Merge branch 'main' into webrtc-voice

7 files changed, 947 insertions, 0 deletions

diff --git a/indra/media_plugins/cef/linux/volume_catcher_linux.cpp b/indra/media_plugins/cef/linux/volume_catcher_linux.cpp
new file mode 100644
index 0000000000..7d33242063
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_linux.cpp
@@ -0,0 +1,78 @@
+/**
+ * @file volume_catcher.cpp
+ * @brief Linux volume catcher which will pick an implementation to use
+ *
+ * @cond
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ * @endcond
+ */
+
+#include "volume_catcher_linux.h"
+
+VolumeCatcher::VolumeCatcher()
+{
+}
+
+void VolumeCatcher::onEnablePipeWireVolumeCatcher(bool enable)
+{
+    if (pimpl != nullptr)
+        return;
+
+    if (enable)
+    {
+        LL_DEBUGS() << "volume catcher using pipewire" << LL_ENDL;
+        pimpl = new VolumeCatcherPipeWire();
+    }
+    else
+    {
+        LL_DEBUGS() << "volume catcher using pulseaudio" << LL_ENDL;
+        pimpl = new VolumeCatcherPulseAudio();
+    }
+}
+
+VolumeCatcher::~VolumeCatcher()
+{
+    if (pimpl != nullptr)
+    {
+        delete pimpl;
+        pimpl = nullptr;
+    }
+}
+
+void VolumeCatcher::setVolume(F32 volume)
+{
+    if (pimpl != nullptr) {
+        pimpl->setVolume(volume);
+    }
+}
+
+void VolumeCatcher::setPan(F32 pan)
+{
+    if (pimpl != nullptr)
+        pimpl->setPan(pan);
+}
+
+void VolumeCatcher::pump()
+{
+    if (pimpl != nullptr)
+        pimpl->pump();
+}
diff --git a/indra/media_plugins/cef/linux/volume_catcher_linux.h b/indra/media_plugins/cef/linux/volume_catcher_linux.h
new file mode 100644
index 0000000000..505f9ffb31
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_linux.h
@@ -0,0 +1,149 @@
+/**
+ * @file volume_catcher_impl.h
+ * @brief
+ *
+ * @cond
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ * @endcond
+ */
+
+#ifndef VOLUME_CATCHER_LINUX_H
+#define VOLUME_CATCHER_LINUX_H
+
+#include "linden_common.h"
+
+#include "../volume_catcher.h"
+
+#include <unordered_set>
+#include <mutex>
+
+extern "C" {
+// There's no special reason why we want the *glib* PA mainloop, but the generic polling implementation seems broken.
+#include <pulse/glib-mainloop.h>
+#include <pulse/context.h>
+
+#include <pipewire/pipewire.h>
+
+#include "apr_pools.h"
+#include "apr_dso.h"
+}
+
+#include "media_plugin_base.h"
+
+class VolumeCatcherImpl
+{
+public:
+    virtual ~VolumeCatcherImpl() = default;
+
+    virtual void setVolume(F32 volume) = 0; // 0.0 - 1.0
+
+    // Set the left-right pan of audio sources
+    // where -1.0 = left, 0 = center, and 1.0 = right
+    virtual void setPan(F32 pan) = 0;
+
+    virtual void pump() = 0; // call this at least a few times a second if you can - it affects how quickly we can 'catch' a new audio source and adjust its volume
+};
+
+class VolumeCatcherPulseAudio : public VolumeCatcherImpl
+{
+public:
+    VolumeCatcherPulseAudio();
+    ~VolumeCatcherPulseAudio();
+
+    void setVolume(F32 volume);
+    void setPan(F32 pan);
+    void pump();
+
+    // for internal use - can't be private because used from our C callbacks
+
+    bool loadsyms(std::string pa_dso_name);
+    void init();
+    void cleanup();
+
+    void update_all_volumes(F32 volume);
+    void update_index_volume(U32 index, F32 volume);
+    void connected_okay();
+
+    std::set<U32> mSinkInputIndices;
+    std::map<U32,U32> mSinkInputNumChannels;
+    F32 mDesiredVolume;
+    pa_glib_mainloop *mMainloop;
+    pa_context *mPAContext;
+    bool mConnected;
+    bool mGotSyms;
+};
+
+class VolumeCatcherPipeWire : public VolumeCatcherImpl
+{
+public:
+    VolumeCatcherPipeWire();
+    ~VolumeCatcherPipeWire();
+
+    bool loadsyms(std::string pw_dso_name);
+    void init();
+    void cleanup();
+
+    // some of these should be private
+
+    void lock();
+    void unlock();
+
+    void setVolume(F32 volume);
+    void setPan(F32 pan);
+    void pump();
+
+    void handleRegistryEventGlobal(
+        uint32_t id, uint32_t permissions, const char* type,
+        uint32_t version, const struct spa_dict* props
+    );
+
+    class ChildNode
+    {
+    public:
+        bool mActive = false;
+
+        pw_proxy* mProxy = nullptr;
+        spa_hook mNodeListener {};
+        spa_hook mProxyListener {};
+        VolumeCatcherPipeWire* mImpl = nullptr;
+
+        void updateVolume();
+        void destroy();
+    };
+
+    bool mGotSyms = false;
+
+    F32 mVolume = 1.0f; // max by default
+    // F32 mPan = 0.0f; // center
+
+    pw_thread_loop* mThreadLoop = nullptr;
+    pw_context* mContext = nullptr;
+    pw_core* mCore = nullptr;
+    pw_registry* mRegistry = nullptr;
+    spa_hook mRegistryListener;
+
+    std::unordered_set<ChildNode*> mChildNodes;
+    std::mutex mChildNodesMutex;
+    std::mutex mCleanupMutex;
+};
+
+#endif // VOLUME_CATCHER_LINUX_H
diff --git a/indra/media_plugins/cef/linux/volume_catcher_pipewire.cpp b/indra/media_plugins/cef/linux/volume_catcher_pipewire.cpp
new file mode 100755
index 0000000000..27fea547c9
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_pipewire.cpp
@@ -0,0 +1,333 @@
+/** 
+ * @file volume_catcher_pipewire.cpp
+ * @brief A Linux-specific, PipeWire-specific hack to detect and volume-adjust new audio sources
+ *
+ * @cond
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ * @endcond
+ */
+
+/*
+  The high-level design is as follows:
+  1) Connect to the PipeWire daemon
+  2) Find all existing and new audio nodes
+  3) Examine PID and parent PID's to see if it belongs to our process
+  4) If so, tell PipeWire to adjust the volume of that node
+  5) Keep a list of all audio nodes and adjust when we setVolume()
+ */
+
+#include "linden_common.h"
+
+#include "volume_catcher_linux.h"
+
+extern "C" {
+#include <spa/pod/builder.h>
+#include <spa/param/props.h>
+}
+
+SymbolGrabber pwSymbolGrabber;
+
+#include "volume_catcher_pipewire_syms.inc"
+
+////////////////////////////////////////////////////
+
+VolumeCatcherPipeWire::VolumeCatcherPipeWire()
+{
+    init();
+}
+
+VolumeCatcherPipeWire::~VolumeCatcherPipeWire()
+{
+    cleanup();
+}
+
+static void registryEventGlobal(
+    void *data, uint32_t id, uint32_t permissions, const char *type,
+    uint32_t version, const struct spa_dict *props)
+{
+    static_cast<VolumeCatcherPipeWire*>(data)->handleRegistryEventGlobal(
+        id, permissions, type, version, props
+    );
+}
+
+static const struct pw_registry_events REGISTRY_EVENTS = {
+    .version = PW_VERSION_REGISTRY_EVENTS,
+    .global = registryEventGlobal,
+};
+
+bool VolumeCatcherPipeWire::loadsyms(std::string pw_dso_name)
+{
+    return pwSymbolGrabber.grabSymbols({ pw_dso_name });
+}
+
+void VolumeCatcherPipeWire::init()
+{
+    LL_DEBUGS() << "init" << LL_ENDL;
+
+    mGotSyms = loadsyms("libpipewire-0.3.so.0");
+
+    if (!mGotSyms)
+        return;
+
+    LL_DEBUGS() << "successfully got symbols" << LL_ENDL;
+
+    llpw_init(nullptr, nullptr);
+
+    mThreadLoop = llpw_thread_loop_new("SL Plugin Volume Adjuster", nullptr);
+
+    if (!mThreadLoop)
+        return;
+
+    // i dont think we need to lock this early
+    // std::lock_guard pwLock(*this);
+
+    mContext = llpw_context_new(
+        llpw_thread_loop_get_loop(mThreadLoop), nullptr, 0
+    );
+
+    if (!mContext)
+        return;
+
+    mCore = llpw_context_connect(mContext, nullptr, 0);
+
+    if (!mCore)
+        return;
+
+    mRegistry = pw_core_get_registry(mCore, PW_VERSION_REGISTRY, 0);
+
+    LL_DEBUGS() << "pw_core_get_registry: " <<  (mRegistry?"success":"nullptr") << LL_ENDL;
+
+    spa_zero(mRegistryListener);
+
+    pw_registry_add_listener(
+        mRegistry, &mRegistryListener, &REGISTRY_EVENTS, this
+    );
+
+    llpw_thread_loop_start(mThreadLoop);
+
+    LL_DEBUGS() << "thread loop started" << LL_ENDL;
+}
+
+void VolumeCatcherPipeWire::cleanup()
+{
+    {
+        std::unique_lock childNodesLock(mChildNodesMutex);
+        for (auto *childNode: mChildNodes)
+            childNode->destroy();
+
+        mChildNodes.clear();
+    }
+
+    {
+        std::unique_lock pwLock(mCleanupMutex);
+        if (mRegistry)
+            llpw_proxy_destroy((struct pw_proxy *) mRegistry);
+
+        spa_zero(mRegistryListener);
+
+        if (mCore)
+            llpw_core_disconnect(mCore);
+        if (mContext)
+            llpw_context_destroy(mContext);
+    }
+
+    if (!mThreadLoop)
+        return;
+
+    llpw_thread_loop_stop(mThreadLoop);
+    llpw_thread_loop_destroy(mThreadLoop);
+
+    LL_DEBUGS() << "cleanup done" << LL_ENDL;
+}
+
+void VolumeCatcherPipeWire::lock()
+{
+    if (!mThreadLoop)
+        return;
+
+    llpw_thread_loop_lock(mThreadLoop);
+}
+
+void VolumeCatcherPipeWire::unlock()
+{
+    if (!mThreadLoop)
+        return;
+
+    llpw_thread_loop_unlock(mThreadLoop);
+}
+
+const uint32_t channels = 1;
+const float resetVolumes[channels] = { 1.0f };
+
+void VolumeCatcherPipeWire::ChildNode::updateVolume()
+{
+    if (!mActive)
+        return;
+
+    F32 volume = std::clamp(mImpl->mVolume, 0.0f, 1.0f);
+
+    const float volumes[channels] = { volume };
+
+    uint8_t buffer[512];
+
+    spa_pod_builder builder;
+    spa_pod_builder_init(&builder, buffer, sizeof(buffer));
+
+    spa_pod_frame frame;
+    spa_pod_builder_push_object(&builder, &frame, SPA_TYPE_OBJECT_Props, SPA_PARAM_Props);
+
+    // resets system-wide memorized volume for chromium (not google chrome) to 100%
+    spa_pod_builder_prop(&builder, SPA_PROP_channelVolumes, 0);
+    spa_pod_builder_array(&builder, sizeof(float), SPA_TYPE_Float, channels, resetVolumes);
+
+    // sets temporary volume
+    spa_pod_builder_prop(&builder, SPA_PROP_softVolumes, 0);
+    spa_pod_builder_array(&builder, sizeof(float), SPA_TYPE_Float, channels, volumes);
+
+    spa_pod* pod = static_cast<spa_pod*>(spa_pod_builder_pop(&builder, &frame));
+
+    {
+        std::lock_guard pwLock(*mImpl);
+        pw_node_set_param(mProxy, SPA_PARAM_Props, 0, pod);
+    }
+}
+
+void VolumeCatcherPipeWire::ChildNode::destroy()
+{
+    if (!mActive)
+        return;
+
+    mActive = false;
+
+    {
+        std::unique_lock childNodesLock(mImpl->mChildNodesMutex);
+        mImpl->mChildNodes.erase(this);
+    }
+
+    spa_hook_remove(&mNodeListener);
+    spa_hook_remove(&mProxyListener);
+
+    {
+        std::lock_guard pwLock(*mImpl);
+        llpw_proxy_destroy(mProxy);
+    }
+}
+
+static void nodeEventInfo(void* data, const struct pw_node_info* info)
+{
+    const char* processId = spa_dict_lookup(info->props, PW_KEY_APP_PROCESS_ID);
+
+    if (processId == nullptr)
+        return;
+
+    pid_t pid = atoll(processId);
+
+    if (!isPluginPid(pid))
+        return;
+
+    const char* appName = spa_dict_lookup(info->props, PW_KEY_APP_NAME);
+    LL_DEBUGS() << "got app: " << appName << LL_ENDL;
+
+    auto* const childNode = static_cast<VolumeCatcherPipeWire::ChildNode*>(data);
+    LL_DEBUGS() << "init volume: " << childNode->mImpl->mVolume  << LL_ENDL;
+
+    childNode->updateVolume();
+
+    {
+        std::lock_guard childNodesLock(childNode->mImpl->mChildNodesMutex);
+        childNode->mImpl->mChildNodes.insert(childNode);
+    }
+}
+
+static const struct pw_node_events NODE_EVENTS = {
+    .version = PW_VERSION_CLIENT_EVENTS,
+    .info = nodeEventInfo,
+};
+
+static void proxyEventDestroy(void* data)
+{
+    auto* const childNode = static_cast<VolumeCatcherPipeWire::ChildNode*>(data);
+    childNode->destroy();
+}
+
+static void proxyEventRemoved(void* data)
+{
+    auto* const childNode = static_cast<VolumeCatcherPipeWire::ChildNode*>(data);
+    childNode->destroy();
+}
+
+static const struct pw_proxy_events PROXY_EVENTS = {
+    .version = PW_VERSION_PROXY_EVENTS,
+    .destroy = proxyEventDestroy,
+    .removed = proxyEventRemoved,
+};
+
+void VolumeCatcherPipeWire::handleRegistryEventGlobal(
+    uint32_t id, uint32_t permissions, const char *type, uint32_t version,
+    const struct spa_dict *props)
+{
+    if (props == nullptr  || type == nullptr || strcmp(type, PW_TYPE_INTERFACE_Node) != 0)
+        return;
+
+    const char* mediaClass = spa_dict_lookup(props, PW_KEY_MEDIA_CLASS);
+
+    if (mediaClass == nullptr || strcmp(mediaClass, "Stream/Output/Audio") != 0)
+        return;
+
+    pw_proxy* proxy = static_cast<pw_proxy*>(
+        pw_registry_bind(mRegistry, id, type, PW_VERSION_CLIENT, sizeof(ChildNode))
+    );
+
+    auto* const childNode = static_cast<ChildNode*>(llpw_proxy_get_user_data(proxy));
+
+    childNode->mActive = true;
+    childNode->mProxy = proxy;
+    childNode->mImpl = this;
+
+    pw_node_add_listener(proxy, &childNode->mNodeListener, &NODE_EVENTS, childNode);
+    llpw_proxy_add_listener(proxy, &childNode->mProxyListener, &PROXY_EVENTS, childNode);
+}
+
+void VolumeCatcherPipeWire::setVolume(F32 volume)
+{
+    LL_DEBUGS() << "setting volume to: " << volume << LL_ENDL;
+
+    mVolume = volume;
+
+    {
+        std::unique_lock childNodeslock(mChildNodesMutex);
+        std::unordered_set<ChildNode *> copyOfChildNodes(mChildNodes);
+
+        LL_DEBUGS() << "found " << copyOfChildNodes.size() << " child nodes" << LL_ENDL;
+
+        for (auto* childNode : copyOfChildNodes)
+            childNode->updateVolume();
+    }
+}
+
+void VolumeCatcherPipeWire::setPan(F32 pan)
+{
+}
+
+void VolumeCatcherPipeWire::pump()
+{
+}
diff --git a/indra/media_plugins/cef/linux/volume_catcher_pipewire_syms.inc b/indra/media_plugins/cef/linux/volume_catcher_pipewire_syms.inc
new file mode 100644
index 0000000000..dbc0f5f169
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_pipewire_syms.inc
@@ -0,0 +1,26 @@
+#define G pwSymbolGrabber
+
+// required symbols to grab
+LL_GRAB_SYM(G, true, pw_init, void, int *argc, char **argv[]);
+// LL_GRAB_SYM(G, true, pw_main_loop_new, struct pw_main_loop *, const struct spa_dict *props);
+// LL_GRAB_SYM(G, true, pw_main_loop_get_loop, struct pw_loop *, struct pw_main_loop *loop);
+// LL_GRAB_SYM(G, true, pw_main_loop_destroy, void, struct pw_main_loop *loop);
+// LL_GRAB_SYM(G, true, pw_main_loop_run, void, struct pw_main_loop *loop);
+LL_GRAB_SYM(G, true, pw_context_new, struct pw_context *, struct pw_loop *main_loop, struct pw_properties *props, size_t user_data_size);
+LL_GRAB_SYM(G, true, pw_context_destroy, void, struct pw_context *context);
+LL_GRAB_SYM(G, true, pw_context_connect, struct pw_core *, struct pw_context *context, struct pw_properties *properties, size_t user_data_size);
+LL_GRAB_SYM(G, true, pw_thread_loop_new, struct pw_thread_loop *, const char *name, const struct spa_dict *props);
+LL_GRAB_SYM(G, true, pw_thread_loop_destroy, void, struct pw_thread_loop *loop);
+LL_GRAB_SYM(G, true, pw_thread_loop_get_loop, struct pw_loop *, struct pw_thread_loop *loop);
+LL_GRAB_SYM(G, true, pw_thread_loop_start, int, struct pw_thread_loop *loop);
+LL_GRAB_SYM(G, true, pw_thread_loop_stop, void, struct pw_thread_loop *loop);
+LL_GRAB_SYM(G, true, pw_thread_loop_lock, void, struct pw_thread_loop *loop);
+LL_GRAB_SYM(G, true, pw_thread_loop_unlock, void, struct pw_thread_loop *loop);
+LL_GRAB_SYM(G, true, pw_proxy_add_listener, void, struct pw_proxy *proxy, struct spa_hook *listener, const struct pw_proxy_events *events, void *data);
+LL_GRAB_SYM(G, true, pw_proxy_destroy, void, struct pw_proxy *proxy);
+LL_GRAB_SYM(G, true, pw_proxy_get_user_data, void *, struct pw_proxy *proxy);
+LL_GRAB_SYM(G, true, pw_core_disconnect, int, struct pw_core *core);
+
+// optional symbols to grab
+
+#undef G
diff --git a/indra/media_plugins/cef/linux/volume_catcher_pulseaudio.cpp b/indra/media_plugins/cef/linux/volume_catcher_pulseaudio.cpp
new file mode 100755
index 0000000000..9417c49d38
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_pulseaudio.cpp
@@ -0,0 +1,322 @@
+/** 
+ * @file volume_catcher_pulseaudio.cpp
+ * @brief A Linux-specific, PulseAudio-specific hack to detect and volume-adjust new audio sources
+ *
+ * @cond
+ * $LicenseInfo:firstyear=2010&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2010, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ * @endcond
+ */
+
+/*
+  The high-level design is as follows:
+  1) Connect to the PulseAudio daemon
+  2) Watch for the creation of new audio players connecting to the daemon (this includes ALSA clients running on the PulseAudio emulation layer, such as Flash plugins)
+  3) Examine any new audio player's PID to see if it belongs to our own process
+  4) If so, tell PA to adjust the volume of that audio player ('sink input' in PA parlance)
+  5) Keep a list of all living audio players that we care about, adjust the volumes of all of them when we get a new setVolume() call
+ */
+
+#include "linden_common.h"
+
+#include "volume_catcher_linux.h"
+
+extern "C" {
+#include <glib.h>
+#include <glib-object.h>
+
+#include <pulse/introspect.h>
+
+#include <pulse/subscribe.h>
+}
+
+SymbolGrabber paSymbolGrabber;
+
+#include "volume_catcher_pulseaudio_syms.inc"
+#include "volume_catcher_pulseaudio_glib_syms.inc"
+
+////////////////////////////////////////////////////
+
+// PulseAudio requires a chain of callbacks with C linkage
+extern "C" {
+    void callback_discovered_sinkinput(pa_context *context, const pa_sink_input_info *i, int eol, void *userdata);
+    void callback_subscription_alert(pa_context *context, pa_subscription_event_type_t t, uint32_t index, void *userdata);
+    void callback_context_state(pa_context *context, void *userdata);
+}
+
+VolumeCatcherPulseAudio::VolumeCatcherPulseAudio()
+    : mDesiredVolume(0.0f),
+      mMainloop(nullptr),
+      mPAContext(nullptr),
+      mConnected(false),
+      mGotSyms(false)
+{
+    init();
+}
+
+VolumeCatcherPulseAudio::~VolumeCatcherPulseAudio()
+{
+    cleanup();
+}
+
+bool VolumeCatcherPulseAudio::loadsyms(std::string pulse_dso_name)
+{
+    return paSymbolGrabber.grabSymbols({ pulse_dso_name });
+}
+
+void VolumeCatcherPulseAudio::init()
+{
+    // try to be as defensive as possible because PA's interface is a
+    // bit fragile and (for our purposes) we'd rather simply not function
+    // than crash
+
+    // we cheat and rely upon libpulse-mainloop-glib.so.0 to pull-in
+    // libpulse.so.0 - this isn't a great assumption, and the two DSOs should
+    // probably be loaded separately.  Our Linux DSO framework needs refactoring,
+    // we do this sort of thing a lot with practically identical logic...
+    mGotSyms = loadsyms("libpulse-mainloop-glib.so.0");
+
+    if (!mGotSyms)
+        mGotSyms = loadsyms("libpulse.so.0");
+
+    if (!mGotSyms)
+        return;
+
+    mMainloop = llpa_glib_mainloop_new(g_main_context_default());
+
+    if (mMainloop)
+    {
+        pa_mainloop_api *api = llpa_glib_mainloop_get_api(mMainloop);
+
+        if (api)
+        {
+            pa_proplist *proplist = llpa_proplist_new();
+
+            if (proplist)
+            {
+                llpa_proplist_sets(proplist, PA_PROP_APPLICATION_ICON_NAME, "multimedia-player");
+                llpa_proplist_sets(proplist, PA_PROP_APPLICATION_ID, "com.secondlife.viewer.mediaplugvoladjust");
+                llpa_proplist_sets(proplist, PA_PROP_APPLICATION_NAME, "SL Plugin Volume Adjuster");
+                llpa_proplist_sets(proplist, PA_PROP_APPLICATION_VERSION, "1");
+
+                // plain old pa_context_new() is broken!
+                mPAContext = llpa_context_new_with_proplist(api, nullptr, proplist);
+
+                llpa_proplist_free(proplist);
+            }
+        }
+    }
+
+    // Now we've set up a PA context and mainloop, try connecting the
+    // PA context to a PA daemon.
+    if (mPAContext)
+    {
+        llpa_context_set_state_callback(mPAContext, callback_context_state, this);
+        pa_context_flags_t cflags = (pa_context_flags)0; // maybe add PA_CONTEXT_NOAUTOSPAWN?
+        if (llpa_context_connect(mPAContext, nullptr, cflags, nullptr) >= 0)
+        {
+            // Okay!  We haven't definitely connected, but we
+            // haven't definitely failed yet.
+        }
+        else
+        {
+            // Failed to connect to PA manager... we'll leave
+            // things like that.  Perhaps we should try again later.
+        }
+    }
+}
+
+void VolumeCatcherPulseAudio::cleanup()
+{
+    mConnected = false;
+
+    if (mGotSyms && mPAContext)
+    {
+        llpa_context_disconnect(mPAContext);
+        llpa_context_unref(mPAContext);
+    }
+
+    mPAContext = nullptr;
+
+    if (mGotSyms && mMainloop)
+        llpa_glib_mainloop_free(mMainloop);
+
+    mMainloop = nullptr;
+}
+
+void VolumeCatcherPulseAudio::setVolume(F32 volume)
+{
+    mDesiredVolume = volume;
+
+    if (!mGotSyms)
+        return;
+
+    if (mConnected && mPAContext)
+    {
+        update_all_volumes(mDesiredVolume);
+    }
+
+    pump();
+}
+
+void VolumeCatcherPulseAudio::setPan(F32 pan)
+{
+}
+
+void VolumeCatcherPulseAudio::pump()
+{
+    gboolean may_block = FALSE;
+    g_main_context_iteration(g_main_context_default(), may_block);
+}
+
+void VolumeCatcherPulseAudio::connected_okay()
+{
+    pa_operation *op;
+
+    // fetch global list of existing sinkinputs
+    if ((op = llpa_context_get_sink_input_info_list(mPAContext,
+                            callback_discovered_sinkinput,
+                            this)))
+    {
+        llpa_operation_unref(op);
+    }
+
+    // subscribe to future global sinkinput changes
+    llpa_context_set_subscribe_callback(mPAContext,
+                        callback_subscription_alert,
+                        this);
+    if ((op = llpa_context_subscribe(mPAContext, (pa_subscription_mask_t)
+                     (PA_SUBSCRIPTION_MASK_SINK_INPUT),
+                                     nullptr, nullptr)))
+    {
+        llpa_operation_unref(op);
+    }
+}
+
+void VolumeCatcherPulseAudio::update_all_volumes(F32 volume)
+{
+    for (std::set<U32>::iterator it = mSinkInputIndices.begin();
+         it != mSinkInputIndices.end(); ++it)
+    {
+        update_index_volume(*it, volume);
+    }
+}
+
+void VolumeCatcherPulseAudio::update_index_volume(U32 index, F32 volume)
+{
+    static pa_cvolume cvol;
+    llpa_cvolume_set(&cvol, mSinkInputNumChannels[index],
+             llpa_sw_volume_from_linear(volume));
+
+    pa_context *c = mPAContext;
+    uint32_t idx = index;
+    const pa_cvolume *cvolumep = &cvol;
+    pa_context_success_cb_t cb = nullptr; // okay as null
+    void *userdata = nullptr; // okay as null
+
+    pa_operation *op;
+    if ((op = llpa_context_set_sink_input_volume(c, idx, cvolumep, cb, userdata)))
+        llpa_operation_unref(op);
+}
+
+void callback_discovered_sinkinput(pa_context *context, const pa_sink_input_info *sii, int eol, void *userdata)
+{
+    VolumeCatcherPulseAudio *impl = dynamic_cast<VolumeCatcherPulseAudio*>((VolumeCatcherPulseAudio*)userdata);
+    llassert(impl);
+
+    if (0 == eol)
+    {
+        pa_proplist *proplist = sii->proplist;
+        pid_t sinkpid = atoll(llpa_proplist_gets(proplist, PA_PROP_APPLICATION_PROCESS_ID));
+
+        if (isPluginPid( sinkpid )) // does the discovered sinkinput belong to this process?
+        {
+            bool is_new = (impl->mSinkInputIndices.find(sii->index) == impl->mSinkInputIndices.end());
+
+            impl->mSinkInputIndices.insert(sii->index);
+            impl->mSinkInputNumChannels[sii->index] = sii->channel_map.channels;
+
+            if (is_new)
+            {
+                // new!
+                impl->update_index_volume(sii->index, impl->mDesiredVolume);
+            }
+            else
+            {
+                // seen it already, do nothing.
+            }
+        }
+    }
+}
+
+void callback_subscription_alert(pa_context *context, pa_subscription_event_type_t t, uint32_t index, void *userdata)
+{
+    VolumeCatcherPulseAudio *impl = dynamic_cast<VolumeCatcherPulseAudio*>((VolumeCatcherPulseAudio*)userdata);
+    llassert(impl);
+
+    switch (t & PA_SUBSCRIPTION_EVENT_FACILITY_MASK)
+    {
+        case PA_SUBSCRIPTION_EVENT_SINK_INPUT:
+            if ((t & PA_SUBSCRIPTION_EVENT_TYPE_MASK) ==  PA_SUBSCRIPTION_EVENT_REMOVE)
+            {
+                // forget this sinkinput, if we were caring about it
+                impl->mSinkInputIndices.erase(index);
+                impl->mSinkInputNumChannels.erase(index);
+            }
+            else if ((t & PA_SUBSCRIPTION_EVENT_TYPE_MASK) == PA_SUBSCRIPTION_EVENT_NEW)
+            {
+                // ask for more info about this new sinkinput
+                pa_operation *op;
+                if ((op = llpa_context_get_sink_input_info(impl->mPAContext, index, callback_discovered_sinkinput, impl)))
+                {
+                    llpa_operation_unref(op);
+                }
+            }
+            else
+            {
+                // property change on this sinkinput - we don't care.
+            }
+            break;
+
+        default:;
+    }
+}
+
+void callback_context_state(pa_context *context, void *userdata)
+{
+    VolumeCatcherPulseAudio *impl = dynamic_cast<VolumeCatcherPulseAudio*>((VolumeCatcherPulseAudio*)userdata);
+    llassert(impl);
+
+    switch (llpa_context_get_state(context))
+    {
+    case PA_CONTEXT_READY:
+        impl->mConnected = true;
+        impl->connected_okay();
+        break;
+    case PA_CONTEXT_TERMINATED:
+        impl->mConnected = false;
+        break;
+    case PA_CONTEXT_FAILED:
+        impl->mConnected = false;
+        break;
+    default:;
+    }
+}
diff --git a/indra/media_plugins/cef/linux/volume_catcher_pulseaudio_glib_syms.inc b/indra/media_plugins/cef/linux/volume_catcher_pulseaudio_glib_syms.inc
new file mode 100755
index 0000000000..e9b7196e51
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_pulseaudio_glib_syms.inc
@@ -0,0 +1,10 @@
+#define G paSymbolGrabber
+
+// required symbols to grab
+LL_GRAB_SYM(G, true, pa_glib_mainloop_free, void, pa_glib_mainloop* g)
+LL_GRAB_SYM(G, true, pa_glib_mainloop_get_api, pa_mainloop_api*, pa_glib_mainloop* g)
+LL_GRAB_SYM(G, true, pa_glib_mainloop_new, pa_glib_mainloop *, GMainContext *c)
+
+// optional symbols to grab
+
+#undef G
diff --git a/indra/media_plugins/cef/linux/volume_catcher_pulseaudio_syms.inc b/indra/media_plugins/cef/linux/volume_catcher_pulseaudio_syms.inc
new file mode 100755
index 0000000000..4859a34405
--- /dev/null
+++ b/indra/media_plugins/cef/linux/volume_catcher_pulseaudio_syms.inc
@@ -0,0 +1,29 @@
+#define G paSymbolGrabber
+
+// required symbols to grab
+LL_GRAB_SYM(G, true, pa_context_connect, int, pa_context *c, const char *server, pa_context_flags_t flags, const pa_spawn_api *api)
+LL_GRAB_SYM(G, true, pa_context_disconnect, void, pa_context *c)
+LL_GRAB_SYM(G, true, pa_context_get_sink_input_info, pa_operation*, pa_context *c, uint32_t idx, pa_sink_input_info_cb_t cb, void *userdata)
+LL_GRAB_SYM(G, true, pa_context_get_sink_input_info_list, pa_operation*, pa_context *c, pa_sink_input_info_cb_t cb, void *userdata)
+LL_GRAB_SYM(G, true, pa_context_get_state, pa_context_state_t, pa_context *c)
+LL_GRAB_SYM(G, true, pa_context_new_with_proplist, pa_context*, pa_mainloop_api *mainloop, const char *name, pa_proplist *proplist)
+LL_GRAB_SYM(G, true, pa_context_set_sink_input_volume, pa_operation*, pa_context *c, uint32_t idx, const pa_cvolume *volume, pa_context_success_cb_t cb, void *userdata)
+LL_GRAB_SYM(G, true, pa_context_set_state_callback, void, pa_context *c, pa_context_notify_cb_t cb, void *userdata)
+LL_GRAB_SYM(G, true, pa_context_set_subscribe_callback, void, pa_context *c, pa_context_subscribe_cb_t cb, void *userdata)
+LL_GRAB_SYM(G, true, pa_context_subscribe, pa_operation*, pa_context *c, pa_subscription_mask_t m, pa_context_success_cb_t cb, void *userdata)
+LL_GRAB_SYM(G, true, pa_context_unref, void, pa_context *c)
+LL_GRAB_SYM(G, true, pa_cvolume_set, pa_cvolume*, pa_cvolume *a, unsigned channels, pa_volume_t v)
+LL_GRAB_SYM(G, true, pa_operation_unref, void, pa_operation *o)
+LL_GRAB_SYM(G, true, pa_proplist_free, void, pa_proplist* p)
+LL_GRAB_SYM(G, true, pa_proplist_gets, const char*, pa_proplist *p, const char *key)
+LL_GRAB_SYM(G, true, pa_proplist_new, pa_proplist*, void)
+LL_GRAB_SYM(G, true, pa_proplist_sets, int, pa_proplist *p, const char *key, const char *value)
+LL_GRAB_SYM(G, true, pa_sw_volume_from_linear, pa_volume_t, double v)
+// LL_GRAB_SYM(G, true, pa_mainloop_free, void, pa_mainloop *m)
+// LL_GRAB_SYM(G, true, pa_mainloop_get_api, pa_mainloop_api *, pa_mainloop *m)
+// LL_GRAB_SYM(G, true, pa_mainloop_iterate, int, pa_mainloop *m, int block, int *retval)
+// LL_GRAB_SYM(G, true, pa_mainloop_new, pa_mainloop *, void)
+
+// optional symbols to grab
+
+#undef G