transcode.go

package main

import "io"
import "os"
import "os/exec"
import "log"
import "net/http"

const TRANSCODER_FORMAT = "mp3"

func StreamTranscodeM4aToMp3(url string, writer http.ResponseWriter) {

	headers := writer.Header()
	headers.Add("Content-Type", "audio/"+TRANSCODER_FORMAT)

	cmd := exec.Command("ffmpeg", "-i", "-", "-f", TRANSCODER_FORMAT, "-")

	stdin, err := cmd.StdinPipe()
	stdout, err := cmd.StdoutPipe()

	resp, _ := http.Get(url)

	ch := make(chan bool)

	defer stdin.Close()
	defer stdout.Close()
	defer close(ch)

	go func(die chan bool) {
		io.Copy(writer, stdout)
	}(ch)

	go func(die chan bool) {
		io.Copy(stdin, resp.Body)
		cmd.Wait()
	}(ch)

	if err != nil {
		log.Fatal(err)
	}
	if err := cmd.Run(); err != nil {
		log.Fatal(err)
	}
}