resample

README

Resample

resample

Package and a cli tool for audio data resampling.

Work in progress, README will be updated in the future.

Documentation

Overview

Example (ResamplingFile)

package main

import (
	"gitlab.com/gunter-go/resample"
	"io"
	"os"
)

func main() {
	input, _ := os.Open("./original.raw")
	output, _ := os.Create("./resampled.raw")

	res, _ := resample.New(output, resample.FormatInt16, 48000, 16000, 2)
	_, _ = io.Copy(res, input)
}

Example (ResamplingSlice)

package main

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"gitlab.com/gunter-go/resample"
)

func main() {
	// Convert slice of values into a slice of bytes
	input := []int16{1, 3, 5}
	inputData := new(bytes.Buffer)
	_ = binary.Write(inputData, binary.LittleEndian, input)

	// Resample
	outBuf := new(bytes.Buffer)
	res, _ := resample.New(outBuf, resample.FormatInt16, 1, 2, 1, resample.WithLinearFilter())
	_, _ = res.Write(inputData.Bytes())

	// Convert bytes back to a slice of values
	output := make([]int16, 5)
	_ = binary.Read(outBuf, binary.LittleEndian, output)

	fmt.Println(output)

}

Output:

[1 2 3 4 5]

Index

• type Format
• type Option
  • func WithKaiserBestFilter() Option
  • func WithKaiserFastFilter() Option
  • func WithKaiserFastestFilter() Option
  • func WithLinearFilter() Option
  • func WithNoMemoization() Option
• type Resampler
  • func New(outBuffer io.Writer, format Format, inRate, outRate, ch int, options ...Option) (*Resampler, error)
  • func (r *Resampler) ReadFrom(reader io.Reader) (int64, error)
  • func (r *Resampler) Write(input []byte) (int, error)

Examples

• Package (ResamplingFile)
• Package (ResamplingSlice)

Types

type Format

type Format int

const (
	FormatInt16 Format = iota
	FormatInt32
	FormatInt64
	FormatFloat32
	FormatFloat64
)

type Option

type Option struct {
	// contains filtered or unexported fields
}

Option is a struct used to configure Resampler.

func WithKaiserBestFilter

func WithKaiserBestFilter() Option

WithKaiserBestFilter function returns option that configures Resampler to use the fastest Kaiser filter.

Used by default.

func WithKaiserFastFilter

func WithKaiserFastFilter() Option

WithKaiserFastFilter function returns option that configures Resampler to use the best Kaiser filter.

Best Kaiser filter provides higher resampling speed in exchange for lower quality.

func WithKaiserFastestFilter

func WithKaiserFastestFilter() Option

WithKaiserFastestFilter function returns option that configures Resampler to use the fast Kaiser filter.

Fastest Kaiser filter provides higher resampling speed in exchange for lower quality.

func WithLinearFilter

func WithLinearFilter() Option

WithLinearFilter function returns option that configures Resampler to use linear filter.

This option should be used only for testing purposes because linear filter provides poor resampling quality.

func WithNoMemoization

func WithNoMemoization() Option

WithNoMemoization function returns option that disables memoization in Resampler.

This option should be used when Resampler consumers too much memory. Such behaviour may occur when resampling between sampling rages with a small greatest common divisor (e.g. 9999 and 10000).

Enabling this function slows the resampling progress significantly. Therefore, Most users should avoid it and should switch used filter instead.

type Resampler

type Resampler struct {
	// contains filtered or unexported fields
}

A Resampler is an object that writes resampled data into an io.Writer.

func New

func New(outBuffer io.Writer, format Format, inRate, outRate, ch int,
	options ...Option) (*Resampler, error)

New creates a new Resampler.

Default filter is kaiser fast filter, use WithXFilter options to change it. Memoization is enabled by default, use WithNoMemoization function to disable it.

func (*Resampler) ReadFrom

func (r *Resampler) ReadFrom(reader io.Reader) (int64, error)

func (*Resampler) Write

func (r *Resampler) Write(input []byte) (int, error)