From 8892d0ee9c1f4ca8b7647ce6340963306f164bbf Mon Sep 17 00:00:00 2001
From: "Dimitri E. Prado" <dprado@e3c.com.br>
Date: Fri, 25 Oct 2013 12:31:55 -0700
Subject: [PATCH] Fix corrupt initial frames
 https://github.com/wang-bin/QtAV/issues/70

There is a race condition where AVDemuxThread starts queueing packets
before AVThread::resetState is called from VideoThread. When AVThread::
resetState gets called, all collected frames get dropped. This patch
waits on a conditional variable for AVThreads to start properly.
---
 src/AVPlayer.cpp              |  2 ++
 src/AVThread.cpp              | 15 ++++++++++++++-
 src/QtAV/AVThread.h           |  2 ++
 src/QtAV/private/AVThread_p.h |  4 ++++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/AVPlayer.cpp b/src/AVPlayer.cpp
index 2d146a791..3f91ae2b9 100644
--- a/src/AVPlayer.cpp
+++ b/src/AVPlayer.cpp
@@ -676,10 +676,12 @@ void AVPlayer::play()
     if (aCodecCtx && audio_thread) {
         qDebug("Starting audio thread...");
         audio_thread->start();
+        audio_thread->waitForReady();
     }
     if (vCodecCtx && video_thread) {
         qDebug("Starting video thread...");
         video_thread->start();
+        video_thread->waitForReady();
     }
     demuxer_thread->start();
     //blockSignals(false);
diff --git a/src/AVThread.cpp b/src/AVThread.cpp
index eaf52b3f0..104402d4d 100644
--- a/src/AVThread.cpp
+++ b/src/AVThread.cpp
@@ -36,6 +36,7 @@ AVThreadPrivate::~AVThreadPrivate() {
         next_pause = false;
         cond.wakeAll();
     }
+    ready_cond.wakeAll();
     packets.setBlocking(true); //???
     packets.clear();
     //not neccesary context is managed by filters.
@@ -120,8 +121,9 @@ void AVThread::stop()
     pause(false);
     if (d.writer)
         d.writer->pause(false); //stop waiting
+    QMutexLocker lock(&d.ready_mutex);
+    d.ready = false;
     //terminate();
-
 }
 
 //TODO: output set
@@ -227,6 +229,9 @@ void AVThread::resetState()
     d.packets.clear();
     //not neccesary context is managed by filters.
     d.filter_context = 0;
+    QMutexLocker lock(&d.ready_mutex);
+    d.ready = true;
+    d.ready_cond.wakeOne();
 }
 
 bool AVThread::tryPause(int timeout)
@@ -260,4 +265,12 @@ void AVThread::setStatistics(Statistics *statistics)
     d.statistics = statistics;
 }
 
+void AVThread::waitForReady()
+{
+    QMutexLocker lock(&d_func().ready_mutex);
+    while (!d_func().ready) {
+        d_func().ready_cond.wait(&d_func().ready_mutex);
+    }
+}
+
 } //namespace QtAV
diff --git a/src/QtAV/AVThread.h b/src/QtAV/AVThread.h
index 68c72dbf7..d160f0cdc 100644
--- a/src/QtAV/AVThread.h
+++ b/src/QtAV/AVThread.h
@@ -68,6 +68,8 @@ class Q_AV_EXPORT AVThread : public QThread
 
     bool isPaused() const;
 
+    void waitForReady();
+
     bool installFilter(Filter *filter, bool lock = true);
     bool uninstallFilter(Filter *filter, bool lock = true);
     const QList<Filter *> &filters() const;
diff --git a/src/QtAV/private/AVThread_p.h b/src/QtAV/private/AVThread_p.h
index d6b88c20a..6e7aca00d 100644
--- a/src/QtAV/private/AVThread_p.h
+++ b/src/QtAV/private/AVThread_p.h
@@ -56,6 +56,7 @@ class Q_AV_EXPORT AVThreadPrivate : public DPtrPrivate<AVThread>
       , delay(0)
       , filter_context(0)
       , statistics(0)
+      , ready(false)
     {
     }
     //DO NOT delete dec and writer. We do not own them
@@ -77,6 +78,9 @@ class Q_AV_EXPORT AVThreadPrivate : public DPtrPrivate<AVThread>
     Statistics *statistics; //not obj. Statistics is unique for the player, which is in AVPlayer
     QList<AVOutput*> update_outputs;
     QList<QRunnable*> tasks;
+    QWaitCondition ready_cond;
+    QMutex ready_mutex;
+    bool ready;
 };
 
 } //namespace QtAV