You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
51 lines
1.7 KiB
C++
51 lines
1.7 KiB
C++
/*
|
|
* Copyright (c) Contributors to the Open 3D Engine Project.
|
|
* For complete copyright and license terms please see the LICENSE at the root of this distribution.
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0 OR MIT
|
|
*
|
|
*/
|
|
|
|
#include "SimpleDownsample.h"
|
|
|
|
#include <cmath>
|
|
|
|
size_t GetDownsampleSize(size_t sourceSize, AZ::u32 sourceSampleRate, AZ::u32 targetSampleRate)
|
|
{
|
|
return (size_t)round((float)sourceSize / ((float)sourceSampleRate / (float)targetSampleRate));
|
|
}
|
|
|
|
void Downsample(AZ::s16* inBuffer, size_t inBufferSize, AZ::u32 inBufferSampleRate,
|
|
AZ::s16* outBuffer, size_t outBufferSize, AZ::u32 outBufferSampleRate)
|
|
{
|
|
if(inBufferSampleRate == outBufferSampleRate)
|
|
{
|
|
return; // nothing to do here!
|
|
}
|
|
|
|
if(inBufferSampleRate < outBufferSampleRate)
|
|
{
|
|
AZ_Error("SimpleDownsample", false, "Out buffer sample rate is higher than in buffer sample rate, must be lower");
|
|
return;
|
|
}
|
|
|
|
float sampleRateRatio = (float)inBufferSampleRate / (float)outBufferSampleRate;
|
|
size_t offsetResult = 0;
|
|
size_t offsetBuffer = 0;
|
|
while(offsetResult < outBufferSize)
|
|
{
|
|
size_t nextOffsetBuffer = static_cast<size_t>(round((float)(offsetResult + 1) * sampleRateRatio));
|
|
AZ::s32 accum = 0; // this must be int 32 so it doesn't overflow with multiple int 16's possibly at max
|
|
size_t count = 0;
|
|
for(size_t i = offsetBuffer; i < nextOffsetBuffer && i < inBufferSize; ++i)
|
|
{
|
|
accum += inBuffer[i];
|
|
count++;
|
|
}
|
|
// do the math in floating point then convert to signed 16
|
|
outBuffer[offsetResult] = (AZ::s16)((float)accum / (float)count);
|
|
offsetResult++;
|
|
offsetBuffer = nextOffsetBuffer;
|
|
}
|
|
}
|