Add outgoing audio packet interval option

README.md

@@ -140,6 +140,20 @@ If you modify the config file while Barnard is running, your changes may be over
 You can set username and defaultserver in your config file, and they will be used if none is specified when launching barnard.
 (Note that the default username (an empty string) and the default server name (localhost:64738) have been the defaults for barnard up to this  point, and have been left that way for compatibility.)
 
+## Audio Packet Duration
+
+Barnard sends 10 ms audio packets by default. On a slow or unstable connection,
+using larger packets can reduce packet overhead and make short dropouts less
+noticeable, at the cost of additional voice latency. Start Barnard with one of
+the supported durations:
+
+```sh
+barnard --audio-interval 20
+```
+
+Supported values are `10`, `20`, `40`, and `60` milliseconds. Try `20` ms
+first; use `40` ms only if the connection remains unreliable.
+
 ## Audio Devices
 
 You can set the default input and output devices in the config file as well.

client_notification_test.go

@@ -70,6 +70,22 @@ func TestNotificationExpansionIsSinglePassAndNotifyDoesNotBlock(t *testing.T) {
 	}
 }
 
+func TestAudioIntervalDuration(t *testing.T) {
+	for _, milliseconds := range []int{10, 20, 40, 60} {
+		got, err := audioIntervalDuration(milliseconds)
+		if err != nil {
+			t.Errorf("audioIntervalDuration(%d): %v", milliseconds, err)
+			continue
+		}
+		if got != time.Duration(milliseconds)*time.Millisecond {
+			t.Errorf("audioIntervalDuration(%d) = %v", milliseconds, got)
+		}
+	}
+	if _, err := audioIntervalDuration(30); err == nil {
+		t.Fatal("audioIntervalDuration accepted unsupported duration")
+	}
+}
+
 func TestServerAddressDefaultsPortWithoutBreakingIPv6(t *testing.T) {
 	for input, want := range map[string]string{
 		"server":          "server:64738",

main.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"os"
 	"strings"
+	"time"
 
 	barnlog "git.stormux.org/storm/barnard/log"
 
@@ -84,6 +85,7 @@ func main() {
 	configSet := false
 	certificateSet := false
 	buffers := flag.Int("buffers", 16, "number of audio buffers to use")
+	audioInterval := flag.Int("audio-interval", 10, "outgoing audio packet duration in ms (10, 20, 40, or 60)")
 	profile := flag.Bool("profile", false, "add http server to serve profiles")
 	noiseSuppressionEnabled := flag.Bool("noise-suppression", false, "enable noise suppression for microphone input")
 	autoTransmit := flag.Bool("auto-transmit", false, "start transmitting immediately on connect")
@@ -94,6 +96,10 @@ func main() {
 	logFile := flag.String("logfile", "", "write logs to this file (logging is disabled when omitted)")
 
 	flag.Parse()
+	selectedAudioInterval, err := audioIntervalDuration(*audioInterval)
+	if err != nil {
+		handle_raw_error(err)
+	}
 
 	// Set up logging
 	var level barnlog.Level
@@ -192,6 +198,7 @@ func main() {
 		NoiseSuppressor: noise.NewSuppressor(),
 	}
 	b.Config.Buffers = *buffers
+	b.Config.AudioInterval = selectedAudioInterval
 	b.Config.DisableUDP = *tcpOnly
 
 	b.Hotkeys = b.UserConfig.GetHotkeys()
@@ -238,6 +245,18 @@ func main() {
 	handle_error(&b)
 }
 
+// audioIntervalDuration converts the packet duration requested at startup to
+// one of the Opus durations supported by Mumble.
+func audioIntervalDuration(milliseconds int) (time.Duration, error) {
+	interval := time.Duration(milliseconds) * time.Millisecond
+	switch interval {
+	case 10 * time.Millisecond, 20 * time.Millisecond, 40 * time.Millisecond, 60 * time.Millisecond:
+		return interval, nil
+	default:
+		return 0, fmt.Errorf("audio interval must be 10, 20, 40, or 60 ms, got %d", milliseconds)
+	}
+}
+
 // serverAddress adds Mumble's default port without corrupting an IPv6 literal.
 func serverAddress(address string) string {
 	if _, port, err := net.SplitHostPort(address); err == nil && port != "" {