gecko-dev/dom/media/StreamBuffer.h

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/* -*- 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_STREAMBUFFER_H_
#define MOZILLA_STREAMBUFFER_H_
#include "MediaSegment.h"
#include "nsAutoPtr.h"
namespace mozilla {
/**
* Media time relative to the start of a StreamBuffer.
*/
typedef MediaTime StreamTime;
const StreamTime STREAM_TIME_MAX = MEDIA_TIME_MAX;
/**
* Unique ID for track within a StreamBuffer. Tracks from different
* StreamBuffers may have the same ID; this matters when appending StreamBuffers,
* since tracks with the same ID are matched. Only IDs greater than 0 are allowed.
*/
typedef int32_t TrackID;
const TrackID TRACK_NONE = 0;
const TrackID TRACK_INVALID = -1;
inline TrackTicks RateConvertTicksRoundDown(TrackRate aOutRate,
TrackRate aInRate,
TrackTicks aTicks)
{
NS_ASSERTION(0 < aOutRate && aOutRate <= TRACK_RATE_MAX, "Bad out rate");
NS_ASSERTION(0 < aInRate && aInRate <= TRACK_RATE_MAX, "Bad in rate");
NS_WARN_IF_FALSE(0 <= aTicks && aTicks <= TRACK_TICKS_MAX, "Bad ticks"); // bug 957691
return (aTicks * aOutRate) / aInRate;
}
inline TrackTicks RateConvertTicksRoundUp(TrackRate aOutRate,
TrackRate aInRate, TrackTicks aTicks)
{
NS_ASSERTION(0 < aOutRate && aOutRate <= TRACK_RATE_MAX, "Bad out rate");
NS_ASSERTION(0 < aInRate && aInRate <= TRACK_RATE_MAX, "Bad in rate");
NS_ASSERTION(0 <= aTicks && aTicks <= TRACK_TICKS_MAX, "Bad ticks");
return (aTicks * aOutRate + aInRate - 1) / aInRate;
}
inline TrackTicks SecondsToTicksRoundDown(TrackRate aRate, double aSeconds)
{
NS_ASSERTION(0 < aRate && aRate <= TRACK_RATE_MAX, "Bad rate");
NS_ASSERTION(0 <= aSeconds && aSeconds <= TRACK_TICKS_MAX/TRACK_RATE_MAX,
"Bad seconds");
return aSeconds * aRate;
}
inline double TrackTicksToSeconds(TrackRate aRate, TrackTicks aTicks)
{
NS_ASSERTION(0 < aRate && aRate <= TRACK_RATE_MAX, "Bad rate");
NS_ASSERTION(0 <= aTicks && aTicks <= TRACK_TICKS_MAX, "Bad ticks");
return static_cast<double>(aTicks)/aRate;
}
/**
* This object contains the decoded data for a stream's tracks.
* A StreamBuffer can be appended to. Logically a StreamBuffer only gets longer,
* but we also have the ability to "forget" data before a certain time that
* we know won't be used again. (We prune a whole number of seconds internally.)
*
* StreamBuffers should only be used from one thread at a time.
*
* A StreamBuffer has a set of tracks that can be of arbitrary types ---
* the data for each track is a MediaSegment. The set of tracks can vary
* over the timeline of the StreamBuffer.
*/
class StreamBuffer {
public:
/**
* Every track has a start time --- when it started in the StreamBuffer.
* It has an end flag; when false, no end point is known; when true,
* the track ends when the data we have for the track runs out.
* Tracks have a unique ID assigned at creation. This allows us to identify
* the same track across StreamBuffers. A StreamBuffer should never have
* two tracks with the same ID (even if they don't overlap in time).
* TODO Tracks can also be enabled and disabled over time.
* TODO Add TimeVarying<TrackTicks,bool> mEnabled.
* Takes ownership of aSegment.
*/
class Track {
Track(TrackID aID, TrackRate aRate, TrackTicks aStart, MediaSegment* aSegment, TrackRate aGraphRate)
: mStart(aStart),
mSegment(aSegment),
mRate(aRate),
mGraphRate(aGraphRate),
mID(aID),
mEnded(false)
{
MOZ_COUNT_CTOR(Track);
NS_ASSERTION(aID > TRACK_NONE, "Bad track ID");
NS_ASSERTION(0 < aRate && aRate <= TRACK_RATE_MAX, "Invalid rate");
NS_ASSERTION(0 <= aStart && aStart <= aSegment->GetDuration(), "Bad start position");
}
public:
~Track()
{
MOZ_COUNT_DTOR(Track);
}
template <class T> T* Get() const
{
if (mSegment->GetType() == T::StaticType()) {
return static_cast<T*>(mSegment.get());
}
return nullptr;
}
MediaSegment* GetSegment() const { return mSegment; }
TrackRate GetRate() const { return mRate; }
TrackID GetID() const { return mID; }
bool IsEnded() const { return mEnded; }
TrackTicks GetStart() const { return mStart; }
TrackTicks GetEnd() const { return mSegment->GetDuration(); }
StreamTime GetEndTimeRoundDown() const
{
return TicksToTimeRoundDown(mSegment->GetDuration());
}
StreamTime GetStartTimeRoundDown() const
{
return TicksToTimeRoundDown(mStart);
}
TrackTicks TimeToTicksRoundDown(StreamTime aTime) const
{
return RateConvertTicksRoundDown(mRate, mGraphRate, aTime);
}
StreamTime TicksToTimeRoundDown(TrackTicks aTicks) const
{
return RateConvertTicksRoundDown(mGraphRate, mRate, aTicks);
}
MediaSegment::Type GetType() const { return mSegment->GetType(); }
void SetEnded() { mEnded = true; }
void AppendFrom(Track* aTrack)
{
NS_ASSERTION(!mEnded, "Can't append to ended track");
NS_ASSERTION(aTrack->mID == mID, "IDs must match");
NS_ASSERTION(aTrack->mStart == 0, "Source track must start at zero");
NS_ASSERTION(aTrack->mSegment->GetType() == GetType(), "Track types must match");
NS_ASSERTION(aTrack->mRate == mRate, "Track rates must match");
mSegment->AppendFrom(aTrack->mSegment);
mEnded = aTrack->mEnded;
}
MediaSegment* RemoveSegment()
{
return mSegment.forget();
}
void ForgetUpTo(TrackTicks aTime)
{
mSegment->ForgetUpTo(aTime);
}
void FlushAfter(TrackTicks aNewEnd)
{
// Forget everything after a given endpoint
// a specified amount
mSegment->FlushAfter(aNewEnd);
}
size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
{
size_t amount = aMallocSizeOf(this);
if (mSegment) {
amount += mSegment->SizeOfIncludingThis(aMallocSizeOf);
}
return amount;
}
protected:
friend class StreamBuffer;
// Start offset is in ticks at rate mRate
TrackTicks mStart;
// The segment data starts at the start of the owning StreamBuffer, i.e.,
// there's mStart silence/no video at the beginning.
nsAutoPtr<MediaSegment> mSegment;
TrackRate mRate; // track rate in ticks per second
TrackRate mGraphRate; // graph rate in StreamTime per second
// Unique ID
TrackID mID;
// True when the track ends with the data in mSegment
bool mEnded;
};
class CompareTracksByID {
public:
bool Equals(Track* aA, Track* aB) const {
return aA->GetID() == aB->GetID();
}
bool LessThan(Track* aA, Track* aB) const {
return aA->GetID() < aB->GetID();
}
};
StreamBuffer()
: mTracksKnownTime(0), mForgottenTime(0)
#ifdef DEBUG
, mGraphRateIsSet(false)
#endif
{
MOZ_COUNT_CTOR(StreamBuffer);
}
~StreamBuffer()
{
MOZ_COUNT_DTOR(StreamBuffer);
}
size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
{
size_t amount = 0;
amount += mTracks.SizeOfExcludingThis(aMallocSizeOf);
for (size_t i = 0; i < mTracks.Length(); i++) {
amount += mTracks[i]->SizeOfIncludingThis(aMallocSizeOf);
}
return amount;
}
/**
* Initialize the graph rate for use in calculating StreamTimes from track
* ticks. Called when a MediaStream's graph pointer is initialized.
*/
void InitGraphRate(TrackRate aGraphRate)
{
mGraphRate = aGraphRate;
#if DEBUG
MOZ_ASSERT(!mGraphRateIsSet);
mGraphRateIsSet = true;
#endif
}
TrackRate GraphRate() const
{
MOZ_ASSERT(mGraphRateIsSet);
return mGraphRate;
}
/**
* Takes ownership of aSegment. Don't do this while iterating, or while
* holding a Track reference.
* aSegment must have aStart worth of null data.
*/
Track& AddTrack(TrackID aID, TrackRate aRate, TrackTicks aStart, MediaSegment* aSegment)
{
NS_ASSERTION(!FindTrack(aID), "Track with this ID already exists");
Track* track = new Track(aID, aRate, aStart, aSegment, GraphRate());
mTracks.InsertElementSorted(track, CompareTracksByID());
if (mTracksKnownTime == STREAM_TIME_MAX) {
// There exists code like
// http://mxr.mozilla.org/mozilla-central/source/media/webrtc/signaling/src/mediapipeline/MediaPipeline.cpp?rev=96b197deb91e&mark=1292-1297#1292
NS_WARNING("Adding track to StreamBuffer that should have no more tracks");
} else {
NS_ASSERTION(track->TimeToTicksRoundDown(mTracksKnownTime) <= aStart,
"Start time too early");
}
return *track;
}
void AdvanceKnownTracksTime(StreamTime aKnownTime)
{
NS_ASSERTION(aKnownTime >= mTracksKnownTime, "Can't move tracks-known time earlier");
mTracksKnownTime = aKnownTime;
}
/**
* The end time for the StreamBuffer is the latest time for which we have
* data for all tracks that haven't ended by that time.
*/
StreamTime GetEnd() const;
/**
* Returns the earliest time >= 0 at which all tracks have ended
* and all their data has been played out and no new tracks can be added,
* or STREAM_TIME_MAX if there is no such time.
*/
StreamTime GetAllTracksEnd() const;
#ifdef DEBUG
void DumpTrackInfo() const;
#endif
Track* FindTrack(TrackID aID);
class TrackIter {
public:
/**
* Iterate through the tracks of aBuffer in order of ID.
*/
explicit TrackIter(const StreamBuffer& aBuffer) :
mBuffer(&aBuffer.mTracks), mIndex(0), mMatchType(false) {}
/**
* Iterate through the tracks of aBuffer with type aType, in order of ID.
*/
TrackIter(const StreamBuffer& aBuffer, MediaSegment::Type aType) :
mBuffer(&aBuffer.mTracks), mIndex(0), mType(aType), mMatchType(true) { FindMatch(); }
bool IsEnded() { return mIndex >= mBuffer->Length(); }
void Next()
{
++mIndex;
FindMatch();
}
Track* get() { return mBuffer->ElementAt(mIndex); }
Track& operator*() { return *mBuffer->ElementAt(mIndex); }
Track* operator->() { return mBuffer->ElementAt(mIndex); }
private:
void FindMatch()
{
if (!mMatchType)
return;
while (mIndex < mBuffer->Length() &&
mBuffer->ElementAt(mIndex)->GetType() != mType) {
++mIndex;
}
}
const nsTArray<nsAutoPtr<Track> >* mBuffer;
uint32_t mIndex;
MediaSegment::Type mType;
bool mMatchType;
};
friend class TrackIter;
/**
* Forget stream data before aTime; they will no longer be needed.
* Also can forget entire tracks that have ended at or before aTime.
* Can't be used to forget beyond GetEnd().
*/
void ForgetUpTo(StreamTime aTime);
/**
* Returns the latest time passed to ForgetUpTo.
*/
StreamTime GetForgottenDuration()
{
return mForgottenTime;
}
protected:
TrackRate mGraphRate; // StreamTime per second
// Any new tracks added will start at or after this time. In other words, the track
// list is complete and correct for all times less than this time.
StreamTime mTracksKnownTime;
StreamTime mForgottenTime;
// All known tracks for this StreamBuffer
nsTArray<nsAutoPtr<Track> > mTracks;
#ifdef DEBUG
bool mGraphRateIsSet;
#endif
};
}
#endif /* MOZILLA_STREAMBUFFER_H_ */