From a6f2b6b31ab4539957021656571ff984154c4108 Mon Sep 17 00:00:00 2001
From: Jakob Ketterl <jakob.ketterl@gmx.de>
Date: Sat, 18 Jun 2022 20:23:50 +0200
Subject: [PATCH] add opus server-side integration

---
 csdr/chain/clientaudio.py            | 16 +++++++--
 htdocs/lib/AudioEngine.js            | 54 ++++++++++++++++++----------
 htdocs/openwebrx.js                  |  2 +-
 owrx/controllers/settings/general.py |  1 +
 4 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/csdr/chain/clientaudio.py b/csdr/chain/clientaudio.py
index febfd15..50c25f1 100644
--- a/csdr/chain/clientaudio.py
+++ b/csdr/chain/clientaudio.py
@@ -1,5 +1,5 @@
 from csdr.chain import Chain
-from pycsdr.modules import AudioResampler, Convert, AdpcmEncoder, Limit
+from pycsdr.modules import AudioResampler, Convert, AdpcmEncoder, OpusEncoder, Limit
 from pycsdr.types import Format
 
 
@@ -27,6 +27,8 @@ class ClientAudioChain(Chain):
             workers += [converter]
         if compression == "adpcm":
             workers += [AdpcmEncoder(sync=True)]
+        elif compression == "opus":
+            workers += [OpusEncoder()]
         super().__init__(workers)
 
     def _buildConverter(self):
@@ -63,10 +65,18 @@ class ClientAudioChain(Chain):
         self._updateConverter()
 
     def setAudioCompression(self, compression: str) -> None:
-        index = self.indexOf(lambda x: isinstance(x, AdpcmEncoder))
+        index = self.indexOf(lambda x: isinstance(x, AdpcmEncoder) or isinstance(x, OpusEncoder))
+        newEncoder = None
         if compression == "adpcm":
+            newEncoder = AdpcmEncoder(sync=True)
+        elif compression == "opus":
+            newEncoder = OpusEncoder()
+
+        if newEncoder:
             if index < 0:
-                self.append(AdpcmEncoder(sync=True))
+                self.append(newEncoder)
+            else:
+                self.replace(index, newEncoder)
         else:
             if index >= 0:
                 self.remove(index)
diff --git a/htdocs/lib/AudioEngine.js b/htdocs/lib/AudioEngine.js
index 48efb26..4258c6e 100644
--- a/htdocs/lib/AudioEngine.js
+++ b/htdocs/lib/AudioEngine.js
@@ -21,7 +21,11 @@ function AudioEngine(maxBufferLength, audioReporter) {
         me._start();
     }
 
-    this.audioCodec = new ImaAdpcmCodec();
+    this.audioCodecs = {
+        "adpcm": new ImaAdpcmCodec(),
+        "opus": new OpusCodec(this.audioContext)
+    };
+
     this.compression = 'none';
 
     this.setupResampling();
@@ -277,25 +281,31 @@ AudioEngine.prototype.getSampleRate = function() {
 };
 
 AudioEngine.prototype.processAudio = function(data, resampler) {
+    var me = this;
+
     if (!this.audioNode) return;
     this.audioBytes.add(data.byteLength);
-    var buffer;
-    if (this.compression === "adpcm") {
-        //resampling & ADPCM
-        buffer = this.audioCodec.decodeWithSync(new Uint8Array(data));
-    } else {
-        buffer = new Int16Array(data);
-    }
-    buffer = resampler.process(buffer);
-    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);
+
+    var audioDataCallback = function(buffer) {
+        buffer = resampler.process(buffer);
+        if (me.audioNode.port) {
+            // AudioWorklets supported
+            me.audioNode.port.postMessage(buffer);
+        } else {
+            // silently drop excess samples
+            if (this.getBuffersize() + buffer.length <= this.maxBufferSize) {
+                this.audioBuffers.push(buffer);
+            }
         }
     }
+
+    if (this.compression !== "none") {
+        //resampling & ADPCM
+        this.audioCodecs[this.compression].decodeAsync(new Uint8Array(data), audioDataCallback);
+    } else {
+        audioDataCallback(new Int16Array(data))
+    }
+
 }
 
 AudioEngine.prototype.pushAudio = function(data) {
@@ -357,7 +367,7 @@ ImaAdpcmCodec.prototype.decode = function(data) {
     return output;
 };
 
-ImaAdpcmCodec.prototype.decodeWithSync = function(data) {
+ImaAdpcmCodec.prototype.decodeAsync = function(data, callback) {
     var output = new Int16Array(data.length * 2);
     var index = this.skip;
     var oi = 0;
@@ -391,7 +401,7 @@ ImaAdpcmCodec.prototype.decodeWithSync = function(data) {
         }
     }
     this.skip = index - data.length;
-    return output.slice(0, oi);
+    callback(output.slice(0, oi));
 };
 
 ImaAdpcmCodec.prototype.decodeNibble = function(nibble) {
@@ -412,6 +422,14 @@ ImaAdpcmCodec.prototype.decodeNibble = function(nibble) {
     return this.predictor;
 };
 
+function OpusCodec(context) {
+    this.context = context;
+}
+
+OpusCodec.prototype.decodeAsync = function(data, callback) {
+    this.context.decodeAudioData(new ArrayBuffer(data)).then(callback);
+};
+
 function Interpolator(factor) {
     this.factor = factor;
     this.lowpass = new Lowpass(factor)
diff --git a/htdocs/openwebrx.js b/htdocs/openwebrx.js
index 5c43ea7..21e076e 100644
--- a/htdocs/openwebrx.js
+++ b/htdocs/openwebrx.js
@@ -754,7 +754,7 @@ function on_ws_recv(evt) {
                         if ('audio_compression' in config) {
                             var audio_compression = config['audio_compression'];
                             audioEngine.setCompression(audio_compression);
-                            divlog("Audio stream is " + ((audio_compression === "adpcm") ? "compressed" : "uncompressed") + ".");
+                            divlog("Audio stream is " + ((audio_compression !== "none") ? "compressed" : "uncompressed") + ".");
                         }
                         if ('fft_compression' in config) {
                             fft_compression = config['fft_compression'];
diff --git a/owrx/controllers/settings/general.py b/owrx/controllers/settings/general.py
index 232c543..e85e761 100644
--- a/owrx/controllers/settings/general.py
+++ b/owrx/controllers/settings/general.py
@@ -132,6 +132,7 @@ class GeneralSettingsController(SettingsFormController):
                     "Audio compression",
                     options=[
                         Option("adpcm", "ADPCM"),
+                        Option("opus", "OPUS"),
                         Option("none", "None"),
                     ],
                 ),