Ladybird+LibWeb+WebContent: Create a platform plugin for playing audio

This creates (and installs upon WebContent startup) a platform plugin to
play audio data.

On Serenity, we use AudioServer to play audio over IPC. Unfortunately,
AudioServer is currently coupled with Serenity's audio devices, and thus
cannot be used in Ladybird on Lagom. Instead, we use a Qt audio device
to play the audio, which requires the Qt multimedia package.

While we use Qt to play the audio, note that we can still use LibAudio
to decode the audio data and retrieve samples - we simply send Qt the
raw PCM signals.

Userland/Services/WebContent/AudioCodecPluginSerenity.cpp

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibAudio/ConnectionToServer.h>
+#include <WebContent/AudioCodecPluginSerenity.h>
+
+namespace WebContent {
+
+ErrorOr<NonnullOwnPtr<AudioCodecPluginSerenity>> AudioCodecPluginSerenity::create()
+{
+    auto connection = TRY(Audio::ConnectionToServer::try_create());
+    return adopt_nonnull_own_or_enomem(new (nothrow) AudioCodecPluginSerenity(move(connection)));
+}
+
+AudioCodecPluginSerenity::AudioCodecPluginSerenity(NonnullRefPtr<Audio::ConnectionToServer> connection)
+    : m_connection(move(connection))
+{
+}
+
+AudioCodecPluginSerenity::~AudioCodecPluginSerenity() = default;
+
+size_t AudioCodecPluginSerenity::device_sample_rate()
+{
+    if (!m_device_sample_rate.has_value())
+        m_device_sample_rate = m_connection->get_sample_rate();
+    return *m_device_sample_rate;
+}
+
+void AudioCodecPluginSerenity::enqueue_samples(FixedArray<Audio::Sample> samples)
+{
+    m_connection->async_enqueue(move(samples)).release_value_but_fixme_should_propagate_errors();
+}
+
+size_t AudioCodecPluginSerenity::remaining_samples() const
+{
+    return m_connection->remaining_samples();
+}
+
+void AudioCodecPluginSerenity::resume_playback()
+{
+    m_connection->async_start_playback();
+}
+
+void AudioCodecPluginSerenity::pause_playback()
+{
+    m_connection->async_start_playback();
+}
+
+void AudioCodecPluginSerenity::playback_ended()
+{
+    m_connection->async_pause_playback();
+    m_connection->clear_client_buffer();
+    m_connection->async_clear_buffer();
+}
+
+}

Userland/Services/WebContent/AudioCodecPluginSerenity.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/Optional.h>
+#include <LibAudio/Forward.h>
+#include <LibWeb/Platform/AudioCodecPlugin.h>
+
+namespace WebContent {
+
+class AudioCodecPluginSerenity final : public Web::Platform::AudioCodecPlugin {
+public:
+    static ErrorOr<NonnullOwnPtr<AudioCodecPluginSerenity>> create();
+    virtual ~AudioCodecPluginSerenity() override;
+
+    virtual size_t device_sample_rate() override;
+
+    virtual void enqueue_samples(FixedArray<Audio::Sample>) override;
+    virtual size_t remaining_samples() const override;
+
+    virtual void resume_playback() override;
+    virtual void pause_playback() override;
+    virtual void playback_ended() override;
+
+private:
+    explicit AudioCodecPluginSerenity(NonnullRefPtr<Audio::ConnectionToServer>);
+
+    NonnullRefPtr<Audio::ConnectionToServer> m_connection;
+    Optional<size_t> m_device_sample_rate;
+};
+
+}

Userland/Services/WebContent/CMakeLists.txt

@@ -11,6 +11,7 @@ compile_ipc(WebDriverClient.ipc WebDriverClientEndpoint.h)
 compile_ipc(WebDriverServer.ipc WebDriverServerEndpoint.h)
 
 set(SOURCES
+    AudioCodecPluginSerenity.cpp
     ConnectionFromClient.cpp
     ConsoleGlobalEnvironmentExtensions.cpp
     ImageCodecPluginSerenity.cpp
@@ -28,5 +29,5 @@ set(GENERATED_SOURCES
 )
 
 serenity_bin(WebContent)
-target_link_libraries(WebContent PRIVATE LibCore LibFileSystem LibIPC LibGfx LibImageDecoderClient LibJS LibWebView LibWeb LibLocale LibMain)
+target_link_libraries(WebContent PRIVATE LibCore LibFileSystem LibIPC LibGfx LibAudio LibImageDecoderClient LibJS LibWebView LibWeb LibLocale LibMain)
 link_with_locale_data(WebContent)

Userland/Services/WebContent/main.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include "AudioCodecPluginSerenity.h"
 #include "ImageCodecPluginSerenity.h"
 #include <LibCore/EventLoop.h>
 #include <LibCore/LocalServer.h>
@@ -25,7 +26,7 @@
 ErrorOr<int> serenity_main(Main::Arguments)
 {
     Core::EventLoop event_loop;
-    TRY(Core::System::pledge("stdio recvfd sendfd accept unix rpath thread"));
+    TRY(Core::System::pledge("stdio recvfd sendfd accept unix rpath thread proc"));
 
     // This must be first; we can't check if /tmp/webdriver exists once we've unveiled other paths.
     auto webdriver_socket_path = DeprecatedString::formatted("{}/webdriver", TRY(Core::StandardPaths::runtime_directory()));
@@ -35,6 +36,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
     TRY(Core::System::unveil("/res", "r"));
     TRY(Core::System::unveil("/etc/timezone", "r"));
     TRY(Core::System::unveil("/usr/lib", "r"));
+    TRY(Core::System::unveil("/tmp/session/%sid/portal/audio", "rw"));
     TRY(Core::System::unveil("/tmp/session/%sid/portal/request", "rw"));
     TRY(Core::System::unveil("/tmp/session/%sid/portal/image", "rw"));
     TRY(Core::System::unveil("/tmp/session/%sid/portal/websocket", "rw"));
@@ -44,6 +46,10 @@ ErrorOr<int> serenity_main(Main::Arguments)
     Web::Platform::ImageCodecPlugin::install(*new WebContent::ImageCodecPluginSerenity);
     Web::Platform::FontPlugin::install(*new Web::Platform::FontPluginSerenity);
 
+    Web::Platform::AudioCodecPlugin::install_creation_hook([] {
+        return WebContent::AudioCodecPluginSerenity::create();
+    });
+
     Web::WebSockets::WebSocketClientManager::initialize(TRY(WebView::WebSocketClientManagerAdapter::try_create()));
     Web::ResourceLoader::initialize(TRY(WebView::RequestServerAdapter::try_create()));
     TRY(Web::Bindings::initialize_main_thread_vm());