Split audio files into constant-length chunks

main.go

package main

import (
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"

	"github.com/unixpickle/essentials"
	"github.com/unixpickle/ffmpego"
)

const (
	SampleRate = 16000
	ChunkSize  = SampleRate * 15
	ChunkMin   = SampleRate * 4
)

func main() {
	if len(os.Args) < 3 {
		fmt.Fprintln(os.Stderr, "Usage: splitaudio <input> [input ...] <output dir>")
		os.Exit(1)
	}
	inputs := os.Args[1 : len(os.Args)-1]
	outputDir := os.Args[len(os.Args)-1]

	chunkIdx := 0
	for _, file := range inputs {
		log.Println("Splitting up", file)
		SplitFile(file, outputDir, &chunkIdx)
	}
}

func SplitFile(path, outputDir string, chunkIdx *int) {
	ar, err := ffmpego.NewAudioReaderResampled(path, SampleRate)
	essentials.Must(err)
	defer ar.Close()

	for {
		chunk := make([]float64, ChunkSize)
		n, err := ar.ReadSamples(chunk)
		if n > ChunkMin {
			*chunkIdx += 1
			name := fmt.Sprintf("chunk_%06d.flac", *chunkIdx)
			aw, err := ffmpego.NewAudioWriter(filepath.Join(outputDir, name), SampleRate)
			essentials.Must(err)
			essentials.Must(aw.WriteSamples(chunk))
			aw.Close()
		}
		if err == io.EOF {
			break
		}
		essentials.Must(err)
	}
}