anbox · awaken1ng · Jan 20, 2019 · Jan 20, 2019 · Jul 16, 2019
diff --git a/android/audio/audio_hw.cpp b/android/audio/audio_hw.cpp
@@ -180,6 +180,14 @@ static ssize_t out_write(struct audio_stream_out *stream, const void *buffer,
   pthread_mutex_lock(&adev->lock);
   if (out->fd >= 0)
     bytes = write(out->fd, buffer, bytes);
+
+  // wait until session writes the data we sent,
+  // this will block if sink queue is full,
+  // acting as synchronization to time audio
+  int64_t arrived_us;
+  read(out->fd, &arrived_us, sizeof(arrived_us));
+  (void) arrived_us;
+
   pthread_mutex_unlock(&adev->lock);
   return bytes;
 }

diff --git a/src/anbox/audio/server.cpp b/src/anbox/audio/server.cpp
@@ -31,8 +31,10 @@ using namespace std::placeholders;
 namespace {
 class AudioForwarder : public anbox::network::MessageProcessor {
  public:
-  AudioForwarder(const std::shared_ptr<anbox::audio::Sink> &sink) :
-    sink_(sink) {
+  AudioForwarder(const std::shared_ptr<anbox::audio::Sink> &sink, 
+                 const std::shared_ptr<anbox::network::LocalSocketMessenger> &messenger) :
+    sink_(sink), 
+    messenger_(messenger) {
   }
 
   bool process_data(const std::vector<std::uint8_t> &data) override {
@@ -42,6 +44,7 @@ class AudioForwarder : public anbox::network::MessageProcessor {
 
  private:
   std::shared_ptr<anbox::audio::Sink> sink_;
+  std::shared_ptr<anbox::network::LocalSocketMessenger> messenger_;
 };
 }
 
@@ -81,7 +84,7 @@ void Server::create_connection_for(std::shared_ptr<boost::asio::basic_stream_soc
 
   switch (client_info.type) {
   case ClientInfo::Type::Playback:
-    processor = std::make_shared<AudioForwarder>(platform_->create_audio_sink());
+    processor = std::make_shared<AudioForwarder>(platform_->create_audio_sink(messenger), messenger);
     break;
   case ClientInfo::Type::Recording:
     break;

diff --git a/src/anbox/platform/base_platform.h b/src/anbox/platform/base_platform.h
@@ -20,6 +20,7 @@
 
 #include "anbox/graphics/rect.h"
 #include "anbox/wm/window_state.h"
+#include "anbox/network/local_socket_messenger.h"
 
 #include <memory>
 
@@ -51,7 +52,7 @@ class BasePlatform {
   virtual void set_clipboard_data(const ClipboardData &data) = 0;
   virtual ClipboardData get_clipboard_data() = 0;
 
-  virtual std::shared_ptr<audio::Sink> create_audio_sink() = 0;
+  virtual std::shared_ptr<audio::Sink> create_audio_sink(const std::shared_ptr<anbox::network::LocalSocketMessenger> &messenger) = 0;
   virtual std::shared_ptr<audio::Source> create_audio_source() = 0;
 
   virtual void set_renderer(const std::shared_ptr<Renderer> &renderer) = 0;

diff --git a/src/anbox/platform/null/platform.cpp b/src/anbox/platform/null/platform.cpp
@@ -48,7 +48,8 @@ NullPlatform::ClipboardData NullPlatform::get_clipboard_data() {
   return ClipboardData{};
 }
 
-std::shared_ptr<audio::Sink> NullPlatform::create_audio_sink() {
+std::shared_ptr<audio::Sink> NullPlatform::create_audio_sink(const std::shared_ptr<network::LocalSocketMessenger> &messenger) {
+  (void) messenger;
   ERROR("Not implemented");
   return nullptr;
 }

diff --git a/src/anbox/platform/null/platform.h b/src/anbox/platform/null/platform.h
@@ -31,7 +31,7 @@ class NullPlatform : public BasePlatform {
       const std::string &title) override;
   void set_clipboard_data(const ClipboardData &data) override;
   ClipboardData get_clipboard_data() override;
-  std::shared_ptr<audio::Sink> create_audio_sink() override;
+  std::shared_ptr<audio::Sink> create_audio_sink(const std::shared_ptr<network::LocalSocketMessenger> &messenger) override;
   std::shared_ptr<audio::Source> create_audio_source() override;
   void set_renderer(const std::shared_ptr<Renderer> &renderer) override;
   void set_window_manager(const std::shared_ptr<wm::Manager> &window_manager) override;

diff --git a/src/anbox/platform/sdl/audio_sink.cpp b/src/anbox/platform/sdl/audio_sink.cpp
@@ -19,17 +19,19 @@
 #include "anbox/logger.h"
 
 #include <stdexcept>
+#include <time.h>
 
 #include <boost/throw_exception.hpp>
 
 namespace {
-const constexpr size_t max_queue_size{16};
+const constexpr size_t max_queue_size{1};
 }
 
 namespace anbox {
 namespace platform {
 namespace sdl {
-AudioSink::AudioSink() :
+AudioSink::AudioSink(const std::shared_ptr<network::LocalSocketMessenger> &messenger) :
+  messenger_(messenger),
   device_id_(0),
   queue_(max_queue_size) {
 }
@@ -113,6 +115,20 @@ void AudioSink::write_data(const std::vector<std::uint8_t> &data) {
   }
   graphics::Buffer buffer{data.data(), data.data() + data.size()};
   queue_.push_locked(std::move(buffer), l);
+
+  // Android side is waiting for "confirmation" that data arrived,
+  // if sink queue is full, Android audio thread will be blocked 
+  // untill there's space available in the queue
+  // 
+  // this acts as sychronization to time audio
+  //
+  // at the time of implementation, 
+  // the data we send to Android is not actually used
+  timespec t;
+  clock_gettime(CLOCK_MONOTONIC, &t);
+  int64_t now_us = (t.tv_sec * 1000000000LL + t.tv_nsec) / 1000;
+
+  messenger_->send(reinterpret_cast<char*>(&now_us), sizeof(now_us));
 }
 } // namespace sdl
 } // namespace platform

diff --git a/src/anbox/platform/sdl/audio_sink.h b/src/anbox/platform/sdl/audio_sink.h
@@ -21,6 +21,7 @@
 #include "anbox/audio/sink.h"
 #include "anbox/graphics/buffer_queue.h"
 #include "anbox/platform/sdl/sdl_wrapper.h"
+#include "anbox/network/local_socket_messenger.h"
 
 #include <thread>
 
@@ -29,7 +30,7 @@ namespace platform {
 namespace sdl {
 class AudioSink : public audio::Sink {
  public:
-  AudioSink();
+  AudioSink(const std::shared_ptr<network::LocalSocketMessenger> &messenger);
   ~AudioSink();
 
   void write_data(const std::vector<std::uint8_t> &data) override;
@@ -40,7 +41,8 @@ class AudioSink : public audio::Sink {
   void read_data(std::uint8_t *buffer, int size);
 
   static void on_data_requested(void *user_data, std::uint8_t *buffer, int size);
-
+
+  std::shared_ptr<anbox::network::LocalSocketMessenger> messenger_;
   std::mutex lock_;
   SDL_AudioSpec spec_;
   SDL_AudioDeviceID device_id_;

diff --git a/src/anbox/platform/sdl/platform.cpp b/src/anbox/platform/sdl/platform.cpp
@@ -491,8 +491,8 @@ Platform::ClipboardData Platform::get_clipboard_data() {
   return data;
 }
 
-std::shared_ptr<audio::Sink> Platform::create_audio_sink() {
-  return std::make_shared<AudioSink>();
+std::shared_ptr<audio::Sink> Platform::create_audio_sink(const std::shared_ptr<network::LocalSocketMessenger> &messenger) {
+  return std::make_shared<AudioSink>(messenger);
 }
 
 std::shared_ptr<audio::Source> Platform::create_audio_source() {

diff --git a/src/anbox/platform/sdl/platform.h b/src/anbox/platform/sdl/platform.h
@@ -64,7 +64,7 @@ class Platform : public std::enable_shared_from_this<Platform>,
   void set_clipboard_data(const ClipboardData &data) override;
   ClipboardData get_clipboard_data() override;
 
-  std::shared_ptr<audio::Sink> create_audio_sink() override;
+  std::shared_ptr<audio::Sink> create_audio_sink(const std::shared_ptr<network::LocalSocketMessenger> &messenger) override;
   std::shared_ptr<audio::Source> create_audio_source() override;
 
   bool supports_multi_window() const override;