converttointegraltypeoperator.h

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/********************************************************************************************
 * Twitch Broadcasting SDK
 *
 * This software is supplied under the terms of a license agreement with Twitch Interactive, Inc. and
 * may not be copied or used except in accordance with the terms of that agreement
 * Copyright (c) 2012-2017 Twitch Interactive, Inc.
 *
 *********************************************************************************************/

#pragma once

#include "twitchsdk/broadcast/internal/audioconvert/dsputilities.h"

namespace ttv
{
    template <typename InputSource, typename IntegralType, typename ContextType>
    class ConvertToIntegralTypeOperator
    {
    public:
        ConvertToIntegralTypeOperator(ContextType& context)
        :   mInputSource(context)
        {
        }
        
        using InputSampleType = typename InputSource::SampleType;
        static_assert(std::is_floating_point<InputSampleType>::value, "Input sample type must be floating point.");
        static_assert(std::is_integral<IntegralType>::value, "Output sample type must be integral.");
        static_assert(std::is_signed<IntegralType>::value, "Output sample type must be signed.");
        
        using SampleType = IntegralType;
        static constexpr size_t SampleRate = InputSource::SampleRate;
        
        
        InputSource& GetInputSource()
        {
            return mInputSource;
        }

        
        SampleRange GetSampleRange() const
        {
            return mInputSource.GetSampleRange();
        }

        
        SampleType operator[](size_t index) const
        {
            assert(index >= GetSampleRange().startIndex);
            assert(index < GetSampleRange().startIndex + GetSampleRange().sampleCount);

            InputSampleType inputSample = mInputSource[index];
            
            assert(inputSample <= 1.0);
            assert(inputSample >= -1.0);
            
            InputSampleType ditheredSample = ContextType::Options::Ditherer::DitherFloatValue(inputSample * static_cast<InputSampleType>(BisectRange<SampleType>()));
            
            // Make sure to clamp the upper end of integral types, since it can't be represented by an integer.
            ditheredSample = std::min(ditheredSample, static_cast<InputSampleType>(std::numeric_limits<SampleType>::max()));
            return static_cast<SampleType>(ditheredSample);
        }
        
    private:
        InputSource mInputSource;
    };
}