mirror of
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352 lines
9.7 KiB
C++
352 lines
9.7 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_MEDIASEGMENT_H_
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#define MOZILLA_MEDIASEGMENT_H_
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#include "nsTArray.h"
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#ifdef MOZILLA_INTERNAL_API
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#include "mozilla/TimeStamp.h"
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#endif
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#include <algorithm>
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#include "Latency.h"
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namespace mozilla {
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/**
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* We represent media times in 64-bit fixed point. So 1 MediaTime is
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* 1/(2^MEDIA_TIME_FRAC_BITS) seconds.
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*/
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typedef int64_t MediaTime;
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const int64_t MEDIA_TIME_FRAC_BITS = 20;
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const int64_t MEDIA_TIME_MAX = INT64_MAX;
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inline MediaTime MillisecondsToMediaTime(int32_t aMS)
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{
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return (MediaTime(aMS) << MEDIA_TIME_FRAC_BITS)/1000;
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}
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inline MediaTime SecondsToMediaTime(double aS)
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{
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NS_ASSERTION(aS <= (MEDIA_TIME_MAX >> MEDIA_TIME_FRAC_BITS),
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"Out of range");
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return MediaTime(aS * (1 << MEDIA_TIME_FRAC_BITS));
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}
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inline double MediaTimeToSeconds(MediaTime aTime)
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{
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return aTime*(1.0/(1 << MEDIA_TIME_FRAC_BITS));
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}
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inline int64_t MediaTimeToMicroseconds(MediaTime aTime)
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{
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return aTime*(1000000.0/(1 << MEDIA_TIME_FRAC_BITS));
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}
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/**
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* A number of ticks at a rate determined by some underlying track (e.g.
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* audio sample rate). We want to make sure that multiplying TrackTicks by
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* 2^MEDIA_TIME_FRAC_BITS doesn't overflow, so we set its max accordingly.
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*/
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typedef int64_t TrackTicks;
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const int64_t TRACK_TICKS_MAX = INT64_MAX >> MEDIA_TIME_FRAC_BITS;
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/**
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* A MediaSegment is a chunk of media data sequential in time. Different
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* types of data have different subclasses of MediaSegment, all inheriting
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* from MediaSegmentBase.
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* All MediaSegment data is timed using TrackTicks. The actual tick rate
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* is defined on a per-track basis. For some track types, this can be
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* a fixed constant for all tracks of that type (e.g. 1MHz for video).
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*
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* Each media segment defines a concept of "null media data" (e.g. silence
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* for audio or "no video frame" for video), which can be efficiently
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* represented. This is used for padding.
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*/
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class MediaSegment {
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public:
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virtual ~MediaSegment()
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{
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MOZ_COUNT_DTOR(MediaSegment);
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}
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enum Type {
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AUDIO,
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VIDEO,
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TYPE_COUNT
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};
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/**
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* Gets the total duration of the segment.
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*/
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TrackTicks GetDuration() const { return mDuration; }
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Type GetType() const { return mType; }
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/**
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* Create a MediaSegment of the same type.
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*/
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virtual MediaSegment* CreateEmptyClone() const = 0;
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/**
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* Moves contents of aSource to the end of this segment.
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*/
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virtual void AppendFrom(MediaSegment* aSource) = 0;
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/**
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* Append a slice of aSource to this segment.
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*/
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virtual void AppendSlice(const MediaSegment& aSource,
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TrackTicks aStart, TrackTicks aEnd) = 0;
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/**
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* Replace all contents up to aDuration with null data.
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*/
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virtual void ForgetUpTo(TrackTicks aDuration) = 0;
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/**
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* Insert aDuration of null data at the start of the segment.
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*/
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virtual void InsertNullDataAtStart(TrackTicks aDuration) = 0;
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/**
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* Insert aDuration of null data at the end of the segment.
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*/
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virtual void AppendNullData(TrackTicks aDuration) = 0;
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/**
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* Replace contents with disabled data of the same duration
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*/
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virtual void ReplaceWithDisabled() = 0;
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/**
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* Remove all contents, setting duration to 0.
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*/
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virtual void Clear() = 0;
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protected:
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MediaSegment(Type aType) : mDuration(0), mType(aType)
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{
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MOZ_COUNT_CTOR(MediaSegment);
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}
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TrackTicks mDuration; // total of mDurations of all chunks
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Type mType;
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};
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/**
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* C is the implementation class subclassed from MediaSegmentBase.
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* C must contain a Chunk class.
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*/
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template <class C, class Chunk> class MediaSegmentBase : public MediaSegment {
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public:
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virtual MediaSegment* CreateEmptyClone() const
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{
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return new C();
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}
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virtual void AppendFrom(MediaSegment* aSource)
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{
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NS_ASSERTION(aSource->GetType() == C::StaticType(), "Wrong type");
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AppendFromInternal(static_cast<C*>(aSource));
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}
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void AppendFrom(C* aSource)
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{
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AppendFromInternal(aSource);
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}
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virtual void AppendSlice(const MediaSegment& aSource,
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TrackTicks aStart, TrackTicks aEnd)
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{
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NS_ASSERTION(aSource.GetType() == C::StaticType(), "Wrong type");
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AppendSliceInternal(static_cast<const C&>(aSource), aStart, aEnd);
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}
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void AppendSlice(const C& aOther, TrackTicks aStart, TrackTicks aEnd)
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{
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AppendSliceInternal(aOther, aStart, aEnd);
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}
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/**
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* Replace the first aDuration ticks with null media data, because the data
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* will not be required again.
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*/
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virtual void ForgetUpTo(TrackTicks aDuration)
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{
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if (mChunks.IsEmpty() || aDuration <= 0) {
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return;
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}
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if (mChunks[0].IsNull()) {
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TrackTicks extraToForget = std::min(aDuration, mDuration) - mChunks[0].GetDuration();
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if (extraToForget > 0) {
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RemoveLeading(extraToForget, 1);
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mChunks[0].mDuration += extraToForget;
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mDuration += extraToForget;
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}
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return;
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}
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RemoveLeading(aDuration, 0);
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mChunks.InsertElementAt(0)->SetNull(aDuration);
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mDuration += aDuration;
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}
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virtual void InsertNullDataAtStart(TrackTicks aDuration)
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{
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if (aDuration <= 0) {
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return;
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}
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if (!mChunks.IsEmpty() && mChunks[0].IsNull()) {
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mChunks[0].mDuration += aDuration;
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} else {
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mChunks.InsertElementAt(0)->SetNull(aDuration);
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}
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#ifdef MOZILLA_INTERNAL_API
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mChunks[0].mTimeStamp = mozilla::TimeStamp::Now();
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#endif
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mDuration += aDuration;
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}
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virtual void AppendNullData(TrackTicks aDuration)
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{
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if (aDuration <= 0) {
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return;
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}
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if (!mChunks.IsEmpty() && mChunks[mChunks.Length() - 1].IsNull()) {
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mChunks[mChunks.Length() - 1].mDuration += aDuration;
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} else {
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mChunks.AppendElement()->SetNull(aDuration);
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}
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mDuration += aDuration;
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}
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virtual void ReplaceWithDisabled()
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{
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if (GetType() != AUDIO) {
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MOZ_CRASH("Disabling unknown segment type");
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}
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TrackTicks duration = GetDuration();
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Clear();
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AppendNullData(duration);
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}
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virtual void Clear()
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{
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mDuration = 0;
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mChunks.Clear();
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}
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class ChunkIterator {
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public:
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ChunkIterator(MediaSegmentBase<C, Chunk>& aSegment)
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: mSegment(aSegment), mIndex(0) {}
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bool IsEnded() { return mIndex >= mSegment.mChunks.Length(); }
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void Next() { ++mIndex; }
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Chunk& operator*() { return mSegment.mChunks[mIndex]; }
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Chunk* operator->() { return &mSegment.mChunks[mIndex]; }
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private:
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MediaSegmentBase<C, Chunk>& mSegment;
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uint32_t mIndex;
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};
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void RemoveLeading(TrackTicks aDuration)
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{
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RemoveLeading(aDuration, 0);
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}
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#ifdef MOZILLA_INTERNAL_API
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void GetStartTime(TimeStamp &aTime) {
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aTime = mChunks[0].mTimeStamp;
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}
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#endif
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protected:
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MediaSegmentBase(Type aType) : MediaSegment(aType) {}
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/**
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* Appends the contents of aSource to this segment, clearing aSource.
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*/
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void AppendFromInternal(MediaSegmentBase<C, Chunk>* aSource)
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{
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MOZ_ASSERT(aSource->mDuration >= 0);
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mDuration += aSource->mDuration;
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aSource->mDuration = 0;
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if (!mChunks.IsEmpty() && !aSource->mChunks.IsEmpty() &&
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mChunks[mChunks.Length() - 1].CanCombineWithFollowing(aSource->mChunks[0])) {
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mChunks[mChunks.Length() - 1].mDuration += aSource->mChunks[0].mDuration;
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aSource->mChunks.RemoveElementAt(0);
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}
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mChunks.MoveElementsFrom(aSource->mChunks);
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}
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void AppendSliceInternal(const MediaSegmentBase<C, Chunk>& aSource,
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TrackTicks aStart, TrackTicks aEnd)
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{
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NS_ASSERTION(aStart <= aEnd, "Endpoints inverted");
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NS_ASSERTION(aStart >= 0 && aEnd <= aSource.mDuration,
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"Slice out of range");
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mDuration += aEnd - aStart;
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TrackTicks offset = 0;
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for (uint32_t i = 0; i < aSource.mChunks.Length() && offset < aEnd; ++i) {
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const Chunk& c = aSource.mChunks[i];
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TrackTicks start = std::max(aStart, offset);
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TrackTicks nextOffset = offset + c.GetDuration();
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TrackTicks end = std::min(aEnd, nextOffset);
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if (start < end) {
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mChunks.AppendElement(c)->SliceTo(start - offset, end - offset);
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}
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offset = nextOffset;
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}
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}
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Chunk* AppendChunk(TrackTicks aDuration)
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{
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MOZ_ASSERT(aDuration >= 0);
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Chunk* c = mChunks.AppendElement();
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c->mDuration = aDuration;
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mDuration += aDuration;
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return c;
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}
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Chunk* FindChunkContaining(TrackTicks aOffset, TrackTicks* aStart = nullptr)
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{
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if (aOffset < 0) {
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return nullptr;
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}
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TrackTicks offset = 0;
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for (uint32_t i = 0; i < mChunks.Length(); ++i) {
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Chunk& c = mChunks[i];
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TrackTicks nextOffset = offset + c.GetDuration();
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if (aOffset < nextOffset) {
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if (aStart) {
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*aStart = offset;
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}
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return &c;
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}
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offset = nextOffset;
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}
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return nullptr;
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}
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Chunk* GetLastChunk()
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{
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if (mChunks.IsEmpty()) {
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return nullptr;
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}
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return &mChunks[mChunks.Length() - 1];
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}
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void RemoveLeading(TrackTicks aDuration, uint32_t aStartIndex)
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{
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NS_ASSERTION(aDuration >= 0, "Can't remove negative duration");
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TrackTicks t = aDuration;
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uint32_t chunksToRemove = 0;
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for (uint32_t i = aStartIndex; i < mChunks.Length() && t > 0; ++i) {
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Chunk* c = &mChunks[i];
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if (c->GetDuration() > t) {
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c->SliceTo(t, c->GetDuration());
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t = 0;
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break;
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}
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t -= c->GetDuration();
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chunksToRemove = i + 1 - aStartIndex;
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}
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mChunks.RemoveElementsAt(aStartIndex, chunksToRemove);
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mDuration -= aDuration - t;
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}
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nsTArray<Chunk> mChunks;
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#ifdef MOZILLA_INTERNAL_API
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mozilla::TimeStamp mTimeStamp;
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#endif
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};
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}
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#endif /* MOZILLA_MEDIASEGMENT_H_ */
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