openwebrx-clone/htdocs/lib/AudioEngine.js
2019-10-20 23:38:58 +02:00

215 lines
7.6 KiB
JavaScript

// this controls if the new AudioWorklet API should be used if available.
// the engine will still fall back to the ScriptProcessorNode if this is set to true but not available in the browser.
var useAudioWorklets = true;
function AudioEngine(maxBufferLength, audioReporter) {
this.audioReporter = audioReporter;
this.resetStats();
var ctx = window.AudioContext || window.webkitAudioContext;
if (!ctx) {
return;
}
this.audioContext = new ctx();
this.allowed = this.audioContext.state === 'running';
this.started = false;
this.audioCodec = new sdrjs.ImaAdpcm();
this.compression = 'none';
this.setupResampling();
this.resampler = new sdrjs.RationalResamplerFF(this.resamplingFactor, 1);
this.maxBufferSize = maxBufferLength * this.getSampleRate();
}
AudioEngine.prototype.start = function(callback) {
var me = this;
if (me.resamplingFactor === 0) return; //if failed to find a valid resampling factor...
if (me.started) {
if (callback) callback(false);
return;
}
me.audioContext.resume().then(function(){
me.allowed = me.audioContext.state === 'running';
if (!me.allowed) {
if (callback) callback(false);
return;
}
me.started = true;
me.gainNode = me.audioContext.createGain();
me.gainNode.connect(me.audioContext.destination);
if (useAudioWorklets && me.audioContext.audioWorklet) {
me.audioContext.audioWorklet.addModule('static/lib/AudioProcessor.js').then(function(){
me.audioNode = new AudioWorkletNode(me.audioContext, 'openwebrx-audio-processor', {
numberOfInputs: 0,
numberOfOutputs: 1,
outputChannelCount: [1],
processorOptions: {
maxBufferSize: me.maxBufferSize
}
});
me.audioNode.connect(me.gainNode);
me.audioNode.port.addEventListener('message', function(m){
var json = JSON.parse(m.data);
if (typeof(json.buffersize) !== 'undefined') {
me.audioReporter(json);
}
});
me.audioNode.port.start();
if (callback) callback(true, 'AudioWorklet');
});
} else {
me.audioBuffers = [];
if (!AudioBuffer.prototype.copyToChannel) { //Chrome 36 does not have it, Firefox does
AudioBuffer.prototype.copyToChannel = function (input, channel) //input is Float32Array
{
var cd = this.getChannelData(channel);
for (var i = 0; i < input.length; i++) cd[i] = input[i];
}
}
var bufferSize;
if (me.audioContext.sampleRate < 44100 * 2)
bufferSize = 4096;
else if (me.audioContext.sampleRate >= 44100 * 2 && me.audioContext.sampleRate < 44100 * 4)
bufferSize = 4096 * 2;
else if (me.audioContext.sampleRate > 44100 * 4)
bufferSize = 4096 * 4;
function audio_onprocess(e) {
var total = 0;
var out = new Float32Array(bufferSize);
while (me.audioBuffers.length) {
var b = me.audioBuffers.shift();
var newLength = total + b.length;
// not enough space to fit all data, so splice and put back in the queue
if (newLength > bufferSize) {
var tokeep = b.subarray(0, bufferSize - total);
out.set(tokeep, total);
var tobuffer = b.subarray(bufferSize - total, b.length);
me.audioBuffers.unshift(tobuffer);
break;
} else {
out.set(b, total);
}
total = newLength;
}
e.outputBuffer.copyToChannel(out, 0);
}
//on Chrome v36, createJavaScriptNode has been replaced by createScriptProcessor
var method = 'createScriptProcessor';
if (me.audioContext.createJavaScriptNode) {
method = 'createJavaScriptNode';
}
me.audioNode = me.audioContext[method](bufferSize, 0, 1);
me.audioNode.onaudioprocess = audio_onprocess;
me.audioNode.connect(me.gainNode);
if (callback) callback(true, 'ScriptProcessorNode');
}
setInterval(me.reportStats.bind(me), 1000);
});
};
AudioEngine.prototype.isAllowed = function() {
return this.allowed;
};
AudioEngine.prototype.reportStats = function() {
var stats = {};
if (this.audioNode.port) {
this.audioNode.port.postMessage(JSON.stringify({cmd:'getBuffers'}));
} else {
stats.buffersize = this.getBuffersize();
}
stats.audioRate = this.stats.audioSamples;
var elapsed = new Date() - this.stats.startTime;
stats.audioByteRate = this.stats.audioBytes * 1000 / elapsed;
this.audioReporter(stats);
// sample rate is just measuring the last seconds
this.stats.audioSamples = 0;
};
AudioEngine.prototype.resetStats = function() {
this.stats = {
startTime: new Date(),
audioBytes: 0,
audioSamples: 0
};
};
AudioEngine.prototype.setupResampling = function() { //both at the server and the client
var output_range_max = 12000;
var output_range_min = 8000;
var targetRate = this.audioContext.sampleRate;
var i = 1;
while (true) {
var audio_server_output_rate = Math.floor(targetRate / i);
if (audio_server_output_rate < output_range_min) {
this.resamplingFactor = 0;
this.outputRate = 0;
divlog('Your audio card sampling rate (' + targetRate + ') is not supported.<br />Please change your operating system default settings in order to fix this.', 1);
break;
} else if (audio_server_output_rate >= output_range_min && audio_server_output_rate <= output_range_max) {
this.resamplingFactor = i;
this.outputRate = audio_server_output_rate;
break; //okay, we're done
}
i++;
}
};
AudioEngine.prototype.getOutputRate = function() {
return this.outputRate;
};
AudioEngine.prototype.getSampleRate = function() {
return this.audioContext.sampleRate;
};
AudioEngine.prototype.pushAudio = function(data) {
if (!this.audioNode) return;
this.stats.audioBytes += data.byteLength;
var buffer;
if (this.compression === "adpcm") {
//resampling & ADPCM
buffer = this.audioCodec.decode(new Uint8Array(data));
} else {
buffer = new Int16Array(data);
}
buffer = this.resampler.process(sdrjs.ConvertI16_F(buffer));
this.stats.audioSamples += buffer.length;
if (this.audioNode.port) {
// AudioWorklets supported
this.audioNode.port.postMessage(buffer);
} else {
// silently drop excess samples
if (this.getBuffersize() + buffer.length <= this.maxBufferSize) {
this.audioBuffers.push(buffer);
}
}
};
AudioEngine.prototype.setCompression = function(compression) {
this.compression = compression;
};
AudioEngine.prototype.setVolume = function(volume) {
this.gainNode.gain.value = volume;
};
AudioEngine.prototype.getBuffersize = function() {
// only available when using ScriptProcessorNode
if (!this.audioBuffers) return 0;
return this.audioBuffers.map(function(b){ return b.length; }).reduce(function(a, b){ return a + b; }, 0);
};