main.go

package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"os/exec"
)

func main() {
	var err error
	if err = run(os.Args); err != nil {
		log.Fatal(err)
	}
	fmt.Println("done")
}

func run(args []string) (err error) {
	var count int
	var input string = args[1]
	var output string

	for {
		count++
		output = fmt.Sprintf("rec-%v-%v", count, input)

		ctx, cancel := context.WithCancel(context.Background())
		cmd1 := exec.CommandContext(ctx, "play", input)
		cmd2 := exec.CommandContext(ctx, "rec", output)

		go func() {
			cmd1.Run()
			cancel()
		}()
		go cmd2.Run()
		_ = <-ctx.Done()

		cmd3 := exec.Command("play", "-m", input, output)
		cmd3.Run()
	}
	return
}