av/cmd/audio-player/looper/pi0.go

// +build pi0

package main

import (
	"os/exec"
	"time"

	"bitbucket.org/ausocean/utils/logger"
)

const audioCmd = "play"

func initCommand(log *logger.Logger) {
	const soundcardPath = "/usr/share/doc/audioInjector/asound.state.RCA.thru.test"
	const sleepDur = 1 * time.Second

	// alsactl is a command that ensures the sound will be played through the correct soundcard.
	path, err := exec.LookPath("alsactl")
	if err != nil {
		log.Log(logger.Fatal, "didn't find 'alsactl' executable")
	}
	log.Log(logger.Debug, "'alsactl' executable path", "path", path)

	for {
		cmdInit := exec.Command("alsactl", "-f", soundcardPath, "restore")
		err := cmdInit.Run()
		if err == nil {
			break
		}
		log.Log(logger.Warning, "cmd.Run() for 'alsactl' failed", "error", err.Error())
		time.Sleep(sleepDur)
	}

	// Making sure that play command is on the pi.
	path, err = exec.LookPath(audioCmd)
	if err != nil {
		log.Log(logger.Fatal, "didn't find 'play' executable")
	}
	log.Log(logger.Debug, "'play' executable path", "path", path)
}