fix(linux): port audio engine 2.0 (stereo+eq) to linux

cmd/tui/model.go

@@ -102,7 +102,15 @@ type Model struct {
 	playbackVol      int       // 0-100
 	micLevel         int       // 0-100 (current input level)
 	isMuted          bool      // Mic muted
-	isPTT         bool // Push-to-talk active
+	isPTT            bool      // Push-to-talk active (Manual TX)
+	vadEnabled       bool      // Voice Activation Detection active
+	vadThreshold     int       // 0-100 threshold for VAD
+	vadLastTriggered time.Time // Last time VAD threshold was exceeded
+
+	// Popup State
+	showPokePopup    bool
+	pokePopupSender  string
+	pokePopupMessage string
 
 	// Program reference for sending messages from event handlers
 	program *tea.Program
@@ -112,6 +120,9 @@ type Model struct {
 	showUserView bool
 	viewUser     *UserNode
 	pokeID       uint16 // Target ID for pending poke
+
+	// Interactive EQ
+	eqBandIdx int // 0-4
 }
 
 // addLog adds a message to the log panel
@@ -135,6 +146,8 @@ func NewModel(serverAddr, nickname string) *Model {
 		logMessages:    []string{"Starting..."},
 		talkingClients: make(map[uint16]bool),
 		playbackVol:    80, // Default 80% volume
+		vadEnabled:     true,
+		vadThreshold:   50,
 	}
 }
 
@@ -294,16 +307,53 @@ func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		} else {
 			m.audioCapturer = capturer
 			// Set callback to send audio to server when PTT is active
+			// Set callback to send audio to server when PTT is active
 			m.audioCapturer.SetCallback(func(samples []int16) {
-				if m.isPTT && m.client != nil && !m.isMuted {
+				// Calculate level of this frame for VAD decision
+				// Note: GetLevel() is smoothed, we might want instant frame level for VAD trigger?
+				// But pkg/audio/level.go is efficient. Let's re-calculate for precision.
+				level := audio.CalculateRMSLevel(samples)
+
+				// Determine if we should transmit
+				shouldTransmit := false
+
+				// Manual PTT (Locked on with 'v')
+				if m.isPTT {
+					shouldTransmit = true
+				}
+
+				// VAD Logic
+				if m.vadEnabled && !m.isMuted {
+					if level > m.vadThreshold {
+						shouldTransmit = true
+						m.vadLastTriggered = time.Now()
+					} else if !m.vadLastTriggered.IsZero() && time.Since(m.vadLastTriggered) < 1*time.Second {
+						// Hold VAD open for 1 second (decay)
+						shouldTransmit = true
+					}
+				}
+
+				// Allow transmission if forced or VAD triggered
+				if shouldTransmit && m.client != nil && !m.isMuted {
 					m.client.SendAudio(samples)
 				}
-				// Update mic level for display
+
+				// Update mic level for display (use the calculated level)
 				if m.program != nil {
-					m.program.Send(micLevelMsg(m.audioCapturer.GetLevel()))
+					// Use goroutine to prevent blocking the capture loop if the UI is busy (e.g. shutting down)
+					go m.program.Send(micLevelMsg(level))
 				}
 			})
 			m.addLog("Audio capturer initialized")
+
+			// Start capture immediately if VAD is enabled or PTT is active
+			if m.vadEnabled || m.isPTT {
+				if err := m.audioCapturer.Start(); err != nil {
+					m.addLog("Error starting audio capture: %v", err)
+				} else {
+					m.addLog("Audio capture started (VAD/PTT active)")
+				}
+			}
 		}
 
 		// Connect asynchronously
@@ -343,16 +393,7 @@ func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			}
 		}
 
-		// Update mic level when PTT is active (multiply for better visibility)
-		if m.isPTT && m.audioCapturer != nil {
-			level := m.audioCapturer.GetLevel() * 4 // Boost for visibility
-			if level > 100 {
-				level = 100
-			}
-			m.micLevel = level
-		} else {
-			m.micLevel = 0 // Reset when not transmitting
-		}
+		// Legacy mic level handling removed to support VAD event-driven updates
 
 		// Continue ticking (100ms for responsive mic level)
 		return m, tea.Tick(100*time.Millisecond, func(t time.Time) tea.Msg {
@@ -398,12 +439,19 @@ func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		return m, nil
 
 	case pokeMsg:
+		// Append to chat as well
 		m.chatMessages = append(m.chatMessages, ChatMessage{
 			Time:    time.Now(),
 			Sender:  "POKE",
 			Content: fmt.Sprintf("[%s]: %s", msg.senderName, msg.message),
 		})
 		m.addLog("Received poke from %s: %s", msg.senderName, msg.message)
+
+		// Trigger Popup
+		m.showPokePopup = true
+		m.pokePopupSender = msg.senderName
+		m.pokePopupMessage = msg.message
+
 		return m, nil
 
 	case chatMsg:
@@ -545,8 +593,18 @@ func (m *Model) updateChannelList(channels []*ts3client.Channel) {
 }
 
 func (m *Model) handleKeyPress(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
+	key := msg.String()
+
+	// Global Key Handling for Popup
+	if m.showPokePopup {
+		if key == "esc" || key == "enter" || key == "q" {
+			m.showPokePopup = false
+		}
+		return m, nil
+	}
+
 	// 1. Absolute Globals (Always active)
-	switch msg.String() {
+	switch key {
 	case "ctrl+c":
 		if m.client != nil {
 			m.client.Disconnect()
@@ -627,16 +685,58 @@ func (m *Model) handleKeyPress(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 			}
 			return m, nil
 
+		case "ctrl+up", "ctrl+right":
+			// Increase VAD threshold
+			m.vadThreshold += 5
+			if m.vadThreshold > 100 {
+				m.vadThreshold = 100
+			}
+			m.addLog("VAD Threshold: %d", m.vadThreshold)
+			return m, nil
+
+		case "ctrl+down", "ctrl+left":
+			// Decrease VAD threshold
+			m.vadThreshold -= 5
+			if m.vadThreshold < 0 {
+				m.vadThreshold = 0
+			}
+			m.addLog("VAD Threshold: %d", m.vadThreshold)
+			return m, nil
+
+		case "g", "G":
+			// Toggle VAD (Gate)
+			m.vadEnabled = !m.vadEnabled
+			state := "OFF"
+			if m.vadEnabled {
+				state = "ON"
+				// Ensure capturer is running if VAD is on
+				if m.audioCapturer != nil && !m.audioCapturer.IsRunning() {
+					if err := m.audioCapturer.Start(); err != nil {
+						m.addLog("Error starting VAD capture: %v", err)
+					}
+				}
+			} else {
+				// Stop if PTT is also off
+				if !m.isPTT && m.audioCapturer != nil && m.audioCapturer.IsRunning() {
+					m.audioCapturer.Stop()
+				}
+			}
+			m.addLog("Voice Activation (Gate): %s", state)
+			return m, nil
+
 		case "v", "V":
 			// Toggle voice (PTT)
 			m.isPTT = !m.isPTT
 			if m.isPTT {
-				if m.audioCapturer != nil {
-					m.audioCapturer.Start()
+				if m.audioCapturer != nil && !m.audioCapturer.IsRunning() {
+					if err := m.audioCapturer.Start(); err != nil {
+						m.addLog("Audio capture error: %v", err)
+					}
 				}
 				m.addLog("🎤 Transmitting...")
 			} else {
-				if m.audioCapturer != nil {
+				// Stop only if VAD is also off
+				if !m.vadEnabled && m.audioCapturer != nil && m.audioCapturer.IsRunning() {
 					m.audioCapturer.Stop()
 				}
 				m.addLog("🎤 Stopped transmitting")
@@ -723,6 +823,28 @@ func (m *Model) handleUserViewKeys(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 			newVol = 0.0
 		}
 		m.audioPlayer.SetUserVolume(u.ID, newVol)
+
+	case "right", "l":
+		// Increase Gain for selected band
+		current := m.audioPlayer.GetUserGain(u.ID, m.eqBandIdx)
+		m.audioPlayer.SetUserGain(u.ID, m.eqBandIdx, current+1.0)
+
+	case "left", "h":
+		// Decrease Gain
+		current := m.audioPlayer.GetUserGain(u.ID, m.eqBandIdx)
+		m.audioPlayer.SetUserGain(u.ID, m.eqBandIdx, current-1.0)
+
+	case "up", "k":
+		m.eqBandIdx--
+		if m.eqBandIdx < 0 {
+			m.eqBandIdx = 4
+		}
+
+	case "down", "j":
+		m.eqBandIdx++
+		if m.eqBandIdx > 4 {
+			m.eqBandIdx = 0
+		}
 	}
 	return m, nil
 }
@@ -836,6 +958,32 @@ func (m *Model) handleInputKeys(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 
 // View renders the UI
 func (m *Model) View() string {
+	if m.showPokePopup {
+		boxStyle := lipgloss.NewStyle().
+			Border(lipgloss.DoubleBorder()).
+			BorderForeground(lipgloss.Color("196")). // Red for Poke
+			Padding(1, 2).
+			Width(50).
+			Align(lipgloss.Center)
+
+		titleStyle := lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("226")).MarginBottom(1)
+		senderStyle := lipgloss.NewStyle().Foreground(lipgloss.Color("208")).Bold(true)
+		msgStyle := lipgloss.NewStyle().Foreground(lipgloss.Color("255")).Italic(true)
+		helpStyle := lipgloss.NewStyle().Faint(true).MarginTop(2)
+
+		content := lipgloss.JoinVertical(lipgloss.Center,
+			titleStyle.Render("YOU WERE POKED!"),
+			"",
+			fmt.Sprintf("From: %s", senderStyle.Render(m.pokePopupSender)),
+			"",
+			msgStyle.Render(fmt.Sprintf("%q", m.pokePopupMessage)),
+			"",
+			helpStyle.Render("(Press Esc/Enter to close)"),
+		)
+
+		return lipgloss.Place(m.width, m.height, lipgloss.Center, lipgloss.Center, boxStyle.Render(content))
+	}
+
 	if m.focus == FocusAbout {
 		return m.renderAboutView()
 	}
@@ -962,7 +1110,7 @@ func (m *Model) View() string {
 	if m.showLog {
 		logHelp = "L chat"
 	}
-	help := lipgloss.NewStyle().Faint(true).Render(fmt.Sprintf("↑↓ navigate │ Enter join │ Tab switch │ %s │ V talk │ M mute │ +/- vol │ q quit", logHelp))
+	help := lipgloss.NewStyle().Faint(true).Render(fmt.Sprintf("↑↓ nav │ Ent join │ Tab switch │ %s │ V PTT │ G VAD │ ^↕↔ thresh │ M mute │ +/- vol │ q quit", logHelp))
 
 	// Combine panels
 	panels := lipgloss.JoinHorizontal(lipgloss.Top, channelPanel, rightPanel)
@@ -1005,12 +1153,85 @@ func (m *Model) renderStatusBar() string {
 	}
 	volPart := fmt.Sprintf("%s:%s%d%%", muteIcon, volBar, m.playbackVol)
 
-	micBar := audio.LevelToBar(m.micLevel, 6)
-	pttIcon := "MIC"
-	if m.isPTT {
-		pttIcon = "*TX*"
+	// Custom Mic Bar with VAD Threshold
+	micBarWidth := 8
+	var micBar string
+
+	if m.vadEnabled {
+		// Calculate threshold position
+		threshPos := m.vadThreshold * micBarWidth / 100
+		if threshPos >= micBarWidth {
+			threshPos = micBarWidth - 1
 		}
-	micPart := fmt.Sprintf("%s:%s", pttIcon, micBar)
+
+		// Calculate filled position based on current level
+		filled := m.micLevel * micBarWidth / 100
+
+		// Build bar
+		var sb strings.Builder
+		for i := 0; i < micBarWidth; i++ {
+			char := "░"
+			if i < filled {
+				char = "█"
+			}
+
+			// Overlay threshold marker
+			if i == threshPos {
+				if i < filled {
+					// Threshold is met
+					char = "▓"
+				} else {
+					// Threshold not met
+					char = "│"
+				}
+			}
+			sb.WriteString(char)
+		}
+		micBar = sb.String()
+	} else {
+		micBar = audio.LevelToBar(m.micLevel, micBarWidth)
+	}
+
+	pttStyle := lipgloss.NewStyle()
+	pttIcon := "MIC"
+
+	if m.isPTT {
+		pttIcon = " ON"                                                  // Manual ON
+		pttStyle = pttStyle.Foreground(lipgloss.Color("196")).Bold(true) // Red
+	} else if m.vadEnabled {
+		pttIcon = "VAD"
+		// Check if actively transmitting (using logic with decay)
+		isTransmitting := false
+		if !m.isMuted {
+			if m.micLevel > m.vadThreshold {
+				isTransmitting = true
+			} else if !m.vadLastTriggered.IsZero() && time.Since(m.vadLastTriggered) < 1*time.Second {
+				isTransmitting = true
+			}
+		}
+
+		if isTransmitting {
+			// Transmitting via VAD: Red/Bold
+			pttStyle = pttStyle.Foreground(lipgloss.Color("196")).Bold(true)
+		} else {
+			// Idle VAD: Gray/Faint
+			pttStyle = pttStyle.Foreground(lipgloss.Color("240")).Faint(true)
+		}
+	} else {
+		// Standard Mic (PTT mode but off)
+		pttStyle = pttStyle.Foreground(lipgloss.Color("255")) // White
+	}
+
+	// Apply status bar background color to prevent cutting
+	pttStyle = pttStyle.Background(lipgloss.Color("57")) // Matches Top Bar Background
+
+	// Style for the bar itself to maintain background continuity
+	barStyle := lipgloss.NewStyle().Background(lipgloss.Color("57")).Foreground(lipgloss.Color("255"))
+
+	micPart := fmt.Sprintf("%s%s%s",
+		pttStyle.Render(pttIcon),
+		barStyle.Render(":"),
+		barStyle.Render(micBar))
 
 	rightPart := fmt.Sprintf("%s | %s ", volPart, micPart)
 
@@ -1216,14 +1437,85 @@ func (m *Model) renderUserView() string {
 		"--- Audio Settings ---",
 		fmt.Sprintf("%s %d%%", labelStyle.Render("Volume:"), int(vol*100)),
 		fmt.Sprintf("%s %s", labelStyle.Render("Local Mute:"), muteStr),
+	}
+
+	// EQ Visualization
+	var eqGraph []string
+	if m.audioPlayer != nil {
+		bands := m.audioPlayer.GetEQBands(u.ID)
+		if len(bands) > 0 {
+			eqGraph = append(eqGraph, "", "--- Interactive Equalizer ---", "")
+
+			// Render bars for 5 bands
+			// 0: Bass, 1: Low-Mid, 2: Mid, 3: High-Mid, 4: High
+			labels := []string{"100Hz", "350Hz", "1kHz", "3kHz", "8kHz"}
+
+			for i, val := range bands {
+				if i >= len(labels) {
+					break
+				}
+
+				// Get current gain setting
+				gain := m.audioPlayer.GetUserGain(u.ID, i)
+
+				// Scale 0.0-1.0 to bars (width 20)
+				const maxBars = 20
+				bars := int(val * maxBars)
+				if bars > maxBars {
+					bars = maxBars
+				}
+
+				// Bar characters: █ ▇ ▆ ▅ ▄ ▃ ▂
+				barStr := ""
+				if bars > 0 {
+					barStr = strings.Repeat("█", bars)
+				}
+
+				// Colorize based on intensity
+				barStyle := lipgloss.NewStyle().Foreground(lipgloss.Color("39")) // Blue default
+				if val > 0.8 {
+					barStyle = barStyle.Foreground(lipgloss.Color("196")) // Red clipping
+				} else if val > 0.5 {
+					barStyle = barStyle.Foreground(lipgloss.Color("208")) // Orange high
+				} else if val > 0.2 {
+					barStyle = barStyle.Foreground(lipgloss.Color("46")) // Green normal
+				}
+
+				// Selection Indicator
+				selector := "  "
+				labelStyle := lipgloss.NewStyle().Foreground(lipgloss.Color("240")).Width(6)
+				gainStyle := lipgloss.NewStyle().Foreground(lipgloss.Color("245")).Width(6)
+
+				if i == m.eqBandIdx {
+					selector = "->"
+					labelStyle = labelStyle.Foreground(lipgloss.Color("226")).Bold(true) // Yellow for selected
+					gainStyle = gainStyle.Foreground(lipgloss.Color("226"))
+				}
+
+				gainStr := fmt.Sprintf("%+3.0fdB", gain)
+
+				line := fmt.Sprintf("%s %s %s | %s",
+					selector,
+					labelStyle.Render(labels[i]),
+					gainStyle.Render(gainStr),
+					barStyle.Render(fmt.Sprintf("%-20s", barStr)))
+
+				eqGraph = append(eqGraph, line)
+			}
+		}
+	}
+
+	info = append(info, eqGraph...)
+	info = append(info,
 		"",
 		"--- Menu ---",
 		"1. Poke",
 		"2. Toggle Local Mute",
 		"+/-: Adjust Volume",
+		"Arrows: Adjust EQ",
 		"",
 		"(Press ESC to close)",
-	}
+	)
 
 	return lipgloss.JoinVertical(lipgloss.Left, info...)
 }
@@ -1246,7 +1538,8 @@ func (m *Model) renderAboutView() string {
 		titleStyle.Render("TS3 TUI CLIENT"),
 		lipgloss.NewStyle().Foreground(lipgloss.Color("250")).Render("Una terminal potente para tus comunidades."),
 		"",
-		lipgloss.NewStyle().Bold(true).Render("Hecho en Antigravity"),
+		lipgloss.NewStyle().Bold(true).Render("Realizado por JosLeDeta"),
+		lipgloss.NewStyle().Italic(true).Faint(true).Render("Hecho en Antigravity"),
 		"",
 		lipgloss.NewStyle().Bold(true).Render("Con la ayuda de:"),
 		lipgloss.NewStyle().Foreground(lipgloss.Color("212")).Render("- Gemini 3 Pro"),

go.mod

@@ -30,6 +30,7 @@ require (
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-localereader v0.0.1 // indirect
 	github.com/mattn/go-runewidth v0.0.16 // indirect
+	github.com/moutend/go-equalizer v0.1.0 // indirect
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
 	github.com/muesli/termenv v0.16.0 // indirect

go.sum

@@ -32,6 +32,8 @@ github.com/mattn/go-localereader v0.0.1 h1:ygSAOl7ZXTx4RdPYinUpg6W99U8jWvWi9Ye2J
 github.com/mattn/go-localereader v0.0.1/go.mod h1:8fBrzywKY7BI3czFoHkuzRoWE9C+EiG4R1k4Cjx5p88=
 github.com/mattn/go-runewidth v0.0.16 h1:E5ScNMtiwvlvB5paMFdw9p4kSQzbXFikJ5SQO6TULQc=
 github.com/mattn/go-runewidth v0.0.16/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
+github.com/moutend/go-equalizer v0.1.0 h1:FDFsTr/zKUpLbNXZQmCMRDgisQhXxFOnX2q0PllJvxs=
+github.com/moutend/go-equalizer v0.1.0/go.mod h1:iahcZcStDm66TNtrkMIhrQuhWdiWbFKSVjZ8yn+7Cgw=
 github.com/moutend/go-wca v0.3.0 h1:IzhsQ44zBzMdT42xlBjiLSVya9cPYOoKx9E+yXVhFo8=
 github.com/moutend/go-wca v0.3.0/go.mod h1:7VrPO512jnjFGJ6rr+zOoCfiYjOHRPNfbttJuxAurcw=
 github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 h1:ZK8zHtRHOkbHy6Mmr5D264iyp3TiX5OmNcI5cIARiQI=

internal/client/client.go

@@ -36,6 +36,7 @@ type Client struct {
 	PingPacketID       uint16 // Type 0x04
 	PongPacketID       uint16 // Type 0x05
 	AckPacketID        uint16 // Type 0x06
+	AckLowPacketID     uint16 // Type 0x07
 
 	// Ping RTT tracking
 	PingSentTimes   map[uint16]time.Time // Map PingPacketID -> Time sent
@@ -48,10 +49,14 @@ type Client struct {
 	ServerName string
 
 	// Fragment reassembly (packet queue like ts3j)
-	CommandQueue       map[uint16]*protocol.Packet // Packets waiting for reassembly
-	ExpectedCommandPID uint16                      // Next expected packet ID
+	CommandQueue       map[uint16]*protocol.Packet // Packets waiting for reassembly (Type 0x02)
+	ExpectedCommandPID uint16                      // Next expected packet ID (Type 0x02)
 	FragmentState      bool                        // Toggle: true = collecting, false = ready
 
+	CommandLowQueue       map[uint16]*protocol.Packet // Packets waiting for reassembly (Type 0x03)
+	ExpectedCommandLowPID uint16                      // Next expected packet ID (Type 0x03)
+	FragmentStateLow      bool                        // Toggle: true = collecting, false = ready
+
 	// Server Data
 	Channels map[uint64]*Channel
 
@@ -71,11 +76,14 @@ func NewClient(nickname string) *Client {
 	return &Client{
 		Nickname:              nickname,
 		PacketIDCounterC2S:    1,
+		AckLowPacketID:        1,
 		VoicePacketID:         1,
 		Channels:              make(map[uint64]*Channel),
 		VoiceDecoders:         make(map[uint16]*opus.Decoder),
 		CommandQueue:          make(map[uint16]*protocol.Packet),
 		ExpectedCommandPID:    0,
+		CommandLowQueue:       make(map[uint16]*protocol.Packet),
+		ExpectedCommandLowPID: 0,
 		PingSentTimes:         make(map[uint16]time.Time),
 		PingRTT:               0,
 		PingDeviation:         0,

internal/client/commands.go

@@ -35,6 +35,21 @@ func sanitizeForLog(s string) string {
 }
 
 func (c *Client) handleCommand(pkt *protocol.Packet) error {
+	// Select the correct queue and counters based on PacketType
+	var queue map[uint16]*protocol.Packet
+	var expectedPID *uint16
+	var fragmentState *bool
+
+	if pkt.Header.PacketType() == protocol.PacketTypeCommandLow {
+		queue = c.CommandLowQueue
+		expectedPID = &c.ExpectedCommandLowPID
+		fragmentState = &c.FragmentStateLow
+	} else {
+		queue = c.CommandQueue
+		expectedPID = &c.ExpectedCommandPID
+		fragmentState = &c.FragmentState
+	}
+
 	// Check if Encrypted
 	// PacketTypeCommand is usually encrypted.
 	// Flag check? The flag is in the Header (e.g. Unencrypted flag).
@@ -100,14 +115,14 @@ func (c *Client) handleCommand(pkt *protocol.Packet) error {
 
 	// Queue-based fragment reassembly (like ts3j)
 	// Store packet in queue
-	c.CommandQueue[pkt.Header.PacketID] = &protocol.Packet{
+	queue[pkt.Header.PacketID] = &protocol.Packet{
 		Header: pkt.Header,
 		Data:   append([]byte{}, data...), // Clone data (already decrypted)
 	}
 
 	// Try to process packets in order
 	for {
-		nextPkt, ok := c.CommandQueue[c.ExpectedCommandPID]
+		nextPkt, ok := queue[*expectedPID]
 		if !ok {
 			// Missing packet, wait for it
 			break
@@ -117,16 +132,16 @@ func (c *Client) handleCommand(pkt *protocol.Packet) error {
 
 		if isFragmented {
 			// Toggle fragment state
-			c.FragmentState = !c.FragmentState
+			*fragmentState = !*fragmentState
 
-			if c.FragmentState {
+			if *fragmentState {
 				// Starting a new fragment sequence
 				// Don't process yet, wait for more
-				c.ExpectedCommandPID++
+				*expectedPID++
 				continue
 			} else {
 				// Ending fragment sequence - reassemble all
-				reassembled, compressed := c.reassembleFragments()
+				reassembled, compressed := c.reassembleFragmentsCustom(queue, *expectedPID)
 				if reassembled == nil {
 					log.Printf("Fragment reassembly failed")
 					break
@@ -144,9 +159,9 @@ func (c *Client) handleCommand(pkt *protocol.Packet) error {
 					}
 				}
 			}
-		} else if c.FragmentState {
+		} else if *fragmentState {
 			// Middle fragment - keep collecting
-			c.ExpectedCommandPID++
+			*expectedPID++
 			continue
 		} else {
 			// Non-fragmented packet - process normally
@@ -165,10 +180,11 @@ func (c *Client) handleCommand(pkt *protocol.Packet) error {
 		}
 
 		// Remove processed packet from queue
-		delete(c.CommandQueue, c.ExpectedCommandPID)
-		c.ExpectedCommandPID++
+		delete(queue, *expectedPID)
+		*expectedPID++
 
 		// Process the command
+		// Fix: processCommand should probably handle execution
 		if err := c.processCommand(data, nextPkt); err != nil {
 			log.Printf("Error processing command: %v", err)
 		}
@@ -177,16 +193,17 @@ func (c *Client) handleCommand(pkt *protocol.Packet) error {
 	return nil
 }
 
-// reassembleFragments collects all buffered fragments in order and returns reassembled data
-func (c *Client) reassembleFragments() ([]byte, bool) {
+// reassembleFragmentsCustom collects all buffered fragments in order from the given queue
+// ending at currentPID.
+func (c *Client) reassembleFragmentsCustom(queue map[uint16]*protocol.Packet, currentPID uint16) ([]byte, bool) {
 	var result []byte
 	compressed := false
 
 	// Find the start of the fragment sequence (scan backwards from current)
-	startPID := c.ExpectedCommandPID
+	startPID := currentPID
 	for {
 		prevPID := startPID - 1
-		pkt, ok := c.CommandQueue[prevPID]
+		pkt, ok := queue[prevPID]
 		if !ok {
 			break
 		}
@@ -198,9 +215,9 @@ func (c *Client) reassembleFragments() ([]byte, bool) {
 		startPID = prevPID
 	}
 
-	// Now collect from startPID to ExpectedCommandPID (inclusive)
-	for pid := startPID; pid <= c.ExpectedCommandPID; pid++ {
-		pkt, ok := c.CommandQueue[pid]
+	// Now collect from startPID to currentPID (inclusive)
+	for pid := startPID; pid <= currentPID; pid++ {
+		pkt, ok := queue[pid]
 		if !ok {
 			log.Printf("Missing fragment PID=%d during reassembly", pid)
 			return nil, false
@@ -212,11 +229,11 @@ func (c *Client) reassembleFragments() ([]byte, bool) {
 		}
 
 		result = append(result, pkt.Data...)
-		delete(c.CommandQueue, pid)
+		delete(queue, pid)
 	}
 
 	log.Printf("Reassembled fragments PID %d-%d, total %d bytes, compressed=%v",
-		startPID, c.ExpectedCommandPID, len(result), compressed)
+		startPID, currentPID, len(result), compressed)
 
 	return result, compressed
 }

internal/client/packet.go

@@ -55,6 +55,46 @@ func (c *Client) handlePacket(pkt *protocol.Packet) error {
 
 		c.Conn.SendPacket(ack)
 
+		return c.handleCommand(pkt)
+	case protocol.PacketTypeCommandLow:
+		// Send ACK Low
+		ackData := make([]byte, 2)
+		binary.BigEndian.PutUint16(ackData, pkt.Header.PacketID)
+
+		ack := protocol.NewPacket(protocol.PacketTypeAckLow, ackData)
+		// Spec/ts3j: AckLow has its own counter
+		c.AckLowPacketID++
+		ack.Header.PacketID = c.AckLowPacketID
+		ack.Header.ClientID = c.ClientID
+		// ACKs usually don't have NewProtocol flag set in Header byte
+		ack.Header.Type &= ^uint8(protocol.PacketFlagNewProtocol)
+
+		// ACKs for Command packets after handshake must be encrypted
+		key := protocol.HandshakeKey
+		nonce := protocol.HandshakeNonce
+
+		if c.Handshake != nil && c.Handshake.Step >= 6 && len(c.Handshake.SharedIV) > 0 {
+			crypto := &protocol.CryptoState{
+				SharedIV:     c.Handshake.SharedIV,
+				SharedMac:    c.Handshake.SharedMac,
+				GenerationID: 0,
+			}
+			key, nonce = crypto.GenerateKeyNonce(&ack.Header, true) // Client->Server=true
+		}
+
+		// Meta for Client->Server: PID(2) + CID(2) + PT(1) = 5 bytes
+		meta := make([]byte, 5)
+		binary.BigEndian.PutUint16(meta[0:2], ack.Header.PacketID)
+		binary.BigEndian.PutUint16(meta[2:4], ack.Header.ClientID)
+		meta[4] = ack.Header.Type
+
+		encData, mac, _ := protocol.EncryptEAX(key, nonce, meta, ack.Data)
+		ack.Data = encData
+		copy(ack.Header.MAC[:], mac)
+		// log.Printf("Sending ACK Low for server CommandLow PID=%d", pkt.Header.PacketID)
+
+		c.Conn.SendPacket(ack)
+
 		return c.handleCommand(pkt)
 	case protocol.PacketTypeVoice:
 		c.handleVoice(pkt)

pkg/audio/biquad.go

@@ -0,0 +1,135 @@
+package audio
+
+import (
+	"github.com/moutend/go-equalizer/pkg/equalizer"
+)
+
+// EQChain manages a cascade of filters using go-equalizer library
+// Now supports Stereo processing (Left/Right)
+// EQChain manages a cascade of filters using go-equalizer library
+// Now supports Stereo processing (Left/Right)
+type EQChain struct {
+	FiltersLeft  []*equalizer.Filter
+	FiltersRight []*equalizer.Filter
+	buffer       []float64 // Reusable scratch buffer for processing
+	currentGains []float64 // Cache of current gain values
+}
+
+// NewEQChain creates the standard 5-band EQ chain (Stereo)
+func NewEQChain(sampleRate float64) *EQChain {
+	// Standard bands: 100, 350, 1000, 3000, 8000
+	// Width = 1.0 (approx 1 octave)
+
+	createChain := func() []*equalizer.Filter {
+		f1 := equalizer.NewPeaking(sampleRate, 100, 1.0, 0)
+		f2 := equalizer.NewPeaking(sampleRate, 350, 1.0, 0)
+		f3 := equalizer.NewPeaking(sampleRate, 1000, 1.0, 0)
+		f4 := equalizer.NewPeaking(sampleRate, 3000, 1.0, 0)
+		f5 := equalizer.NewPeaking(sampleRate, 8000, 1.0, 0)
+		return []*equalizer.Filter{f1, f2, f3, f4, f5}
+	}
+
+	return &EQChain{
+		FiltersLeft:  createChain(),
+		FiltersRight: createChain(),
+		buffer:       make([]float64, 1920), // Pre-allocate for Stereo 20ms frame (960*2)
+		currentGains: make([]float64, 5),    // Initialize cache with 0.0
+	}
+}
+
+// SetGain sets the gain for a specific band index (0-4)
+func (e *EQChain) SetGain(bandIdx int, dbGain float64) {
+	if bandIdx < 0 || bandIdx >= 5 {
+		return
+	}
+
+	// Optimization: If gain hasn't changed, DO NOT recreate filter.
+	// Recreating the filter resets its internal history state (bi-quad delay buffers),
+	// causing audible clicks/pops (discontinuities) at every 20ms frame boundary.
+	const epsilon = 0.001
+	if delta := dbGain - e.currentGains[bandIdx]; delta > -epsilon && delta < epsilon {
+		return
+	}
+
+	rate := 48000.0 // Assuming fixed rate for now
+	// Frequencies map to our standard bands
+	freqs := []float64{100, 350, 1000, 3000, 8000}
+
+	// Create new filter with updated gain
+	// We use width=1.0 consistent with constructor
+	// Update BOTH Left and Right to keep balance
+	e.FiltersLeft[bandIdx] = equalizer.NewPeaking(rate, freqs[bandIdx], 1.0, dbGain)
+	e.FiltersRight[bandIdx] = equalizer.NewPeaking(rate, freqs[bandIdx], 1.0, dbGain)
+
+	// Update cache
+	e.currentGains[bandIdx] = dbGain
+}
+
+// Reset clears history of all filters
+func (e *EQChain) Reset() {
+	// The library does not expose a Reset method.
+}
+
+// Process processes a slice of samples (Interleaved Stereo)
+func (e *EQChain) Process(samples []int16) []int16 {
+	// Grow buffer if needed
+	if cap(e.buffer) < len(samples) {
+		e.buffer = make([]float64, len(samples))
+	}
+	e.buffer = e.buffer[:len(samples)]
+
+	// Float conversion with normalization (-1.0 to 1.0)
+	// We also apply a slight pre-attenuation (Headroom) to avoid clipping when boosting EQ.
+	// -3dB = 0.707
+	const headroom = 0.707
+	const norm = 1.0 / 32768.0
+
+	for i, s := range samples {
+		e.buffer[i] = float64(s) * norm * headroom
+	}
+
+	// Filter processing
+	// Input is assumed to be Interleaved Stereo: L, R, L, R...
+	// We iterate by 2 to process pairs.
+
+	for i := 0; i < len(e.buffer); i += 2 {
+		if i+1 >= len(e.buffer) {
+			break
+		}
+
+		valL := e.buffer[i]
+		valR := e.buffer[i+1]
+
+		// Run through LEFT chain
+		for _, f := range e.FiltersLeft {
+			valL = f.Apply(valL)
+		}
+
+		// Run through RIGHT chain
+		for _, f := range e.FiltersRight {
+			valR = f.Apply(valR)
+		}
+
+		// Write back to buffer
+		e.buffer[i] = valL
+		e.buffer[i+1] = valR
+	}
+
+	// Convert back to int16
+	for i, val := range e.buffer {
+		// Denormalize
+		val = val * 32767.0
+
+		// Hard clipping
+		if val > 32767 {
+			val = 32767
+		} else if val < -32768 {
+			val = -32768
+		}
+
+		// Write back directly to samples
+		samples[i] = int16(val)
+	}
+
+	return samples
+}

pkg/audio/capture.go

@@ -22,6 +22,7 @@ type Capturer struct {
 	running       bool
 	mu            sync.Mutex
 	stopChan      chan struct{}
+	wg            sync.WaitGroup
 
 	// Callback for captured audio (called with 960-sample frames)
 	onAudio func(samples []int16)
@@ -136,6 +137,7 @@ func (c *Capturer) Start() error {
 		return fmt.Errorf("failed to start audio client: %w", err)
 	}
 
+	c.wg.Add(1)
 	go c.captureLoop()
 	return nil
 }
@@ -151,6 +153,7 @@ func (c *Capturer) Stop() {
 	c.mu.Unlock()
 
 	close(c.stopChan)
+	c.wg.Wait() // Wait for capture loop to finish before proceeding
 	c.client.Stop()
 }
 
@@ -180,6 +183,7 @@ func (c *Capturer) IsRunning() bool {
 }
 
 func (c *Capturer) captureLoop() {
+	defer c.wg.Done()
 	ticker := time.NewTicker(10 * time.Millisecond) // Check more often than 20ms
 	defer ticker.Stop()
 

pkg/audio/common.go

@@ -10,4 +10,6 @@ const (
 type UserSettings struct {
 	Volume  float32 // 0.0 - 1.0 (or higher for boost)
 	Muted   bool
+	Gains   []float64 // 5-band Equalizer Gains in dB
+	EQBands []float64
 }

pkg/audio/fft.go

@@ -0,0 +1,138 @@
+package audio
+
+import (
+	"math"
+)
+
+// CalculateEQBands computes frequency magnitudes for 5 EQ bands from PCM samples.
+// It uses a simplified approach tailored for visualization:
+// 1. Converts int16 PCM to float64
+// 2. Applies a Window function (Hanning)
+// 3. Performs a simple DFT (Discrete Fourier Transform) - sufficient for small N/visualization
+// 4. Aggregates bins into 5 bands: Bass, Low-Mid, Mid, Hybrid-High, High
+func CalculateEQBands(samples []int16, sampleRate int) []float64 {
+	// We'll use a relatively small window size for responsiveness and performance
+	// 512 samples at 48kHz is ~10ms, which is very fast.
+	// 1024 samples is ~21ms.
+
+	const windowSize = 1024
+	if len(samples) < windowSize {
+		// Not enough data, return empty or zeroed bands
+		// Pad with zeros if we really wanted to processing, but for vis just return what we have?
+		// Actually, let's just make a copy and pad with zeros to windowSize
+		padded := make([]int16, windowSize)
+		copy(padded, samples)
+		samples = padded
+	} else {
+		// Take the last windowSize samples (most recent audio)
+		samples = samples[len(samples)-windowSize:]
+	}
+
+	// Prepare complex input
+	real := make([]float64, windowSize)
+	imag := make([]float64, windowSize)
+
+	// Apply Hanning Window
+	for i := 0; i < windowSize; i++ {
+		val := float64(samples[i]) / 32768.0 // Normalize to -1.0..1.0
+		// Hanning window formula
+		window := 0.5 * (1 - math.Cos(2*math.Pi*float64(i)/float64(windowSize-1)))
+		real[i] = val * window
+	}
+
+	// Perform basic FFT (Cooley-Tukey)
+	// Since windowSize is power of 2 (1024), we can use a recursive or iterative FFT.
+	// For simplicity in a single file without deps, we'll write a small recursive one or iterative.
+	// Given typical Go performance, a simple recursive one is fine for N=1024 per user talk event.
+	fft(real, imag)
+
+	// Calculate magnitudes and bucket into bands
+	// Freq resolution = SampleRate / WindowSize = 48000 / 1024 ~= 46.875 Hz per bin
+	// Nyquist = 24000 Hz (Bin 512)
+
+	// Band definitions (approximate range):
+	// 1. Sub/Bass: 0 - 250 Hz (Bins 0-5)
+	// 2. Low Mids: 250 - 500 Hz (Bins 6-10)
+	// 3. Mids: 500 - 2000 Hz (Bins 11-42)
+	// 4. Upper Mids: 2000 - 4000 Hz (Bins 43-85)
+	// 5. Highs: 4000Hz+ (Bins 86-512)
+
+	bands := make([]float64, 5)
+
+	// Helper to collect energy
+	collectEnergy := func(startBin, endBin int) float64 {
+		sum := 0.0
+		for i := startBin; i <= endBin && i < windowSize/2; i++ {
+			// Magnitude = sqrt(re^2 + im^2)
+			mag := math.Sqrt(real[i]*real[i] + imag[i]*imag[i])
+			sum += mag
+		}
+		// Average
+		count := float64(endBin - startBin + 1)
+		if count > 0 {
+			return sum / count
+		}
+		return 0
+	}
+
+	bands[0] = collectEnergy(1, 6) // Skip DC (bin 0)
+	bands[1] = collectEnergy(7, 12)
+	bands[2] = collectEnergy(13, 45)
+	bands[3] = collectEnergy(46, 90)
+	bands[4] = collectEnergy(91, 511)
+
+	// Normalize output for visualization (0.0 to 1.0)
+	// We need some scaling factor. Based on expected signals.
+	const scale = 10.0 // Reduced from 50.0 to fix saturation
+	for i := range bands {
+		bands[i] = bands[i] * scale
+		if bands[i] > 1.0 {
+			bands[i] = 1.0
+		}
+	}
+
+	return bands
+}
+
+// Simple in-place Cooley-Tukey FFT.
+// n must be power of 2.
+func fft(real, imag []float64) {
+	n := len(real)
+	if n <= 1 {
+		return
+	}
+
+	// Split even and odd
+	half := n / 2
+	realEven := make([]float64, half)
+	imagEven := make([]float64, half)
+	realOdd := make([]float64, half)
+	imagOdd := make([]float64, half)
+
+	for i := 0; i < half; i++ {
+		realEven[i] = real[2*i]
+		imagEven[i] = imag[2*i]
+		realOdd[i] = real[2*i+1]
+		imagOdd[i] = imag[2*i+1]
+	}
+
+	// Recursion
+	fft(realEven, imagEven)
+	fft(realOdd, imagOdd)
+
+	// Combine
+	for k := 0; k < half; k++ {
+		tReal := math.Cos(-2 * math.Pi * float64(k) / float64(n))
+		tImag := math.Sin(-2 * math.Pi * float64(k) / float64(n))
+
+		// Multiply odd by twist factor (tReal+itImag) * (oddReal+iOddImag)
+		// (ac - bd) + i(ad + bc)
+		twistReal := tReal*realOdd[k] - tImag*imagOdd[k]
+		twistImag := tReal*imagOdd[k] + tImag*realOdd[k]
+
+		real[k] = realEven[k] + twistReal
+		imag[k] = imagEven[k] + twistImag
+		real[k+half] = realEven[k] - twistReal
+		imag[k+half] = imagEven[k] - twistImag
+	}
+}

pkg/audio/level.go

@@ -4,7 +4,7 @@ import (
 	"math"
 )
 
-// CalculateRMSLevel calculates the RMS level of PCM samples and returns 0-100
+// CalculateRMSLevel calculates the RMS level of PCM samples and returns 0-100 (Logarithmic/dB)
 func CalculateRMSLevel(samples []int16) int {
 	if len(samples) == 0 {
 		return 0
@@ -16,15 +16,33 @@ func CalculateRMSLevel(samples []int16) int {
 	}
 
 	rms := math.Sqrt(sum / float64(len(samples)))
-	// Normalize to 0-100 (max int16 is 32767)
-	level := int(rms / 32767.0 * 100.0)
+
+	// Normalize to 0.0 - 1.0
+	val := rms / 32768.0
+	if val < 0.000001 { // Avoid log(0)
+		return 0
+	}
+
+	// Convert to dB
+	db := 20 * math.Log10(val)
+
+	// Map -50dB (silence floor) to 0dB (max) to 0-100
+	const minDB = -50.0
+
+	if db < minDB {
+		return 0
+	}
+
+	// Scale
+	level := int((db - minDB) * (100.0 / (0 - minDB)))
+
 	if level > 100 {
 		level = 100
 	}
 	return level
 }
 
-// CalculatePeakLevel returns the peak level of PCM samples as 0-100
+// CalculatePeakLevel returns the peak level of PCM samples as 0-100 (Logarithmic/dB)
 func CalculatePeakLevel(samples []int16) int {
 	if len(samples) == 0 {
 		return 0
@@ -40,7 +58,26 @@ func CalculatePeakLevel(samples []int16) int {
 		}
 	}
 
-	return int(float64(peak) / 32767.0 * 100.0)
+	// Normalize
+	val := float64(peak) / 32768.0
+	if val < 0.000001 {
+		return 0
+	}
+
+	db := 20 * math.Log10(val)
+	const minDB = -50.0
+
+	if db < minDB {
+		// Linear falloff for very low signals to avoid clutter
+		return 0
+	}
+
+	level := int((db - minDB) * (100.0 / (0 - minDB)))
+	if level > 100 {
+		level = 100
+	}
+
+	return level
 }
 
 // LevelToBar converts a 0-100 level to a visual bar string

pkg/audio/playback.go

@@ -30,6 +30,9 @@ type Player struct {
 	// map[SenderID] -> AudioQueue
 	userBuffers map[uint16][]int16
 
+	// User EQs (DSP Filters)
+	userEQs map[uint16]*EQChain
+
 	// User settings
 	userSettings map[uint16]*UserSettings
 	bufferMu     sync.Mutex
@@ -66,11 +69,11 @@ func NewPlayer() (*Player, error) {
 
 	waveFormat := &wca.WAVEFORMATEX{
 		WFormatTag:      wca.WAVE_FORMAT_PCM,
-		NChannels:       1,
+		NChannels:       2, // STEREO
 		NSamplesPerSec:  48000,
 		WBitsPerSample:  16,
-		NBlockAlign:     2,
-		NAvgBytesPerSec: 96000,
+		NBlockAlign:     4,      // 16bit * 2 channels / 8 = 4 bytes
+		NAvgBytesPerSec: 192000, // 48000 * 4
 		CbSize:          0,
 	}
 
@@ -108,6 +111,7 @@ func NewPlayer() (*Player, error) {
 		muted:        false,
 		stopChan:     make(chan struct{}),
 		userBuffers:  make(map[uint16][]int16),
+		userEQs:      make(map[uint16]*EQChain),
 		userSettings: make(map[uint16]*UserSettings),
 	}, nil
 }
@@ -163,22 +167,112 @@ func (p *Player) PlayPCM(senderID uint16, samples []int16) {
 		return
 	}
 
+	// ---------------------------------------------------------
+	// PHASE 1: Read Configuration (Safe Copy)
+	// ---------------------------------------------------------
 	p.bufferMu.Lock()
-	defer p.bufferMu.Unlock()
 
 	// Check per-user mute
-	if settings, ok := p.userSettings[senderID]; ok && settings.Muted {
+	settings, hasSettings := p.userSettings[senderID]
+	if hasSettings && settings.Muted {
+		p.bufferMu.Unlock()
 		return
 	}
 
-	// Append to user's specific buffer
-	// This ensures sequential playback for the same user
-	p.userBuffers[senderID] = append(p.userBuffers[senderID], samples...)
+	// Get EQ Instance (Create if needed)
+	if _, ok := p.userEQs[senderID]; !ok {
+		p.userEQs[senderID] = NewEQChain(48000)
+	}
+	userEQ := p.userEQs[senderID]
 
-	// Limit buffer size per user to avoid memory leaks if stalled
-	if len(p.userBuffers[senderID]) > 48000*2 { // 2 seconds max
+	// Check/Copy Gains
+	var gains []float64
+	hasActiveEQ := false
+	if hasSettings && len(settings.Gains) == 5 {
+		// Copy gains to avoid race if UI changes them while we process
+		gains = make([]float64, 5)
+		copy(gains, settings.Gains)
+
+		for _, g := range gains {
+			if g != 0 {
+				hasActiveEQ = true
+				break
+			}
+		}
+	}
+
+	p.bufferMu.Unlock()
+	// ---------------------------------------------------------
+	// END PHASE 1 (Lock Released)
+	// ---------------------------------------------------------
+
+	// ---------------------------------------------------------
+	// PHASE 2: Heavy Processing (Concurrent)
+	// ---------------------------------------------------------
+
+	// Normalize to Stereo (Interleaved)
+	// If input is Mono (960 samples), expand to Stereo (1920 samples)
+	// If input is already Stereo, using it as is.
+	var stereoSamples []int16
+
+	if len(samples) < 1500 { // Heuristic for Mono (960)
+		stereoSamples = make([]int16, len(samples)*2)
+		for i, s := range samples {
+			stereoSamples[i*2] = s
+			stereoSamples[i*2+1] = s
+		}
+	} else {
+		// Already stereo (assumed)
+		stereoSamples = make([]int16, len(samples))
+		copy(stereoSamples, samples)
+	}
+
+	// Apply EQ Filters if needed
+	if hasActiveEQ {
+		// Update gains on the private EQ instance (Thread-safe per user)
+		for i, g := range gains {
+			userEQ.SetGain(i, g)
+		}
+		// Process Stereo
+		stereoSamples = userEQ.Process(stereoSamples)
+	}
+
+	// Calculate EQ bands for visualization
+	// Downmix to Mono for FFT visualization to save CPU and complexity
+	vizSamples := make([]int16, len(stereoSamples)/2)
+	for i := 0; i < len(vizSamples); i++ {
+		// Average L+R
+		val := (int32(stereoSamples[i*2]) + int32(stereoSamples[i*2+1])) / 2
+		vizSamples[i] = int16(val)
+	}
+	bands := CalculateEQBands(vizSamples, 48000)
+
+	// ---------------------------------------------------------
+	// PHASE 3: Write Output (Lock Acquired)
+	// ---------------------------------------------------------
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+
+	// Re-check existence (could have disconnected?)
+	// Update user settings with new bands
+	if _, ok := p.userSettings[senderID]; !ok {
+		p.userSettings[senderID] = &UserSettings{Volume: 1.0, Muted: false}
+	}
+	p.userSettings[senderID].EQBands = bands
+
+	// Append to user's specific buffer
+	p.userBuffers[senderID] = append(p.userBuffers[senderID], stereoSamples...)
+
+	// Limit buffer size per user (Stereo 2sec = 48000*2*2 = 192000 items)
+	// frameSamples is 960 (20ms). 2sec = 100 frames * 960 * 2 = 192000
+	const maxBufferSize = 48000 * 2 * 2 // 2 seconds stereo
+	if len(p.userBuffers[senderID]) > maxBufferSize {
 		// Drop oldest
-		drop := len(p.userBuffers[senderID]) - 48000
+		drop := len(p.userBuffers[senderID]) - maxBufferSize
+		// Ensure we drop aligned to stereo frame (even number)
+		if drop%2 != 0 {
+			drop++
+		}
 		p.userBuffers[senderID] = p.userBuffers[senderID][drop:]
 	}
 }
@@ -249,6 +343,66 @@ func (p *Player) GetUserSettings(clientID uint16) (float32, bool) {
 	return 1.0, false
 }
 
+// GetEQBands returns the current 5-band EQ values for a user (0.0-1.0)
+func (p *Player) GetEQBands(clientID uint16) []float64 {
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+
+	if settings, ok := p.userSettings[clientID]; ok {
+		return settings.EQBands
+	}
+	return nil
+}
+
+// SetUserGain sets the EQ gain for a specific band (0-4) and user.
+// Gain is in dB (e.g. -12.0 to +12.0)
+func (p *Player) SetUserGain(clientID uint16, bandIdx int, gainDb float64) {
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+
+	p.ensureUserSettings(clientID)
+
+	// Ensure Gains slice exists
+	if len(p.userSettings[clientID].Gains) != 5 {
+		p.userSettings[clientID].Gains = make([]float64, 5)
+	}
+
+	if bandIdx >= 0 && bandIdx < 5 {
+		p.userSettings[clientID].Gains[bandIdx] = gainDb
+	}
+}
+
+// GetUserGain returns the gain for a band
+func (p *Player) GetUserGain(clientID uint16, bandIdx int) float64 {
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+
+	if settings, ok := p.userSettings[clientID]; ok {
+		if len(settings.Gains) > bandIdx {
+			return settings.Gains[bandIdx]
+		}
+	}
+	return 0.0
+}
+
+func (p *Player) ensureUserSettings(clientID uint16) {
+	if _, ok := p.userSettings[clientID]; !ok {
+		p.userSettings[clientID] = &UserSettings{
+			Volume: 1.0,
+			Muted:  false,
+			Gains:  make([]float64, 5),
+		}
+	}
+}
+
+func (p *Player) ensureEQ(clientID uint16) {
+	if _, ok := p.userEQs[clientID]; !ok {
+		// New EQ chain
+		// Assume 48000 Hz, would be better to pass actual stream rate
+		p.userEQs[clientID] = NewEQChain(48000)
+	}
+}
+
 func (p *Player) playbackLoop() {
 	ticker := time.NewTicker(10 * time.Millisecond)
 	defer ticker.Stop()
@@ -278,7 +432,8 @@ func (p *Player) writeFrame() {
 		p.bufferMu.Lock()
 
 		// Mix audio from all active user buffers
-		mixed := make([]int32, frameSamples)
+		// Stereo mixing: buffer size is frameSamples * 2
+		mixed := make([]int32, frameSamples*2)
 		activeUsers := 0
 		hasAnyAudio := false
 
@@ -286,12 +441,15 @@ func (p *Player) writeFrame() {
 			if len(buf) > 0 {
 				hasAnyAudio = true
 				activeUsers++
-				// Take up to frameSamples from this user
-				toTake := frameSamples
-				if len(buf) < frameSamples {
+				// Take up to frameSamples*2 (Stereo) from this user
+				toTake := frameSamples * 2
+				if len(buf) < int(frameSamples)*2 {
 					toTake = len(buf)
 				}
 
+				// Ensure we take pairs (alignment)
+				toTake = toTake &^ 1 // clear lowest bit
+
 				for i := 0; i < toTake; i++ {
 					sample := int32(buf[i])
 
@@ -304,10 +462,10 @@ func (p *Player) writeFrame() {
 				}
 
 				// Advance buffer
-				if len(buf) <= frameSamples {
-					delete(p.userBuffers, id)
+				if len(buf) <= toTake {
+					delete(p.userBuffers, id) // Finished this buffer
 				} else {
-					p.userBuffers[id] = buf[frameSamples:]
+					p.userBuffers[id] = buf[toTake:]
 				}
 			}
 		}
@@ -330,8 +488,19 @@ func (p *Player) writeFrame() {
 		p.mu.Unlock()
 
 		// Write mixed samples with clipping protection and volume application
-		bufSlice := unsafe.Slice(buffer, int(frameSamples)*2)
-		for i := 0; i < int(frameSamples); i++ {
+		// Output buffer is for Stereo (frameSamples * 2 channels)
+		bufSlice := unsafe.Slice(buffer, int(frameSamples)*2*2) // *2 channels *2 bytes? No, unsafe.Slice takes count of Type.
+		// If buffer is *byte, we need bytes. frameSamples * 2 channels * 2 bytes/sample.
+		// Wait, GetBuffer returns BYTE pointer.
+		// Let's use uint16 slice.
+
+		// The logic below was: binary.LittleEndian.PutUint16(bufSlice[i*2:], ...)
+		// frameSamples was 960. loop 0..960.
+		// Now we have Stereo mixed buffer. Length = frameSamples * 2.
+		// We need to write frameSamples * 2 samples.
+
+		// Correct loop for Stereo:
+		for i := 0; i < int(frameSamples)*2; i++ { // Iterate over all samples (L, R, L, R...)
 			val := mixed[i]
 
 			// Apply master volume
@@ -343,6 +512,10 @@ func (p *Player) writeFrame() {
 			} else if val < -32768 {
 				val = -32768
 			}
+
+			// Map to output byte buffer
+			// i is sample index. Each sample is 2 bytes.
+			// Offset = i * 2.
 			binary.LittleEndian.PutUint16(bufSlice[i*2:], uint16(val))
 		}
 

pkg/audio/playback_linux.go

@@ -18,8 +18,12 @@ type Player struct {
 	running  bool
 	stopChan chan struct{}
 
-	// User buffers for mixing
+	// User buffers for mixing (Stereo Interleaved)
 	userBuffers map[uint16][]int16
+
+	// User EQs (DSP Filters)
+	userEQs map[uint16]*EQChain
+
 	// User settings
 	userSettings map[uint16]*UserSettings
 	bufferMu     sync.Mutex
@@ -35,6 +39,7 @@ func NewPlayer() (*Player, error) {
 		muted:        false,
 		stopChan:     make(chan struct{}),
 		userBuffers:  make(map[uint16][]int16),
+		userEQs:      make(map[uint16]*EQChain),
 		userSettings: make(map[uint16]*UserSettings),
 	}
 
@@ -48,10 +53,10 @@ func (p *Player) Start() error {
 		return nil
 	}
 
-	// Create stream (Mono, 48kHz, 16-bit)
+	// Create stream (Stereo, 48kHz, 16-bit)
 	// We'll use a callback-based stream for lower latency
 	var err error
-	p.stream, err = portaudio.OpenDefaultStream(0, 1, 48000, frameSamples, p.processAudio)
+	p.stream, err = portaudio.OpenDefaultStream(0, 2, 48000, frameSamples, p.processAudio)
 	if err != nil {
 		p.mu.Unlock()
 		return fmt.Errorf("failed to open portaudio stream: %w", err)
@@ -108,6 +113,8 @@ func (p *Player) processAudio(out []int16) {
 	vol := p.volume
 	p.mu.Unlock()
 
+	// Output `out` is Stereo Interleaved (L, R, L, R...)
+	// Its length is frameSamples * 2.
 	mixed := make([]int32, len(out))
 
 	for id, buf := range p.userBuffers {
@@ -117,6 +124,9 @@ func (p *Player) processAudio(out []int16) {
 				toTake = len(buf)
 			}
 
+			// Ensure pair alignment
+			toTake = toTake &^ 1
+
 			for i := 0; i < toTake; i++ {
 				sample := int32(buf[i])
 				if settings, ok := p.userSettings[id]; ok {
@@ -126,10 +136,10 @@ func (p *Player) processAudio(out []int16) {
 			}
 
 			// Advance buffer
-			if len(buf) <= len(out) {
+			if len(buf) <= toTake {
 				delete(p.userBuffers, id)
 			} else {
-				p.userBuffers[id] = buf[len(out):]
+				p.userBuffers[id] = buf[toTake:]
 			}
 		}
 	}
@@ -147,20 +157,144 @@ func (p *Player) processAudio(out []int16) {
 }
 
 func (p *Player) PlayPCM(senderID uint16, samples []int16) {
-	p.bufferMu.Lock()
-	defer p.bufferMu.Unlock()
-
-	if settings, ok := p.userSettings[senderID]; ok && settings.Muted {
+	if p.muted {
 		return
 	}
 
-	p.userBuffers[senderID] = append(p.userBuffers[senderID], samples...)
-	if len(p.userBuffers[senderID]) > 48000*2 {
-		drop := len(p.userBuffers[senderID]) - 48000
+	// ---------------------------------------------------------
+	// PHASE 1: Read Configuration (Safe Copy)
+	// ---------------------------------------------------------
+	p.bufferMu.Lock()
+
+	// Check per-user mute
+	settings, hasSettings := p.userSettings[senderID]
+	if hasSettings && settings.Muted {
+		p.bufferMu.Unlock()
+		return
+	}
+
+	// Get EQ Instance (Create if needed)
+	if _, ok := p.userEQs[senderID]; !ok {
+		p.userEQs[senderID] = NewEQChain(48000)
+	}
+	userEQ := p.userEQs[senderID]
+
+	// Check/Copy Gains
+	var gains []float64
+	hasActiveEQ := false
+	if hasSettings && len(settings.Gains) == 5 {
+		gains = make([]float64, 5)
+		copy(gains, settings.Gains)
+		for _, g := range gains {
+			if g != 0 {
+				hasActiveEQ = true
+				break
+			}
+		}
+	}
+
+	p.bufferMu.Unlock()
+
+	// ---------------------------------------------------------
+	// PHASE 2: Heavy Processing (Concurrent)
+	// ---------------------------------------------------------
+
+	// Normalize to Stereo
+	var stereoSamples []int16
+	if len(samples) < 1500 { // Mono
+		stereoSamples = make([]int16, len(samples)*2)
+		for i, s := range samples {
+			stereoSamples[i*2] = s
+			stereoSamples[i*2+1] = s
+		}
+	} else {
+		// Already stereo
+		stereoSamples = make([]int16, len(samples))
+		copy(stereoSamples, samples)
+	}
+
+	if hasActiveEQ {
+		for i, g := range gains {
+			userEQ.SetGain(i, g)
+		}
+		stereoSamples = userEQ.Process(stereoSamples)
+	}
+
+	// Calculate EQ bands (Downmix for visualization)
+	vizSamples := make([]int16, len(stereoSamples)/2)
+	for i := 0; i < len(vizSamples); i++ {
+		val := (int32(stereoSamples[i*2]) + int32(stereoSamples[i*2+1])) / 2
+		vizSamples[i] = int16(val)
+	}
+	bands := CalculateEQBands(vizSamples, 48000)
+
+	// ---------------------------------------------------------
+	// PHASE 3: Write Output (Lock Acquired)
+	// ---------------------------------------------------------
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+
+	if _, ok := p.userSettings[senderID]; !ok {
+		p.userSettings[senderID] = &UserSettings{Volume: 1.0, Muted: false}
+	}
+	p.userSettings[senderID].EQBands = bands
+
+	p.userBuffers[senderID] = append(p.userBuffers[senderID], stereoSamples...)
+	const maxBufferSize = 48000 * 2 * 2 // 2 seconds stereo
+	if len(p.userBuffers[senderID]) > maxBufferSize {
+		drop := len(p.userBuffers[senderID]) - maxBufferSize
+		if drop%2 != 0 {
+			drop++
+		}
 		p.userBuffers[senderID] = p.userBuffers[senderID][drop:]
 	}
 }
 
+// GetEQBands returns the current 5-band EQ values for a user (0.0-1.0)
+func (p *Player) GetEQBands(clientID uint16) []float64 {
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+	if settings, ok := p.userSettings[clientID]; ok {
+		return settings.EQBands
+	}
+	return nil
+}
+
+// SetUserGain sets the EQ gain for a specific band (0-4) and user.
+func (p *Player) SetUserGain(clientID uint16, bandIdx int, gainDb float64) {
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+	p.ensureUserSettings(clientID)
+	if len(p.userSettings[clientID].Gains) != 5 {
+		p.userSettings[clientID].Gains = make([]float64, 5)
+	}
+	if bandIdx >= 0 && bandIdx < 5 {
+		p.userSettings[clientID].Gains[bandIdx] = gainDb
+	}
+}
+
+// GetUserGain returns the gain for a band
+func (p *Player) GetUserGain(clientID uint16, bandIdx int) float64 {
+	p.bufferMu.Lock()
+	defer p.bufferMu.Unlock()
+	if settings, ok := p.userSettings[clientID]; ok {
+		if len(settings.Gains) > bandIdx {
+			return settings.Gains[bandIdx]
+		}
+	}
+	return 0.0
+}
+
+func (p *Player) ensureUserSettings(clientID uint16) {
+	if _, ok := p.userSettings[clientID]; !ok {
+		p.userSettings[clientID] = &UserSettings{
+			Volume: 1.0,
+			Muted:  false,
+			Gains:  make([]float64, 5),
+		}
+	}
+}
+
 func (p *Player) SetVolume(vol float32) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
@@ -176,18 +310,14 @@ func (p *Player) SetMuted(muted bool) {
 func (p *Player) SetUserVolume(clientID uint16, vol float32) {
 	p.bufferMu.Lock()
 	defer p.bufferMu.Unlock()
-	if _, ok := p.userSettings[clientID]; !ok {
-		p.userSettings[clientID] = &UserSettings{Volume: 1.0, Muted: false}
-	}
+	p.ensureUserSettings(clientID)
 	p.userSettings[clientID].Volume = vol
 }
 
 func (p *Player) SetUserMuted(clientID uint16, muted bool) {
 	p.bufferMu.Lock()
 	defer p.bufferMu.Unlock()
-	if _, ok := p.userSettings[clientID]; !ok {
-		p.userSettings[clientID] = &UserSettings{Volume: 1.0, Muted: false}
-	}
+	p.ensureUserSettings(clientID)
 	p.userSettings[clientID].Muted = muted
 }
 

scripts/run.ps1

@@ -4,4 +4,4 @@ $env:PKG_CONFIG_PATH = "D:\esto_al_path\msys64\mingw64\lib\pkgconfig"
 Write-Host "Starting TeamSpeak Client (Windows Native)..." -ForegroundColor Cyan
 # go run ./cmd/client/main.go --server localhost:9987
 # go run ./cmd/example --server localhost:9987
-go run ./cmd/tui --server ts.vlazaro.es:9987 --nickname Adam --debug
+go run ./cmd/tui --server 127.0.0.1:9987 --nickname Adam --debug