From edfac528c8381f510ca83a8edb94db9a3e3e10f7 Mon Sep 17 00:00:00 2001
From: Lorn Potter <lorn.potter@gmail.com>
Date: Fri, 10 Jun 2022 11:42:16 +1000
Subject: wasm: update and fix qwasmaudiodevice

- set min and max sample rates according to AudioContext docs
- remove use of EM_ASM to allow better use of multithreading
- ensure feature thread is used

Fixes: QTBUG-104045
Change-Id: Id0bf8905c68f4364abc6f3a9029f75cc5275ff0b
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@gmail.com>
(cherry picked from commit 731e6b6f510b01e496860a208d304789aa72fca3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 CMakeLists.txt                           |  5 +++++
 src/multimedia/wasm/qwasmaudiodevice.cpp | 26 +++++++++++++++++---------
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 033d02ec5..96b2f8cb3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,5 +21,10 @@ if(NOT TARGET Qt::Network)
     message(NOTICE "Skipping the build as the condition \"TARGET Qt::Network\" is not met.")
     return()
 endif()
+if(NOT QT_FEATURE_thread)
+    message(NOTICE "Skipping the build as the QT_FEATURE_thread is not met.")
+    return()
+endif()
+
 
 qt_build_repo()
diff --git a/src/multimedia/wasm/qwasmaudiodevice.cpp b/src/multimedia/wasm/qwasmaudiodevice.cpp
index 18eb9e967..b8f3532b5 100644
--- a/src/multimedia/wasm/qwasmaudiodevice.cpp
+++ b/src/multimedia/wasm/qwasmaudiodevice.cpp
@@ -3,6 +3,9 @@
 
 #include "qwasmaudiodevice_p.h"
 #include <emscripten.h>
+#include <emscripten/val.h>
+#include <emscripten/bind.h>
+
 #include <AL/al.h>
 #include <AL/alc.h>
 
@@ -16,8 +19,8 @@ QWasmAudioDevice::QWasmAudioDevice(const char *device, const char *desc, bool is
 
     minimumChannelCount = 1;
     maximumChannelCount = 2;
-    minimumSampleRate = 1;
-    maximumSampleRate = 192'000;
+    minimumSampleRate = 8000;
+    maximumSampleRate = 96000; // js AudioContext max according to docs
 
     // native openAL formats
     supportedSampleFormats.append(QAudioFormat::UInt8);
@@ -29,13 +32,18 @@ QWasmAudioDevice::QWasmAudioDevice(const char *device, const char *desc, bool is
 
     preferredFormat.setChannelCount(2);
 
-    preferredFormat.setSampleRate(EM_ASM_INT({
-        var AudioContext = window.AudioContext || window.webkitAudioContext;
-        var ctx = new AudioContext();
-        var sr = ctx.sampleRate;
-        ctx.close();
-        return sr;
-    }));
+    // FIXME: firefox
+    // An AudioContext was prevented from starting automatically.
+    // It must be created or resumed after a user gesture on the page.
+    emscripten::val audioContext = emscripten::val::global("window")["AudioContext"].new_();
+    if (audioContext == emscripten::val::undefined())
+        audioContext = emscripten::val::global("window")["webkitAudioContext"].new_();
+
+    if (audioContext != emscripten::val::undefined()) {
+        int sRate = audioContext["sampleRate"].as<int>();
+        audioContext.call<void>("close");
+        preferredFormat.setSampleRate(sRate);
+    }
 
     auto f = QAudioFormat::Float;
 
-- 
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