Add final mix VU meters

daw-backend/src/audio/engine.rs

@@ -71,6 +71,16 @@ pub struct Engine {
     // Disk reader for streaming playback of compressed files
     disk_reader: Option<crate::audio::disk_reader::DiskReader>,
 
+    // Input monitoring and metering
+    input_monitoring: bool,
+    input_gain: f32,
+    input_level_peak: f32,
+    input_level_counter: usize,
+    output_level_peak_l: f32,
+    output_level_peak_r: f32,
+    output_level_counter: usize,
+    track_level_counter: usize,
+
     // Callback timing diagnostics (enabled by DAW_AUDIO_DEBUG=1)
     debug_audio: bool,
     callback_count: u64,
@@ -138,6 +148,14 @@ impl Engine {
             metronome: Metronome::new(sample_rate),
             recording_sample_buffer: Vec::with_capacity(4096),
             disk_reader: Some(disk_reader),
+            input_monitoring: false,
+            input_gain: 1.0,
+            input_level_peak: 0.0,
+            input_level_counter: 0,
+            output_level_peak_l: 0.0,
+            output_level_peak_r: 0.0,
+            output_level_counter: 0,
+            track_level_counter: 0,
             debug_audio: std::env::var("DAW_AUDIO_DEBUG").map_or(false, |v| v == "1"),
             callback_count: 0,
             timing_worst_total_us: 0,
@@ -380,73 +398,116 @@ impl Engine {
             self.process_live_midi(output);
         }
 
-        // Process recording if active (independent of playback state)
+        // Compute stereo output peaks for master VU meter (independent of playback state)
-        if let Some(recording) = &mut self.recording_state {
+        {
+            let channels = self.channels as usize;
+            for frame in output.chunks(channels) {
+                if channels >= 2 {
+                    self.output_level_peak_l = self.output_level_peak_l.max(frame[0].abs());
+                    self.output_level_peak_r = self.output_level_peak_r.max(frame[1].abs());
+                } else {
+                    let v = frame[0].abs();
+                    self.output_level_peak_l = self.output_level_peak_l.max(v);
+                    self.output_level_peak_r = self.output_level_peak_r.max(v);
+                }
+            }
+            self.output_level_counter += output.len();
+            let meter_interval = self.sample_rate as usize / 20; // ~50ms
+            if self.output_level_counter >= meter_interval {
+                let _ = self.event_tx.push(AudioEvent::OutputLevel(self.output_level_peak_l, self.output_level_peak_r));
+                self.output_level_peak_l = 0.0;
+                self.output_level_peak_r = 0.0;
+                self.output_level_counter = 0;
+            }
+
+            // Send per-track peak levels periodically
+            self.track_level_counter += output.len();
+            if self.track_level_counter >= meter_interval {
+                let levels = self.project.collect_track_peaks();
+                let _ = self.event_tx.push(AudioEvent::TrackLevels(levels));
+                self.track_level_counter = 0;
+            }
+        }
+
+        // Process input monitoring and/or recording (independent of playback state)
+        let is_recording = self.recording_state.is_some();
+        if is_recording || self.input_monitoring {
             if let Some(input_rx) = &mut self.input_rx {
-                // Phase 1: Discard stale samples by popping without storing
+                // Phase 1: Discard stale samples during recording skip phase
-                // (fast — no Vec push, no add_samples overhead)
+                if let Some(recording) = &mut self.recording_state {
-                while recording.samples_to_skip > 0 {
+                    while recording.samples_to_skip > 0 {
-                    match input_rx.pop() {
+                        match input_rx.pop() {
-                        Ok(_) => recording.samples_to_skip -= 1,
+                            Ok(_) => recording.samples_to_skip -= 1,
-                        Err(_) => break,
+                            Err(_) => break,
+                        }
                     }
                 }
 
-                // Phase 2: Pull fresh samples for actual recording
+                // Phase 2: Pull fresh samples
                 self.recording_sample_buffer.clear();
                 while let Ok(sample) = input_rx.pop() {
-                    self.recording_sample_buffer.push(sample);
+                    // Apply input gain
+                    self.recording_sample_buffer.push(sample * self.input_gain);
                 }
 
-                // Add samples to recording
                 if !self.recording_sample_buffer.is_empty() {
-                    // Calculate how many samples will be skipped (stale buffer data)
+                    // Compute input peak for VU metering
-                    let skip = if recording.paused {
+                    let input_peak = self.recording_sample_buffer.iter().map(|s| s.abs()).fold(0.0f32, f32::max);
-                        self.recording_sample_buffer.len()
+                    self.input_level_peak = self.input_level_peak.max(input_peak);
-                    } else {
+                    self.input_level_counter += self.recording_sample_buffer.len();
-                        recording.samples_to_skip.min(self.recording_sample_buffer.len())
+                    let meter_interval = self.sample_rate as usize / 20; // ~50ms
-                    };
+                    if self.input_level_counter >= meter_interval {
+                        let _ = self.event_tx.push(AudioEvent::InputLevel(self.input_level_peak));
+                        self.input_level_peak = 0.0;
+                        self.input_level_counter = 0;
+                    }
 
-                    match recording.add_samples(&self.recording_sample_buffer) {
+                    // Feed samples to recording if active
-                        Ok(_flushed) => {
+                    if let Some(recording) = &mut self.recording_state {
-                            // Mirror non-skipped samples to UI for live waveform display
+                        let skip = if recording.paused {
-                            if skip < self.recording_sample_buffer.len() {
+                            self.recording_sample_buffer.len()
-                                if let Some(ref mut mirror_tx) = self.recording_mirror_tx {
+                        } else {
-                                    for &sample in &self.recording_sample_buffer[skip..] {
+                            recording.samples_to_skip.min(self.recording_sample_buffer.len())
-                                        let _ = mirror_tx.push(sample);
+                        };
+
+                        match recording.add_samples(&self.recording_sample_buffer) {
+                            Ok(_flushed) => {
+                                // Mirror non-skipped samples to UI for live waveform display
+                                if skip < self.recording_sample_buffer.len() {
+                                    if let Some(ref mut mirror_tx) = self.recording_mirror_tx {
+                                        for &sample in &self.recording_sample_buffer[skip..] {
+                                            let _ = mirror_tx.push(sample);
+                                        }
                                     }
                                 }
-                            }
 
-                            // Update clip duration every callback for sample-accurate timing
+                                // Update clip duration every callback for sample-accurate timing
-                            let duration = recording.duration();
+                                let duration = recording.duration();
-                            let clip_id = recording.clip_id;
+                                let clip_id = recording.clip_id;
-                            let track_id = recording.track_id;
+                                let track_id = recording.track_id;
 
-                            // Update clip duration in project as recording progresses
+                                // Update clip duration in project as recording progresses
-                            if let Some(crate::audio::track::TrackNode::Audio(track)) = self.project.get_track_mut(track_id) {
+                                if let Some(crate::audio::track::TrackNode::Audio(track)) = self.project.get_track_mut(track_id) {
-                                if let Some(clip) = track.clips.iter_mut().find(|c| c.id == clip_id) {
+                                    if let Some(clip) = track.clips.iter_mut().find(|c| c.id == clip_id) {
-                                    // Update both internal_end and external_duration as recording progresses
+                                        clip.internal_end = clip.internal_start + duration;
-                                    clip.internal_end = clip.internal_start + duration;
+                                        clip.external_duration = duration;
-                                    clip.external_duration = duration;
+                                    }
+                                }
+
+                                // Send progress event periodically (every ~0.1 seconds)
+                                self.recording_progress_counter += self.recording_sample_buffer.len();
+                                if self.recording_progress_counter >= (self.sample_rate as usize / 10) {
+                                    let _ = self.event_tx.push(AudioEvent::RecordingProgress(clip_id, duration));
+                                    self.recording_progress_counter = 0;
                                 }
                             }
-
+                            Err(e) => {
-                            // Send progress event periodically (every ~0.1 seconds)
+                                let _ = self.event_tx.push(AudioEvent::RecordingError(
-                            self.recording_progress_counter += self.recording_sample_buffer.len();
+                                    format!("Recording write error: {}", e)
-                            if self.recording_progress_counter >= (self.sample_rate as usize / 10) {
+                                ));
-                                let _ = self.event_tx.push(AudioEvent::RecordingProgress(clip_id, duration));
+                                self.recording_state = None;
-                                self.recording_progress_counter = 0;
                             }
                         }
-                        Err(e) => {
-                            // Recording error occurred
-                            let _ = self.event_tx.push(AudioEvent::RecordingError(
-                                format!("Recording write error: {}", e)
-                            ));
-                            // Stop recording on error
-                            self.recording_state = None;
-                        }
                     }
                 }
             }
@@ -1136,6 +1197,14 @@ impl Engine {
                 self.metronome.set_enabled(enabled);
             }
 
+            Command::SetInputMonitoring(enabled) => {
+                self.input_monitoring = enabled;
+            }
+
+            Command::SetInputGain(gain) => {
+                self.input_gain = gain;
+            }
+
             Command::SetTempo(bpm, time_sig) => {
                 self.metronome.update_timing(bpm, time_sig);
                 self.project.set_tempo(bpm, time_sig.0);
@@ -2851,6 +2920,16 @@ impl EngineController {
         let _ = self.command_tx.push(Command::SetTrackSolo(track_id, solo));
     }
 
+    /// Enable or disable input monitoring (mic level metering)
+    pub fn set_input_monitoring(&mut self, enabled: bool) {
+        let _ = self.command_tx.push(Command::SetInputMonitoring(enabled));
+    }
+
+    /// Set the input gain multiplier (applied before recording)
+    pub fn set_input_gain(&mut self, gain: f32) {
+        let _ = self.command_tx.push(Command::SetInputGain(gain));
+    }
+
     /// Move a clip to a new timeline position (changes external_start)
     pub fn move_clip(&mut self, track_id: TrackId, clip_id: ClipId, new_start_time: f64) {
         let _ = self.command_tx.push(Command::MoveClip(track_id, clip_id, new_start_time));

daw-backend/src/audio/project.rs

@@ -441,13 +441,34 @@ impl Project {
         // Handle audio track vs MIDI track vs group track
         match self.tracks.get_mut(&track_id) {
             Some(TrackNode::Audio(track)) => {
-                // Render audio track directly into output
+                // Render audio track into a temp buffer for peak measurement
-                track.render(output, audio_pool, ctx.playhead_seconds, ctx.sample_rate, ctx.channels);
+                let mut track_buffer = buffer_pool.acquire();
+                track_buffer.resize(output.len(), 0.0);
+                track_buffer.fill(0.0);
+                track.render(&mut track_buffer, audio_pool, ctx.playhead_seconds, ctx.sample_rate, ctx.channels);
+                // Accumulate peak level for VU metering (max over meter interval)
+                let buffer_peak = track_buffer.iter().map(|s| s.abs()).fold(0.0f32, f32::max);
+                track.peak_level = track.peak_level.max(buffer_peak);
+                // Mix into output
+                for (out, src) in output.iter_mut().zip(track_buffer.iter()) {
+                    *out += src;
+                }
+                buffer_pool.release(track_buffer);
             }
             Some(TrackNode::Midi(track)) => {
-                // Render MIDI track directly into output
+                // Render MIDI track into a temp buffer for peak measurement
-                // Access midi_clip_pool from self - safe because we only need immutable access
+                let mut track_buffer = buffer_pool.acquire();
-                track.render(output, &self.midi_clip_pool, ctx.playhead_seconds, ctx.sample_rate, ctx.channels);
+                track_buffer.resize(output.len(), 0.0);
+                track_buffer.fill(0.0);
+                track.render(&mut track_buffer, &self.midi_clip_pool, ctx.playhead_seconds, ctx.sample_rate, ctx.channels);
+                // Accumulate peak level for VU metering (max over meter interval)
+                let buffer_peak = track_buffer.iter().map(|s| s.abs()).fold(0.0f32, f32::max);
+                track.peak_level = track.peak_level.max(buffer_peak);
+                // Mix into output
+                for (out, src) in output.iter_mut().zip(track_buffer.iter()) {
+                    *out += src;
+                }
+                buffer_pool.release(track_buffer);
             }
             Some(TrackNode::Group(group)) => {
                 // Skip rendering if playhead is outside the metatrack's trim window
@@ -534,6 +555,25 @@ impl Project {
         }
     }
 
+    /// Collect per-track peak levels for VU metering and reset accumulators
+    pub fn collect_track_peaks(&mut self) -> Vec<(TrackId, f32)> {
+        let mut levels = Vec::new();
+        for (id, track) in &mut self.tracks {
+            match track {
+                TrackNode::Audio(t) => {
+                    levels.push((*id, t.peak_level));
+                    t.peak_level = 0.0;
+                }
+                TrackNode::Midi(t) => {
+                    levels.push((*id, t.peak_level));
+                    t.peak_level = 0.0;
+                }
+                TrackNode::Group(_) => {}
+            }
+        }
+        levels
+    }
+
     /// Stop all notes on all MIDI tracks
     pub fn stop_all_notes(&mut self) {
         for track in self.tracks.values_mut() {

daw-backend/src/audio/track.rs

@@ -435,6 +435,10 @@ pub struct MidiTrack {
     /// Used to detect when the playhead exits a clip, so we can send all-notes-off.
     #[serde(skip)]
     prev_active_instances: HashSet<MidiClipInstanceId>,
+
+    /// Peak level of last render() call (for VU metering)
+    #[serde(skip, default)]
+    pub peak_level: f32,
 }
 
 impl Clone for MidiTrack {
@@ -452,6 +456,7 @@ impl Clone for MidiTrack {
             next_automation_id: self.next_automation_id,
             live_midi_queue: Vec::new(), // Don't clone live MIDI queue
             prev_active_instances: HashSet::new(),
+            peak_level: 0.0,
         }
     }
 }
@@ -479,6 +484,7 @@ impl MidiTrack {
             next_automation_id: 0,
             live_midi_queue: Vec::new(),
             prev_active_instances: HashSet::new(),
+            peak_level: 0.0,
         }
     }
 
@@ -705,6 +711,10 @@ pub struct AudioTrack {
     /// Pre-allocated buffer for clip rendering (avoids heap allocation per callback)
     #[serde(skip, default)]
     clip_render_buffer: Vec<f32>,
+
+    /// Peak level of last render() call (for VU metering)
+    #[serde(skip, default)]
+    pub peak_level: f32,
 }
 
 impl Clone for AudioTrack {
@@ -721,6 +731,7 @@ impl Clone for AudioTrack {
             effects_graph_preset: self.effects_graph_preset.clone(),
             effects_graph: default_audio_graph(), // Create fresh graph, not cloned
             clip_render_buffer: Vec::new(),
+            peak_level: 0.0,
         }
     }
 }
@@ -764,6 +775,7 @@ impl AudioTrack {
             effects_graph_preset: None,
             effects_graph,
             clip_render_buffer: Vec::new(),
+            peak_level: 0.0,
         }
     }
 
@@ -987,7 +999,7 @@ impl AudioTrack {
         }
 
         // Calculate combined gain
-        let combined_gain = clip.gain * self.volume;
+        let combined_gain = clip.gain;
 
         let mut total_rendered = 0;
 

daw-backend/src/command/types.rs

@@ -226,6 +226,12 @@ pub enum Command {
         priority: u8, // 0=Low, 1=Medium, 2=High
     },
 
+    // Input monitoring/gain commands
+    /// Enable or disable input monitoring (mic level metering)
+    SetInputMonitoring(bool),
+    /// Set the input gain multiplier (applied before recording)
+    SetInputGain(f32),
+
     // Async audio import
     /// Import an audio file asynchronously. The engine probes the file format
     /// and either memory-maps it (WAV/AIFF) or sets up stream decode
@@ -333,6 +339,13 @@ pub enum AudioEvent {
         channels: u32,
     },
 
+    /// Peak amplitude of mic input (for input monitoring meter)
+    InputLevel(f32),
+    /// Peak amplitude of mix output (for master meter), stereo (left, right)
+    OutputLevel(f32, f32),
+    /// Per-track playback peak levels
+    TrackLevels(Vec<(TrackId, f32)>),
+
     /// Background waveform decode progress/completion for a compressed audio file.
     /// Internal event — consumed by the engine to update the pool, not forwarded to UI.
     /// `decoded_frames` < `total_frames` means partial; equal means complete.

lightningbeam-ui/lightningbeam-core/src/actions/set_layer_properties.rs

@@ -12,6 +12,7 @@ use uuid::Uuid;
 #[derive(Clone, Debug)]
 pub enum LayerProperty {
     Volume(f64),
+    InputGain(f64),
     Muted(bool),
     Soloed(bool),
     Locked(bool),
@@ -25,6 +26,7 @@ pub enum LayerProperty {
 #[derive(Clone, Debug)]
 enum OldValue {
     Volume(f64),
+    InputGain(f64),
     Muted(bool),
     Soloed(bool),
     Locked(bool),
@@ -85,6 +87,7 @@ impl Action for SetLayerPropertiesAction {
                 if self.old_values[i].is_none() {
                     self.old_values[i] = Some(match &self.property {
                         LayerProperty::Volume(_) => OldValue::Volume(layer.volume()),
+                        LayerProperty::InputGain(_) => OldValue::InputGain(layer.layer().input_gain),
                         LayerProperty::Muted(_) => OldValue::Muted(layer.muted()),
                         LayerProperty::Soloed(_) => OldValue::Soloed(layer.soloed()),
                         LayerProperty::Locked(_) => OldValue::Locked(layer.locked()),
@@ -104,6 +107,7 @@ impl Action for SetLayerPropertiesAction {
                 // Set new value
                 match &self.property {
                     LayerProperty::Volume(v) => layer.set_volume(*v),
+                    LayerProperty::InputGain(g) => layer.layer_mut().input_gain = *g,
                     LayerProperty::Muted(m) => layer.set_muted(*m),
                     LayerProperty::Soloed(s) => layer.set_soloed(*s),
                     LayerProperty::Locked(l) => layer.set_locked(*l),
@@ -128,6 +132,7 @@ impl Action for SetLayerPropertiesAction {
                 if let Some(old_value) = &self.old_values[i] {
                     match old_value {
                         OldValue::Volume(v) => layer.set_volume(*v),
+                        OldValue::InputGain(g) => layer.layer_mut().input_gain = *g,
                         OldValue::Muted(m) => layer.set_muted(*m),
                         OldValue::Soloed(s) => layer.set_soloed(*s),
                         OldValue::Locked(l) => layer.set_locked(*l),
@@ -159,6 +164,7 @@ impl Action for SetLayerPropertiesAction {
             if let Some(&track_id) = backend.layer_to_track_map.get(&layer_id) {
                 match &self.property {
                     LayerProperty::Volume(v) => controller.set_track_volume(track_id, *v as f32),
+                    LayerProperty::InputGain(g) => controller.set_input_gain(*g as f32),
                     LayerProperty::Muted(m) => controller.set_track_mute(track_id, *m),
                     LayerProperty::Soloed(s) => controller.set_track_solo(track_id, *s),
                     _ => {} // Locked/Opacity/Visible/CameraEnabled are UI-only
@@ -183,6 +189,7 @@ impl Action for SetLayerPropertiesAction {
                 if let Some(old_value) = &self.old_values[i] {
                     match old_value {
                         OldValue::Volume(v) => controller.set_track_volume(track_id, *v as f32),
+                        OldValue::InputGain(g) => controller.set_input_gain(*g as f32),
                         OldValue::Muted(m) => controller.set_track_mute(track_id, *m),
                         OldValue::Soloed(s) => controller.set_track_solo(track_id, *s),
                         _ => {} // Locked/Opacity/Visible are UI-only
@@ -196,6 +203,7 @@ impl Action for SetLayerPropertiesAction {
     fn description(&self) -> String {
         let property_name = match &self.property {
             LayerProperty::Volume(_) => "volume",
+            LayerProperty::InputGain(_) => "input gain",
             LayerProperty::Muted(_) => "mute",
             LayerProperty::Soloed(_) => "solo",
             LayerProperty::Locked(_) => "lock",

lightningbeam-ui/lightningbeam-core/src/layer.rs

@@ -60,6 +60,8 @@ pub trait LayerTrait {
     fn set_locked(&mut self, locked: bool);
 }
 
+fn default_input_gain() -> f64 { 1.0 }
+
 /// Base layer structure
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct Layer {
@@ -84,6 +86,10 @@ pub struct Layer {
     /// Audio volume (1.0 = 100%, affects nested audio layers/clips)
     pub volume: f64,
 
+    /// Input gain for recording (1.0 = unity, range 0.0–4.0)
+    #[serde(default = "default_input_gain")]
+    pub input_gain: f64,
+
     /// Audio mute state
     pub muted: bool,
 
@@ -108,6 +114,7 @@ impl Layer {
             visible: true,
             opacity: 1.0,
             volume: 1.0,             // 100% volume
+            input_gain: 1.0,
             muted: false,
             soloed: false,
             locked: false,
@@ -125,6 +132,7 @@ impl Layer {
             visible: true,
             opacity: 1.0,
             volume: 1.0,
+            input_gain: 1.0,
             muted: false,
             soloed: false,
             locked: false,

lightningbeam-ui/lightningbeam-editor/src/main.rs

@@ -814,6 +814,11 @@ struct EditorApp {
     region_selection: Option<lightningbeam_core::selection::RegionSelection>,
     region_select_mode: lightningbeam_core::tool::RegionSelectMode,
 
+    // VU meter levels
+    input_level: f32,
+    output_level: (f32, f32),
+    track_levels: HashMap<daw_backend::TrackId, f32>,
+
     /// Cache for MIDI event data (keyed by backend midi_clip_id)
     /// Prevents repeated backend queries for the same MIDI clip
     /// Format: (timestamp, note_number, velocity, is_note_on)
@@ -1057,6 +1062,9 @@ impl EditorApp {
             polygon_sides: 5,                // Default to pentagon
             region_selection: None,
             region_select_mode: lightningbeam_core::tool::RegionSelectMode::default(),
+            input_level: 0.0,
+            output_level: (0.0, 0.0),
+            track_levels: HashMap::new(),
             midi_event_cache: HashMap::new(), // Initialize empty MIDI event cache
             audio_duration_cache: HashMap::new(), // Initialize empty audio duration cache
             audio_pools_with_new_waveforms: HashSet::new(), // Track pool indices with new raw audio
@@ -4672,6 +4680,19 @@ impl eframe::App for EditorApp {
                             );
                             ctx.request_repaint();
                         }
+                        AudioEvent::InputLevel(peak) => {
+                            self.input_level = self.input_level.max(peak);
+                        }
+                        AudioEvent::OutputLevel(peak_l, peak_r) => {
+                            self.output_level.0 = self.output_level.0.max(peak_l);
+                            self.output_level.1 = self.output_level.1.max(peak_r);
+                        }
+                        AudioEvent::TrackLevels(levels) => {
+                            for (track_id, peak) in levels {
+                                let entry = self.track_levels.entry(track_id).or_insert(0.0);
+                                *entry = entry.max(peak);
+                            }
+                        }
                         _ => {} // Ignore other events for now
                     }
                 }
@@ -4686,6 +4707,39 @@ impl eframe::App for EditorApp {
             }
         }
 
+        // Update input monitoring based on active layer
+        if let Some(controller) = &self.audio_controller {
+            let should_monitor = self.active_layer_id.map_or(false, |layer_id| {
+                let doc = self.action_executor.document();
+                if let Some(layer) = doc.get_layer(&layer_id) {
+                    matches!(layer, lightningbeam_core::layer::AnyLayer::Audio(a) if a.audio_layer_type == lightningbeam_core::layer::AudioLayerType::Sampled)
+                } else {
+                    false
+                }
+            });
+            if let Ok(mut ctrl) = controller.try_lock() {
+                ctrl.set_input_monitoring(should_monitor);
+            }
+        }
+
+        // Decay VU meter levels (~1.5s full fall at 60fps)
+        {
+            let decay = 0.97f32;
+            self.input_level *= decay;
+            self.output_level.0 *= decay;
+            self.output_level.1 *= decay;
+            for level in self.track_levels.values_mut() {
+                *level *= decay;
+            }
+            // Request repaint while any level is visible
+            let any_active = self.input_level > 0.001
+                || self.output_level.0 > 0.001 || self.output_level.1 > 0.001
+                || self.track_levels.values().any(|&v| v > 0.001);
+            if any_active {
+                ctx.request_repaint();
+            }
+        }
+
         let _post_events_ms = _frame_start.elapsed().as_secs_f64() * 1000.0;
 
         // Request continuous repaints when playing to update time display
@@ -5075,6 +5129,10 @@ impl eframe::App for EditorApp {
                     target_format: self.target_format,
                     pending_menu_actions: &mut pending_menu_actions,
                     clipboard_manager: &mut self.clipboard_manager,
+                    input_level: self.input_level,
+                    output_level: self.output_level,
+                    track_levels: &self.track_levels,
+                    track_to_layer_map: &self.track_to_layer_map,
                     waveform_stereo: self.config.waveform_stereo,
                     project_generation: &mut self.project_generation,
                     script_to_edit: &mut self.script_to_edit,

lightningbeam-ui/lightningbeam-editor/src/panes/mod.rs

@@ -244,6 +244,12 @@ pub struct SharedPaneState<'a> {
     pub pending_menu_actions: &'a mut Vec<crate::menu::MenuAction>,
     /// Clipboard manager for cut/copy/paste operations
     pub clipboard_manager: &'a mut lightningbeam_core::clipboard::ClipboardManager,
+    // VU meter levels
+    pub input_level: f32,
+    pub output_level: (f32, f32),
+    pub track_levels: &'a std::collections::HashMap<daw_backend::TrackId, f32>,
+    #[allow(dead_code)] // Available for panes that need reverse track->layer lookup
+    pub track_to_layer_map: &'a std::collections::HashMap<daw_backend::TrackId, Uuid>,
     /// Whether to show waveforms as stacked stereo (true) or combined mono (false)
     pub waveform_stereo: bool,
     /// Generation counter - incremented on project load to force reloads

lightningbeam-ui/lightningbeam-editor/src/panes/timeline.rs

@@ -1260,6 +1260,9 @@ impl TimelinePane {
         pending_actions: &mut Vec<Box<dyn lightningbeam_core::action::Action>>,
         _document: &lightningbeam_core::document::Document,
         context_layers: &[&lightningbeam_core::layer::AnyLayer],
+        layer_to_track_map: &std::collections::HashMap<uuid::Uuid, daw_backend::TrackId>,
+        track_levels: &std::collections::HashMap<daw_backend::TrackId, f32>,
+        input_level: f32,
     ) {
         // Background for header column
         let header_style = theme.style(".timeline-header", ui.ctx());
@@ -1659,6 +1662,10 @@ impl TimelinePane {
                 (response, temp_slider_value)
             }).inner;
 
+            // Block layer drag while interacting with the slider
+            if volume_response.0.dragged() || volume_response.0.has_focus() {
+                self.layer_control_clicked = true;
+            }
             if volume_response.0.changed() {
                 self.layer_control_clicked = true;
                 // Map slider position (0.0-1.0) back to volume (0.0-2.0)
@@ -1678,6 +1685,93 @@ impl TimelinePane {
                 ));
             }
 
+            // Input gain slider for sampled audio layers (below volume slider)
+            if let lightningbeam_core::layer::AnyLayer::Audio(audio_layer) = layer_for_controls {
+                if audio_layer.audio_layer_type == lightningbeam_core::layer::AudioLayerType::Sampled {
+                    let gain_slider_rect = egui::Rect::from_min_size(
+                        egui::pos2(controls_right - slider_width, controls_top + 22.0),
+                        egui::vec2(slider_width, 16.0),
+                    );
+                    let current_gain = audio_layer.layer.input_gain;
+
+                    // Map gain (0.0-4.0) to slider (0.0-1.0): linear
+                    let mut slider_val = (current_gain / 4.0) as f32;
+                    let gain_response = ui.scope_builder(egui::UiBuilder::new().max_rect(gain_slider_rect), |ui| {
+                        let slider = egui::Slider::new(&mut slider_val, 0.0..=1.0f32)
+                            .show_value(false);
+                        ui.add(slider)
+                    }).inner;
+
+                    // Block layer drag while interacting with the slider
+                    if gain_response.dragged() || gain_response.has_focus() {
+                        self.layer_control_clicked = true;
+                    }
+                    if gain_response.changed() {
+                        self.layer_control_clicked = true;
+                        let new_gain = (slider_val * 4.0) as f64;
+                        pending_actions.push(Box::new(
+                            lightningbeam_core::actions::SetLayerPropertiesAction::new(
+                                layer_id,
+                                lightningbeam_core::actions::LayerProperty::InputGain(new_gain),
+                            )
+                        ));
+                    }
+
+                    // Label
+                    let label_rect = egui::Rect::from_min_size(
+                        egui::pos2(gain_slider_rect.min.x - 26.0, controls_top + 22.0),
+                        egui::vec2(24.0, 16.0),
+                    );
+                    ui.painter().text(
+                        label_rect.center(),
+                        egui::Align2::CENTER_CENTER,
+                        "Gain",
+                        egui::FontId::proportional(9.0),
+                        egui::Color32::from_gray(140),
+                    );
+                }
+            }
+
+            // Per-layer VU meter bar (4px tall at bottom of header)
+            {
+                // Look up the track level for this layer
+                let mut level = 0.0f32;
+                if let Some(&track_id) = layer_to_track_map.get(&layer_id) {
+                    if let Some(&track_level) = track_levels.get(&track_id) {
+                        level = track_level;
+                    }
+                }
+
+                // For active sampled audio layer, show max of track level and input level
+                let is_active_sampled_audio = active_layer_id.map_or(false, |id| id == layer_id)
+                    && matches!(layer_for_controls, lightningbeam_core::layer::AnyLayer::Audio(a) if a.audio_layer_type == lightningbeam_core::layer::AudioLayerType::Sampled);
+                if is_active_sampled_audio {
+                    level = level.max(input_level);
+                }
+
+                if level > 0.001 {
+                    let meter_height = 4.0;
+                    let meter_rect = egui::Rect::from_min_size(
+                        egui::pos2(header_rect.min.x, header_rect.max.y - meter_height - 1.0),
+                        egui::vec2(header_rect.width(), meter_height),
+                    );
+                    let clamped = level.min(1.0);
+                    let filled_width = meter_rect.width() * clamped;
+                    let color = if clamped > 0.9 {
+                        egui::Color32::from_rgb(220, 50, 50)
+                    } else if clamped > 0.7 {
+                        egui::Color32::from_rgb(220, 200, 50)
+                    } else {
+                        egui::Color32::from_rgb(50, 200, 80)
+                    };
+                    let filled = egui::Rect::from_min_size(
+                        meter_rect.left_top(),
+                        egui::vec2(filled_width, meter_rect.height()),
+                    );
+                    ui.painter().rect_filled(filled, 0.0, color);
+                }
+            }
+
             // Separator line at bottom
             ui.painter().line_segment(
                 [
@@ -4140,6 +4234,42 @@ impl PaneRenderer for TimelinePane {
 
             ui.separator();
 
+            // Stereo mix output VU meter (two stacked bars: L on top, R on bottom)
+            {
+                let meter_width = 80.0;
+                let meter_height = 14.0; // total height for both bars + gap
+                let bar_height = 6.0;
+                let gap = 2.0;
+                let (meter_rect, _) = ui.allocate_exact_size(
+                    egui::vec2(meter_width, meter_height),
+                    egui::Sense::hover(),
+                );
+                // Background
+                ui.painter().rect_filled(meter_rect, 2.0, egui::Color32::from_gray(30));
+
+                let levels = [shared.output_level.0.min(1.0), shared.output_level.1.min(1.0)];
+                for (i, &level) in levels.iter().enumerate() {
+                    let bar_y = meter_rect.min.y + i as f32 * (bar_height + gap);
+                    if level > 0.001 {
+                        let filled_width = meter_rect.width() * level;
+                        let color = if level > 0.9 {
+                            egui::Color32::from_rgb(220, 50, 50)
+                        } else if level > 0.7 {
+                            egui::Color32::from_rgb(220, 200, 50)
+                        } else {
+                            egui::Color32::from_rgb(50, 200, 80)
+                        };
+                        let filled_rect = egui::Rect::from_min_size(
+                            egui::pos2(meter_rect.min.x, bar_y),
+                            egui::vec2(filled_width, bar_height),
+                        );
+                        ui.painter().rect_filled(filled_rect, 1.0, color);
+                    }
+                }
+            }
+
+            ui.separator();
+
             // BPM control
             let mut bpm_val = bpm;
             ui.label("BPM:");
@@ -4278,7 +4408,7 @@ impl PaneRenderer for TimelinePane {
 
         // Render layer header column with clipping
         ui.set_clip_rect(layer_headers_rect.intersect(original_clip_rect));
-        self.render_layer_headers(ui, layer_headers_rect, shared.theme, shared.active_layer_id, shared.focus, &mut shared.pending_actions, document, &context_layers);
+        self.render_layer_headers(ui, layer_headers_rect, shared.theme, shared.active_layer_id, shared.focus, &mut shared.pending_actions, document, &context_layers, shared.layer_to_track_map, shared.track_levels, shared.input_level);
 
         // Render time ruler (clip to ruler rect)
         ui.set_clip_rect(ruler_rect.intersect(original_clip_rect));