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57 lines
2.1 KiB
C++
57 lines
2.1 KiB
C++
/*
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* All or portions of this file Copyright (c) Amazon.com, Inc. or its affiliates or
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* its licensors.
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*
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* For complete copyright and license terms please see the LICENSE at the root of this
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* distribution (the "License"). All use of this software is governed by the License,
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* or, if provided, by the license below or the license accompanying this file. Do not
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* remove or modify any license notices. This file is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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*
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*/
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#include "Microphone_precompiled.h"
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#include "SimpleDownsample.h"
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#include <cmath>
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AZStd::size_t GetDownsampleSize(AZStd::size_t sourceSize, AZ::u32 sourceSampleRate, AZ::u32 targetSampleRate)
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{
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return (AZStd::size_t)round((float)sourceSize / ((float)sourceSampleRate / (float)targetSampleRate));
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}
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void Downsample(AZ::s16* inBuffer, AZStd::size_t inBufferSize, AZ::u32 inBufferSampleRate,
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AZ::s16* outBuffer, AZStd::size_t outBufferSize, AZ::u32 outBufferSampleRate)
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{
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if(inBufferSampleRate == outBufferSampleRate)
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{
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return; // nothing to do here!
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}
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if(inBufferSampleRate < outBufferSampleRate)
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{
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AZ_Error("SimpleDownsample", false, "Out buffer sample rate is higher than in buffer sample rate, must be lower");
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return;
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}
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float sampleRateRatio = (float)inBufferSampleRate / (float)outBufferSampleRate;
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AZStd::size_t offsetResult = 0;
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AZStd::size_t offsetBuffer = 0;
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while(offsetResult < outBufferSize)
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{
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AZStd::size_t nextOffsetBuffer = static_cast<AZStd::size_t>(round((float)(offsetResult + 1) * sampleRateRatio));
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AZ::s32 accum = 0; // this must be int 32 so it doesn't overflow with multiple int 16's possibly at max
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AZStd::size_t count = 0;
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for(AZStd::size_t i = offsetBuffer; i < nextOffsetBuffer && i < inBufferSize; ++i)
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{
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accum += inBuffer[i];
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count++;
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}
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// do the math in floating point then convert to signed 16
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outBuffer[offsetResult] = (AZ::s16)((float)accum / (float)count);
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offsetResult++;
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offsetBuffer = nextOffsetBuffer;
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}
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}
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