LibvlcCamera: Convert ThreadData with std::condition_variable

src/zm_libvlc_camera.cpp

@@ -94,7 +94,11 @@ void LibvlcUnlockBuffer(void* opaque, void* picture, void *const *planes) {
   // Return frames slightly faster than 1fps (if time() supports greater than one second resolution)
   if ( newFrame || difftime(now, data->prevTime) >= 0.8 ) {
     data->prevTime = now;
-    data->newImage.updateValueSignal(true);
+    {
+      std::lock_guard<std::mutex> lck(data->newImageMutex);
+      data->newImage = true;
+    }
+    data->newImageCv.notify_all();
   }
 }
 
@@ -165,6 +169,9 @@ LibvlcCamera::~LibvlcCamera() {
   if ( capture ) {
     Terminate();
   }
+
+  mLibvlcData.newImageCv.notify_all(); // to unblock on termination (zm_terminate)
+
   if ( mLibvlcMediaPlayer != nullptr ) {
     (*libvlc_media_player_release_f)(mLibvlcMediaPlayer);
     mLibvlcMediaPlayer = nullptr;
@@ -255,8 +262,8 @@ int LibvlcCamera::PrimeCapture() {
   // Libvlc wants 32 byte alignment for images (should in theory do this for all image lines)
   mLibvlcData.buffer = (uint8_t*)zm_mallocaligned(64, mLibvlcData.bufferSize);
   mLibvlcData.prevBuffer = (uint8_t*)zm_mallocaligned(64, mLibvlcData.bufferSize);
-  
-  mLibvlcData.newImage.setValueImmediate(false);
+
+  mLibvlcData.newImage = false;
 
   (*libvlc_media_player_play_f)(mLibvlcMediaPlayer);
 
@@ -271,17 +278,19 @@ int LibvlcCamera::PreCapture() {
 // Should not return -1 as cancels capture. Always wait for image if available.
 int LibvlcCamera::Capture( ZMPacket &zm_packet ) {   
   // newImage is a mutex/condition based flag to tell us when there is an image available
-  while( !mLibvlcData.newImage.getValueImmediate() ) {
-    if (zm_terminate)
-      return 0;
-    mLibvlcData.newImage.getUpdatedValue(1);
+  {
+    std::unique_lock<std::mutex> lck(mLibvlcData.newImageMutex);
+    mLibvlcData.newImageCv.wait(lck, [&]{ return mLibvlcData.newImage || zm_terminate; });
+    mLibvlcData.newImage = false;
   }
 
+  if (zm_terminate)
+    return 0;
+
   mLibvlcData.mutex.lock();
   zm_packet.image->Assign(width, height, colours, subpixelorder, mLibvlcData.buffer, width * height * mBpp);
   zm_packet.packet.stream_index = mVideoStreamId;
   zm_packet.stream = mVideoStream;
-  mLibvlcData.newImage.setValueImmediate(false);
   mLibvlcData.mutex.unlock();
 
   return 1;

src/zm_libvlc_camera.h

@@ -21,7 +21,8 @@
 #define ZM_LIBVLC_CAMERA_H
 
 #include "zm_camera.h"
-#include "zm_thread.h"
+#include <condition_variable>
+#include <mutex>
 
 #if HAVE_LIBVLC
 
@@ -35,8 +36,11 @@ struct LibvlcPrivateData {
   uint8_t* prevBuffer;
   time_t prevTime;
   uint32_t bufferSize;
-  Mutex mutex;
-  ThreadData<bool> newImage;
+  std::mutex mutex;
+
+  bool newImage;
+  std::mutex newImageMutex;
+  std::condition_variable newImageCv;
 };
 
 class LibvlcCamera : public Camera {