OpusAudioInfo.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    OpusAudioInfo.h: Unreal audio opus decompression interface object.
=============================================================================*/
 
#pragma once
 
#include "CoreMinimal.h"
#include "AudioDecompress.h"
 
struct FOpusDecoderWrapper;
struct FSoundQualityInfo;
 
class FOpusAudioInfo : public IStreamedCompressedInfo
{
public:
    OPUSAUDIODECODER_API FOpusAudioInfo();
    OPUSAUDIODECODER_API virtual ~FOpusAudioInfo();
    //~ Begin IStreamedCompressedInfo Interface
    bool ParseHeader(const uint8* InSrcBufferData, uint32 InSrcBufferDataSize, FSoundQualityInfo* QualityInfo) override;
    int32 GetFrameSize() override;
    uint32 GetMaxFrameSizeSamples() const override;
    bool CreateDecoder() override;
    FDecodeResult Decode(const uint8* CompressedData, const int32 CompressedDataSize, uint8* OutPCMData, const int32 OutputPCMDataSize) override;
    void PrepareToLoop() override;
    void SeekToTime(const float SeekTime) override;
    void SeekToFrame(const uint32 SeekFrame) override;
    //~ End IStreamedCompressedInfo Interface
    struct FHeader
    {
        char Identifier[8];
        uint8 Version = 0;
        uint8 NumChannels = 0;
        uint32 SampleRate = 0;
        uint32 EncodedSampleRate = 0;
        uint64 ActiveSampleCount = 0;
        uint32 NumEncodedFrames = 0;
        int32 NumPreSkipSamples = 0;
        int32 NumSilentSamplesAtBeginning = 0;
        int32 NumSilentSamplesAtEnd = 0;
 
        void Reset()
        {
            FMemory::Memzero(Identifier);
            Version = 0;
            NumChannels = 0;
            SampleRate = 0;
            EncodedSampleRate = 0;
            ActiveSampleCount = 0;
            NumEncodedFrames = 0;
            NumPreSkipSamples = 0;
            NumSilentSamplesAtBeginning = 0;
            NumSilentSamplesAtEnd = 0;
        }
 
        static inline const char OPUS_ID[8] {'U','E','O','P','U','S','\0','\0'};
        static constexpr int32 HeaderSize()
        {
            return
                  sizeof(char)*8    // Identifier
                + sizeof(uint8)     // Version
                + sizeof(uint8)     // NumChannels
                + sizeof(uint32)    // SampleRate
                + sizeof(uint32)    // EncodedSampleRate
                + sizeof(uint64)    // ActiveSampleCount
                + sizeof(uint32)    // NumEncodedFrames
                + sizeof(int32)     // NumPreSkipSamples
                + sizeof(int32)     // NumSilentSamplesAtBeginning
                + sizeof(int32);    // NumSilentSamplesAtEnd
        }
    };
    static OPUSAUDIODECODER_API bool ParseHeader(FHeader& OutHeader, uint32& OutNumRead, const uint8* InSrcBufferData, uint32 InSrcBufferDataSize);
protected:
    FOpusDecoderWrapper* OpusDecoderWrapper;
 
    FHeader Header;
    
    int32 NumRemainingSamplesToSkip = 0;
 
    TArray<uint8> PreviousDecodedUnusedSamples;
};