Slice buffer on last frame

aio_test.go

@@ -182,7 +182,7 @@ func TestAudioBuffer(t *testing.T) {
 	// buffer[0:10] = [209 252 172 253 82 255 5 0 94 0]
 	buffer := audio.Buffer()
 
-	assertEquals(len(buffer), audio.SampleRate()*audio.Channels()*audio.BitsPerSample()/8)
+	assertEquals(len(buffer), 512)
 	assertEquals(buffer[0], byte(209))
 	assertEquals(buffer[1], byte(252))
 	assertEquals(buffer[2], byte(172))
@@ -212,6 +212,8 @@ func TestAudioPlayback(t *testing.T) {
 	}
 	defer player.Close()
 
+	audio.SetBuffer(make([]byte, audio.Total()*4))
+
 	for audio.Read() {
 		player.Play(audio.Buffer())
 	}
@@ -236,11 +238,9 @@ func TestAudioCopying(t *testing.T) {
 		panic(err2)
 	}
 
-	data := make([]int16, audio.SampleRate()*audio.Channels()*audio.BitsPerSample()/8/2)
 	for audio.Read() {
 		samples := audio.Samples().([]int16)
-		copy(data, samples)
-		writer.Write(data)
+		writer.Write(samples)
 	}
 
 	defer writer.Close()

audio.go

@@ -21,6 +21,7 @@ type Audio struct {
 	codec      string            // Codec used for video encoding.
 	bps        int               // Bits per sample.
 	stream     int               // Stream Index.
+	ended      bool              // Flag storing whether Audio reading has ended.
 	buffer     []byte            // Raw audio data.
 	metadata   map[string]string // Audio Metadata.
 	pipe       *io.ReadCloser    // Stdout pipe for ffmpeg process.
@@ -229,6 +230,7 @@ func (audio *Audio) init() error {
 		return err
 	}
 	audio.pipe = &pipe
+
 	if err := cmd.Start(); err != nil {
 		return err
 	}
@@ -240,9 +242,13 @@ func (audio *Audio) init() error {
 	return nil
 }
 
-// Reads the next frame from of audio and stores it in the buffer.
-// If the last frame has been read, returns false, otherwise true.
+// Reads the next frame of audio and stores it in the buffer.
+// If the last audio frame has been read, returns false, otherwise true.
 func (audio *Audio) Read() bool {
+	if audio.ended {
+		return false
+	}
+
 	// If cmd is nil, video reading has not been initialized.
 	if audio.cmd == nil {
 		if err := audio.init(); err != nil {
@@ -253,18 +259,23 @@ func (audio *Audio) Read() bool {
 	total := 0
 	for total < len(audio.buffer) {
 		n, err := (*audio.pipe).Read(audio.buffer[total:])
+		total += n
 		if err == io.EOF {
+			// When the user reaches the end of the audio stream, the buffer will have to be shortened
+			// such that the audio stream is accurately represented.
+			// The rest of this sliced array is not garbage collected.
+			audio.buffer = audio.buffer[:total]
 			audio.Close()
-			return false
+			break
 		}
-		total += n
 	}
 
 	return true
 }
 
 // Closes the pipe and stops the ffmpeg process.
 func (audio *Audio) Close() {
+	audio.ended = true
 	if audio.pipe != nil {
 		(*audio.pipe).Close()
 	}

audiowriter.go

@@ -178,6 +178,7 @@ func (writer *AudioWriter) Write(samples interface{}) error {
 			return err
 		}
 	}
+
 	total := 0
 	for total < len(buffer) {
 		n, err := (*writer.pipe).Write(buffer[total:])
@@ -186,6 +187,7 @@ func (writer *AudioWriter) Write(samples interface{}) error {
 		}
 		total += n
 	}
+
 	return nil
 }
 

microphone.go

@@ -243,11 +243,13 @@ func (mic *Microphone) Read() bool {
 			return false
 		}
 	}
+
 	total := 0
 	for total < len(mic.buffer) {
 		n, _ := (*mic.pipe).Read(mic.buffer[total:])
 		total += n
 	}
+
 	return true
 }
 

utils.go

@@ -31,13 +31,11 @@ func exists(filename string) bool {
 // Checks if the given program is installed.
 func installed(program string) error {
 	cmd := exec.Command(program, "-version")
-	errmsg := fmt.Errorf("%s is not installed", program)
-	if err := cmd.Start(); err != nil {
-		return errmsg
-	}
-	if err := cmd.Wait(); err != nil {
-		return errmsg
+
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("%s is not installed", program)
 	}
+
 	return nil
 }
 
@@ -164,6 +162,7 @@ func parseDevices(buffer string) []string {
 			devices = append(devices, pair.name)
 		}
 	}
+
 	return devices
 }
 
@@ -176,16 +175,6 @@ func contains(list []string, item string) bool {
 	return false
 }
 
-// Check audio format string.
-func checkFormat(format string) error {
-	match := regexp.MustCompile(`^(([us]8)|([us]((16)|(24)|(32))[bl]e)|(f((32)|(64))[bl]e))$`)
-	if len(match.FindString(format)) == 0 {
-		formats := "u8, s8, u16, s16, u24, s24, u32, s32, f32, or f64"
-		return fmt.Errorf("audio format %s is not supported, must be one of %s", format[:len(format)-2], formats)
-	}
-	return nil
-}
-
 // Returns the microphone device name.
 // On windows, ffmpeg output from the -list_devices command is parsed to find the device name.
 func getDevicesWindows() ([]string, error) {
@@ -197,10 +186,13 @@ func getDevicesWindows() ([]string, error) {
 		"-f", "dshow",
 		"-i", "dummy",
 	)
+
 	pipe, err := cmd.StderrPipe()
 	if err != nil {
 		return nil, err
 	}
+
+	// Start the command and immediately continue so that the pipe can be read.
 	if err := cmd.Start(); err != nil {
 		return nil, err
 	}
@@ -216,12 +208,23 @@ func getDevicesWindows() ([]string, error) {
 		}
 	}
 
+	// Wait for the command to finish.
 	cmd.Wait()
 
 	devices := parseDevices(builder.String())
 	return devices, nil
 }
 
+// Check audio format string.
+func checkFormat(format string) error {
+	match := regexp.MustCompile(`^(([us]8)|([us]((16)|(24)|(32))[bl]e)|(f((32)|(64))[bl]e))$`)
+	if len(match.FindString(format)) == 0 {
+		formats := "u8, s8, u16, s16, u24, s24, u32, s32, f32, or f64"
+		return fmt.Errorf("audio format %s is not supported, must be one of %s", format[:len(format)-2], formats)
+	}
+	return nil
+}
+
 func createFormat(format string) string {
 	switch format {
 	case "u8", "s8":