diff --git a/poc/offline-audio-context/helpers.js b/poc/offline-audio-context/helpers.js
index 93269b2..804e792 100644
--- a/poc/offline-audio-context/helpers.js
+++ b/poc/offline-audio-context/helpers.js
@@ -123,6 +123,6 @@ const forceDownload = (blob, filename = 'output.wav') => {
document.body.removeChild(link)
}
-const makeDownload = (abuffer, totalSamples) => {
- forceDownload(bufferToWave(abuffer, totalSamples), 'dummy.wav')
+const makeDownload = (abuffer, totalSamples, filename) => {
+ forceDownload(bufferToWave(abuffer, totalSamples), `${filename}-${Date.now()}.wav`)
}
diff --git a/poc/offline-audio-context/script.js b/poc/offline-audio-context/script.js
index c2b35d3..f4f36ab 100644
--- a/poc/offline-audio-context/script.js
+++ b/poc/offline-audio-context/script.js
@@ -32,7 +32,7 @@ const demo = () => {
render(a, ctx)
ctx.startRendering().then(abuffer => {
- makeDownload(abuffer, ctx.length)
+ makeDownload(abuffer, ctx.length, 'offline-audio-context')
}).catch(e => {
console.error(e)
})
diff --git a/poc/scheduled-sequencing/helpers.js b/poc/scheduled-sequencing/helpers.js
new file mode 100644
index 0000000..804e792
--- /dev/null
+++ b/poc/scheduled-sequencing/helpers.js
@@ -0,0 +1,128 @@
+/* global Blob, URL */
+
+/*
+function floatTo16BitPCM(output, offset, input) {
+ for (let i = 0; i < input.length; i++, offset += 2) {
+ let s = Math.max(-1, Math.min(1, input[i]));
+ output.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7FFF, true);
+ }
+}
+
+function writeString(view, offset, string) {
+ for (let i = 0; i < string.length; i++) {
+ view.setUint8(offset + i, string.charCodeAt(i));
+ }
+}
+
+function encodeWAV(samples) {
+ let buffer = new ArrayBuffer(44 + samples.length * 2);
+ let view = new DataView(buffer);
+
+ // RIFF identifier
+ writeString(view, 0, 'RIFF');
+ // RIFF chunk length
+ view.setUint32(4, 36 + samples.length * 2, true);
+ // RIFF type
+ writeString(view, 8, 'WAVE');
+ // format chunk identifier
+ writeString(view, 12, 'fmt ');
+ // format chunk length
+ view.setUint32(16, 16, true);
+ // sample format (raw)
+ view.setUint16(20, 1, true);
+ // channel count
+ view.setUint16(22, numChannels, true);
+ // sample rate
+ view.setUint32(24, sampleRate, true);
+ // byte rate (sample rate * block align)
+ view.setUint32(28, sampleRate * 4, true);
+ // block align (channel count * bytes per sample)
+ view.setUint16(32, numChannels * 2, true);
+ // bits per sample
+ view.setUint16(34, 16, true);
+ // data chunk identifier
+ writeString(view, 36, 'data');
+ // data chunk length
+ view.setUint32(40, samples.length * 2, true);
+
+ floatTo16BitPCM(view, 44, samples);
+
+ return view;
+}
+*/
+
+// Convert an AudioBuffer to a Blob using WAVE representation
+const bufferToWave = (abuffer, len) => {
+ const numOfChan = abuffer.numberOfChannels
+
+ const length = len * numOfChan * 2 + 44
+
+ const buffer = new ArrayBuffer(length)
+
+ const view = new DataView(buffer)
+
+ const channels = []; let i; let sample
+
+ let offset = 0
+
+ let pos = 0
+
+ // write WAVE header
+ setUint32(0x46464952) // "RIFF"
+ setUint32(length - 8) // file length - 8
+ setUint32(0x45564157) // "WAVE"
+
+ setUint32(0x20746d66) // "fmt " chunk
+ setUint32(16) // length = 16
+ setUint16(1) // PCM (uncompressed)
+ setUint16(numOfChan)
+ setUint32(abuffer.sampleRate)
+ setUint32(abuffer.sampleRate * 2 * numOfChan) // avg. bytes/sec
+ setUint16(numOfChan * 2) // block-align
+ setUint16(16) // 16-bit (hardcoded in this demo)
+
+ setUint32(0x61746164) // "data" - chunk
+ setUint32(length - pos - 4) // chunk length
+
+ // write interleaved data
+ for (i = 0; i < abuffer.numberOfChannels; i++) { channels.push(abuffer.getChannelData(i)) }
+
+ while (pos < length) {
+ for (i = 0; i < numOfChan; i++) { // interleave channels
+ sample = Math.max(-1, Math.min(1, channels[i][offset])) // clamp
+ sample = (0.5 + sample < 0 ? sample * 32768 : sample * 32767) | 0 // scale to 16-bit signed int
+ view.setInt16(pos, sample, true) // write 16-bit sample
+ pos += 2
+ }
+ offset++ // next source sample
+ }
+
+ // create Blob
+ return new Blob([buffer], { type: 'audio/wav' })
+
+ function setUint16 (data) {
+ view.setUint16(pos, data, true)
+ pos += 2
+ }
+
+ function setUint32 (data) {
+ view.setUint32(pos, data, true)
+ pos += 4
+ }
+}
+
+const forceDownload = (blob, filename = 'output.wav') => {
+ const url = URL.createObjectURL(blob)
+ const link = document.createElement('a')
+ document.body.appendChild(link)
+ link.style = 'display:none'
+ link.href = url
+ link.download = filename
+ link.click()
+ URL.revokeObjectURL(url)
+ document.body.removeChild(link)
+}
+
+const makeDownload = (abuffer, totalSamples, filename) => {
+ forceDownload(bufferToWave(abuffer, totalSamples), `${filename}-${Date.now()}.wav`)
+}
diff --git a/poc/scheduled-sequencing/index.html b/poc/scheduled-sequencing/index.html
index 9d5ceae..d64cc44 100644
--- a/poc/scheduled-sequencing/index.html
+++ b/poc/scheduled-sequencing/index.html
@@ -9,10 +9,12 @@
demo index ยป scheduled sequencing
Play a few notes, which were pre-scheduled and not triggered via setTimeout
-
+
+
+
diff --git a/poc/scheduled-sequencing/script.js b/poc/scheduled-sequencing/script.js
index 2f50534..b66ce8b 100644
--- a/poc/scheduled-sequencing/script.js
+++ b/poc/scheduled-sequencing/script.js
@@ -1,4 +1,4 @@
-/* global virtualWebaudio, AudioContext, once */
+/* global virtualWebaudio, AudioContext, OfflineAudioContext, once, makeDownload */
const { VirtualAudioContext, render } = virtualWebaudio
@@ -35,10 +35,20 @@ const create = () => {
const a = create()
-const demo = () => {
- const ctx = new AudioContext()
+const playDemo = () => {
+ render(a, new AudioContext())
+}
+
+const renderDemo = () => {
+ const ctx = new OfflineAudioContext(1, 44100 * 5, 44100)
render(a, ctx)
+ ctx.startRendering().then(abuffer => {
+ makeDownload(abuffer, ctx.length, 'scheduled-playback')
+ }).catch(e => {
+ console.error(e)
+ })
}
-document.getElementsByTagName('button')[0].addEventListener('click', once(demo))
+document.getElementById('play').addEventListener('click', once(playDemo))
+document.getElementById('render').addEventListener('click', once(renderDemo))