FVectorLinearResampler

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FVectorLinearResampler

Performs a basic linear resampling using SIMD for optimization.

Advancing is done in fixed point - 65536 is a 1.0f sample rate.

Stereo requires a deinterleaved format.

The design is based on a "pull" model, assuming you need to fill a buffer from a source, rather than computing how much output you would need to resample a given input. If you need to do that, just run the resampler in chunks until you drain the input, appending to the output as you go.

Usage: FVectorLinearResample Resampler = {};

uint32 FixedSampleRate = (uint32)(1.0f * 65536);

/ the example source buffer is assumed to be stereo deinterleaved with the / right channel directly after the left. float* SourceFrames = 0;//; uint32 SourceBufferFrameCount = 0;//<# of frames - i.e.len(SourceFrames) / (sizeof(float) * 2) since stereo>; uint32 SourceBufferFloatsToRightChannel = SourceBufferFrameCount; // right channel directly after the left

const uint32 OutputChunkFrames = 512; while (SourceBufferFrameCount) { / stereo output chunk. Or pointer to wherever you're mixing to. float OutputFrames[OutputChunkFrames * 2];

/ find out how much input we need for the resampler to be able to generate / our chunk. uint32 SourceFramesNeeded = Resampler.SourceFramesNeeded(OutputChunkFrames, FixedSampleRate);

/ make sure we have that available. if (SourceFramesNeeded <= SourceBufferFrameCount) { / direct resample uint32 SourceFramesConsumed = Resampler.ResampleStereo(OutputChunkFrames, FixedSampleRate, SourceFrames, SourceBufferFloatsToRightChannel, OutputFrames, OutputChunkFrames);

do something with output_frames

/ advance the input SourceFrames += SourceFramesConsumed; SourceBufferFrameCount -= SourceFramesConsumed; continue; }

/ here we need to append zeroes as we don't have enough input to fill. / usually need a temp buffer unless you can make dramatic assumptions about / your source buffer. float* TempSource = FMemory::Malloc(sizeof(float) * 2 * SourceFramesNeeded); float* TempSourceLeft = TempSource; float* TempSourceRight = TempSource + SourceFramesNeeded;

uint32 ZeroedFramesNeeded = SourceFramesNeeded - SourceBufferFrameCount;

/ left FMemory::Memcpy(TempSourceLeft, SourceFrames, SourceBufferFrameCount * sizeof(float));

/ left tail FMemory::Memset(TempSourceLeft + SourceBufferFrameCount, 0, ZeroedFramesNeeded * sizeof(float));

/ right FMemory::Memcpy(TempSourceRight, SourceFrames + SourceBufferFloatsToRightChannel, SourceBufferFrameCount * sizeof(float));

/ right tail FMemory::Memset(TempSourceRight + SourceBufferFrameCount, 0, ZeroedFramesNeeded * sizeof(float));

Resampler.ResampleStereo(OutputChunkFrames, FixedSampleRate, TempSource, SourceFramesNeeded, OutputFrames, OutputChunkFrames);

FMemory::Free(TempSource);

SourceBufferFrameCount = 0; }

Syntax

struct FVectorLinearResampler  
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struct FVectorLinearResampler

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