1 files changed, 508 insertions, 0 deletions
diff --git a/dom/media/MediaSegment.h b/dom/media/MediaSegment.h
new file mode 100644
index 000000000..5c4805b30
--- /dev/null
+++ b/dom/media/MediaSegment.h
@@ -0,0 +1,508 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef MOZILLA_MEDIASEGMENT_H_
+#define MOZILLA_MEDIASEGMENT_H_
+
+#include "nsTArray.h"
+#include "nsIPrincipal.h"
+#include "nsProxyRelease.h"
+#ifdef MOZILLA_INTERNAL_API
+#include "mozilla/TimeStamp.h"
+#endif
+#include <algorithm>
+#include "Latency.h"
+
+namespace mozilla {
+
+/**
+ * Track or graph rate in Hz. Maximum 1 << TRACK_RATE_MAX_BITS Hz. This
+ * maximum avoids overflow in conversions between track rates and conversions
+ * from seconds.
+ */
+typedef int32_t TrackRate;
+const int64_t TRACK_RATE_MAX_BITS = 20;
+const TrackRate TRACK_RATE_MAX = 1 << TRACK_RATE_MAX_BITS;
+
+/**
+ * A number of ticks at a rate determined by some underlying track (e.g.
+ * audio sample rate). We want to make sure that multiplying TrackTicks by
+ * a TrackRate doesn't overflow, so we set its max accordingly.
+ * StreamTime should be used instead when we're working with MediaStreamGraph's
+ * rate, but TrackTicks can be used outside MediaStreams when we have data
+ * at a different rate.
+ */
+typedef int64_t TrackTicks;
+const int64_t TRACK_TICKS_MAX = INT64_MAX >> TRACK_RATE_MAX_BITS;
+
+/**
+ * We represent media times in 64-bit audio frame counts or ticks.
+ * All tracks in a MediaStreamGraph have the same rate.
+ */
+typedef int64_t MediaTime;
+const int64_t MEDIA_TIME_MAX = TRACK_TICKS_MAX;
+
+/**
+ * Media time relative to the start of a StreamTracks.
+ */
+typedef MediaTime StreamTime;
+const StreamTime STREAM_TIME_MAX = MEDIA_TIME_MAX;
+
+/**
+ * Media time relative to the start of the graph timeline.
+ */
+typedef MediaTime GraphTime;
+const GraphTime GRAPH_TIME_MAX = MEDIA_TIME_MAX;
+
+/**
+ * We pass the principal through the MediaStreamGraph by wrapping it in a thread
+ * safe nsMainThreadPtrHandle, since it cannot be used directly off the main
+ * thread. We can compare two PrincipalHandles to each other on any thread, but
+ * they can only be created and converted back to nsIPrincipal* on main thread.
+ */
+typedef nsMainThreadPtrHandle<nsIPrincipal> PrincipalHandle;
+
+inline PrincipalHandle MakePrincipalHandle(nsIPrincipal* aPrincipal)
+{
+  RefPtr<nsMainThreadPtrHolder<nsIPrincipal>> holder =
+    new nsMainThreadPtrHolder<nsIPrincipal>(aPrincipal);
+  return PrincipalHandle(holder);
+}
+
+#define PRINCIPAL_HANDLE_NONE nullptr
+
+inline nsIPrincipal* GetPrincipalFromHandle(PrincipalHandle& aPrincipalHandle)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  return aPrincipalHandle.get();
+}
+
+inline bool PrincipalHandleMatches(PrincipalHandle& aPrincipalHandle,
+                                   nsIPrincipal* aOther)
+{
+  if (!aOther) {
+    return false;
+  }
+
+  nsIPrincipal* principal = GetPrincipalFromHandle(aPrincipalHandle);
+  if (!principal) {
+    return false;
+  }
+
+  bool result;
+  if (NS_FAILED(principal->Equals(aOther, &result))) {
+    NS_ERROR("Principal check failed");
+    return false;
+  }
+
+  return result;
+}
+
+/**
+ * A MediaSegment is a chunk of media data sequential in time. Different
+ * types of data have different subclasses of MediaSegment, all inheriting
+ * from MediaSegmentBase.
+ * All MediaSegment data is timed using StreamTime. The actual tick rate
+ * is defined on a per-track basis. For some track types, this can be
+ * a fixed constant for all tracks of that type (e.g. 1MHz for video).
+ *
+ * Each media segment defines a concept of "null media data" (e.g. silence
+ * for audio or "no video frame" for video), which can be efficiently
+ * represented. This is used for padding.
+ */
+class MediaSegment {
+public:
+  virtual ~MediaSegment()
+  {
+    MOZ_COUNT_DTOR(MediaSegment);
+  }
+
+  enum Type {
+    AUDIO,
+    VIDEO,
+    TYPE_COUNT
+  };
+
+  /**
+   * Gets the total duration of the segment.
+   */
+  StreamTime GetDuration() const { return mDuration; }
+  Type GetType() const { return mType; }
+
+  /**
+   * Gets the last principal id that was appended to this segment.
+   */
+  PrincipalHandle GetLastPrincipalHandle() const { return mLastPrincipalHandle; }
+  /**
+   * Called by the MediaStreamGraph as it appends a chunk with a different
+   * principal id than the current one.
+   */
+  void SetLastPrincipalHandle(PrincipalHandle aLastPrincipalHandle)
+  {
+    mLastPrincipalHandle = aLastPrincipalHandle;
+  }
+
+  /**
+   * Create a MediaSegment of the same type.
+   */
+  virtual MediaSegment* CreateEmptyClone() const = 0;
+  /**
+   * Moves contents of aSource to the end of this segment.
+   */
+  virtual void AppendFrom(MediaSegment* aSource) = 0;
+  /**
+   * Append a slice of aSource to this segment.
+   */
+  virtual void AppendSlice(const MediaSegment& aSource,
+                           StreamTime aStart, StreamTime aEnd) = 0;
+  /**
+   * Replace all contents up to aDuration with null data.
+   */
+  virtual void ForgetUpTo(StreamTime aDuration) = 0;
+  /**
+   * Forget all data buffered after a given point
+   */
+  virtual void FlushAfter(StreamTime aNewEnd) = 0;
+  /**
+   * Insert aDuration of null data at the start of the segment.
+   */
+  virtual void InsertNullDataAtStart(StreamTime aDuration) = 0;
+  /**
+   * Insert aDuration of null data at the end of the segment.
+   */
+  virtual void AppendNullData(StreamTime aDuration) = 0;
+  /**
+   * Replace contents with disabled (silence/black) data of the same duration
+   */
+  virtual void ReplaceWithDisabled() = 0;
+  /**
+   * Replace contents with null data of the same duration
+   */
+  virtual void ReplaceWithNull() = 0;
+  /**
+   * Remove all contents, setting duration to 0.
+   */
+  virtual void Clear() = 0;
+
+  virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    return 0;
+  }
+
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+protected:
+  explicit MediaSegment(Type aType)
+    : mDuration(0), mType(aType), mLastPrincipalHandle(PRINCIPAL_HANDLE_NONE)
+  {
+    MOZ_COUNT_CTOR(MediaSegment);
+  }
+
+  StreamTime mDuration; // total of mDurations of all chunks
+  Type mType;
+
+  // The latest principal handle that the MediaStreamGraph has processed for
+  // this segment.
+  PrincipalHandle mLastPrincipalHandle;
+};
+
+/**
+ * C is the implementation class subclassed from MediaSegmentBase.
+ * C must contain a Chunk class.
+ */
+template <class C, class Chunk> class MediaSegmentBase : public MediaSegment {
+public:
+  MediaSegment* CreateEmptyClone() const override
+  {
+    return new C();
+  }
+  void AppendFrom(MediaSegment* aSource) override
+  {
+    NS_ASSERTION(aSource->GetType() == C::StaticType(), "Wrong type");
+    AppendFromInternal(static_cast<C*>(aSource));
+  }
+  void AppendFrom(C* aSource)
+  {
+    AppendFromInternal(aSource);
+  }
+  void AppendSlice(const MediaSegment& aSource,
+                   StreamTime aStart, StreamTime aEnd) override
+  {
+    NS_ASSERTION(aSource.GetType() == C::StaticType(), "Wrong type");
+    AppendSliceInternal(static_cast<const C&>(aSource), aStart, aEnd);
+  }
+  void AppendSlice(const C& aOther, StreamTime aStart, StreamTime aEnd)
+  {
+    AppendSliceInternal(aOther, aStart, aEnd);
+  }
+  /**
+   * Replace the first aDuration ticks with null media data, because the data
+   * will not be required again.
+   */
+  void ForgetUpTo(StreamTime aDuration) override
+  {
+    if (mChunks.IsEmpty() || aDuration <= 0) {
+      return;
+    }
+    if (mChunks[0].IsNull()) {
+      StreamTime extraToForget = std::min(aDuration, mDuration) - mChunks[0].GetDuration();
+      if (extraToForget > 0) {
+        RemoveLeading(extraToForget, 1);
+        mChunks[0].mDuration += extraToForget;
+        mDuration += extraToForget;
+      }
+      return;
+    }
+    RemoveLeading(aDuration, 0);
+    mChunks.InsertElementAt(0)->SetNull(aDuration);
+    mDuration += aDuration;
+  }
+  void FlushAfter(StreamTime aNewEnd) override
+  {
+    if (mChunks.IsEmpty()) {
+      return;
+    }
+
+    if (mChunks[0].IsNull()) {
+      StreamTime extraToKeep = aNewEnd - mChunks[0].GetDuration();
+      if (extraToKeep < 0) {
+        // reduce the size of the Null, get rid of everthing else
+        mChunks[0].SetNull(aNewEnd);
+        extraToKeep = 0;
+      }
+      RemoveTrailing(extraToKeep, 1);
+    } else {
+      if (aNewEnd > mDuration) {
+        NS_ASSERTION(aNewEnd <= mDuration, "can't add data in FlushAfter");
+        return;
+      }
+      RemoveTrailing(aNewEnd, 0);
+    }
+    mDuration = aNewEnd;
+  }
+  void InsertNullDataAtStart(StreamTime aDuration) override
+  {
+    if (aDuration <= 0) {
+      return;
+    }
+    if (!mChunks.IsEmpty() && mChunks[0].IsNull()) {
+      mChunks[0].mDuration += aDuration;
+    } else {
+      mChunks.InsertElementAt(0)->SetNull(aDuration);
+    }
+#ifdef MOZILLA_INTERNAL_API
+    mChunks[0].mTimeStamp = mozilla::TimeStamp::Now();
+#endif
+    mDuration += aDuration;
+  }
+  void AppendNullData(StreamTime aDuration) override
+  {
+    if (aDuration <= 0) {
+      return;
+    }
+    if (!mChunks.IsEmpty() && mChunks[mChunks.Length() - 1].IsNull()) {
+      mChunks[mChunks.Length() - 1].mDuration += aDuration;
+    } else {
+      mChunks.AppendElement()->SetNull(aDuration);
+    }
+    mDuration += aDuration;
+  }
+  void ReplaceWithDisabled() override
+  {
+    if (GetType() != AUDIO) {
+      MOZ_CRASH("Disabling unknown segment type");
+    }
+    ReplaceWithNull();
+  }
+  void ReplaceWithNull() override
+  {
+    StreamTime duration = GetDuration();
+    Clear();
+    AppendNullData(duration);
+  }
+  void Clear() override
+  {
+    mDuration = 0;
+    mChunks.Clear();
+  }
+
+  class ChunkIterator {
+  public:
+    explicit ChunkIterator(MediaSegmentBase<C, Chunk>& aSegment)
+      : mSegment(aSegment), mIndex(0) {}
+    bool IsEnded() { return mIndex >= mSegment.mChunks.Length(); }
+    void Next() { ++mIndex; }
+    Chunk& operator*() { return mSegment.mChunks[mIndex]; }
+    Chunk* operator->() { return &mSegment.mChunks[mIndex]; }
+  private:
+    MediaSegmentBase<C, Chunk>& mSegment;
+    uint32_t mIndex;
+  };
+  class ConstChunkIterator {
+  public:
+    explicit ConstChunkIterator(const MediaSegmentBase<C, Chunk>& aSegment)
+      : mSegment(aSegment), mIndex(0) {}
+    bool IsEnded() { return mIndex >= mSegment.mChunks.Length(); }
+    void Next() { ++mIndex; }
+    const Chunk& operator*() { return mSegment.mChunks[mIndex]; }
+    const Chunk* operator->() { return &mSegment.mChunks[mIndex]; }
+  private:
+    const MediaSegmentBase<C, Chunk>& mSegment;
+    uint32_t mIndex;
+  };
+
+  Chunk* FindChunkContaining(StreamTime aOffset, StreamTime* aStart = nullptr)
+  {
+    if (aOffset < 0) {
+      return nullptr;
+    }
+    StreamTime offset = 0;
+    for (uint32_t i = 0; i < mChunks.Length(); ++i) {
+      Chunk& c = mChunks[i];
+      StreamTime nextOffset = offset + c.GetDuration();
+      if (aOffset < nextOffset) {
+        if (aStart) {
+          *aStart = offset;
+        }
+        return &c;
+      }
+      offset = nextOffset;
+    }
+    return nullptr;
+  }
+
+  void RemoveLeading(StreamTime aDuration)
+  {
+    RemoveLeading(aDuration, 0);
+  }
+
+#ifdef MOZILLA_INTERNAL_API
+  void GetStartTime(TimeStamp &aTime) {
+    aTime = mChunks[0].mTimeStamp;
+  }
+#endif
+
+  size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
+  {
+    size_t amount = mChunks.ShallowSizeOfExcludingThis(aMallocSizeOf);
+    for (size_t i = 0; i < mChunks.Length(); i++) {
+      amount += mChunks[i].SizeOfExcludingThisIfUnshared(aMallocSizeOf);
+    }
+    return amount;
+  }
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  Chunk* GetLastChunk()
+  {
+    if (mChunks.IsEmpty()) {
+      return nullptr;
+    }
+    return &mChunks[mChunks.Length() - 1];
+  }
+
+protected:
+  explicit MediaSegmentBase(Type aType) : MediaSegment(aType) {}
+
+  /**
+   * Appends the contents of aSource to this segment, clearing aSource.
+   */
+  void AppendFromInternal(MediaSegmentBase<C, Chunk>* aSource)
+  {
+    MOZ_ASSERT(aSource->mDuration >= 0);
+    mDuration += aSource->mDuration;
+    aSource->mDuration = 0;
+    if (!mChunks.IsEmpty() && !aSource->mChunks.IsEmpty() &&
+        mChunks[mChunks.Length() - 1].CanCombineWithFollowing(aSource->mChunks[0])) {
+      mChunks[mChunks.Length() - 1].mDuration += aSource->mChunks[0].mDuration;
+      aSource->mChunks.RemoveElementAt(0);
+    }
+    mChunks.AppendElements(Move(aSource->mChunks));
+  }
+
+  void AppendSliceInternal(const MediaSegmentBase<C, Chunk>& aSource,
+                           StreamTime aStart, StreamTime aEnd)
+  {
+    MOZ_ASSERT(aStart <= aEnd, "Endpoints inverted");
+    NS_ASSERTION(aStart >= 0 && aEnd <= aSource.mDuration, "Slice out of range");
+    mDuration += aEnd - aStart;
+    StreamTime offset = 0;
+    for (uint32_t i = 0; i < aSource.mChunks.Length() && offset < aEnd; ++i) {
+      const Chunk& c = aSource.mChunks[i];
+      StreamTime start = std::max(aStart, offset);
+      StreamTime nextOffset = offset + c.GetDuration();
+      StreamTime end = std::min(aEnd, nextOffset);
+      if (start < end) {
+        mChunks.AppendElement(c)->SliceTo(start - offset, end - offset);
+      }
+      offset = nextOffset;
+    }
+  }
+
+  Chunk* AppendChunk(StreamTime aDuration)
+  {
+    MOZ_ASSERT(aDuration >= 0);
+    Chunk* c = mChunks.AppendElement();
+    c->mDuration = aDuration;
+    mDuration += aDuration;
+    return c;
+  }
+
+  void RemoveLeading(StreamTime aDuration, uint32_t aStartIndex)
+  {
+    NS_ASSERTION(aDuration >= 0, "Can't remove negative duration");
+    StreamTime t = aDuration;
+    uint32_t chunksToRemove = 0;
+    for (uint32_t i = aStartIndex; i < mChunks.Length() && t > 0; ++i) {
+      Chunk* c = &mChunks[i];
+      if (c->GetDuration() > t) {
+        c->SliceTo(t, c->GetDuration());
+        t = 0;
+        break;
+      }
+      t -= c->GetDuration();
+      chunksToRemove = i + 1 - aStartIndex;
+    }
+    mChunks.RemoveElementsAt(aStartIndex, chunksToRemove);
+    mDuration -= aDuration - t;
+  }
+
+  void RemoveTrailing(StreamTime aKeep, uint32_t aStartIndex)
+  {
+    NS_ASSERTION(aKeep >= 0, "Can't keep negative duration");
+    StreamTime t = aKeep;
+    uint32_t i;
+    for (i = aStartIndex; i < mChunks.Length(); ++i) {
+      Chunk* c = &mChunks[i];
+      if (c->GetDuration() > t) {
+        c->SliceTo(0, t);
+        break;
+      }
+      t -= c->GetDuration();
+      if (t == 0) {
+        break;
+      }
+    }
+    if (i+1 < mChunks.Length()) {
+      mChunks.RemoveElementsAt(i+1, mChunks.Length() - (i+1));
+    }
+    // Caller must adjust mDuration
+  }
+
+  nsTArray<Chunk> mChunks;
+#ifdef MOZILLA_INTERNAL_API
+  mozilla::TimeStamp mTimeStamp;
+#endif
+};
+
+} // namespace mozilla
+
+#endif /* MOZILLA_MEDIASEGMENT_H_ */