MediaSampleCache.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Containers/Array.h"
#include "Containers/LruCache.h"
#include "Containers/Set.h"
#include "CoreTypes.h"
#include "HAL/CriticalSection.h"
#include "IMediaAudioSample.h"
#include "IMediaBinarySample.h"
#include "IMediaOverlaySample.h"
#include "IMediaTextureSample.h"
#include "Math/RangeSet.h"
#include "Misc/Timespan.h"
#include "Templates/SharedPointer.h"
 
class IMediaAudioSample;
class IMediaBinarySample;
class IMediaOverlaySample;
class IMediaPlayer;
class IMediaSamples;
class IMediaTextureSample;
template <typename ElementType> class TRangeSet;
 
 
class FMediaSampleCache
{
    template<typename SampleType>
    struct TSampleKeyFuncs
        : BaseKeyFuncs<TSharedPtr<SampleType, ESPMode::ThreadSafe>, FTimespan, false>
    {
        static inline FTimespan GetSetKey(const TSharedPtr<SampleType, ESPMode::ThreadSafe>& Element)
        {
            return Element->GetTime().Time;
        }
 
        static inline bool Matches(FTimespan A, FTimespan B)
        {
            return A == B;
        }
 
        static inline uint32 GetKeyHash(FTimespan Key)
        {
            return GetTypeHash(Key);
        }
    };
 
    template<typename SampleType>
    using TSampleSet = TSet<TSharedPtr<SampleType, ESPMode::ThreadSafe>, TSampleKeyFuncs<SampleType>>;
 
public:
 
    MEDIAUTILS_API FMediaSampleCache();
 
public:
 
    MEDIAUTILS_API void Empty();
 
    MEDIAUTILS_API TSharedPtr<IMediaAudioSample, ESPMode::ThreadSafe> GetAudioSample(FTimespan Time);
 
    MEDIAUTILS_API void GetCachedAudioSampleRanges(TRangeSet<FTimespan>& OutTimeRanges) const;
 
    MEDIAUTILS_API void GetCachedVideoSampleRanges(TRangeSet<FTimespan>& OutTimeRanges) const;
 
    MEDIAUTILS_API void GetOverlaySamples(FTimespan Time, TArray<TSharedPtr<IMediaOverlaySample, ESPMode::ThreadSafe>>& OutSamples);
 
    MEDIAUTILS_API TSharedPtr<IMediaTextureSample, ESPMode::ThreadSafe> GetVideoSample(FTimespan Time, bool Forward);
 
    void SetCacheWindow(FTimespan Ahead, FTimespan Behind)
    {
        CacheAhead = Ahead;
        CacheBehind = Behind;
    }
 
    MEDIAUTILS_API void Tick(FTimespan DeltaTime, float Rate, FTimespan Time);
 
private:
 
    TSampleSet<IMediaAudioSample> AudioSamples;
 
    TSampleSet<IMediaBinarySample> MetadataSamples;
 
    TSampleSet<IMediaOverlaySample> OverlaySamples;
 
    TSampleSet<IMediaTextureSample> VideoSamples;
 
private:
 
    FTimespan CacheAhead;
 
    FTimespan CacheBehind;
 
    mutable FCriticalSection CriticalSection;
};