From 9628c1371f2e003a7f22df0216892b8c515bb5e5 Mon Sep 17 00:00:00 2001
From: Jean-Yves Avenard <jyavenard@mozilla.com>
Date: Tue, 25 Aug 2015 15:33:23 +1000
Subject: [PATCH] Bug 1198094: P1. Limit rate at which InputExhausted could be
 called by mac decoder. r=rillian

---
 dom/media/platforms/apple/AppleVDADecoder.cpp | 34 ++++++++++++++-----
 dom/media/platforms/apple/AppleVDADecoder.h   |  5 +++
 dom/media/platforms/apple/AppleVTDecoder.cpp  | 15 ++++----
 3 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/dom/media/platforms/apple/AppleVDADecoder.cpp b/dom/media/platforms/apple/AppleVDADecoder.cpp
index c75105061f0c..a1ac4590913a 100644
--- a/dom/media/platforms/apple/AppleVDADecoder.cpp
+++ b/dom/media/platforms/apple/AppleVDADecoder.cpp
@@ -44,6 +44,7 @@ AppleVDADecoder::AppleVDADecoder(const VideoInfo& aConfig,
   , mIsShutDown(false)
   , mUseSoftwareImages(false)
   , mIs106(!nsCocoaFeatures::OnLionOrLater())
+  , mQueuedSamples(0)
   , mMonitor("AppleVideoDecoder")
   , mIsFlushing(false)
   , mDecoder(nullptr)
@@ -213,15 +214,13 @@ PlatformCallback(void* decompressionOutputRefCon,
   // FIXME: Distinguish between errors and empty flushed frames.
   if (status != noErr || !image) {
     NS_WARNING("AppleVDADecoder decoder returned no data");
-    return;
-  }
-  MOZ_ASSERT(CFGetTypeID(image) == CVPixelBufferGetTypeID(),
-             "AppleVDADecoder returned an unexpected image type");
-
-  if (infoFlags & kVDADecodeInfo_FrameDropped)
-  {
+    image = nullptr;
+  } else if (infoFlags & kVDADecodeInfo_FrameDropped) {
     NS_WARNING("  ...frame dropped...");
-    return;
+    image = nullptr;
+  } else {
+    MOZ_ASSERT(image || CFGetTypeID(image) == CVPixelBufferGetTypeID(),
+               "AppleVDADecoder returned an unexpected image type");
   }
 
   AppleVDADecoder* decoder =
@@ -278,6 +277,7 @@ AppleVDADecoder::DrainReorderedFrames()
   while (!mReorderQueue.IsEmpty()) {
     mCallback->Output(mReorderQueue.Pop().get());
   }
+  mQueuedSamples = 0;
 }
 
 void
@@ -286,6 +286,7 @@ AppleVDADecoder::ClearReorderedFrames()
   while (!mReorderQueue.IsEmpty()) {
     mReorderQueue.Pop();
   }
+  mQueuedSamples = 0;
 }
 
 // Copy and return a decoded frame.
@@ -308,6 +309,19 @@ AppleVDADecoder::OutputFrame(CFRefPtr<CVPixelBufferRef> aImage,
       aFrameRef.is_sync_point ? " keyframe" : ""
   );
 
+  if (mQueuedSamples > mMaxRefFrames) {
+    // We had stopped requesting more input because we had received too much at
+    // the time. We can ask for more once again.
+    mCallback->InputExhausted();
+  }
+  MOZ_ASSERT(mQueuedSamples);
+  mQueuedSamples--;
+
+  if (!aImage) {
+    // Image was dropped by decoder.
+    return NS_OK;
+  }
+
   // Where our resulting image will end up.
   nsRefPtr<VideoData> data;
   // Bounds.
@@ -471,6 +485,8 @@ AppleVDADecoder::SubmitFrame(MediaRawData* aSample)
                        &kCFTypeDictionaryKeyCallBacks,
                        &kCFTypeDictionaryValueCallBacks);
 
+  mQueuedSamples++;
+
   OSStatus rv = VDADecoderDecode(mDecoder,
                                  0,
                                  block,
@@ -494,7 +510,7 @@ AppleVDADecoder::SubmitFrame(MediaRawData* aSample)
   }
 
   // Ask for more data.
-  if (!mInputIncoming) {
+  if (!mInputIncoming && mQueuedSamples <= mMaxRefFrames) {
     LOG("AppleVDADecoder task queue empty; requesting more data");
     mCallback->InputExhausted();
   }
diff --git a/dom/media/platforms/apple/AppleVDADecoder.h b/dom/media/platforms/apple/AppleVDADecoder.h
index 441f34c1caad..09f845f5f67e 100644
--- a/dom/media/platforms/apple/AppleVDADecoder.h
+++ b/dom/media/platforms/apple/AppleVDADecoder.h
@@ -122,6 +122,11 @@ protected:
   bool mUseSoftwareImages;
   bool mIs106;
 
+  // Number of times a sample was queued via Input(). Will be decreased upon
+  // the decoder's callback being invoked.
+  // This is used to calculate how many frames has been buffered by the decoder.
+  uint32_t mQueuedSamples;
+
   // For wait on mIsFlushing during Shutdown() process.
   Monitor mMonitor;
   // Set on reader/decode thread calling Flush() to indicate that output is
diff --git a/dom/media/platforms/apple/AppleVTDecoder.cpp b/dom/media/platforms/apple/AppleVTDecoder.cpp
index a33476abf807..84e37dc3f162 100644
--- a/dom/media/platforms/apple/AppleVTDecoder.cpp
+++ b/dom/media/platforms/apple/AppleVTDecoder.cpp
@@ -167,14 +167,13 @@ PlatformCallback(void* decompressionOutputRefCon,
   // Validate our arguments.
   if (status != noErr || !image) {
     NS_WARNING("VideoToolbox decoder returned no data");
-    return;
-  }
-  if (flags & kVTDecodeInfo_FrameDropped) {
+    image = nullptr;
+  } else if (flags & kVTDecodeInfo_FrameDropped) {
     NS_WARNING("  ...frame tagged as dropped...");
+  } else {
+    MOZ_ASSERT(CFGetTypeID(image) == CVPixelBufferGetTypeID(),
+      "VideoToolbox returned an unexpected image type");
   }
-  MOZ_ASSERT(CFGetTypeID(image) == CVPixelBufferGetTypeID(),
-    "VideoToolbox returned an unexpected image type");
-
   nsCOMPtr<nsIRunnable> task =
     NS_NewRunnableMethodWithArgs<CFRefPtr<CVPixelBufferRef>, AppleVTDecoder::AppleFrameRef>(
       decoder, &AppleVTDecoder::OutputFrame, image, *frameRef);
@@ -242,6 +241,8 @@ AppleVTDecoder::SubmitFrame(MediaRawData* aSample)
     return NS_ERROR_FAILURE;
   }
 
+  mQueuedSamples++;
+
   VTDecodeFrameFlags decodeFlags =
     kVTDecodeFrame_EnableAsynchronousDecompression;
   rv = VTDecompressionSessionDecodeFrame(mSession,
@@ -257,7 +258,7 @@ AppleVTDecoder::SubmitFrame(MediaRawData* aSample)
   }
 
   // Ask for more data.
-  if (!mInputIncoming) {
+  if (!mInputIncoming && mQueuedSamples <= mMaxRefFrames) {
     LOG("AppleVTDecoder task queue empty; requesting more data");
     mCallback->InputExhausted();
   }