libretro core: fix (most?) audio glitches.

It was reading a number of bytes not multiple of "2 * channels".

Signed-off-by: Andrea Odetti <mariofutire@gmail.com>

linux.md

@@ -108,7 +108,7 @@ In order to have a better experience with the keyboard, one should probably enab
 
 Video works, but the vertical flip is done in software.
 
-Audio (speaker) works with some glitches.
+Audio (speaker) works.
 
 Must be manually configured:
 ``cmake -DLIBRETRO_PATH=/path/to/libretro-common``

source/frontends/common2/speed.cpp

@@ -16,11 +16,11 @@ void Speed::reset()
   myStartCycles = g_nCumulativeCycles;
 }
 
-size_t Speed::getCyclesTillNext(const size_t milliseconds) const
+size_t Speed::getCyclesTillNext(const size_t microseconds) const
 {
   if (myFixedSpeed)
   {
-    const size_t cycles = static_cast<uint64_t>(milliseconds * g_fCurrentCLK6502 * 1.0e-3);
+    const size_t cycles = static_cast<uint64_t>(microseconds * g_fCurrentCLK6502 * 1.0e-6);
     return cycles;
   }
   else
@@ -28,11 +28,11 @@ size_t Speed::getCyclesTillNext(const size_t milliseconds) const
     const uint64_t currentCycles = g_nCumulativeCycles;
     const auto currentTime = std::chrono::steady_clock::now();
 
-    const auto currentDelta = std::chrono::duration_cast<std::chrono::milliseconds>(currentTime - myStartTime).count();
+    const auto currentDelta = std::chrono::duration_cast<std::chrono::microseconds>(currentTime - myStartTime).count();
     // target the next time we will be called
-    const auto targetDeltaInMillis = currentDelta + milliseconds;
+    const auto targetDeltaInMicros = currentDelta + microseconds;
 
-    const uint64_t targetCycles = static_cast<uint64_t>(targetDeltaInMillis * g_fCurrentCLK6502 * 1.0e-3) + myStartCycles;
+    const uint64_t targetCycles = static_cast<uint64_t>(targetDeltaInMicros * g_fCurrentCLK6502 * 1.0e-6) + myStartCycles;
     if (targetCycles > currentCycles)
     {
       // number of cycles to fill this period

source/frontends/common2/speed.h

@@ -10,8 +10,8 @@ public:
   void reset();
 
   // calculate the number of cycles to execute in the current period
-  // assuming the next call will happen in x milliseconds
+  // assuming the next call will happen in x microseconds
-  size_t getCyclesTillNext(const size_t milliseconds) const;
+  size_t getCyclesTillNext(const size_t microseconds) const;
 
 private:
 

source/frontends/libretro/game.cpp

@@ -26,24 +26,6 @@
 namespace
 {
 
-  void runOneFrame(Speed & speed)
-  {
-    if (g_nAppMode == MODE_RUNNING)
-    {
-      const size_t cyclesToExecute = speed.getCyclesTillNext(16);
-
-      const bool bVideoUpdate = true;
-      const UINT dwClksPerFrame = NTSC_GetCyclesPerFrame();
-
-      const DWORD executedCycles = CpuExecute(cyclesToExecute, bVideoUpdate);
-
-      g_dwCyclesThisFrame = (g_dwCyclesThisFrame + executedCycles) % dwClksPerFrame;
-      GetCardMgr().GetDisk2CardMgr().UpdateDriveState(executedCycles);
-      MB_PeriodicUpdate(executedCycles);
-      SpkrUpdate(executedCycles);
-    }
-  }
-
   void updateWindowTitle()
   {
     GetAppleWindowTitle();
@@ -88,9 +70,23 @@ Game::~Game()
   uninitialiseEmulator();
 }
 
+retro_usec_t Game::ourFrameTime = 0;
+
 void Game::executeOneFrame()
 {
-  runOneFrame(mySpeed);
+  const size_t cyclesToExecute = mySpeed.getCyclesTillNext(ourFrameTime);
+  if (g_nAppMode == MODE_RUNNING)
+  {
+    const bool bVideoUpdate = true;
+    const UINT dwClksPerFrame = NTSC_GetCyclesPerFrame();
+
+    const DWORD executedCycles = CpuExecute(cyclesToExecute, bVideoUpdate);
+
+    g_dwCyclesThisFrame = (g_dwCyclesThisFrame + executedCycles) % dwClksPerFrame;
+    GetCardMgr().GetDisk2CardMgr().UpdateDriveState(executedCycles);
+    MB_PeriodicUpdate(executedCycles);
+    SpkrUpdate(executedCycles);
+  }
 }
 
 void Game::processInputEvents()
@@ -111,6 +107,11 @@ void Game::keyboardCallback(bool down, unsigned keycode, uint32_t character, uin
   }
 }
 
+void Game::frameTimeCallback(retro_usec_t usec)
+{
+  ourFrameTime = usec;
+}
+
 void Game::processKeyDown(unsigned keycode, uint32_t character, uint16_t key_modifiers)
 {
   BYTE ch = 0;

source/frontends/libretro/game.h

@@ -18,7 +18,10 @@ public:
 
   static void keyboardCallback(bool down, unsigned keycode, uint32_t character, uint16_t key_modifiers);
 
+  static void frameTimeCallback(retro_usec_t usec);
+  static constexpr size_t FPS = 60;
   static unsigned input_devices[MAX_PADS];
+  static retro_usec_t ourFrameTime;
 
 private:
   Speed mySpeed;  // fixed speed

source/frontends/libretro/libretro.cpp

@@ -91,7 +91,7 @@ void retro_get_system_av_info(retro_system_av_info *info)
   info->geometry.max_height   = GetFrameBufferBorderlessHeight();
   info->geometry.aspect_ratio = 0;
 
-  info->timing.fps            = 60;
+  info->timing.fps            = Game::FPS;
   info->timing.sample_rate    = SPKR_SAMPLE_RATE;
 }
 
@@ -124,6 +124,9 @@ void retro_set_environment(retro_environment_t cb)
 
   retro_audio_buffer_status_callback audioCallback = {&RDirectSound::bufferStatusCallback};
   cb(RETRO_ENVIRONMENT_SET_AUDIO_BUFFER_STATUS_CALLBACK, &audioCallback);
+
+  retro_frame_time_callback timeCallback = {&Game::frameTimeCallback, 1000000 / Game::FPS};
+  cb(RETRO_ENVIRONMENT_SET_FRAME_TIME_CALLBACK, &timeCallback);
 }
 
 void retro_set_audio_sample(retro_audio_sample_t cb)

source/frontends/libretro/rdirectsound.cpp

@@ -12,6 +12,10 @@
 namespace
 {
 
+  // we can only run 1 generator at a time
+  // 1 is for speaker (2 would be Mockingboard)
+  const size_t ourChannels = 1;
+
   class DirectSoundGenerator
   {
   public:
@@ -20,6 +24,9 @@ namespace
     void writeAudio(const size_t ms);
     void playSilence(const size_t ms);
 
+    bool isRunning() const;
+    size_t getNumberOfChannels() const;
+
   private:
     IDirectSoundBuffer * myBuffer;
 
@@ -27,14 +34,24 @@ namespace
 
     size_t myBytesPerSecond;
 
-    bool isRunning() const;
-
     void mixBuffer(const void * ptr, const size_t size);
   };
 
-
   std::unordered_map<IDirectSoundBuffer *, std::shared_ptr<DirectSoundGenerator>> activeSoundGenerators;
 
+  std::shared_ptr<DirectSoundGenerator> findRunningGenerator(const size_t channels)
+  {
+    for (auto & it : activeSoundGenerators)
+    {
+      const std::shared_ptr<DirectSoundGenerator> & generator = it.second;
+      if (generator->isRunning() && generator->getNumberOfChannels() == channels)
+      {
+	return generator;
+      }
+    }
+    return std::shared_ptr<DirectSoundGenerator>();
+  }
+
   DirectSoundGenerator::DirectSoundGenerator(IDirectSoundBuffer * buffer)
     : myBuffer(buffer)
   {
@@ -45,17 +62,21 @@ namespace
   {
     DWORD dwStatus;
     myBuffer->GetStatus(&dwStatus);
-    if (!(dwStatus & DSBSTATUS_PLAYING))
+    if (dwStatus & DSBSTATUS_PLAYING)
     {
-      return false;
+      return true;
     }
     else
     {
-      // for now, just play speaker audio
+      return false;
-      return myBuffer->channels == 1;
     }
   }
 
+  size_t DirectSoundGenerator::getNumberOfChannels() const
+  {
+    return myBuffer->channels;
+  }
+
   void DirectSoundGenerator::mixBuffer(const void * ptr, const size_t size)
   {
     const int16_t frames = size / (sizeof(int16_t) * myBuffer->channels);
@@ -67,7 +88,7 @@ namespace
     }
     else
     {
-      myMixerBuffer.resize(2 * size);
+      myMixerBuffer.resize(2 * frames);
       for (int16_t i = 0; i < frames; ++i)
       {
 	myMixerBuffer[i * 2] = data[i];
@@ -96,8 +117,7 @@ namespace
     }
 
     const size_t frames = ms * myBuffer->sampleRate / 1000;
-    const size_t bytesToWrite = frames * sizeof(int16_t) * 2;
+    myMixerBuffer.resize(2 * frames);
-    myMixerBuffer.resize(bytesToWrite);
     std::fill(myMixerBuffer.begin(), myMixerBuffer.end(), 0);
     audio_batch_cb(myMixerBuffer.data(), frames);
   }
@@ -111,7 +131,8 @@ namespace
       return;
     }
 
-    const size_t bytesToRead = ms * myBytesPerSecond / 1000;
+    const size_t frames = ms * myBuffer->sampleRate / 1000;
+    const size_t bytesToRead = frames * myBuffer->channels * sizeof(int16_t);
 
     LPVOID lpvAudioPtr1, lpvAudioPtr2;
     DWORD dwAudioBytes1, dwAudioBytes2;
@@ -149,18 +170,18 @@ namespace RDirectSound
 
   void writeAudio(const size_t ms)
   {
-    for (auto & it : activeSoundGenerators)
+    const auto generator = findRunningGenerator(ourChannels);
+    if (generator)
     {
-      const std::shared_ptr<DirectSoundGenerator> & generator = it.second;
       generator->writeAudio(ms);
     }
   }
 
   void playSilence(const size_t ms)
   {
-    for (auto & it : activeSoundGenerators)
+    const auto generator = findRunningGenerator(ourChannels);
+    if (generator)
     {
-      const std::shared_ptr<DirectSoundGenerator> & generator = it.second;
       generator->playSilence(ms);
     }
   }
@@ -170,10 +191,17 @@ namespace RDirectSound
     if (active)
     {
       // I am not sure this is any useful
-      if (underrun_likely || occupancy < 40)
+      if (underrun_likely)
       {
-	log_cb(RETRO_LOG_INFO, "RA2: %s occupancy = %d, underrun_likely = %d\n", __FUNCTION__, occupancy, underrun_likely);
+	if (occupancy < 20)
-	playSilence(10);
+	{
+	  log_cb(RETRO_LOG_INFO, "RA2: %s occupancy = %d, underrun_likely = %d\n", __FUNCTION__, occupancy, underrun_likely);
+	  playSilence(10);
+	}
+	if (occupancy > 80)
+	{
+	  log_cb(RETRO_LOG_INFO, "RA2: %s occupancy = %d, underrun_likely = %d\n", __FUNCTION__, occupancy, underrun_likely);
+	}
       }
     }
   }

source/frontends/sdl/emulator.cpp

@@ -168,7 +168,7 @@ void Emulator::execute(const size_t next)
 {
   if (g_nAppMode == MODE_RUNNING)
   {
-    const size_t cyclesToExecute = mySpeed.getCyclesTillNext(next);
+    const size_t cyclesToExecute = mySpeed.getCyclesTillNext(next * 1000);
 
     const bool bVideoUpdate = true;
     const UINT dwClksPerFrame = NTSC_GetCyclesPerFrame();