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applet.audio.yamaha_opl: implement WAV export.
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This also makes the applet more efficient by performing the unsigned-
to-signed conversion with numpy, or avoiding a roundtrip, in case
libsamplerate is used.
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@whitequark
whitequark committed Mar 25, 2019
1 parent 68bd607 commit aab4127
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Showing 2 changed files with 136 additions and 9 deletions.
21 changes: 14 additions & 7 deletions software/glasgow/applet/audio/yamaha_opl/__init__.py
View file
Expand Up @@ -559,16 +559,21 @@ async def serve_index(self, request):
return web.Response(text=index_html, content_type="text/html")

def _make_resampler(self, actual, preferred):
import numpy

try:
import numpy
import samplerate
except ImportError as e:
self._logger.warning("samplerate not installed; expect glitches during playback")
async def resample(input_queue, output_queue):
while True:
data = await input_queue.get()
await output_queue.put(data)
if not data:
input_data = await input_queue.get()
input_array = numpy.frombuffer(input_data, dtype="<u2")
output_array = (output_array - 32768).astype(numpy.int16)
if input_data:
await output_queue.put(output_array.tobytes())
if not input_data:
await output_queue.put(b"")
break
return resample, actual

Expand All @@ -578,7 +583,7 @@ def resample_worker(input_data, end):
input_array = (input_array.astype(numpy.float32) - 32768) / 32768
output_array = resampler.process(
input_array, ratio=preferred / actual, end_of_input=end)
output_array = (output_array * 32768 + 32768).astype(numpy.uint16)
output_array = (output_array * 32768).astype(numpy.int16)
return output_array.tobytes()
async def resample(input_queue, output_queue):
while True:
Expand Down Expand Up @@ -746,8 +751,10 @@ class AudioYamahaOPLApplet(GlasgowApplet, name="audio-yamaha-opl"):
$ play -r 49715 output.u16
For the web interface, the browser dictates the sample rate. Streaming at the sample rate other
than the one requested by the browser is possible, but degrades quality. To stream with
the best possible quality, install the samplerate library.
than the one requested by the browser is possible, but degrades quality. This interface also
has additional Python dependencies:
* numpy (mandatory)
* samplerate (optional, required for best possible quality)
"""

__pin_sets = ("d", "a")
Expand Down
124 changes: 122 additions & 2 deletions software/glasgow/applet/audio/yamaha_opl/index.html
View file
Expand Up @@ -7,6 +7,7 @@ <h1>Yamaha OP* Web Gateway</h1>
<p>This webpage lets you submit commands to a real Yamaha synthesizer and listen to the output. The synthesizer is a <b>shared resource</b> (and isn't very fast, although it does not have to run in real time), and everyone who submits a file is in the same queue, so you might have to wait until it's your turn.</p>
<p>Supported chips: {{chips}}.</p>
<p>Play a <a href="https://vgmrips.net/packs/chips">VGM/VGZ file</a>: <input type="file" id="file" accept=".vgm,.vgz"> <input type="button" id="play" value="Play"> <input type="button" id="replay" value="Replay" disabled> <input type="checkbox" id="loop"> <label for="loop">Loop</label></p>
<p>Export PCM: <input type="button" id="exportFull" value="Export full"> <input type="button" id="exportLoop" value="Export loop"></p>
<p>Status: <span id="chipStatus">no chip</span>, <span id="netStatus">idle</span>, <span id="playStatus">stopped</span>.</p>
<p id="errorPane" style="color:red; display:none">Error: <span id="error"></span></p>

Expand All @@ -27,6 +28,7 @@ <h1>Yamaha OP* Web Gateway</h1>

this._context = new (window.AudioContext || window.webkitAudioContext);
this._buffers = [];
this._buffersRaw = [];

this._queueStart = 0;
this._queueEnd = 0;
Expand All @@ -43,12 +45,34 @@ <h1>Yamaha OP* Web Gateway</h1>
dataView.byteLength / 2, sampleRate);
var f32Buffer = audioBuffer.getChannelData(0);
for(var i = 0; i < f32Buffer.length; i++)
f32Buffer[i] = (dataView.getUint16(i * 2, /*littleEndian=*/true) - 32768) / 32768;
f32Buffer[i] = dataView.getInt16(i * 2, /*littleEndian=*/true) / 32768;

this._buffers.push(audioBuffer);
this._buffersRaw.push(dataView.buffer);
this._updateStatus();
}

this.getAllSamples = function() {
return this._buffersRaw;
}

this.getLoopSamples = function() {
var buffers = [];
var skipTo = this.loopSkipTo * 2;
var sourcePos = 0;
for(var i = 0; i < this._buffersRaw.length; i++) {
if(skipTo >= sourcePos + this._buffersRaw[i].byteLength) {
// skip
} else if(skipTo >= sourcePos) {
buffers.push(this._buffersRaw[i].slice(skipTo - sourcePos));
} else {
buffers.push(this._buffersRaw[i]);
}
sourcePos += this._buffersRaw[i].byteLength;
}
return buffers;
}

this.scheduleAtLeast = function(atLeast) {
if(this._buffers.length - this._queueEnd < atLeast) {
console.log("need at least", atLeast, "buffers;",
Expand Down Expand Up @@ -143,8 +167,85 @@ <h1>Yamaha OP* Web Gateway</h1>
}
}

function makeWAVFile(fileName, numOfChannels, sampleRate, bytesPerSample, sampleBuffers) {
var totalSampleBytes = 0;
for(var i = 0; i < sampleBuffers.length; i++)
totalSampleBytes += sampleBuffers[i].byteLength;

var id_length = 8,
fmt_subchunk_length = id_length + 16,
data_subchunk_length = id_length + totalSampleBytes,
RIFF_header_length = id_length + 4,
RIFF_chunk_length = RIFF_header_length + fmt_subchunk_length + data_subchunk_length;

var header = new ArrayBuffer(RIFF_header_length + fmt_subchunk_length + id_length);
var headerView = new DataView(header, 0, header.length);

// "RIFF" chunk
// ChunkID
headerView.setUint32(0, /*"RIFF"*/0x52494646,
/*littleEndian=*/false);
// ChunkSize
headerView.setUint32(4, RIFF_chunk_length - id_length,
/*littleEndian=*/true);
// Format
headerView.setUint32(8, /*"WAVE"*/0x57415645,
/*littleEndian=*/false);

// "fmt " subchunk
// Subchunk1ID
headerView.setUint32(12, /*"fmt "*/0x666d7420,
/*littleEndian=*/false);
// Subchunk1Size
headerView.setUint32(16, fmt_subchunk_length - id_length,
/*littleEndian=*/true);
// AudioFormat
headerView.setUint16(20, /*PCM*/1,
/*littleEndian=*/true);
// NumChannels
headerView.setUint16(22, numOfChannels,
/*littleEndian=*/true);
// SampleRate
headerView.setUint32(24, sampleRate,
/*littleEndian=*/true);
// ByteRate
headerView.setUint32(28, sampleRate * numOfChannels * bytesPerSample,
/*littleEndian=*/true);
// BlockAlign
headerView.setUint16(32, numOfChannels * bytesPerSample,
/*littleEndian=*/true);
// BitsPerSample
headerView.setUint16(34, bytesPerSample * 8,
/*littleEndian=*/true);

// "data" subchunk
// Subchunk1ID
headerView.setUint32(36, /*"data"*/0x64617461,
/*littleEndian=*/false);
// Subchunk1Size
headerView.setUint32(40, totalSampleBytes,
/*littleEndian=*/true);

return new File([header].concat(sampleBuffers), fileName, {type: "audio/wav"});
}

function downloadFile(file) {
if(window.fileUrl)
URL.revokeObjectURL(window.fileUrl);
window.fileUrl = URL.createObjectURL(file);

var a = window.document.createElement('a');
a.href = window.fileUrl;
a.download = file.name;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}

var playButton = document.getElementById("play");
var replayButton = document.getElementById("replay");
var exportFullButton = document.getElementById("exportFull");
var exportLoopButton = document.getElementById("exportLoop");
var loopCheckbox = document.getElementById("loop");
var fileInput = document.getElementById("file");
var netStatusSpan = document.getElementById("netStatus");
Expand All @@ -155,6 +256,8 @@ <h1>Yamaha OP* Web Gateway</h1>
playButton.onclick = function(event) {
playButton.disabled = true;
replayButton.disabled = true;
exportFullButton.disabled = true;
exportLoopButton.disabled = true;

var player = new PCMPlayer();
window.player = player;
Expand Down Expand Up @@ -189,6 +292,7 @@ <h1>Yamaha OP* Web Gateway</h1>
var xhr = new XMLHttpRequest();
xhr.open("POST", "vgm", /*async=*/true);
xhr.setRequestHeader("X-Preferred-Sample-Rate", player.preferredSampleRate());
var sampleRate = 0;
var seenBytes = 0;
var totalSamples = 0;
var seenSamples = 0;
Expand All @@ -203,6 +307,7 @@ <h1>Yamaha OP* Web Gateway</h1>
errorPane.style.display = "none";

if(totalSamples == 0) {
sampleRate = parseInt(xhr.getResponseHeader("X-Sample-Rate"));
totalSamples = parseInt(xhr.getResponseHeader("X-Total-Samples"));
player.loopSkipTo = parseInt(xhr.getResponseHeader("X-Loop-Skip-To"));
chipStatusSpan.innerText = "chip " + xhr.getResponseHeader("X-Chip");
Expand All @@ -217,14 +322,17 @@ <h1>Yamaha OP* Web Gateway</h1>
viewLength = bytes.buffer.byteLength;
var view = new DataView(bytes.buffer, 0, viewLength);
seenSamples += view.byteLength / 2;
player.addSamples(view, parseInt(xhr.getResponseHeader("X-Sample-Rate")));
player.addSamples(view, sampleRate);
if(!player._playing)
player.scheduleAtLeast(BUFFER_AT_LEAST);
seenBytes += CHUNK_SIZE;
}

if(xhr.readyState == 4) {
player.complete = true;
exportFullButton.disabled = false;
if(player.loopSkipTo > 0)
exportLoopButton.disabled = false;
}
}

Expand All @@ -239,6 +347,18 @@ <h1>Yamaha OP* Web Gateway</h1>
}
netStatusSpan.innerText = "waiting";
xhr.send(fileInput.files[0]);

exportFullButton.onclick = function(event) {
var fileName = fileInput.files[0].name.replace(/\.vg[mz]$/i, "") + ".wav";
downloadFile(makeWAVFile(fileName, /*numOfChannels=*/1, sampleRate, /*bytesPerSample=*/2,
player.getAllSamples()));
}

exportLoopButton.onclick = function(event) {
var fileName = fileInput.files[0].name.replace(/\.vg[mz]$/i, "") + " (loop).wav";
downloadFile(makeWAVFile(fileName, /*numOfChannels=*/1, sampleRate, /*bytesPerSample=*/2,
player.getLoopSamples()));
}
};
</script>
<script type="text/javascript">
Expand Down

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