Golang : Play .WAV file from command line

Problem:

You have recorded your voice on a .wav file with the previous tutorial on how to activate your microphone, record your voice and save the data into a .wav file from command line.

Now, you want to play back the .wav file from command line.

How to do that?

Solution:

The approach is similar to how the voice in recorded with PlayAudio and encode with wave.Write() function with the exception that this time is to read the .wav file with wave.NewReader() first.

Read the raw data with waveReader.ReadRawSample() and transfer the data into a buffer before writing out to PortAudio.

Here you go!

playwav.go

 package main

 import (
 "fmt"
 "github.com/gordonklaus/portaudio"
 wave "github.com/zenwerk/go-wave"
 "math/rand"
 "os"
 "os/signal"
 "time"
 )

 func errCheck(err error) {

 if err != nil {
 panic(err)
 }
 }

 func main() {

 if len(os.Args) != 2 {
 fmt.Printf("Usage : %s <audiofilename.wav>\n", os.Args[0])
 os.Exit(0)
 }

 audioFileName := os.Args[1]

 fmt.Println("Playing [" + audioFileName + "] Press Ctrl-C to stop.")

 waveReader, err := wave.NewReader(audioFileName)
 errCheck(err)

 // init PortAudio
 portaudio.Initialize()
 defer portaudio.Terminate()

 inputChannels := 0
 outputChannels := 1
 sampleRate := 44100
 framesPerBuffer := make([]byte, 1024)

 stream, err := portaudio.OpenDefaultStream(inputChannels, outputChannels, float64(sampleRate), len(framesPerBuffer), &framesPerBuffer)
 errCheck(err)
 defer stream.Close()

 // recording in progress ticker. From good old DOS days.
 ticker := []string{
 "-",
 "\\",
 "/",
 "|",
 }
 rand.Seed(time.Now().UnixNano())

 errCheck(stream.Start())
 defer stream.Stop()

 sig := make(chan os.Signal, 1)
 signal.Notify(sig, os.Interrupt, os.Kill)

 READERROR:
 for {
 // read into buffer to be played
 //_, err := waveReader.Read(framesPerBuffer)
 framesPerBuffer, err = waveReader.ReadRawSample()

 if err != nil {
 fmt.Println(err.Error())
 break READERROR
 }
 errCheck(stream.Write())
 fmt.Printf("\rPlaying now! [%v]", ticker[rand.Intn(len(ticker)-1)])
 select {
 case <-sig:
 return
 default:
 }

 }

 if waveReader.NumSamples != waveReader.ReadSampleNum {
 fmt.Printf("Actual samples : %d\nRead samples : %d\n", waveReader.NumSamples, waveReader.ReadSampleNum)
 fmt.Println(waveReader.NumSamples, waveReader.ReadSampleNum)
 } else {
 fmt.Println("Wave file played without error")

 }

 }

References:

https://github.com/zenwerk/go-wave/blob/master/reader.go

http://people.csail.mit.edu/hubert/pyaudio/

https://socketloop.com/tutorials/golang-record-voice-audio-from-microphone-to-wav-file