Fix video sync error when framerate or playback rate is low

BUG=18441
TEST=play a low framerate video or under low rate and verify it stays synced
Review URL: http://codereview.chromium.org/160620

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@22683 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 15 insertions, 6 deletions

diff --git a/media/filters/video_renderer_base.cc b/media/filters/video_renderer_base.cc
index 6161852..9f832b4 100644
--- a/media/filters/video_renderer_base.cc
+++ b/media/filters/video_renderer_base.cc
@@ -27,10 +27,13 @@ static const size_t kMaxFrames = 3;
 // A higher value will be a slower frame rate, which looks worse but allows the
 // audio renderer to catch up faster.  A lower value will be a smoother frame
 // rate, but results in the video being out of sync for longer.
-//
-// TODO(scherkus): what if the native frame rate is 15 or 10 fps?
 static const int64 kMaxSleepMilliseconds = 60;
 
+// The number of milliseconds to idle when we do not have anything to do.
+// Nothing special about the value, other than we're being more OS-friendly
+// than sleeping for 1 millisecond.
+static const int kIdleMilliseconds = 10;
+
 VideoRendererBase::VideoRendererBase()
     : width_(0),
       height_(0),
@@ -193,10 +196,9 @@ void VideoRendererBase::ThreadMain() {
       return;
     }
 
-    // Sleep for 10 milliseconds while paused.  Nothing special about the value,
-    // other than we're being more OS-friendly than sleeping for 1 millisecond.
+    // Sleep while paused or seeking.
     if (state == kPaused || state == kSeeking || playback_rate == 0) {
-      PlatformThread::Sleep(10);
+      PlatformThread::Sleep(kIdleMilliseconds);
       continue;
     }
 
@@ -211,6 +213,13 @@ void VideoRendererBase::ThreadMain() {
         continue;
       }
 
+      // Idle if the next frame is too far ahead.
+      base::TimeDelta diff = current_frame_->GetTimestamp() - host()->GetTime();
+      if (diff.InMilliseconds() > kIdleMilliseconds) {
+        PlatformThread::Sleep(kIdleMilliseconds);
+        continue;
+      }
+
       // Otherwise we're playing, so advance the frame and keep reading from the
       // decoder.  |frames_| might be empty if we seeked to the very end of the
       // media where no frames were available.
diff --git a/media/filters/video_renderer_base_unittest.cc b/media/filters/video_renderer_base_unittest.cc
index be5afe1..14f7259 100644
--- a/media/filters/video_renderer_base_unittest.cc
+++ b/media/filters/video_renderer_base_unittest.cc
@@ -27,7 +27,7 @@ class MockVideoRendererBase : public VideoRendererBase {
   virtual ~MockVideoRendererBase() {}
 
   // VideoRendererBase implementation.
-  MOCK_METHOD1(OnInitialize, bool (VideoDecoder* decoder));
+  MOCK_METHOD1(OnInitialize, bool(VideoDecoder* decoder));
   MOCK_METHOD0(OnStop, void());
   MOCK_METHOD0(OnFrameAvailable, void());