CoreAudioStream: Handle parameter changes without restarting

src/core/system.cpp

@@ -4507,7 +4507,10 @@ void System::CheckForSettingsChanges(const Settings& old_settings)
     if (g_settings.audio_backend != old_settings.audio_backend ||
         g_settings.audio_driver != old_settings.audio_driver ||
         g_settings.audio_output_device != old_settings.audio_output_device ||
-        g_settings.audio_stream_parameters != old_settings.audio_stream_parameters)
+        g_settings.audio_stream_parameters.output_latency_ms !=
+          old_settings.audio_stream_parameters.output_latency_ms ||
+        g_settings.audio_stream_parameters.output_latency_minimal !=
+          old_settings.audio_stream_parameters.output_latency_minimal)
     {
       if (g_settings.audio_backend != old_settings.audio_backend)
       {
@@ -4524,6 +4527,10 @@ void System::CheckForSettingsChanges(const Settings& old_settings)
       if (sound_effects_active)
         SoundEffectManager::EnsureInitialized();
     }
+    else if (g_settings.audio_stream_parameters != old_settings.audio_stream_parameters)
+    {
+      SPU::GetOutputStream().UpdateParameters(g_settings.audio_stream_parameters);
+    }
 
     if (g_settings.emulation_speed != old_settings.emulation_speed)
       UpdateThrottlePeriod();

src/util/core_audio_stream.cpp

@@ -134,6 +134,64 @@ bool CoreAudioStream::Initialize(AudioBackend backend, u32 sample_rate, const Au
   return true;
 }
 
+void CoreAudioStream::UpdateParameters(const AudioStreamParameters& params)
+{
+  constexpr auto copy_stretch_params = [](AudioStreamParameters& dest, const AudioStreamParameters& src) {
+    dest.stretch_sequence_length_ms = src.stretch_sequence_length_ms;
+    dest.stretch_seekwindow_ms = src.stretch_seekwindow_ms;
+    dest.stretch_overlap_ms = src.stretch_overlap_ms;
+    dest.stretch_use_quickseek = src.stretch_use_quickseek;
+    dest.stretch_use_aa_filter = src.stretch_use_aa_filter;
+  };
+
+  if (params.buffer_ms != m_parameters.buffer_ms)
+  {
+    Error error;
+
+    // have to pause the stream to change buffer size
+    if (m_stream && !m_paused)
+    {
+      if (!m_stream->Stop(&error))
+      {
+        ERROR_LOG("Failed to stop audio stream for buffer size change: {}", error.GetDescription());
+        return;
+      }
+    }
+
+    StretchDestroy();
+    DestroyBuffer();
+
+    m_parameters.buffer_ms = params.buffer_ms;
+    copy_stretch_params(m_parameters, params);
+
+    AllocateBuffer();
+    StretchAllocate();
+
+    if (m_stream && !m_paused)
+    {
+      if (!m_stream->Start(&error))
+      {
+        ERROR_LOG("Failed to start audio stream after buffer size change: {}", error.GetDescription());
+        m_paused = true;
+      }
+    }
+
+    return;
+  }
+
+  if (params.stretch_mode != m_parameters.stretch_mode)
+  {
+    StretchDestroy();
+    copy_stretch_params(m_parameters, params);
+    StretchAllocate();
+  }
+  else
+  {
+    // easier case: just changing stretch settings
+    StretchUpdateParameters(params);
+  }
+}
+
 void CoreAudioStream::Destroy()
 {
   m_stream.reset();
@@ -583,6 +641,42 @@ void CoreAudioStream::StretchAllocate()
   m_staging_buffer_pos = 0;
 }
 
+void CoreAudioStream::StretchUpdateParameters(const AudioStreamParameters& params)
+{
+  if (m_parameters.stretch_mode == AudioStretchMode::Off)
+    return;
+
+  if (params.stretch_use_quickseek != m_parameters.stretch_use_quickseek)
+  {
+    m_parameters.stretch_use_quickseek = params.stretch_use_quickseek;
+    soundtouch_setSetting(m_soundtouch, SETTING_USE_QUICKSEEK, m_parameters.stretch_use_quickseek);
+  }
+
+  if (params.stretch_use_aa_filter != m_parameters.stretch_use_aa_filter)
+  {
+    m_parameters.stretch_use_aa_filter = params.stretch_use_aa_filter;
+    soundtouch_setSetting(m_soundtouch, SETTING_USE_AA_FILTER, m_parameters.stretch_use_aa_filter);
+  }
+
+  if (params.stretch_sequence_length_ms != m_parameters.stretch_sequence_length_ms)
+  {
+    m_parameters.stretch_sequence_length_ms = params.stretch_sequence_length_ms;
+    soundtouch_setSetting(m_soundtouch, SETTING_SEQUENCE_MS, m_parameters.stretch_sequence_length_ms);
+  }
+
+  if (params.stretch_seekwindow_ms != m_parameters.stretch_seekwindow_ms)
+  {
+    m_parameters.stretch_seekwindow_ms = params.stretch_seekwindow_ms;
+    soundtouch_setSetting(m_soundtouch, SETTING_SEEKWINDOW_MS, m_parameters.stretch_seekwindow_ms);
+  }
+
+  if (params.stretch_overlap_ms != m_parameters.stretch_overlap_ms)
+  {
+    m_parameters.stretch_overlap_ms = params.stretch_overlap_ms;
+    soundtouch_setSetting(m_soundtouch, SETTING_OVERLAP_MS, m_parameters.stretch_overlap_ms);
+  }
+}
+
 void CoreAudioStream::StretchDestroy()
 {
   if (m_soundtouch)

src/util/core_audio_stream.h

@@ -94,6 +94,10 @@ public:
                   std::string_view driver_name, std::string_view device_name, Error* error);
   void Destroy();
 
+  /// Updates stream parameters without recreating the stream.
+  /// NOTE: Cannot handle changes in output latency.
+  void UpdateParameters(const AudioStreamParameters& params);
+
   /// Temporarily pauses the stream, preventing it from requesting data.
   void SetPaused(bool paused);
 
@@ -125,6 +129,7 @@ private:
   void InternalWriteFrames(SampleType* samples, u32 num_frames);
 
   void StretchAllocate();
+  void StretchUpdateParameters(const AudioStreamParameters& params);
   void StretchDestroy();
   void StretchWriteBlock(const float* block);
   void StretchUnderrun();