Commit d4f88926 authored by cajbir's avatar cajbir
Browse files

Bug 976037 - Implement an eviction algorithm for media source extensions - r=kinetik 

--HG--
extra : rebase_source : 9727384f364f88957db822905436c19c4943c019
parent 6dc4d165

content/media/mediasource/MediaSource.cpp

+8 −0
Original line number Diff line number Diff line
@@ -371,6 +371,14 @@ MediaSource::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aScope) 
  return MediaSourceBinding::Wrap(aCx, aScope, this);

}



void

MediaSource::NotifyEvicted(double aStart, double aEnd)

{

  // Cycle through all SourceBuffers and tell them to evict data in

  // the given range.

  mSourceBuffers->Evict(aStart, aEnd);

}



NS_IMPL_CYCLE_COLLECTION_INHERITED_2(MediaSource, nsDOMEventTargetHelper,

                                     mSourceBuffers, mActiveSourceBuffers)

content/media/mediasource/MediaSource.h

+5 −0
Original line number Diff line number Diff line
@@ -85,6 +85,11 @@ public: 
    return mDecoder;

  }



  // Called by SourceBuffers to notify this MediaSource that data has

  // been evicted from the buffered data. The start and end times

  // that were evicted are provided.

  void NotifyEvicted(double aStart, double aEnd);



private:

  explicit MediaSource(nsPIDOMWindow* aWindow);

content/media/mediasource/MediaSourceDecoder.cpp

+9 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include "MediaSource.h"

#include "SubBufferDecoder.h"

#include "SourceBufferResource.h"

#include "VideoUtils.h"



#ifdef PR_LOGGING

extern PRLogModuleInfo* gMediaSourceLog;
@@ -238,4 +239,12 @@ MediaSourceReader::ReadMetadata(MediaInfo* aInfo, MetadataTags** aTags) 
  return NS_OK;

}



double

MediaSourceDecoder::GetMediaSourceDuration()

{

  return mMediaSource ?

           mMediaSource->Duration() :

           mDuration / static_cast<double>(USECS_PER_S);

}



} // namespace mozilla

content/media/mediasource/MediaSourceDecoder.h

+4 −0
Original line number Diff line number Diff line
@@ -79,6 +79,10 @@ public: 
    return mAudioReader;

  }



  // Returns the duration in seconds as provided by the attached MediaSource.

  // If no MediaSource is attached, returns the duration tracked by the decoder.

  double GetMediaSourceDuration();



private:

  dom::MediaSource* mMediaSource;

content/media/mediasource/SourceBuffer.cpp

+66 −0
Original line number Diff line number Diff line
@@ -96,6 +96,23 @@ SubBufferDecoder::GetImageContainer() 
  return mParentDecoder->GetImageContainer();

}



int64_t

SubBufferDecoder::ConvertToByteOffset(double aTime)

{

  // Uses a conversion based on (aTime/duration) * length.  For the

  // purposes of eviction this should be adequate since we have the

  // byte threshold as well to ensure data actually gets evicted and

  // we ensure we don't evict before the current playable point.

  double duration = mParentDecoder->GetMediaSourceDuration();

  if (duration <= 0.0 || IsNaN(duration)) {

    return -1;

  }

  int64_t length = GetResource()->GetLength();

  MOZ_ASSERT(length > 0);

  int64_t offset = (aTime / duration) * length;

  return offset;

}



namespace dom {



void
@@ -330,7 +347,56 @@ SourceBuffer::AppendData(const uint8_t* aData, uint32_t aLength, ErrorResult& aR 
                              mDecoder->GetResource()->GetLength());

  // TODO: Run buffer append algorithm asynchronously (would call StopUpdating()).

  mDecoder->GetResource()->AppendData(aData, aLength);



  // Eviction uses a byte threshold. If the buffer is greater than the

  // number of bytes then data is evicted. The time range for this

  // eviction is reported back to the media source. It will then

  // evict data before that range across all SourceBuffer's it knows

  // about.

  const int evict_threshold = 1000000;

  bool evicted = mDecoder->GetResource()->EvictData(evict_threshold);

  if (evicted) {

    double start = 0.0;

    double end = 0.0;

    GetBufferedStartEndTime(&start, &end);



    // We notify that we've evicted from the time range 0 through to

    // the current start point.

    mMediaSource->NotifyEvicted(0.0, start);

  }

  StopUpdating();



  // Schedule the state machine thread to ensure playback starts

  // if required when data is appended.

  mMediaSource->GetDecoder()->ScheduleStateMachineThread();

}



void

SourceBuffer::GetBufferedStartEndTime(double* aStart, double* aEnd)

{

  nsRefPtr<TimeRanges> ranges = new TimeRanges();

  mDecoder->GetBuffered(ranges);

  ranges->Normalize();

  int length = ranges->Length();

  ErrorResult rv;



  if (aStart) {

    *aStart = length > 0 ? ranges->Start(0, rv) : 0.0;

  }



  if (aEnd) {

    *aEnd = length > 0 ? ranges->End(length - 1, rv) : 0.0;

  }

}



void

SourceBuffer::Evict(double aStart, double aEnd)

{

  // Need to map time to byte offset then evict

  int64_t end = mDecoder->ConvertToByteOffset(aEnd);

  if (end > 0) {

    mDecoder->GetResource()->EvictBefore(end);

  }

}



NS_IMPL_CYCLE_COLLECTION_INHERITED_1(SourceBuffer, nsDOMEventTargetHelper, mMediaSource)