Retro/pcjs
Watch
1
0
Fork
You've already forked pcjs
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Using some things I learned from @stevekinney today, I've tweaked the PC speaker code to no longer stop() and destroy oscillators every time the speaker is toggled off; instead, the ChipSet component now uses one oscillator for the life of the machine (created the first time the PC makes a sound) and simply zeros/sets the gain as needed. We still have the "easing" issue to deal with (whenever the PC the makes sudden changes to the frequency) and I still can't use dot names for any of the AudioContext properties (until I either update the Closure Compiler or manually add an externs file for the AudioContext interfaces).

Browse source
This commit is contained in:
Jeff Parsons 2017-08-11 20:05:48 -07:00 • committed by Jeff Parsons
commit d8e329b12c
8 changed files with 632 additions and 682 deletions
Download patch file Download diff file Expand all files Collapse all files

59
modules/pcx86/lib/chipset.js
View file

@ -146,19 +146,11 @@ class ChipSet extends Component {
this.sDateRTC = parmsChipSet['dateRTC'];
/*
* Here, I'm finally getting around to trying the Web Audio API. Fortunately, based on what little I know about
* sound generation, using the API to make the same noises as the IBM PC speaker seems straightforward.
* Here, I'm finally getting around to trying the Web Audio API. Fortunately, based on what little
* I know about sound generation, using the API to make the same noises as the IBM PC speaker seems
* straightforward.
*
* To start, we create an audio context, unless the 'sound' parameter has been explicitly set to false.
*
* From:
*
* http://developer.apple.com/library/safari/#documentation/AudioVideo/Conceptual/Using_HTML5_Audio_Video/PlayingandSynthesizingSounds/PlayingandSynthesizingSounds.html
*
* "Similar to how HTML5 canvas requires a context on which lines and curves are drawn, Web Audio requires an audio context
* on which sounds are played and manipulated. This context will be the parent object of further audio objects to come....
* Your audio context is typically created when your page initializes and should be long-lived. You can play multiple sounds
* coming from multiple sources within the same context, so it is unnecessary to create more than one audio context per page."
*/
this.fSpeaker = false;
if (parmsChipSet['sound']) {
@ -4607,38 +4599,21 @@ class ChipSet extends Component {
*/
if (freq < 20 || freq > 20000) fOn = false;
if (fOn) {
if (this.sourceAudio) {
this.sourceAudio['frequency']['value'] = freq;
if (this.messageEnabled(Messages.SPEAKER)) this.printMessage("speaker set to " + freq + "hz", true);
} else {
this.sourceAudio = this.contextAudio['createOscillator']();
if (this.sourceAudio) {
if (typeof this.sourceAudio['type'] == "number") {
this.sourceAudio['type'] = 1; // deprecated: 0: "sine", 1: "square", 2: "sawtooth", 3: "triangle"
} else {
this.sourceAudio['type'] = "square";
}
this.sourceAudio['connect'](this.contextAudio['destination']);
this.sourceAudio['frequency']['value'] = freq;
if ('start' in this.sourceAudio) {
this.sourceAudio['start'](0);
} else {
this.sourceAudio['noteOn'](0); // deprecated: this.sourceAudio['noteOn'](0)
}
if (this.messageEnabled(Messages.SPEAKER)) this.printMessage("speaker on at " + freq + "hz", true);
}
}
} else {
if (this.sourceAudio) {
if ('stop' in this.sourceAudio) {
this.sourceAudio['stop'](0);
} else {
this.sourceAudio['noteOff'](0); // deprecated: this.sourceAudio['noteOff'](0)
}
this.sourceAudio['disconnect'](); // QUESTION: is this automatic following a stop(), since this particular source cannot be started again?
delete this.sourceAudio; // QUESTION: ditto?
if (this.messageEnabled(Messages.SPEAKER)) this.printMessage("speaker off at " + freq + "hz", true);
if (!this.oscillatorAudio) {
this.oscillatorAudio = this.contextAudio['createOscillator']();
this.gainAudio = this.contextAudio['createGain']();
this.oscillatorAudio['connect'](this.gainAudio);
this.gainAudio['connect'](this.contextAudio['destination']);
this.oscillatorAudio['frequency']['value'] = freq;
this.oscillatorAudio['type'] = "square";
this.oscillatorAudio['start'](0);
}
this.oscillatorAudio['frequency']['value'] = freq;
this.gainAudio['gain']['value'] = 1;
if (this.messageEnabled(Messages.SPEAKER)) this.printMessage("speaker on at " + freq + "hz", true);
} else if (this.oscillatorAudio) {
this.gainAudio['gain']['value'] = 0;
if (this.messageEnabled(Messages.SPEAKER)) this.printMessage("speaker off at " + freq + "hz", true);
}
} catch(e) {
this.notice("AudioContext exception: " + e.message);