From 50006a9a32cb360706173feabf4677535ffa108c Mon Sep 17 00:00:00 2001
From: tux3 <barrdetwix@gmail.com>
Date: Sat, 24 Oct 2015 05:19:23 +0200
Subject: [PATCH] Faster video device opening

---
 src/video/camerasource.cpp          | 10 +++++++++-
 src/video/camerasource.h            |  1 +
 src/widget/form/settings/avform.cpp |  3 +--
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/video/camerasource.cpp b/src/video/camerasource.cpp
index 586cdbf9a..c006ea863 100644
--- a/src/video/camerasource.cpp
+++ b/src/video/camerasource.cpp
@@ -37,7 +37,7 @@ CameraSource* CameraSource::instance{nullptr};
 CameraSource::CameraSource()
     : deviceName{"none"}, device{nullptr}, mode(VideoMode{0,0,0}),
       cctx{nullptr}, cctxOrig{nullptr}, videoStreamIndex{-1},
-      _isOpen{false}, subscriptions{0}
+      _isOpen{false}, streamBlocker{false}, subscriptions{0}
 {
     subscriptions = 0;
     av_register_all();
@@ -72,10 +72,14 @@ void CameraSource::open(const QString deviceName)
 
 void CameraSource::open(const QString DeviceName, VideoMode Mode)
 {
+    streamBlocker = true;
     QMutexLocker l{&biglock};
 
     if (DeviceName == deviceName && Mode == mode)
+    {
+        streamBlocker = false;
         return;
+    }
 
     if (subscriptions)
         closeDevice();
@@ -86,6 +90,8 @@ void CameraSource::open(const QString DeviceName, VideoMode Mode)
 
     if (subscriptions && _isOpen)
         openDevice();
+
+    streamBlocker = false;
 }
 
 void CameraSource::close()
@@ -348,6 +354,8 @@ void CameraSource::stream()
 
         // Give a chance to other functions to pick up the lock if needed
         biglock.unlock();
+        while (streamBlocker)
+            QThread::yieldCurrentThread();
         QThread::yieldCurrentThread();
     }
 }
diff --git a/src/video/camerasource.h b/src/video/camerasource.h
index 24ee5aada..8b59ce850 100644
--- a/src/video/camerasource.h
+++ b/src/video/camerasource.h
@@ -93,6 +93,7 @@ private:
     int videoStreamIndex; ///< A camera can have multiple streams, this is the one we're decoding
     QMutex biglock, freelistLock; ///< True when locked. Faster than mutexes for video decoding.
     std::atomic_bool _isOpen;
+    std::atomic_bool streamBlocker; ///< Holds the streaming thread still when true
     std::atomic_int subscriptions; ///< Remember how many times we subscribed for RAII
 
     static CameraSource* instance;
diff --git a/src/widget/form/settings/avform.cpp b/src/widget/form/settings/avform.cpp
index 9db9f844c..80be8a100 100644
--- a/src/widget/form/settings/avform.cpp
+++ b/src/widget/form/settings/avform.cpp
@@ -204,14 +204,13 @@ void AVForm::onVideoDevChanged(int index)
         qWarning() << "Invalid index";
         return;
     }
+
     QString dev = videoDeviceList[index].first;
     Settings::getInstance().setVideoDev(dev);
     bool previouslyBlocked = bodyUI->videoModescomboBox->blockSignals(true);
     updateVideoModes(index);
     bodyUI->videoModescomboBox->blockSignals(previouslyBlocked);
     camera.open(dev);
-    killVideoSurface();
-    createVideoSurface();
     if (dev == "none")
         Core::getInstance()->getAv()->sendNoVideo();
 }