#include <VectorLinearResampler.h>

Public Attributes
uint32	CurrentFrameFraction

Detailed Description

    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;//<data from elsewhere>; 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; }

Member Function Documentation

◆ ResampleMono()

uint32 Audio::FVectorLinearResampler::ResampleMono	(	uint32	OutputFramesNeeded,
		uint32	FixedPointSampleRate,
		float const *	SourceFrames,
		float *	OutputFrames
	)

◆ ResampleStereo()

uint32 Audio::FVectorLinearResampler::ResampleStereo	(	uint32	OutputFramesNeeded,
		uint32	FixedPointSampleRate,
		float const *	SourceFrames,
		uint32	SourceFramesStrideFloats,
		float *	OutputFrames,
		uint32	OutputFramesStrideFloats
	)

◆ SourceFramesNeeded()

uint32 Audio::FVectorLinearResampler::SourceFramesNeeded	(	uint32	OutputFramesNeeded,
		uint32	FixedPointSampleRate
	)

inline

Member Data Documentation

◆ CurrentFrameFraction

uint32 Audio::FVectorLinearResampler::CurrentFrameFraction

The documentation for this struct was generated from the following files:

Engine/Source/Runtime/SignalProcessing/Public/DSP/VectorLinearResampler.h
Engine/Source/Runtime/SignalProcessing/Private/VectorLinearResampler.cpp

Public Member Functions
uint32	SourceFramesNeeded (uint32 OutputFramesNeeded, uint32 FixedPointSampleRate)

SIGNALPROCESSING_API uint32	ResampleMono (uint32 OutputFramesNeeded, uint32 FixedPointSampleRate, float const SourceFrames, float OutputFrames)

SIGNALPROCESSING_API uint32	ResampleStereo (uint32 OutputFramesNeeded, uint32 FixedPointSampleRate, float const SourceFrames, uint32 SourceFramesStrideFloats, float OutputFrames, uint32 OutputFramesStrideFloats)

Public Member Functions