From 1668f024f77d20b61b419bd0b906a33813a228a9 Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Wed, 29 Oct 2014 09:30:36 +1300
Subject: [PATCH] Bug 1089480 - Assume a start time of 0 for MSE videos.
 r=cajbir

--HG--
extra : rebase_source : fb44192e9f7f97a9ed1d753dd185dc82fdeaaa48
---
 dom/media/MediaDecoderReader.cpp          | 25 +++++++++++++++--------
 dom/media/MediaDecoderReader.h            |  2 ++
 dom/media/MediaDecoderStateMachine.cpp    | 11 +---------
 dom/media/mediasource/MediaSourceReader.h |  5 +++++
 4 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/dom/media/MediaDecoderReader.cpp b/dom/media/MediaDecoderReader.cpp
index acf892d1080c..e24badc66a85 100644
--- a/dom/media/MediaDecoderReader.cpp
+++ b/dom/media/MediaDecoderReader.cpp
@@ -20,15 +20,10 @@ namespace mozilla {
 
 #ifdef PR_LOGGING
 extern PRLogModuleInfo* gMediaDecoderLog;
-#define DECODER_LOG(type, msg) PR_LOG(gMediaDecoderLog, type, msg)
-#ifdef SEEK_LOGGING
-#define SEEK_LOG(type, msg) PR_LOG(gMediaDecoderLog, type, msg)
+#define DECODER_LOG(x, ...) \
+  PR_LOG(gMediaDecoderLog, PR_LOG_DEBUG, ("Decoder=%p " x, mDecoder, ##__VA_ARGS__))
 #else
-#define SEEK_LOG(type, msg)
-#endif
-#else
-#define DECODER_LOG(type, msg)
-#define SEEK_LOG(type, msg)
+#define DECODER_LOG(x, ...)
 #endif
 
 class VideoQueueMemoryFunctor : public nsDequeFunctor {
@@ -139,6 +134,20 @@ MediaDecoderReader::GetBuffered(mozilla::dom::TimeRanges* aBuffered,
   return NS_OK;
 }
 
+int64_t
+MediaDecoderReader::ComputeStartTime(const VideoData* aVideo, const AudioData* aAudio)
+{
+  int64_t startTime = std::min<int64_t>(aAudio ? aAudio->mTime : INT64_MAX,
+                                        aVideo ? aVideo->mTime : INT64_MAX);
+  if (startTime == INT64_MAX) {
+    startTime = 0;
+  }
+  DECODER_LOG("ComputeStartTime first video frame start %lld", aVideo ? aVideo->mTime : -1);
+  DECODER_LOG("ComputeStartTime first audio frame start %lld", aAudio ? aAudio->mTime : -1);
+  MOZ_ASSERT(startTime >= 0);
+  return startTime;
+}
+
 class RequestVideoWithSkipTask : public nsRunnable {
 public:
   RequestVideoWithSkipTask(MediaDecoderReader* aReader,
diff --git a/dom/media/MediaDecoderReader.h b/dom/media/MediaDecoderReader.h
index d88777af1c9c..c1df1addb80e 100644
--- a/dom/media/MediaDecoderReader.h
+++ b/dom/media/MediaDecoderReader.h
@@ -148,6 +148,8 @@ public:
   virtual nsresult GetBuffered(dom::TimeRanges* aBuffered,
                                int64_t aStartTime);
 
+  virtual int64_t ComputeStartTime(const VideoData* aVideo, const AudioData* aAudio);
+
   // Returns the number of bytes of memory allocated by structures/frames in
   // the video queue.
   size_t SizeOfVideoQueueInBytes() const;
diff --git a/dom/media/MediaDecoderStateMachine.cpp b/dom/media/MediaDecoderStateMachine.cpp
index a27810d7fb84..fc2bbe746bdd 100644
--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -2016,18 +2016,9 @@ MediaDecoderStateMachine::FinishDecodeMetadata()
   }
 
   if (!mScheduler->IsRealTime() && !mDecodingFrozenAtStateMetadata) {
-
     const VideoData* v = VideoQueue().PeekFront();
     const AudioData* a = AudioQueue().PeekFront();
-
-    int64_t startTime = std::min<int64_t>(a ? a->mTime : INT64_MAX,
-                                          v ? v->mTime : INT64_MAX);
-    if (startTime == INT64_MAX) {
-      startTime = 0;
-    }
-    DECODER_LOG("DecodeMetadata first video frame start %lld", v ? v->mTime : -1);
-    DECODER_LOG("DecodeMetadata first audio frame start %lld", a ? a->mTime : -1);
-    SetStartTime(startTime);
+    SetStartTime(mReader->ComputeStartTime(v, a));
     if (VideoQueue().GetSize()) {
       ReentrantMonitorAutoExit exitMon(mDecoder->GetReentrantMonitor());
       RenderVideoFrame(VideoQueue().PeekFront(), TimeStamp::Now());
diff --git a/dom/media/mediasource/MediaSourceReader.h b/dom/media/mediasource/MediaSourceReader.h
index 8227d8121edf..577e5631211d 100644
--- a/dom/media/mediasource/MediaSourceReader.h
+++ b/dom/media/mediasource/MediaSourceReader.h
@@ -70,6 +70,11 @@ public:
     return mInfo.HasAudio();
   }
 
+  // We can't compute a proper start time since we won't necessarily
+  // have the first frame of the resource available. This does the same
+  // as chrome/blink and assumes that we always start at t=0.
+  virtual int64_t ComputeStartTime(const VideoData* aVideo, const AudioData* aAudio) MOZ_OVERRIDE { return 0; }
+
   bool IsMediaSeekable() { return true; }
 
   nsresult ReadMetadata(MediaInfo* aInfo, MetadataTags** aTags) MOZ_OVERRIDE;