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make microphone AGC less aggressive and switchable

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Lower the gain ceiling and slow the attack of the automatic gain
control.
It amplified room noise between words hard enough to be audible as a
rising hiss whenever the speaker paused.

Add an AGC toggle on F12 and an /agc command.
AGC has always been applied unconditionally, which is wrong for a
microphone that is already levelled by hardware or by the system
mixer. The preference is saved and reapplied on connect, defaulting to
on so existing setups are unaffected.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Brandon McGinty
2026-08-20 14:42:52 -04:00
co-authored by Claude Opus 5
parent 17173b779b
commit cb4f91596e
6 changed files with 126 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files
audio/agc.go
+19 -17
View File
@@ -2,6 +2,7 @@ package audio
import (
"math"
"sync/atomic"
)
// AGC (Automatic Gain Control) processor for voice normalization
@@ -13,30 +14,31 @@ type AGC struct {
releaseTime float32 // Release time coefficient
currentGain float32 // Current gain value
envelope float32 // Signal envelope
enabled bool // Whether AGC is enabled
enabled atomic.Bool // Whether AGC is enabled; toggled outside the capture goroutine
compThreshold float32 // Compression threshold
compRatio float32 // Compression ratio
}
// NewAGC creates a new AGC processor with sensible defaults for voice
func NewAGC() *AGC {
return &AGC{
targetLevel: 0.18, // Target 18% of max amplitude (balanced level)
maxGain: 8.0, // Maximum 8x gain (about 18dB)
minGain: 0.1, // Minimum 0.1x gain (-20dB)
attackTime: 0.005, // Fast attack (5ms)
releaseTime: 0.1, // Slower release (100ms)
agc := &AGC{
targetLevel: 0.12, // Target 12% of max amplitude (conservative level)
maxGain: 4.0, // Maximum 4x gain (about 12dB)
minGain: 0.25, // Minimum 0.25x gain (-12dB)
attackTime: 0.008, // Fast attack (8ms)
releaseTime: 0.15, // Slower release (150ms)
currentGain: 1.0, // Start with unity gain
envelope: 0.0, // Start with zero envelope
enabled: true, // Enable by default
compThreshold: 0.7, // Compress signals above 70%
compRatio: 3.0, // 3:1 compression ratio
compThreshold: 0.85, // Compress signals above 85%
compRatio: 2.0, // 2:1 compression ratio (gentler)
}
agc.enabled.Store(true) // Enable by default
return agc
}
// ProcessSamples applies AGC processing to audio samples
func (agc *AGC) ProcessSamples(samples []int16) {
if !agc.enabled || len(samples) == 0 {
if !agc.enabled.Load() || len(samples) == 0 {
return
}
@@ -106,10 +108,10 @@ func (agc *AGC) ProcessSamples(samples []int16) {
}
// Soft limiting to prevent clipping
if processed > 0.90 {
processed = 0.90 + (processed-0.90)*0.1
} else if processed < -0.90 {
processed = -0.90 + (processed+0.90)*0.1
if processed > 0.95 {
processed = 0.95 + (processed-0.95)*0.2
} else if processed < -0.95 {
processed = -0.95 + (processed+0.95)*0.2
}
// Convert back to int16
@@ -125,12 +127,12 @@ func (agc *AGC) ProcessSamples(samples []int16) {
// SetEnabled enables or disables AGC processing
func (agc *AGC) SetEnabled(enabled bool) {
agc.enabled = enabled
agc.enabled.Store(enabled)
}
// IsEnabled returns whether AGC is enabled
func (agc *AGC) IsEnabled() bool {
return agc.enabled
return agc.enabled.Load()
}
// SetTargetLevel sets the target RMS level (0.0-1.0)
client.go
+1
View File
@@ -53,6 +53,7 @@ func (b *Barnard) connect(reconnect bool) bool {
b.Stream = stream
b.Stream.AttachStream(b.Client)
b.Stream.SetNoiseProcessor(b.NoiseSuppressor)
b.Stream.SetAGCEnabled(b.UserConfig.GetAGCEnabled())
// Initialize stereo encoder for file playback
b.Client.AudioEncoderStereo = opus.NewStereoEncoder()
config/hotkey_config.go
+1
View File
@@ -21,4 +21,5 @@ type Hotkeys struct {
ScrollToBottom *uiterm.Key
AdminMenu *uiterm.Key
NoiseSuppressionToggle *uiterm.Key
AGCToggle *uiterm.Key
}
config/user_config.go
+27
View File
@@ -31,6 +31,7 @@ type exportableConfig struct {
Username *string
NotifyCommand *string
NoiseSuppressionEnabled *bool
AGCEnabled *bool
Certificate *string
RecordingFormat *string
RecordingDirectory *string
@@ -109,6 +110,7 @@ func (c *Config) LoadConfig() {
ScrollToBottom: key(uiterm.KeyEnd),
AdminMenu: key(uiterm.KeyF11),
NoiseSuppressionToggle: key(uiterm.KeyF9),
AGCToggle: key(uiterm.KeyF12),
}
if fileExists(c.fn) {
var data []byte
@@ -155,6 +157,11 @@ func (c *Config) LoadConfig() {
enabled := false
jc.NoiseSuppressionEnabled = &enabled
}
if c.config.AGCEnabled == nil {
// AGC has always been active for the microphone, so keep it on by default.
enabled := true
jc.AGCEnabled = &enabled
}
if c.config.Certificate == nil {
cert := string("")
jc.Certificate = &cert
@@ -190,6 +197,7 @@ func (c *Config) ensureHotkeys() {
ScrollToBottom: key(uiterm.KeyEnd),
AdminMenu: key(uiterm.KeyF11),
NoiseSuppressionToggle: key(uiterm.KeyF9),
AGCToggle: key(uiterm.KeyF12),
}
hotkeys := c.config.Hotkeys
if hotkeys.Talk == nil {
@@ -240,6 +248,9 @@ func (c *Config) ensureHotkeys() {
if hotkeys.NoiseSuppressionToggle == nil {
hotkeys.NoiseSuppressionToggle = defaults.NoiseSuppressionToggle
}
if hotkeys.AGCToggle == nil {
hotkeys.AGCToggle = defaults.AGCToggle
}
}
func (c *Config) findServer(address string) *server {
@@ -356,6 +367,22 @@ func (c *Config) SetNoiseSuppressionEnabled(enabled bool) error {
return c.saveConfigLocked()
}
func (c *Config) GetAGCEnabled() bool {
c.mu.Lock()
defer c.mu.Unlock()
if c.config.AGCEnabled == nil {
return true
}
return *c.config.AGCEnabled
}
func (c *Config) SetAGCEnabled(enabled bool) error {
c.mu.Lock()
defer c.mu.Unlock()
c.config.AGCEnabled = &enabled
return c.saveConfigLocked()
}
func (c *Config) GetRecordingFormat() string {
c.mu.Lock()
defer c.mu.Unlock()
config/user_config_test.go
+32
View File
@@ -73,6 +73,38 @@ func TestConfigBackfillsRecordingDefaults(t *testing.T) {
t.Fatalf("expected scroll to bottom end, got %s", got)
}
}
func TestAGCDefaultsOnAndPersists(t *testing.T) {
configPath := filepath.Join(t.TempDir(), "barnard.toml")
if err := os.WriteFile(configPath, []byte("[hotkeys]\ntalk = \"f1\"\n"), 0600); err != nil {
t.Fatal(err)
}
cfg := NewConfig(&configPath)
if !cfg.GetAGCEnabled() {
t.Fatal("expected AGC to default to enabled")
}
if cfg.GetHotkeys().AGCToggle == nil {
t.Fatal("expected AGC toggle hotkey to be backfilled")
}
if got := *cfg.GetHotkeys().AGCToggle; got != uiterm.KeyF12 {
t.Fatalf("expected AGC toggle f12, got %s", got)
}
if err := cfg.SetAGCEnabled(false); err != nil {
t.Fatal(err)
}
reloaded := NewConfig(&configPath)
if reloaded.GetAGCEnabled() {
t.Fatal("expected disabled AGC setting to persist")
}
if got := *reloaded.GetHotkeys().AGCToggle; got != uiterm.KeyF12 {
t.Fatalf("expected saved AGC toggle to reload as f12, got %s", got)
}
}
// Regression: malformed and IPv6 addresses were split at every colon and
// could panic while merely reading a saved user preference.
func TestMakeHostPortHandlesIPv6AndMalformedAddress(t *testing.T) {
host, port := makeHostPort("[2001:db8::1]:64739")
if host != "2001:db8::1" || port != 64739 {
ui.go
+35
View File
@@ -111,6 +111,29 @@ func (b *Barnard) OnNoiseSuppressionToggle(ui *uiterm.Ui, key uiterm.Key) {
}
}
func (b *Barnard) OnAGCToggle(ui *uiterm.Ui, key uiterm.Key) {
enabled := b.toggleAGC()
if enabled {
b.UpdateGeneralStatus("AGC: ON", false)
} else {
b.UpdateGeneralStatus("AGC: OFF", false)
}
}
// toggleAGC flips the saved AGC preference and applies it to the active
// stream, returning the new state.
func (b *Barnard) toggleAGC() bool {
enabled := !b.UserConfig.GetAGCEnabled()
if err := b.UserConfig.SetAGCEnabled(enabled); err != nil {
b.AddOutputLine("AGC: could not save setting: " + err.Error())
}
if b.Stream != nil {
b.Stream.SetAGCEnabled(enabled)
}
return enabled
}
func (b *Barnard) UpdateGeneralStatus(text string, notice bool) {
b.statusText = text
b.statusNotice = notice
@@ -175,6 +198,14 @@ func (b *Barnard) CommandNoiseSuppressionToggle(ui *uiterm.Ui, cmd string) {
}
}
func (b *Barnard) CommandAGCToggle(ui *uiterm.Ui, cmd string) {
if b.toggleAGC() {
b.AddOutputLine("AGC enabled")
} else {
b.AddOutputLine("AGC disabled")
}
}
func (b *Barnard) CommandPlayFile(ui *uiterm.Ui, cmd string) {
// cmd contains just the filename part (everything after "/file ")
filename := strings.TrimSpace(cmd)
@@ -397,6 +428,8 @@ func (b *Barnard) OnTextInput(ui *uiterm.Ui, textbox *uiterm.Textbox, text strin
b.CommandStatus(ui, cmdArgs)
case "noise":
b.CommandNoiseSuppressionToggle(ui, cmdArgs)
case "agc":
b.CommandAGCToggle(ui, cmdArgs)
case "record":
b.CommandRecord(ui, cmdArgs)
case "admin":
@@ -493,6 +526,7 @@ func (b *Barnard) OnUiInitialize(ui *uiterm.Ui) {
b.Ui.AddCommandListener(b.CommandExit, "exit")
b.Ui.AddCommandListener(b.CommandStatus, "status")
b.Ui.AddCommandListener(b.CommandNoiseSuppressionToggle, "noise")
b.Ui.AddCommandListener(b.CommandAGCToggle, "agc")
b.Ui.AddCommandListener(b.CommandPlayFile, "file")
b.Ui.AddCommandListener(b.CommandStopFile, "stop")
b.Ui.AddCommandListener(b.CommandRecord, "record")
@@ -502,6 +536,7 @@ func (b *Barnard) OnUiInitialize(ui *uiterm.Ui) {
b.Ui.AddKeyListener(b.OnVoiceToggle, b.Hotkeys.Talk)
b.Ui.AddKeyListener(b.OnTimestampToggle, b.Hotkeys.ToggleTimestamps)
b.Ui.AddKeyListener(b.OnNoiseSuppressionToggle, b.Hotkeys.NoiseSuppressionToggle)
b.Ui.AddKeyListener(b.OnAGCToggle, b.Hotkeys.AGCToggle)
b.Ui.AddKeyListener(b.OnRecordingToggle, b.Hotkeys.RecordToggle)
b.Ui.AddKeyListener(b.OnQuitPress, b.Hotkeys.Exit)
b.Ui.AddKeyListener(b.OnScrollOutputUp, b.Hotkeys.ScrollUp)