(); 12 | 13 | // Create nodes 14 | this.source = this._getOnesBufferSource(); 15 | this.attackDecayNode = context.createGain(); 16 | this.releaseNode = context.createGain(); 17 | this.ampNode = context.createGain(); 18 | this.outputNode = context.createGain(); 19 | 20 | this.outputNode.gain.value = this.settings.startLevel; 21 | this.ampNode.gain.value = this.settings.maxLevel - this.settings.startLevel; 22 | 23 | // Set up graph 24 | this.source.connect(this.attackDecayNode); 25 | this.source.connect(this.outputNode); 26 | this.attackDecayNode.connect(this.releaseNode); 27 | this.releaseNode.connect(this.ampNode); 28 | this.ampNode.connect(this.outputNode.gain); 29 | } 30 | 31 | 32 | /** 33 | * Deal w/ settings object 34 | */ 35 | _setDefaults() { 36 | 37 | // curve 38 | if (typeof this.settings.curve !== 'string') { 39 | this.settings.curve = 'linear'; 40 | } 41 | 42 | // delayTime 43 | if (typeof this.settings.delayTime !== 'number') { 44 | this.settings.delayTime = 0; 45 | } 46 | 47 | // startLevel 48 | if (typeof this.settings.startLevel !== 'number') { 49 | this.settings.startLevel = 0; 50 | } 51 | // maxLevel 52 | if (typeof this.settings.maxLevel !== 'number') { 53 | this.settings.maxLevel = 1; 54 | } 55 | 56 | // sustainLevel 57 | if (typeof this.settings.sustainLevel !== 'number') { 58 | this.settings.sustainLevel = 1; 59 | } 60 | 61 | // attackTime 62 | if (typeof this.settings.attackTime !== 'number') { 63 | this.settings.attackTime = 0; 64 | } 65 | 66 | // holdTime 67 | if (typeof this.settings.holdTime !== 'number') { 68 | this.settings.holdTime = 0; 69 | } 70 | 71 | // decayTime 72 | if (typeof this.settings.decayTime !== 'number') { 73 | this.settings.decayTime = 0; 74 | } 75 | 76 | // releaseTime 77 | if (typeof this.settings.releaseTime !== 'number') { 78 | this.settings.releaseTime = 0; 79 | } 80 | 81 | // startLevel must not be zero if attack curve is exponential 82 | if (this.settings.startLevel === 0 && this._getRampMethodName('attack') === 'exponentialRampToValueAtTime') { 83 | if (this.settings.maxLevel < 0) { 84 | this.settings.startLevel = -0.001; 85 | } else { 86 | this.settings.startLevel = 0.001; 87 | } 88 | } 89 | 90 | // maxLevel must not be zero if attack, decay, or release curve is exponential 91 | if (this.settings.maxLevel === 0 92 | && (this._getRampMethodName('attack') === 'exponentialRampToValueAtTime' 93 | || this._getRampMethodName('decay') === 'exponentialRampToValueAtTime' 94 | || this._getRampMethodName('release') === 'exponentialRampToValueAtTime' 95 | ) 96 | ) { 97 | if (this.settings.startLevel < 0) { 98 | this.settings.maxLevel = -0.001; 99 | } else { 100 | this.settings.maxLevel = 0.001; 101 | } 102 | } 103 | 104 | // sustainLevel must not be zero if decay or release curve is exponential 105 | if (this.settings.sustainLevel === 0 106 | && (this._getRampMethodName('decay') === 'exponentialRampToValueAtTime' 107 | || this._getRampMethodName('release') === 'exponentialRampToValueAtTime' 108 | ) 109 | ) { 110 | // No need to be negative here as it's a multiplier 111 | this.settings.sustainLevel = 0.001; 112 | } 113 | 114 | // decayTime must not be zero to avoid colliding with attack curve events 115 | if (this.settings.decayTime === 0) { 116 | 117 | this.settings.decayTime = 0.001; 118 | } 119 | 120 | } 121 | 122 | 123 | /** 124 | * Get an audio source that will be pegged at 1, 125 | * providing a signal through our path that can 126 | * drive the AudioParam this is attached to. 127 | * TODO: Can we always cache this? 128 | */ 129 | _getOnesBufferSource() { 130 | let context = this.context; 131 | 132 | // Generate buffer, setting its samples to 1 133 | // Needs to be 2 for safari! 134 | // Hat tip to https://github.com/mmckegg/adsr 135 | let onesBuffer = context.createBuffer(1, 2, context.sampleRate); 136 | let data = onesBuffer.getChannelData(0); 137 | data[0] = 1; 138 | data[1] = 1; 139 | 140 | // Create a source for the buffer, looping it 141 | let source = context.createBufferSource(); 142 | source.buffer = onesBuffer; 143 | source.loop = true; 144 | 145 | return source; 146 | } 147 | 148 | 149 | /** 150 | * Connect the end of the path to the 151 | * targetParam. 152 | * 153 | * TODO: Throw error when not an AudioParam target? 154 | */ 155 | connect(targetParam) { 156 | this.outputNode.connect(targetParam); 157 | } 158 | 159 | 160 | /** 161 | * Begin the envelope, scheduling everything we know 162 | * (attack time, decay time, sustain level). 163 | */ 164 | start(when) { 165 | if (this.settings.initialValueCurve) { 166 | let initial = this.settings.initialValueCurve; 167 | var duration = initial.length * this.settings.sampleRate; 168 | this.attackDecayNode.gain.setValueCurveAtTime(initial, when, initial.length / this.settings.sampleRate); 169 | } else { 170 | let attackRampMethodName = this._getRampMethodName('attack'); 171 | let decayRampMethodName = this._getRampMethodName('decay'); 172 | 173 | let attackStartsAt = when + this.settings.delayTime; 174 | let attackEndsAt = attackStartsAt + this.settings.attackTime; 175 | let decayStartsAt = attackEndsAt + this.settings.holdTime; 176 | let decayEndsAt = decayStartsAt + this.settings.decayTime; 177 | 178 | let attackStartLevel = 0; 179 | if (attackRampMethodName === "exponentialRampToValueAtTime") { 180 | attackStartLevel = 0.001; 181 | } 182 | 183 | this.attackDecayNode.gain 184 | .setValueAtTime(attackStartLevel, 185 | when); 186 | this.attackDecayNode.gain 187 | .setValueAtTime(attackStartLevel, 188 | attackStartsAt); 189 | this.attackDecayNode.gain 190 | [attackRampMethodName](1, 191 | attackEndsAt); 192 | this.attackDecayNode.gain 193 | .setValueAtTime(1, 194 | decayStartsAt); 195 | this.attackDecayNode.gain 196 | [decayRampMethodName](this.settings.sustainLevel, 197 | decayEndsAt); 198 | } 199 | 200 | 201 | this.source.start(when); 202 | 203 | } 204 | 205 | 206 | /** 207 | * Return either linear or exponential 208 | * ramp method names based on a general 209 | * 'curve' setting, which is overridden 210 | * on a per-stage basis by 'attackCurve', 211 | * 'decayCurve', and 'releaseCurve', 212 | * all of which can be set to values of 213 | * either 'linear' or 'exponential'. 214 | */ 215 | _getRampMethodName(stage) { 216 | let exponential = 'exponentialRampToValueAtTime'; 217 | let linear = 'linearRampToValueAtTime'; 218 | 219 | // Handle general case 220 | let generalRampMethodName = linear; 221 | if (this.settings.curve === 'exponential') { 222 | generalRampMethodName = exponential; 223 | } 224 | 225 | switch (stage) { 226 | case 'attack': 227 | if (this.settings.attackCurve) { 228 | if (this.settings.attackCurve === 'exponential') { 229 | return exponential; 230 | } else if (this.settings.attackCurve === 'linear') { 231 | return linear; 232 | } 233 | } 234 | break; 235 | case 'decay': 236 | if (this.settings.decayCurve) { 237 | if (this.settings.decayCurve === 'exponential') { 238 | return exponential; 239 | } else if (this.settings.decayCurve === 'linear') { 240 | return linear; 241 | } 242 | } 243 | break; 244 | case 'release': 245 | if (this.settings.releaseCurve) { 246 | if (this.settings.releaseCurve === 'exponential') { 247 | return exponential; 248 | } else if (this.settings.releaseCurve === 'linear') { 249 | return linear; 250 | } 251 | } 252 | break; 253 | default: 254 | break; 255 | } 256 | return generalRampMethodName; 257 | } 258 | 259 | 260 | /** 261 | * End the envelope, scheduling what we didn't know before 262 | * (release time) 263 | */ 264 | release(when) { 265 | this.releasedAt = when; 266 | 267 | if (this.settings.releaseValueCurve) { 268 | let release = this.settings.releaseValueCurve; 269 | let duration = release.length / this.settings.sampleRate; 270 | this.releaseNode.gain 271 | .setValueCurveAtTime(release, when, duration); 272 | this.settings.releaseTime = duration; 273 | } else { 274 | let releaseEndsAt = this.releasedAt + this.settings.releaseTime; 275 | 276 | let rampMethodName = this._getRampMethodName('release'); 277 | 278 | let releaseTargetLevel = 0; 279 | 280 | if (rampMethodName === "exponentialRampToValueAtTime") { 281 | releaseTargetLevel = 0.001; 282 | } 283 | 284 | this.releaseNode.gain 285 | .setValueAtTime(1, when); 286 | this.releaseNode.gain 287 | [rampMethodName](releaseTargetLevel, releaseEndsAt); 288 | } 289 | 290 | } 291 | 292 | stop(when) { 293 | this.source.stop(when); 294 | } 295 | 296 | 297 | /** 298 | * Provide a helper for consumers to 299 | * know when the release is finished, 300 | * so that a source can be stopped. 301 | */ 302 | getReleaseCompleteTime() { 303 | if (typeof this.releasedAt !== 'number') { 304 | throw new Error("Release has not been called."); 305 | } 306 | return this.releasedAt + this.settings.releaseTime; 307 | } 308 | } 309 | 310 | module.exports = Envelope; 311 | -------------------------------------------------------------------------------- /envelope-generator.js: -------------------------------------------------------------------------------- 1 | 'use strict'; 2 | 3 | var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }(); 4 | 5 | function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } } 6 | 7 | /** 8 | * Create an envelope generator that 9 | * can be attached to an AudioParam 10 | */ 11 | 12 | var Envelope = function () { 13 | function Envelope(context, settings) { 14 | _classCallCheck(this, Envelope); 15 | 16 | // Hold on to these 17 | this.context = context; 18 | this.settings = settings; 19 | 20 | this._setDefaults(); 21 | 22 | // Create nodes 23 | this.source = this._getOnesBufferSource(); 24 | this.attackDecayNode = context.createGain(); 25 | this.releaseNode = context.createGain(); 26 | this.ampNode = context.createGain(); 27 | this.outputNode = context.createGain(); 28 | 29 | this.outputNode.gain.value = this.settings.startLevel; 30 | this.ampNode.gain.value = this.settings.maxLevel - this.settings.startLevel; 31 | 32 | // Set up graph 33 | this.source.connect(this.attackDecayNode); 34 | this.source.connect(this.outputNode); 35 | this.attackDecayNode.connect(this.releaseNode); 36 | this.releaseNode.connect(this.ampNode); 37 | this.ampNode.connect(this.outputNode.gain); 38 | } 39 | 40 | /** 41 | * Deal w/ settings object 42 | */ 43 | 44 | 45 | _createClass(Envelope, [{ 46 | key: '_setDefaults', 47 | value: function _setDefaults() { 48 | 49 | // curve 50 | if (typeof this.settings.curve !== 'string') { 51 | this.settings.curve = 'linear'; 52 | } 53 | 54 | // delayTime 55 | if (typeof this.settings.delayTime !== 'number') { 56 | this.settings.delayTime = 0; 57 | } 58 | 59 | // startLevel 60 | if (typeof this.settings.startLevel !== 'number') { 61 | this.settings.startLevel = 0; 62 | } 63 | // maxLevel 64 | if (typeof this.settings.maxLevel !== 'number') { 65 | this.settings.maxLevel = 1; 66 | } 67 | 68 | // sustainLevel 69 | if (typeof this.settings.sustainLevel !== 'number') { 70 | this.settings.sustainLevel = 1; 71 | } 72 | 73 | // attackTime 74 | if (typeof this.settings.attackTime !== 'number') { 75 | this.settings.attackTime = 0; 76 | } 77 | 78 | // holdTime 79 | if (typeof this.settings.holdTime !== 'number') { 80 | this.settings.holdTime = 0; 81 | } 82 | 83 | // decayTime 84 | if (typeof this.settings.decayTime !== 'number') { 85 | this.settings.decayTime = 0; 86 | } 87 | 88 | // releaseTime 89 | if (typeof this.settings.releaseTime !== 'number') { 90 | this.settings.releaseTime = 0; 91 | } 92 | 93 | // startLevel must not be zero if attack curve is exponential 94 | if (this.settings.startLevel === 0 && this._getRampMethodName('attack') === 'exponentialRampToValueAtTime') { 95 | if (this.settings.maxLevel < 0) { 96 | this.settings.startLevel = -0.001; 97 | } else { 98 | this.settings.startLevel = 0.001; 99 | } 100 | } 101 | 102 | // maxLevel must not be zero if attack, decay, or release curve is exponential 103 | if (this.settings.maxLevel === 0 && (this._getRampMethodName('attack') === 'exponentialRampToValueAtTime' || this._getRampMethodName('decay') === 'exponentialRampToValueAtTime' || this._getRampMethodName('release') === 'exponentialRampToValueAtTime')) { 104 | if (this.settings.startLevel < 0) { 105 | this.settings.maxLevel = -0.001; 106 | } else { 107 | this.settings.maxLevel = 0.001; 108 | } 109 | } 110 | 111 | // sustainLevel must not be zero if decay or release curve is exponential 112 | if (this.settings.sustainLevel === 0 && (this._getRampMethodName('decay') === 'exponentialRampToValueAtTime' || this._getRampMethodName('release') === 'exponentialRampToValueAtTime')) { 113 | // No need to be negative here as it's a multiplier 114 | this.settings.sustainLevel = 0.001; 115 | } 116 | 117 | // decayTime must not be zero to avoid colliding with attack curve events 118 | if (this.settings.decayTime === 0) { 119 | 120 | this.settings.decayTime = 0.001; 121 | } 122 | } 123 | 124 | /** 125 | * Get an audio source that will be pegged at 1, 126 | * providing a signal through our path that can 127 | * drive the AudioParam this is attached to. 128 | * TODO: Can we always cache this? 129 | */ 130 | 131 | }, { 132 | key: '_getOnesBufferSource', 133 | value: function _getOnesBufferSource() { 134 | var context = this.context; 135 | 136 | // Generate buffer, setting its samples to 1 137 | // Needs to be 2 for safari! 138 | // Hat tip to https://github.com/mmckegg/adsr 139 | var onesBuffer = context.createBuffer(1, 2, context.sampleRate); 140 | var data = onesBuffer.getChannelData(0); 141 | data[0] = 1; 142 | data[1] = 1; 143 | 144 | // Create a source for the buffer, looping it 145 | var source = context.createBufferSource(); 146 | source.buffer = onesBuffer; 147 | source.loop = true; 148 | 149 | return source; 150 | } 151 | 152 | /** 153 | * Connect the end of the path to the 154 | * targetParam. 155 | * 156 | * TODO: Throw error when not an AudioParam target? 157 | */ 158 | 159 | }, { 160 | key: 'connect', 161 | value: function connect(targetParam) { 162 | this.outputNode.connect(targetParam); 163 | } 164 | 165 | /** 166 | * Begin the envelope, scheduling everything we know 167 | * (attack time, decay time, sustain level). 168 | */ 169 | 170 | }, { 171 | key: 'start', 172 | value: function start(when) { 173 | 174 | var attackRampMethodName = this._getRampMethodName('attack'); 175 | var decayRampMethodName = this._getRampMethodName('decay'); 176 | 177 | var attackStartsAt = when + this.settings.delayTime; 178 | var attackEndsAt = attackStartsAt + this.settings.attackTime; 179 | var decayStartsAt = attackEndsAt + this.settings.holdTime; 180 | var decayEndsAt = decayStartsAt + this.settings.decayTime; 181 | 182 | var attackStartLevel = 0; 183 | if (attackRampMethodName === "exponentialRampToValueAtTime") { 184 | attackStartLevel = 0.001; 185 | } 186 | 187 | this.attackDecayNode.gain.setValueAtTime(attackStartLevel, when); 188 | this.attackDecayNode.gain.setValueAtTime(attackStartLevel, attackStartsAt); 189 | this.attackDecayNode.gain[attackRampMethodName](1, attackEndsAt); 190 | this.attackDecayNode.gain.setValueAtTime(1, decayStartsAt); 191 | this.attackDecayNode.gain[decayRampMethodName](this.settings.sustainLevel, decayEndsAt); 192 | 193 | this.source.start(when); 194 | } 195 | 196 | /** 197 | * Return either linear or exponential 198 | * ramp method names based on a general 199 | * 'curve' setting, which is overridden 200 | * on a per-stage basis by 'attackCurve', 201 | * 'decayCurve', and 'releaseCurve', 202 | * all of which can be set to values of 203 | * either 'linear' or 'exponential'. 204 | */ 205 | 206 | }, { 207 | key: '_getRampMethodName', 208 | value: function _getRampMethodName(stage) { 209 | var exponential = 'exponentialRampToValueAtTime'; 210 | var linear = 'linearRampToValueAtTime'; 211 | 212 | // Handle general case 213 | var generalRampMethodName = linear; 214 | if (this.settings.curve === 'exponential') { 215 | generalRampMethodName = exponential; 216 | } 217 | 218 | switch (stage) { 219 | case 'attack': 220 | if (this.settings.attackCurve) { 221 | if (this.settings.attackCurve === 'exponential') { 222 | return exponential; 223 | } else if (this.settings.attackCurve === 'linear') { 224 | return linear; 225 | } 226 | } 227 | break; 228 | case 'decay': 229 | if (this.settings.decayCurve) { 230 | if (this.settings.decayCurve === 'exponential') { 231 | return exponential; 232 | } else if (this.settings.decayCurve === 'linear') { 233 | return linear; 234 | } 235 | } 236 | break; 237 | case 'release': 238 | if (this.settings.releaseCurve) { 239 | if (this.settings.releaseCurve === 'exponential') { 240 | return exponential; 241 | } else if (this.settings.releaseCurve === 'linear') { 242 | return linear; 243 | } 244 | } 245 | break; 246 | default: 247 | break; 248 | } 249 | return generalRampMethodName; 250 | } 251 | 252 | /** 253 | * End the envelope, scheduling what we didn't know before 254 | * (release time) 255 | */ 256 | 257 | }, { 258 | key: 'release', 259 | value: function release(when) { 260 | this.releasedAt = when; 261 | var releaseEndsAt = this.releasedAt + this.settings.releaseTime; 262 | 263 | var rampMethodName = this._getRampMethodName('release'); 264 | 265 | var releaseTargetLevel = 0; 266 | 267 | if (rampMethodName === "exponentialRampToValueAtTime") { 268 | releaseTargetLevel = 0.001; 269 | } 270 | 271 | this.releaseNode.gain.setValueAtTime(1, when); 272 | this.releaseNode.gain[rampMethodName](releaseTargetLevel, releaseEndsAt); 273 | } 274 | }, { 275 | key: 'stop', 276 | value: function stop(when) { 277 | this.source.stop(when); 278 | } 279 | 280 | /** 281 | * Provide a helper for consumers to 282 | * know when the release is finished, 283 | * so that a source can be stopped. 284 | */ 285 | 286 | }, { 287 | key: 'getReleaseCompleteTime', 288 | value: function getReleaseCompleteTime() { 289 | if (typeof this.releasedAt !== 'number') { 290 | throw new Error("Release has not been called."); 291 | } 292 | return this.releasedAt + this.settings.releaseTime; 293 | } 294 | }]); 295 | 296 | return Envelope; 297 | }(); 298 | 299 | module.exports = Envelope; 300 | 301 | -------------------------------------------------------------------------------- /test.js: -------------------------------------------------------------------------------- 1 | import Envelope from './index'; 2 | let chai = require('chai'); 3 | let sinon = require('sinon'); 4 | let assert = require('assert'); 5 | chai.should(); 6 | 7 | describe('Envelope', () => { 8 | describe('#constructor', () => { 9 | let audioContext; 10 | class SubClassedEnvelope extends Envelope { 11 | constructor(context, settings) { 12 | super(context, settings); 13 | } 14 | _getOnesBufferSource() { 15 | this.getOnesBufferSourceCalled = true; 16 | return { 17 | connect: sinon.spy() 18 | }; 19 | } 20 | _setDefaults() { 21 | this.setDefaultsCalled = true; 22 | } 23 | } 24 | beforeEach(() => { 25 | audioContext = { 26 | createGain: () => { 27 | return { 28 | connect: sinon.spy(), 29 | gain: {} 30 | }; 31 | } 32 | }; 33 | }); 34 | it('holds on to context', () => { 35 | let env = new SubClassedEnvelope(audioContext, {}); 36 | assert.equal(env.context, audioContext); 37 | }); 38 | it('holds on to settings', () => { 39 | let settings = {}; 40 | let env = new SubClassedEnvelope(audioContext, settings); 41 | assert.equal(env.settings, settings); 42 | }); 43 | it('calls _setDefaults', () => { 44 | let env = new SubClassedEnvelope(audioContext, {}); 45 | assert.equal(env.setDefaultsCalled, true) 46 | }); 47 | it('creates source', () => { 48 | let env = new SubClassedEnvelope(audioContext, {}); 49 | assert(env.source) 50 | }); 51 | it('creates attackDecayNode', () => { 52 | let env = new SubClassedEnvelope(audioContext, {}); 53 | assert(env.attackDecayNode.connect) 54 | }); 55 | it('creates releaseNode', () => { 56 | let env = new SubClassedEnvelope(audioContext, {}); 57 | assert(env.releaseNode.connect) 58 | }); 59 | it('creates ampNode', () => { 60 | let env = new SubClassedEnvelope(audioContext, {}); 61 | assert(env.ampNode.connect) 62 | }); 63 | it('creates outputNode', () => { 64 | let env = new SubClassedEnvelope(audioContext, {}); 65 | assert(env.outputNode.connect) 66 | }); 67 | it('sets outputNode gain to startLevel', () => { 68 | let env = new SubClassedEnvelope(audioContext, { 69 | startLevel: 12 70 | }); 71 | assert.equal(env.outputNode.gain.value, 12); 72 | }); 73 | it('sets ampNode gain to maxLevel - startLevel', () => { 74 | let env = new SubClassedEnvelope(audioContext, { 75 | startLevel: 12, 76 | maxLevel: 15 77 | }); 78 | assert.equal(env.ampNode.gain.value, 3); 79 | }); 80 | it('connects source to attackDecayNode', () => { 81 | let env = new SubClassedEnvelope(audioContext, {}); 82 | assert(env.source.connect.calledWith(env.attackDecayNode)); 83 | }); 84 | it('connects source to outputNode', () => { 85 | let env = new SubClassedEnvelope(audioContext, {}); 86 | assert(env.source.connect.calledWith(env.outputNode)); 87 | }); 88 | it('connects attackDecayNode to releaseNode', () => { 89 | let env = new SubClassedEnvelope(audioContext, {}); 90 | assert(env.attackDecayNode.connect.calledWith(env.releaseNode)); 91 | }); 92 | it('connects releaseNode to ampNode', () => { 93 | let env = new SubClassedEnvelope(audioContext, {}); 94 | assert(env.releaseNode.connect.calledWith(env.ampNode)); 95 | }); 96 | it('connects ampNode to outputNode.gain', () => { 97 | let env = new SubClassedEnvelope(audioContext, {}); 98 | assert(env.ampNode.connect.calledWith(env.outputNode.gain)); 99 | }); 100 | }); 101 | describe('#_setDefaults', () => { 102 | let context = {}; 103 | beforeEach(() => { 104 | context = { 105 | settings: { 106 | curve: 'linear' 107 | }, 108 | }; 109 | context._getRampMethodName = Envelope.prototype 110 | ._getRampMethodName.bind(context); 111 | }); 112 | it('sets curve to "linear"', () => { 113 | Envelope.prototype._setDefaults.apply(context); 114 | context.settings.curve.should.equal('linear'); 115 | }); 116 | it("doesn't override curve: 'exponential'", () => { 117 | context.settings.curve = "exponential"; 118 | Envelope.prototype._setDefaults.apply(context); 119 | context.settings.curve.should.equal('exponential'); 120 | }); 121 | it('sets delayTime to 0', () => { 122 | Envelope.prototype._setDefaults.apply(context); 123 | context.settings.delayTime.should.equal(0); 124 | }); 125 | it('sets startLevel to 0', () => { 126 | Envelope.prototype._setDefaults.apply(context); 127 | context.settings.startLevel.should.equal(0); 128 | }); 129 | it('sets maxLevel to 1', () => { 130 | Envelope.prototype._setDefaults.apply(context); 131 | context.settings.maxLevel.should.equal(1); 132 | }); 133 | it('sets sustainLevel to 1', () => { 134 | Envelope.prototype._setDefaults.apply(context); 135 | context.settings.sustainLevel.should.equal(1); 136 | }); 137 | it('sets attackTime to 0', () => { 138 | Envelope.prototype._setDefaults.apply(context); 139 | context.settings.attackTime.should.equal(0); 140 | }); 141 | it('sets holdTime to 0', () => { 142 | Envelope.prototype._setDefaults.apply(context); 143 | context.settings.holdTime.should.equal(0); 144 | }); 145 | it('sets decayTime to 0.001', () => { 146 | Envelope.prototype._setDefaults.apply(context); 147 | context.settings.decayTime.should.equal(0.001); 148 | }); 149 | it('sets releaseTime to 0', () => { 150 | Envelope.prototype._setDefaults.apply(context); 151 | context.settings.releaseTime.should.equal(0); 152 | }); 153 | it('if exponential, 0 startLevel becomes 0.001', () => { 154 | context.settings.curve = 'exponential'; 155 | Envelope.prototype._setDefaults.apply(context); 156 | context.settings.startLevel.should.equal(0.001); 157 | }); 158 | it('if exponential, 0 maxLevel becomes 0.001', () => { 159 | context.settings.curve = 'exponential'; 160 | context.settings.maxLevel = 0; 161 | context.settings.startLevel = 1; 162 | Envelope.prototype._setDefaults.apply(context); 163 | context.settings.maxLevel.should.equal(0.001); 164 | }); 165 | it('if exponential and negative maxLevel, 0 startLevel becomes -0.001', () => { 166 | context.settings.curve = 'exponential'; 167 | context.settings.startLevel = 0; 168 | context.settings.maxLevel = -10; 169 | Envelope.prototype._setDefaults.apply(context); 170 | context.settings.startLevel.should.equal(-0.001); 171 | }); 172 | it('if exponential and negative startlevel, 0 maxLevel becomes -0.001', () => { 173 | context.settings.curve = 'exponential'; 174 | context.settings.maxLevel = 0; 175 | context.settings.startLevel = -10; 176 | Envelope.prototype._setDefaults.apply(context); 177 | context.settings.maxLevel.should.equal(-0.001); 178 | }); 179 | it('if exponential, 0 sustainLevel becomes 0.001', () => { 180 | context.settings.curve = 'exponential'; 181 | context.settings.sustainLevel = 0; 182 | Envelope.prototype._setDefaults.apply(context); 183 | context.settings.sustainLevel.should.equal(0.001); 184 | }); 185 | }); 186 | describe("#_getOnesBufferSource", () => { 187 | let context; 188 | beforeEach(() => { 189 | let audioContext = { 190 | createBuffer: () => { 191 | let buffer = {}; 192 | buffer.arr = [0, 0]; 193 | buffer.getChannelData = (index) => { 194 | if (index === 0) { 195 | return buffer.arr; 196 | } 197 | } 198 | return buffer; 199 | }, 200 | createBufferSource: () => { 201 | return { 202 | type: "buffer-source" 203 | }; 204 | } 205 | }; 206 | context = { context: audioContext }; 207 | }); 208 | it("returns a buffer source", () => { 209 | let source = Envelope.prototype._getOnesBufferSource.apply(context); 210 | assert.equal(source.type, "buffer-source"); 211 | }); 212 | it("returns a looped buffer source", () => { 213 | let source = Envelope.prototype._getOnesBufferSource.apply(context); 214 | assert.equal(source.loop, true); 215 | }); 216 | it("assigns a buffer to source", () => { 217 | let source = Envelope.prototype._getOnesBufferSource.apply(context); 218 | assert(source.buffer); 219 | }); 220 | it("assigns a buffer of 1s as the source's buffer", () => { 221 | let source = Envelope.prototype._getOnesBufferSource.apply(context); 222 | assert.equal(source.buffer.getChannelData(0).length, 2) 223 | assert.equal(source.buffer.getChannelData(0)[0], 1) 224 | assert.equal(source.buffer.getChannelData(0)[1], 1) 225 | }); 226 | }); 227 | describe("#connect", () => { 228 | it('connects argument to outputNode', () => { 229 | let context = { 230 | outputNode: { 231 | connect: sinon.spy() 232 | } 233 | } 234 | Envelope.prototype.connect.apply(context, ["test"]); 235 | assert(context.outputNode.connect.calledWith("test")); 236 | }); 237 | }); 238 | describe("#start", () => { 239 | let context; 240 | beforeEach(() => { 241 | context = { 242 | source: { 243 | start: sinon.spy() 244 | }, 245 | attackDecayNode: { 246 | gain: { 247 | setValueAtTime: sinon.spy(), 248 | linearRampToValueAtTime: sinon.spy(), 249 | exponentialRampToValueAtTime: sinon.spy() 250 | } 251 | }, 252 | settings: { 253 | curve: 'linear', 254 | delayTime: 0.1, 255 | attackTime: 0.2, 256 | holdTime: 0.3, 257 | decayTime: 0.4, 258 | startLevel: 0.5, 259 | sustainLevel: 0.7 260 | } 261 | }; 262 | context._getRampMethodName = Envelope.prototype._getRampMethodName.bind(context); 263 | }); 264 | it("if linear, sets attackDecayNode to 0 at start", () => { 265 | let when = 0.6; 266 | context.settings.curve = "linear"; 267 | Envelope.prototype.start.apply(context, [when]); 268 | assert(context.attackDecayNode.gain 269 | .setValueAtTime.calledWith(0, when)); 270 | }); 271 | it("if exponential, sets attackDecayNode to 0.001 at start", () => { 272 | let when = 0.6; 273 | context.settings.curve = "exponential"; 274 | Envelope.prototype.start.apply(context, [when]); 275 | assert(context.attackDecayNode.gain 276 | .setValueAtTime.calledWith(0.001, when)); 277 | }); 278 | it("if linear, sets attackDecayNode to 0 after delayTime", () => { 279 | let when = 0.6; 280 | context.settings.curve = "linear"; 281 | let attackStartTime = when + context.settings.delayTime; 282 | Envelope.prototype.start.apply(context, [when]); 283 | assert(context.attackDecayNode.gain 284 | .setValueAtTime.calledWith(0, attackStartTime)); 285 | }); 286 | it("if exponential, sets attackDecayNode to 0.001 after delayTime", () => { 287 | let when = 0.6; 288 | context.settings.curve = "exponential"; 289 | let attackStartTime = when + context.settings.delayTime; 290 | Envelope.prototype.start.apply(context, [when]); 291 | assert(context.attackDecayNode.gain 292 | .setValueAtTime.calledWith(0.001, attackStartTime)); 293 | }); 294 | it("ramps to 1 by delayTime + attackTime", () => { 295 | let when = 0.6; 296 | let attackStartTime = when + context.settings.delayTime; 297 | let attackEndTime = attackStartTime + context.settings.attackTime; 298 | Envelope.prototype.start.apply(context, [when]); 299 | assert(context.attackDecayNode.gain 300 | .linearRampToValueAtTime.calledWith(1, attackEndTime)); 301 | }); 302 | it("holds decay until holdTime after attack ends", () => { 303 | let when = 0.6; 304 | let attackStartTime = when + context.settings.delayTime; 305 | let attackEndTime = attackStartTime + context.settings.attackTime; 306 | let decayStartTime = attackEndTime + context.settings.holdTime; 307 | Envelope.prototype.start.apply(context, [when]); 308 | assert(context.attackDecayNode.gain 309 | .setValueAtTime.calledWith(1, decayStartTime)); 310 | }); 311 | it("ramps to sustainLevel after holdTime", () => { 312 | let when = 0.6; 313 | let attackStartTime = when + context.settings.delayTime; 314 | let attackEndTime = attackStartTime + context.settings.attackTime; 315 | let decayStartTime = attackEndTime + context.settings.holdTime; 316 | let decayEndTime = decayStartTime + context.settings.decayTime; 317 | Envelope.prototype.start.apply(context, [when]); 318 | assert(context.attackDecayNode.gain 319 | .linearRampToValueAtTime.calledWith(context.settings.sustainLevel, decayEndTime)); 320 | }); 321 | it("begins source", () => { 322 | let when = 0.6; 323 | Envelope.prototype.start.apply(context, [when]); 324 | assert(context.source.start.calledWith(when)); 325 | }); 326 | it("if attackCurve is exponential, uses exponential ramp", () => { 327 | let when = 0.6; 328 | let attackStartTime = when + context.settings.delayTime; 329 | let attackEndTime = attackStartTime + context.settings.attackTime; 330 | context.settings.attackCurve = "exponential"; 331 | Envelope.prototype.start.apply(context, [when]); 332 | assert(context.attackDecayNode.gain 333 | .exponentialRampToValueAtTime.calledWith(1, attackEndTime)); 334 | }); 335 | it("if decayCurve is exponential, uses exponential ramp", () => { 336 | let when = 0.6; 337 | let attackStartTime = when + context.settings.delayTime; 338 | let attackEndTime = attackStartTime + context.settings.attackTime; 339 | let decayStartTime = attackEndTime + context.settings.holdTime; 340 | let decayEndTime = decayStartTime + context.settings.decayTime; 341 | context.settings.decayCurve = "exponential"; 342 | Envelope.prototype.start.apply(context, [when]); 343 | assert(context.attackDecayNode.gain 344 | .exponentialRampToValueAtTime.calledWith(context.settings.sustainLevel, decayEndTime)); 345 | }); 346 | }); 347 | describe("#_getRampMethodName", () => { 348 | it("returns linear without anything set", () => { 349 | let settings = {}; 350 | let name = Envelope.prototype._getRampMethodName.apply({ settings: settings}); 351 | assert.equal(name, "linearRampToValueAtTime"); 352 | }); 353 | it("returns exponential if curve: exponential", () => { 354 | let settings = { curve: "exponential" }; 355 | let name = Envelope.prototype._getRampMethodName.apply({ settings: settings}); 356 | assert.equal(name, "exponentialRampToValueAtTime"); 357 | }); 358 | it("attackCurve wins if asking for attack", () => { 359 | let settings = { curve: "exponential", attackCurve: "linear" }; 360 | let name = Envelope.prototype._getRampMethodName.apply({ settings: settings}, ["attack"]); 361 | assert.equal(name, "linearRampToValueAtTime"); 362 | }); 363 | it("decayCurve wins if asking for decay", () => { 364 | let settings = { curve: "linear", decayCurve: "exponential" }; 365 | let name = Envelope.prototype._getRampMethodName.apply({ settings: settings}, ["decay"]); 366 | assert.equal(name, "exponentialRampToValueAtTime"); 367 | }); 368 | it("releaseCurve wins if asking for release", () => { 369 | let settings = { curve: "linear", releaseCurve: "exponential" }; 370 | let name = Envelope.prototype._getRampMethodName.apply({ settings: settings}, ["release"]); 371 | assert.equal(name, "exponentialRampToValueAtTime"); 372 | }); 373 | }); 374 | describe("#release", () => { 375 | let context; 376 | beforeEach(() => { 377 | context = { 378 | releaseNode: { 379 | gain: { 380 | setValueAtTime: sinon.spy(), 381 | linearRampToValueAtTime: sinon.spy(), 382 | exponentialRampToValueAtTime: sinon.spy() 383 | } 384 | }, 385 | settings: { 386 | curve: 'linear', 387 | startLevel: 0.5, 388 | releaseTime: 0.8 389 | } 390 | }; 391 | context._getRampMethodName = Envelope.prototype._getRampMethodName.bind(context); 392 | }); 393 | it("sets value to 1 at release start", () => { 394 | let when = 0.9; 395 | Envelope.prototype.release.apply(context, [when]); 396 | assert(context.releaseNode.gain.setValueAtTime.calledWith(1, when)); 397 | }); 398 | it("if linear, ramps to 0 by release end", () => { 399 | let when = 0.9; 400 | context.settings.curve = "linear"; 401 | Envelope.prototype.release.apply(context, [when]); 402 | let releaseEndsAt = when + context.settings.releaseTime; 403 | assert(context.releaseNode.gain.linearRampToValueAtTime 404 | .calledWith(0, releaseEndsAt)); 405 | }); 406 | it("if exponential, ramps to 0.001 by release end", () => { 407 | let when = 0.9; 408 | context.settings.curve = "exponential"; 409 | Envelope.prototype.release.apply(context, [when]); 410 | let releaseEndsAt = when + context.settings.releaseTime; 411 | assert(context.releaseNode.gain.exponentialRampToValueAtTime 412 | .calledWith(0.001, releaseEndsAt)); 413 | }); 414 | }); 415 | describe("#stop", () => { 416 | it("stops source", () => { 417 | context = { 418 | source: { 419 | stop: sinon.spy() 420 | } 421 | } 422 | let when = 0.9; 423 | Envelope.prototype.stop.apply(context, [when]); 424 | assert(context.source.stop.calledWith(when)); 425 | }); 426 | }); 427 | describe("#getReleaseCompleteTime", () => { 428 | it("returns releasedAt + releaseTime", () => { 429 | let context = { 430 | releasedAt: 1, 431 | settings: { 432 | releaseTime: 3 433 | } 434 | }; 435 | let completeAt = Envelope.prototype.getReleaseCompleteTime.apply(context); 436 | assert.equal(completeAt, 4); 437 | }); 438 | it("throws an error if no releasedAt", () => { 439 | let context = { 440 | settings: { 441 | releaseTime: 3 442 | } 443 | }; 444 | assert.throws(() => { 445 | let completeAt = Envelope.prototype.getReleaseCompleteTime.apply(context); 446 | }, (err) => { 447 | return /Release has not been called/.test(err.message); 448 | }, "unexpected error"); 449 | }); 450 | }); 451 | }); 452 | -------------------------------------------------------------------------------- /LICENSE.MD: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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No Surrender of Others' Freedom. 541 | 542 | If conditions are imposed on you (whether by court order, agreement or 543 | otherwise) that contradict the conditions of this License, they do not 544 | excuse you from the conditions of this License. If you cannot convey a 545 | covered work so as to satisfy simultaneously your obligations under this 546 | License and any other pertinent obligations, then as a consequence you may 547 | not convey it at all. For example, if you agree to terms that obligate you 548 | to collect a royalty for further conveying from those to whom you convey 549 | the Program, the only way you could satisfy both those terms and this 550 | License would be to refrain entirely from conveying the Program. 551 | 552 | 13. Use with the GNU Affero General Public License. 553 | 554 | Notwithstanding any other provision of this License, you have 555 | permission to link or combine any covered work with a work licensed 556 | under version 3 of the GNU Affero General Public License into a single 557 | combined work, and to convey the resulting work. The terms of this 558 | License will continue to apply to the part which is the covered work, 559 | but the special requirements of the GNU Affero General Public License, 560 | section 13, concerning interaction through a network will apply to the 561 | combination as such. 562 | 563 | 14. Revised Versions of this License. 564 | 565 | The Free Software Foundation may publish revised and/or new versions of 566 | the GNU General Public License from time to time. Such new versions will 567 | be similar in spirit to the present version, but may differ in detail to 568 | address new problems or concerns. 569 | 570 | Each version is given a distinguishing version number. If the 571 | Program specifies that a certain numbered version of the GNU General 572 | Public License "or any later version" applies to it, you have the 573 | option of following the terms and conditions either of that numbered 574 | version or of any later version published by the Free Software 575 | Foundation. If the Program does not specify a version number of the 576 | GNU General Public License, you may choose any version ever published 577 | by the Free Software Foundation. 578 | 579 | If the Program specifies that a proxy can decide which future 580 | versions of the GNU General Public License can be used, that proxy's 581 | public statement of acceptance of a version permanently authorizes you 582 | to choose that version for the Program. 583 | 584 | Later license versions may give you additional or different 585 | permissions. However, no additional obligations are imposed on any 586 | author or copyright holder as a result of your choosing to follow a 587 | later version. 588 | 589 | 15. Disclaimer of Warranty. 590 | 591 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 592 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 593 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 594 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 595 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 596 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 597 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 598 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 599 | 600 | 16. Limitation of Liability. 601 | 602 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 610 | SUCH DAMAGES. 611 | 612 | 17. Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | {one line to give the program's name and a brief idea of what it does.} 635 | Copyright (C) {year} {name of author} 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | {project} Copyright (C) {year} {fullname} 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | --------------------------------------------------------------------------------