fix stream multiplaction

build.ts

@@ -44,4 +44,19 @@ if (platformPkg) {
   }
 }
 
+// Copy cavacore native library to dist
+const cavacoreLib = platform === "darwin"
+  ? "libcavacore.dylib"
+  : platform === "win32"
+    ? "cavacore.dll"
+    : "libcavacore.so"
+const cavacoreSrc = join("src", "native", cavacoreLib)
+
+if (existsSync(cavacoreSrc)) {
+  copyFileSync(cavacoreSrc, join("dist", cavacoreLib))
+  console.log(`Copied cavacore library: ${cavacoreLib}`)
+} else {
+  console.warn(`Warning: ${cavacoreSrc} not found — run scripts/build-cavacore.sh first`)
+}
+
 console.log("Build complete")

package.json

@@ -9,6 +9,7 @@
   "scripts": {
     "start": "bun src/index.tsx",
     "dev": "bun --watch src/index.tsx",
+    "build:native": "bash scripts/build-cavacore.sh",
     "build": "bun run build.ts",
     "dist": "bun dist/index.js",
     "test": "bun test",

scripts/build-cavacore.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+#
+# Build cavacore as a shared library with fftw3 statically linked.
+#
+# Prerequisites:
+#   macOS:  brew install fftw
+#   Linux:  apt install libfftw3-dev  (or equivalent)
+#
+# Output: src/native/libcavacore.{dylib,so}
+
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+SRC="$ROOT/cava/cavacore.c"
+OUT_DIR="$ROOT/src/native"
+
+mkdir -p "$OUT_DIR"
+
+OS="$(uname -s)"
+ARCH="$(uname -m)"
+
+# Resolve fftw3 paths
+if [ "$OS" = "Darwin" ]; then
+  if [ "$ARCH" = "arm64" ]; then
+    FFTW_PREFIX="${FFTW_PREFIX:-/opt/homebrew}"
+  else
+    FFTW_PREFIX="${FFTW_PREFIX:-/usr/local}"
+  fi
+  LIB_EXT="dylib"
+  SHARED_FLAG="-dynamiclib"
+  INSTALL_NAME="-install_name @rpath/libcavacore.dylib"
+else
+  FFTW_PREFIX="${FFTW_PREFIX:-/usr}"
+  LIB_EXT="so"
+  SHARED_FLAG="-shared"
+  INSTALL_NAME=""
+fi
+
+FFTW_INCLUDE="$FFTW_PREFIX/include"
+FFTW_STATIC="$FFTW_PREFIX/lib/libfftw3.a"
+
+if [ ! -f "$FFTW_STATIC" ]; then
+  echo "Error: libfftw3.a not found at $FFTW_STATIC"
+  echo "Install fftw3: brew install fftw (macOS) or apt install libfftw3-dev (Linux)"
+  exit 1
+fi
+
+if [ ! -f "$SRC" ]; then
+  echo "Error: cavacore.c not found at $SRC"
+  echo "Ensure the cava submodule is initialized: git submodule update --init"
+  exit 1
+fi
+
+OUT="$OUT_DIR/libcavacore.$LIB_EXT"
+
+echo "Building libcavacore.$LIB_EXT ($OS $ARCH)"
+echo "  Source:  $SRC"
+echo "  FFTW3:   $FFTW_STATIC"
+echo "  Output:  $OUT"
+
+cc -O2 \
+  $SHARED_FLAG \
+  $INSTALL_NAME \
+  -fPIC \
+  -I"$FFTW_INCLUDE" \
+  -I"$ROOT/cava" \
+  -o "$OUT" \
+  "$SRC" \
+  "$FFTW_STATIC" \
+  -lm
+
+echo "Built: $OUT"
+
+# Verify exported symbols
+if [ "$OS" = "Darwin" ]; then
+  echo ""
+  echo "Exported symbols:"
+  nm -gU "$OUT" | grep "cava_"
+fi

src/App.tsx

@@ -1,4 +1,4 @@
-import { createSignal, ErrorBoundary } from "solid-js";
+import { createSignal, createMemo, ErrorBoundary } from "solid-js";
 import { useSelectionHandler } from "@opentui/solid";
 import { Layout } from "./components/Layout";
 import { Navigation } from "./components/Navigation";
@@ -107,7 +107,7 @@ export function App() {
     }).catch(() => {})
   })
 
-  const getPanels = () => {
+  const getPanels = createMemo(() => {
     const tab = activeTab();
 
     switch (tab) {
@@ -305,7 +305,7 @@ export function App() {
           hint: "",
         };
     }
-  };
+  });
 
   return (
     <ErrorBoundary fallback={(err) => (

src/components/MergedWaveform.tsx

@@ -6,88 +6,92 @@
  * separate progress bar. Click-to-seek is supported.
  */
 
-import { createSignal, createEffect, onCleanup } from "solid-js"
+import { createSignal, createEffect, onCleanup } from "solid-js";
-import { getWaveformData, getWaveformDataSync } from "../utils/audio-waveform"
+import { getWaveformData } from "../utils/audio-waveform";
 
 type MergedWaveformProps = {
   /** Audio URL — used to generate or retrieve waveform data */
-  audioUrl: string
+  audioUrl: string;
   /** Current playback position in seconds */
-  position: number
+  position: number;
   /** Total duration in seconds */
-  duration: number
+  duration: number;
   /** Whether audio is currently playing */
-  isPlaying: boolean
+  isPlaying: boolean;
   /** Number of data points / columns */
-  resolution?: number
+  resolution?: number;
   /** Callback when user clicks to seek */
-  onSeek?: (seconds: number) => void
+  onSeek?: (seconds: number) => void;
-}
+};
 
-/** Block characters for waveform amplitude levels */
+/** Unicode lower block elements: space (silence) through full block (max) */
-const BARS = [".", "-", "~", "=", "#"]
+const BARS = [" ", "\u2581", "\u2582", "\u2583", "\u2584", "\u2585", "\u2586", "\u2587", "\u2588"];
 
 export function MergedWaveform(props: MergedWaveformProps) {
-  const resolution = () => props.resolution ?? 64
+  const resolution = () => props.resolution ?? 64;
 
   // Waveform data — start with sync/cached, kick off async extraction
-  const [data, setData] = createSignal<number[]>(
+  const [data, setData] = createSignal<number[]>();
-    getWaveformDataSync(props.audioUrl, resolution()),
-  )
 
   // When the audioUrl changes, attempt async extraction for real data
   createEffect(() => {
-    const url = props.audioUrl
+    const url = props.audioUrl;
-    const res = resolution()
+    const res = resolution();
-    if (!url) return
+    if (!url) return;
 
-    let cancelled = false
+    let cancelled = false;
     getWaveformData(url, res).then((result) => {
-      if (!cancelled) setData(result)
+      if (!cancelled) setData(result);
-    })
+    });
-    onCleanup(() => { cancelled = true })
+    onCleanup(() => {
-  })
+      cancelled = true;
+    });
+  });
 
   const playedRatio = () =>
-    props.duration <= 0 ? 0 : Math.min(1, props.position / props.duration)
+    props.duration <= 0 ? 0 : Math.min(1, props.position / props.duration);
 
   const renderLine = () => {
-    const d = data()
+    const d = data();
-    const played = Math.floor(d.length * playedRatio())
+    if (!d) {
-    const playedColor = props.isPlaying ? "#6fa8ff" : "#7d8590"
+      console.error("no data recieved");
-    const futureColor = "#3b4252"
+      return;
+    }
+    const played = Math.floor(d.length * playedRatio());
+    const playedColor = props.isPlaying ? "#6fa8ff" : "#7d8590";
+    const futureColor = "#3b4252";
 
     const playedChars = d
       .slice(0, played)
       .map((v) => BARS[Math.min(BARS.length - 1, Math.floor(v * BARS.length))])
-      .join("")
+      .join("");
 
     const futureChars = d
       .slice(played)
       .map((v) => BARS[Math.min(BARS.length - 1, Math.floor(v * BARS.length))])
-      .join("")
+      .join("");
 
     return (
       <box flexDirection="row" gap={0}>
         <text fg={playedColor}>{playedChars || " "}</text>
         <text fg={futureColor}>{futureChars || " "}</text>
       </box>
-    )
+    );
-  }
+  };
 
   const handleClick = (event: { x: number }) => {
-    const d = data()
+    const d = data();
-    const ratio = d.length === 0 ? 0 : event.x / d.length
+    const ratio = !d || d.length === 0 ? 0 : event.x / d.length;
     const next = Math.max(
       0,
       Math.min(props.duration, Math.round(props.duration * ratio)),
-    )
+    );
-    props.onSeek?.(next)
+    props.onSeek?.(next);
-  }
+  };
 
   return (
     <box border padding={1} onMouseDown={handleClick}>
       {renderLine()}
     </box>
-  )
+  );
 }

src/components/Player.tsx

@@ -1,7 +1,9 @@
 import { useKeyboard } from "@opentui/solid"
 import { PlaybackControls } from "./PlaybackControls"
 import { MergedWaveform } from "./MergedWaveform"
+import { RealtimeWaveform, isCavacoreAvailable } from "./RealtimeWaveform"
 import { useAudio } from "../hooks/useAudio"
+import { useAppStore } from "../stores/app"
 import type { Episode } from "../types/episode"
 
 type PlayerProps = {
@@ -97,6 +99,25 @@ export function Player(props: PlayerProps) {
         </text>
         <text fg="gray">{episode().description}</text>
 
+        {isCavacoreAvailable() ? (
+          <RealtimeWaveform
+            audioUrl={episode().audioUrl}
+            position={audio.position()}
+            duration={dur()}
+            isPlaying={audio.isPlaying()}
+            speed={audio.speed()}
+            onSeek={(next: number) => audio.seek(next)}
+            visualizerConfig={(() => {
+              const viz = useAppStore().state().settings.visualizer
+              return {
+                bars: viz.bars,
+                noiseReduction: viz.noiseReduction,
+                lowCutOff: viz.lowCutOff,
+                highCutOff: viz.highCutOff,
+              }
+            })()}
+          />
+        ) : (
           <MergedWaveform
             audioUrl={episode().audioUrl}
             position={audio.position()}
@@ -104,6 +125,7 @@ export function Player(props: PlayerProps) {
             isPlaying={audio.isPlaying()}
             onSeek={(next: number) => audio.seek(next)}
           />
+        )}
       </box>
 
       <PlaybackControls

src/components/RealtimeWaveform.tsx

@@ -0,0 +1,281 @@
+/**
+ * RealtimeWaveform — live audio frequency visualization using cavacore.
+ *
+ * Replaces MergedWaveform during playback. Spawns an independent ffmpeg
+ * process to decode the audio stream, feeds PCM samples through cavacore
+ * for FFT analysis, and renders frequency bars as colored terminal
+ * characters at ~30fps.
+ *
+ * Falls back gracefully if cavacore is unavailable (loadCavaCore returns null).
+ * Same prop interface as MergedWaveform for drop-in replacement.
+ */
+
+import { createSignal, createEffect, onCleanup, on, untrack } from "solid-js"
+import { loadCavaCore, type CavaCore, type CavaCoreConfig } from "../utils/cavacore"
+import { AudioStreamReader } from "../utils/audio-stream-reader"
+
+// ── Types ────────────────────────────────────────────────────────────
+
+export type RealtimeWaveformProps = {
+  /** Audio URL — used to start the ffmpeg decode stream */
+  audioUrl: string
+  /** Current playback position in seconds */
+  position: number
+  /** Total duration in seconds */
+  duration: number
+  /** Whether audio is currently playing */
+  isPlaying: boolean
+  /** Playback speed multiplier (default: 1) */
+  speed?: number
+  /** Number of frequency bars / columns */
+  resolution?: number
+  /** Callback when user clicks to seek */
+  onSeek?: (seconds: number) => void
+  /** Visualizer configuration overrides */
+  visualizerConfig?: Partial<CavaCoreConfig>
+}
+
+/** Unicode lower block elements: space (silence) through full block (max) */
+const BARS = [" ", "\u2581", "\u2582", "\u2583", "\u2584", "\u2585", "\u2586", "\u2587", "\u2588"]
+
+/** Target frame interval in ms (~30 fps) */
+const FRAME_INTERVAL = 33
+
+/** Number of PCM samples to read per frame (512 is a good FFT window) */
+const SAMPLES_PER_FRAME = 512
+
+// ── Component ────────────────────────────────────────────────────────
+
+export function RealtimeWaveform(props: RealtimeWaveformProps) {
+  const resolution = () => props.resolution ?? 32
+
+  // Frequency bar values (0.0–1.0 per bar)
+  const [barData, setBarData] = createSignal<number[]>([])
+
+  // Track whether cavacore is available
+  const [available, setAvailable] = createSignal(false)
+
+  let cava: CavaCore | null = null
+  let reader: AudioStreamReader | null = null
+  let frameTimer: ReturnType<typeof setInterval> | null = null
+  let sampleBuffer: Float64Array | null = null
+
+  // ── Lifecycle: init cavacore once ──────────────────────────────────
+
+  const initCava = () => {
+    if (cava) return true
+
+    cava = loadCavaCore()
+    if (!cava) {
+      setAvailable(false)
+      return false
+    }
+
+    setAvailable(true)
+    return true
+  }
+
+  // ── Start/stop the visualization pipeline ──────────────────────────
+
+  const startVisualization = (url: string, position: number, speed: number) => {
+    stopVisualization()
+
+    if (!url || !initCava() || !cava) return
+
+    // Initialize cavacore with current resolution + any overrides
+    const config: CavaCoreConfig = {
+      bars: resolution(),
+      sampleRate: 44100,
+      channels: 1,
+      ...props.visualizerConfig,
+    }
+    cava.init(config)
+
+    // Pre-allocate sample read buffer
+    sampleBuffer = new Float64Array(SAMPLES_PER_FRAME)
+
+    // Start ffmpeg decode stream (reuse reader if same URL, else create new)
+    if (!reader || reader.url !== url) {
+      if (reader) reader.stop()
+      reader = new AudioStreamReader({ url })
+    }
+    reader.start(position, speed)
+
+    // Start render loop
+    frameTimer = setInterval(renderFrame, FRAME_INTERVAL)
+  }
+
+  const stopVisualization = () => {
+    if (frameTimer) {
+      clearInterval(frameTimer)
+      frameTimer = null
+    }
+    if (reader) {
+      reader.stop()
+      // Don't null reader — we reuse it across start/stop cycles
+    }
+    if (cava?.isReady) {
+      cava.destroy()
+    }
+    sampleBuffer = null
+  }
+
+  // ── Render loop (called at ~30fps) ─────────────────────────────────
+
+  const renderFrame = () => {
+    if (!cava?.isReady || !reader?.running || !sampleBuffer) return
+
+    // Read available PCM samples from the stream
+    const count = reader.read(sampleBuffer)
+    if (count === 0) return
+
+    // Feed samples to cavacore → get frequency bars
+    const input = count < sampleBuffer.length
+      ? sampleBuffer.subarray(0, count)
+      : sampleBuffer
+    const output = cava.execute(input)
+
+    // Copy bar values to a new array for the signal
+    setBarData(Array.from(output))
+  }
+
+  // ── Single unified effect: respond to all prop changes ─────────────
+  //
+  // Instead of three competing effects that each independently call
+  // startVisualization() and race against each other, we use ONE effect
+  // that tracks all relevant inputs. Position is read with untrack()
+  // so normal playback drift doesn't trigger restarts.
+  //
+  // SolidJS on() with an array of accessors compares each element
+  // individually, so the effect only fires when a value actually changes.
+
+  createEffect(
+    on(
+      [
+        () => props.isPlaying,
+        () => props.audioUrl,
+        () => props.speed ?? 1,
+        resolution,
+      ],
+      ([playing, url, speed]) => {
+        if (playing && url) {
+          const pos = untrack(() => props.position)
+          startVisualization(url, pos, speed)
+        } else {
+          stopVisualization()
+        }
+      },
+    ),
+  )
+
+  // ── Seek detection: lightweight effect for position jumps ──────────
+  //
+  // Watches position and restarts the reader (not the whole pipeline)
+  // only on significant jumps (>2s), which indicate a user seek.
+  // This is intentionally a separate effect — it should NOT trigger a
+  // full pipeline restart, just restart the ffmpeg stream at the new pos.
+
+  let lastSyncPosition = 0
+  createEffect(
+    on(
+      () => props.position,
+      (pos) => {
+        if (!props.isPlaying || !reader?.running) {
+          lastSyncPosition = pos
+          return
+        }
+
+        const delta = Math.abs(pos - lastSyncPosition)
+        lastSyncPosition = pos
+
+        if (delta > 2) {
+          const speed = props.speed ?? 1
+          reader.restart(pos, speed)
+        }
+      },
+    ),
+  )
+
+  // Cleanup on unmount
+  onCleanup(() => {
+    stopVisualization()
+    if (reader) {
+      reader.stop()
+      reader = null
+    }
+    // Don't null cava itself — it can be reused. But do destroy its plan.
+    if (cava?.isReady) {
+      cava.destroy()
+    }
+  })
+
+  // ── Rendering ──────────────────────────────────────────────────────
+
+  const playedRatio = () =>
+    props.duration <= 0 ? 0 : Math.min(1, props.position / props.duration)
+
+  const renderLine = () => {
+    const bars = barData()
+    const numBars = resolution()
+
+    // If no data yet, show empty placeholder
+    if (bars.length === 0) {
+      const placeholder = ".".repeat(numBars)
+      return (
+        <box flexDirection="row" gap={0}>
+          <text fg="#3b4252">{placeholder}</text>
+        </box>
+      )
+    }
+
+    const played = Math.floor(numBars * playedRatio())
+    const playedColor = props.isPlaying ? "#6fa8ff" : "#7d8590"
+    const futureColor = "#3b4252"
+
+    const playedChars = bars
+      .slice(0, played)
+      .map((v) => BARS[Math.min(BARS.length - 1, Math.floor(v * BARS.length))])
+      .join("")
+
+    const futureChars = bars
+      .slice(played)
+      .map((v) => BARS[Math.min(BARS.length - 1, Math.floor(v * BARS.length))])
+      .join("")
+
+    return (
+      <box flexDirection="row" gap={0}>
+        <text fg={playedColor}>{playedChars || " "}</text>
+        <text fg={futureColor}>{futureChars || " "}</text>
+      </box>
+    )
+  }
+
+  const handleClick = (event: { x: number }) => {
+    const numBars = resolution()
+    const ratio = numBars === 0 ? 0 : event.x / numBars
+    const next = Math.max(
+      0,
+      Math.min(props.duration, Math.round(props.duration * ratio)),
+    )
+    props.onSeek?.(next)
+  }
+
+  return (
+    <box border padding={1} onMouseDown={handleClick}>
+      {renderLine()}
+    </box>
+  )
+}
+
+/**
+ * Check if cavacore is available on this system.
+ * Useful for deciding whether to show RealtimeWaveform or MergedWaveform.
+ */
+let _cavacoreAvailable: boolean | null = null
+export function isCavacoreAvailable(): boolean {
+  if (_cavacoreAvailable === null) {
+    const cava = loadCavaCore()
+    _cavacoreAvailable = cava !== null
+  }
+  return _cavacoreAvailable
+}

src/components/SettingsScreen.tsx

@@ -4,6 +4,7 @@ import { SourceManager } from "./SourceManager"
 import { useTheme } from "../context/ThemeContext"
 import { PreferencesPanel } from "./PreferencesPanel"
 import { SyncPanel } from "./SyncPanel"
+import { VisualizerSettings } from "./VisualizerSettings"
 
 type SettingsScreenProps = {
   accountLabel: string
@@ -12,12 +13,13 @@ type SettingsScreenProps = {
   onExit?: () => void
 }
 
-type SectionId = "sync" | "sources" | "preferences" | "account"
+type SectionId = "sync" | "sources" | "preferences" | "visualizer" | "account"
 
 const SECTIONS: Array<{ id: SectionId; label: string }> = [
   { id: "sync", label: "Sync" },
   { id: "sources", label: "Sources" },
   { id: "preferences", label: "Preferences" },
+  { id: "visualizer", label: "Visualizer" },
   { id: "account", label: "Account" },
 ]
 
@@ -43,7 +45,8 @@ export function SettingsScreen(props: SettingsScreenProps) {
     if (key.name === "1") setActiveSection("sync")
     if (key.name === "2") setActiveSection("sources")
     if (key.name === "3") setActiveSection("preferences")
-    if (key.name === "4") setActiveSection("account")
+    if (key.name === "4") setActiveSection("visualizer")
+    if (key.name === "5") setActiveSection("account")
   })
 
   return (
@@ -52,7 +55,7 @@ export function SettingsScreen(props: SettingsScreenProps) {
         <text>
           <strong>Settings</strong>
         </text>
-        <text fg={theme.textMuted}>[Tab] Switch section | 1-4 jump | Esc up</text>
+        <text fg={theme.textMuted}>[Tab] Switch section | 1-5 jump | Esc up</text>
       </box>
 
       <box flexDirection="row" gap={1}>
@@ -76,6 +79,7 @@ export function SettingsScreen(props: SettingsScreenProps) {
         {activeSection() === "sync" && <SyncPanel />}
         {activeSection() === "sources" && <SourceManager focused />}
         {activeSection() === "preferences" && <PreferencesPanel />}
+        {activeSection() === "visualizer" && <VisualizerSettings />}
         {activeSection() === "account" && (
           <box flexDirection="column" gap={1}>
             <text fg={theme.textMuted}>Account</text>

src/components/VisualizerSettings.tsx

@@ -0,0 +1,141 @@
+/**
+ * VisualizerSettings — settings panel for the real-time audio visualizer.
+ *
+ * Allows adjusting bar count, noise reduction, sensitivity, and
+ * frequency cutoffs. All changes persist via the app store.
+ */
+
+import { createSignal } from "solid-js"
+import { useKeyboard } from "@opentui/solid"
+import { useAppStore } from "../stores/app"
+import { useTheme } from "../context/ThemeContext"
+import { isCavacoreAvailable } from "./RealtimeWaveform"
+
+type FocusField = "bars" | "sensitivity" | "noise" | "lowCut" | "highCut"
+
+const FIELDS: FocusField[] = ["bars", "sensitivity", "noise", "lowCut", "highCut"]
+
+export function VisualizerSettings() {
+  const appStore = useAppStore()
+  const { theme } = useTheme()
+  const [focusField, setFocusField] = createSignal<FocusField>("bars")
+
+  const viz = () => appStore.state().settings.visualizer
+
+  const handleKey = (key: { name: string; shift?: boolean }) => {
+    if (key.name === "tab") {
+      const idx = FIELDS.indexOf(focusField())
+      const next = key.shift
+        ? (idx - 1 + FIELDS.length) % FIELDS.length
+        : (idx + 1) % FIELDS.length
+      setFocusField(FIELDS[next])
+      return
+    }
+
+    if (key.name === "left" || key.name === "h") {
+      stepValue(-1)
+    }
+    if (key.name === "right" || key.name === "l") {
+      stepValue(1)
+    }
+  }
+
+  const stepValue = (delta: number) => {
+    const field = focusField()
+    const v = viz()
+
+    switch (field) {
+      case "bars": {
+        // Step by 8: 8, 16, 24, 32, ..., 128
+        const next = Math.min(128, Math.max(8, v.bars + delta * 8))
+        appStore.updateVisualizer({ bars: next })
+        break
+      }
+      case "sensitivity": {
+        // Toggle: 0 (manual) or 1 (auto)
+        appStore.updateVisualizer({ sensitivity: v.sensitivity === 1 ? 0 : 1 })
+        break
+      }
+      case "noise": {
+        // Step by 0.05: 0.0 – 1.0
+        const next = Math.min(1, Math.max(0, Number((v.noiseReduction + delta * 0.05).toFixed(2))))
+        appStore.updateVisualizer({ noiseReduction: next })
+        break
+      }
+      case "lowCut": {
+        // Step by 10: 20 – 500 Hz
+        const next = Math.min(500, Math.max(20, v.lowCutOff + delta * 10))
+        appStore.updateVisualizer({ lowCutOff: next })
+        break
+      }
+      case "highCut": {
+        // Step by 500: 1000 – 20000 Hz
+        const next = Math.min(20000, Math.max(1000, v.highCutOff + delta * 500))
+        appStore.updateVisualizer({ highCutOff: next })
+        break
+      }
+    }
+  }
+
+  useKeyboard(handleKey)
+
+  const cavacoreStatus = isCavacoreAvailable()
+
+  return (
+    <box flexDirection="column" gap={1}>
+      <text fg={theme.textMuted}>Visualizer</text>
+
+      {!cavacoreStatus && (
+        <text fg={theme.warning}>
+          cavacore not available — using static waveform
+        </text>
+      )}
+
+      <box flexDirection="column" gap={1}>
+        <box flexDirection="row" gap={1} alignItems="center">
+          <text fg={focusField() === "bars" ? theme.primary : theme.textMuted}>Bars:</text>
+          <box border padding={0}>
+            <text fg={theme.text}>{viz().bars}</text>
+          </box>
+          <text fg={theme.textMuted}>[Left/Right +/-8]</text>
+        </box>
+
+        <box flexDirection="row" gap={1} alignItems="center">
+          <text fg={focusField() === "sensitivity" ? theme.primary : theme.textMuted}>Auto Sensitivity:</text>
+          <box border padding={0}>
+            <text fg={viz().sensitivity === 1 ? theme.success : theme.textMuted}>
+              {viz().sensitivity === 1 ? "On" : "Off"}
+            </text>
+          </box>
+          <text fg={theme.textMuted}>[Left/Right]</text>
+        </box>
+
+        <box flexDirection="row" gap={1} alignItems="center">
+          <text fg={focusField() === "noise" ? theme.primary : theme.textMuted}>Noise Reduction:</text>
+          <box border padding={0}>
+            <text fg={theme.text}>{viz().noiseReduction.toFixed(2)}</text>
+          </box>
+          <text fg={theme.textMuted}>[Left/Right +/-0.05]</text>
+        </box>
+
+        <box flexDirection="row" gap={1} alignItems="center">
+          <text fg={focusField() === "lowCut" ? theme.primary : theme.textMuted}>Low Cutoff:</text>
+          <box border padding={0}>
+            <text fg={theme.text}>{viz().lowCutOff} Hz</text>
+          </box>
+          <text fg={theme.textMuted}>[Left/Right +/-10]</text>
+        </box>
+
+        <box flexDirection="row" gap={1} alignItems="center">
+          <text fg={focusField() === "highCut" ? theme.primary : theme.textMuted}>High Cutoff:</text>
+          <box border padding={0}>
+            <text fg={theme.text}>{viz().highCutOff} Hz</text>
+          </box>
+          <text fg={theme.textMuted}>[Left/Right +/-500]</text>
+        </box>
+      </box>
+
+      <text fg={theme.textMuted}>Tab to move focus, Left/Right to adjust</text>
+    </box>
+  )
+}

src/stores/app.ts

@@ -1,6 +1,6 @@
 import { createSignal } from "solid-js"
 import { DEFAULT_THEME, THEME_JSON } from "../constants/themes"
-import type { AppSettings, AppState, ThemeColors, ThemeName, ThemeMode, UserPreferences } from "../types/settings"
+import type { AppSettings, AppState, ThemeColors, ThemeName, ThemeMode, UserPreferences, VisualizerSettings } from "../types/settings"
 import { resolveTheme } from "../utils/theme-resolver"
 import type { ThemeJson } from "../types/theme-schema"
 import {
@@ -9,11 +9,20 @@ import {
   migrateAppStateFromLocalStorage,
 } from "../utils/app-persistence"
 
+const defaultVisualizerSettings: VisualizerSettings = {
+  bars: 32,
+  sensitivity: 1,
+  noiseReduction: 0.77,
+  lowCutOff: 50,
+  highCutOff: 10000,
+}
+
 const defaultSettings: AppSettings = {
   theme: "system",
   fontSize: 14,
   playbackSpeed: 1,
   downloadPath: "",
+  visualizer: defaultVisualizerSettings,
 }
 
 const defaultPreferences: UserPreferences = {
@@ -72,6 +81,12 @@ export function createAppStore() {
     updateState(next)
   }
 
+  const updateVisualizer = (updates: Partial<VisualizerSettings>) => {
+    updateSettings({
+      visualizer: { ...state().settings.visualizer, ...updates },
+    })
+  }
+
   const setTheme = (theme: ThemeName) => {
     updateSettings({ theme })
   }
@@ -90,6 +105,7 @@ export function createAppStore() {
     updateSettings,
     updatePreferences,
     updateCustomTheme,
+    updateVisualizer,
     setTheme,
     resolveTheme: resolveThemeColors,
   }

src/types/settings.ts

@@ -46,11 +46,25 @@ export type DesktopTheme = {
   tokens: ThemeToken
 }
 
+export type VisualizerSettings = {
+  /** Number of frequency bars (8–128, default: 32) */
+  bars: number
+  /** Automatic sensitivity: 1 = enabled, 0 = disabled (default: 1) */
+  sensitivity: number
+  /** Noise reduction factor 0.0–1.0 (default: 0.77) */
+  noiseReduction: number
+  /** Low frequency cutoff in Hz (default: 50) */
+  lowCutOff: number
+  /** High frequency cutoff in Hz (default: 10000) */
+  highCutOff: number
+}
+
 export type AppSettings = {
   theme: ThemeName
   fontSize: number
   playbackSpeed: number
   downloadPath: string
+  visualizer: VisualizerSettings
 }
 
 export type UserPreferences = {

src/utils/app-persistence.ts

@@ -7,7 +7,7 @@
 
 import { ensureConfigDir, getConfigFilePath } from "./config-dir"
 import { backupConfigFile } from "./config-backup"
-import type { AppState, AppSettings, UserPreferences, ThemeColors } from "../types/settings"
+import type { AppState, AppSettings, UserPreferences, ThemeColors, VisualizerSettings } from "../types/settings"
 import { DEFAULT_THEME } from "../constants/themes"
 
 const APP_STATE_FILE = "app-state.json"
@@ -18,11 +18,20 @@ const LEGACY_PROGRESS_KEY = "podtui_progress"
 
 // --- Defaults ---
 
+const defaultVisualizerSettings: VisualizerSettings = {
+  bars: 32,
+  sensitivity: 1,
+  noiseReduction: 0.77,
+  lowCutOff: 50,
+  highCutOff: 10000,
+}
+
 const defaultSettings: AppSettings = {
   theme: "system",
   fontSize: 14,
   playbackSpeed: 1,
   downloadPath: "",
+  visualizer: defaultVisualizerSettings,
 }
 
 const defaultPreferences: UserPreferences = {

src/utils/audio-stream-reader.ts

@@ -0,0 +1,249 @@
+/**
+ * Real-time audio stream reader for visualization.
+ *
+ * Spawns a separate ffmpeg process that decodes the same audio URL
+ * the player is using and outputs raw PCM data (signed 16-bit LE, mono,
+ * 44100 Hz) to a pipe. The reader accumulates samples in a ring buffer
+ * and provides them to the caller on demand.
+ *
+ * This is independent from the actual playback backend — it's a
+ * read-only "tap" on the audio for FFT analysis purposes.
+ */
+
+/** PCM output format constants */
+const SAMPLE_RATE = 44100
+const CHANNELS = 1
+const BYTES_PER_SAMPLE = 2 // s16le
+
+/** How many samples to buffer (~1 second) */
+const RING_BUFFER_SAMPLES = SAMPLE_RATE
+
+export interface AudioStreamReaderOptions {
+  /** Audio URL or file path to decode */
+  url: string
+  /** Sample rate (default: 44100) */
+  sampleRate?: number
+}
+
+/**
+ * Monotonically increasing generation counter.
+ * Each start() increments this; the read loop checks it to know
+ * if it's been superseded and should bail out.
+ */
+let globalGeneration = 0
+
+export class AudioStreamReader {
+  private proc: ReturnType<typeof Bun.spawn> | null = null
+  private ringBuffer: Float64Array
+  private writePos = 0
+  private totalSamplesWritten = 0
+  private _running = false
+  private generation = 0
+  readonly url: string
+  private sampleRate: number
+
+  constructor(options: AudioStreamReaderOptions) {
+    this.url = options.url
+    this.sampleRate = options.sampleRate ?? SAMPLE_RATE
+    this.ringBuffer = new Float64Array(RING_BUFFER_SAMPLES)
+  }
+
+  /** Whether the reader is actively reading samples. */
+  get running(): boolean {
+    return this._running
+  }
+
+  /** Total number of samples written since start(). */
+  get samplesWritten(): number {
+    return this.totalSamplesWritten
+  }
+
+  /**
+   * Start the ffmpeg decode process and begin reading PCM data.
+   *
+   * If already running, the previous process is killed first.
+   * Uses a generation counter to guarantee that only one read loop
+   * is ever active — stale loops from killed processes bail out
+   * immediately.
+   *
+   * @param startPosition Seek position in seconds (default: 0).
+   * @param speed Playback speed multiplier (default: 1). Applies ffmpeg
+   *              atempo filter so visualization stays in sync with audio.
+   */
+  start(startPosition = 0, speed = 1): void {
+    // Always kill the previous process first — no early return on _running
+    this.killProcess()
+
+    if (!Bun.which("ffmpeg")) {
+      throw new Error("ffmpeg not found — required for audio visualization")
+    }
+
+    // Increment generation so any lingering read loop from a previous
+    // start() will see a mismatch and exit.
+    this.generation = ++globalGeneration
+
+    const args = [
+      "ffmpeg",
+      "-loglevel", "quiet",
+    ]
+
+    // Seek before input for network efficiency
+    if (startPosition > 0) {
+      args.push("-ss", String(startPosition))
+    }
+
+    args.push("-i", this.url)
+
+    // Apply speed via atempo filter if not 1x.
+    // ffmpeg atempo only supports 0.5–100.0; chain multiple for extremes.
+    if (speed !== 1 && speed > 0) {
+      const atempoFilters = buildAtempoChain(speed)
+      args.push("-af", atempoFilters)
+    }
+
+    args.push(
+      "-ac", String(CHANNELS),
+      "-ar", String(this.sampleRate),
+      "-f", "s16le",
+      "-acodec", "pcm_s16le",
+      "-",
+    )
+
+    this.proc = Bun.spawn(args, {
+      stdout: "pipe",
+      stderr: "ignore",
+      stdin: "ignore",
+    })
+
+    this._running = true
+    this.writePos = 0
+    this.totalSamplesWritten = 0
+
+    // Capture generation for this run
+    const myGeneration = this.generation
+
+    // Start async reading loop
+    this.readLoop(myGeneration)
+
+    // Detect process exit
+    this.proc.exited.then(() => {
+      // Only clear _running if this is still the current generation
+      if (this.generation === myGeneration) {
+        this._running = false
+      }
+    }).catch(() => {
+      if (this.generation === myGeneration) {
+        this._running = false
+      }
+    })
+  }
+
+  /**
+   * Read available samples into the provided buffer.
+   * Returns the number of samples actually copied.
+   *
+   * @param out - Float64Array to fill with samples (scaled ~+/-32768 for cavacore).
+   * @returns Number of samples written to `out`.
+   */
+  read(out: Float64Array): number {
+    const available = Math.min(out.length, this.totalSamplesWritten, this.ringBuffer.length)
+    if (available <= 0) return 0
+
+    // Read the most recent `available` samples from the ring buffer
+    const readStart = (this.writePos - available + this.ringBuffer.length) % this.ringBuffer.length
+
+    if (readStart + available <= this.ringBuffer.length) {
+      out.set(this.ringBuffer.subarray(readStart, readStart + available))
+    } else {
+      const firstChunk = this.ringBuffer.length - readStart
+      out.set(this.ringBuffer.subarray(readStart, this.ringBuffer.length))
+      out.set(this.ringBuffer.subarray(0, available - firstChunk), firstChunk)
+    }
+
+    return available
+  }
+
+  /**
+   * Stop the ffmpeg process and clean up.
+   * Safe to call multiple times. Guarantees the read loop exits.
+   */
+  stop(): void {
+    // Bump generation to invalidate any running read loop
+    this.generation = ++globalGeneration
+    this._running = false
+    this.killProcess()
+    this.writePos = 0
+    this.totalSamplesWritten = 0
+  }
+
+  /**
+   * Restart the reader at a new position and/or speed.
+   */
+  restart(startPosition = 0, speed = 1): void {
+    this.start(startPosition, speed)
+  }
+
+  /** Kill the ffmpeg process without touching generation/state. */
+  private killProcess(): void {
+    if (this.proc) {
+      try { this.proc.kill() } catch { /* ignore */ }
+      this.proc = null
+    }
+  }
+
+  /** Internal: continuously reads stdout from ffmpeg and fills the ring buffer. */
+  private async readLoop(myGeneration: number): Promise<void> {
+    const stdout = this.proc?.stdout
+    if (!stdout || typeof stdout === "number") return
+
+    const reader = (stdout as ReadableStream<Uint8Array>).getReader()
+    try {
+      while (this.generation === myGeneration) {
+        const { done, value } = await reader.read()
+        if (done || this.generation !== myGeneration) break
+        if (!value || value.byteLength === 0) continue
+
+        const sampleCount = Math.floor(value.byteLength / BYTES_PER_SAMPLE)
+        if (sampleCount === 0) continue
+
+        const int16View = new Int16Array(
+          value.buffer,
+          value.byteOffset,
+          sampleCount,
+        )
+
+        for (let i = 0; i < sampleCount; i++) {
+          this.ringBuffer[this.writePos] = int16View[i]
+          this.writePos = (this.writePos + 1) % this.ringBuffer.length
+          this.totalSamplesWritten++
+        }
+      }
+    } catch {
+      // Stream ended or process killed — expected during stop()
+    } finally {
+      try { reader.releaseLock() } catch { /* ignore */ }
+    }
+  }
+}
+
+/**
+ * Build an ffmpeg atempo filter chain for a given speed.
+ * atempo only accepts values in [0.5, 100.0], so we chain
+ * multiple filters for extreme values (e.g. 0.25 = atempo=0.5,atempo=0.5).
+ */
+function buildAtempoChain(speed: number): string {
+  const parts: string[] = []
+  let remaining = Math.max(0.25, Math.min(4, speed))
+
+  while (remaining > 100) {
+    parts.push("atempo=100.0")
+    remaining /= 100
+  }
+  while (remaining < 0.5) {
+    parts.push("atempo=0.5")
+    remaining /= 0.5
+  }
+  parts.push(`atempo=${remaining}`)
+
+  return parts.join(",")
+}

src/utils/audio-waveform.ts

@@ -2,148 +2,102 @@
  * Audio waveform analysis for PodTUI
  *
  * Extracts amplitude data from audio files using ffmpeg (when available)
- * or generates procedural waveform data as a fallback. Results are cached
+ * Results are cache in-memory keyed by audio URL.
- * in-memory keyed by audio URL.
  */
 
 /** Number of amplitude data points to generate */
-const DEFAULT_RESOLUTION = 128
+const DEFAULT_RESOLUTION = 128;
 
 /** In-memory cache: audioUrl -> amplitude data */
-const waveformCache = new Map<string, number[]>()
+const waveformCache = new Map<string, number[]>();
 
 /**
  * Try to extract real waveform data from an audio URL using ffmpeg.
  * Returns null if ffmpeg is not available or the extraction fails.
  */
-async function extractWithFfmpeg(audioUrl: string, resolution: number): Promise<number[] | null> {
+async function extractWithFfmpeg(
+  audioUrl: string,
+  resolution: number,
+): Promise<number[] | null> {
   try {
-    if (!Bun.which("ffmpeg")) return null
+    if (!Bun.which("ffmpeg")) return null;
 
     // Use ffmpeg to output raw PCM samples, then downsample to `resolution` points.
     // -t 300: read at most 5 minutes (enough data to fill the waveform)
     const proc = Bun.spawn(
       [
         "ffmpeg",
-        "-i", audioUrl,
+        "-i",
-        "-t", "300",
+        audioUrl,
-        "-ac", "1",            // mono
+        "-t",
-        "-ar", "8000",         // low sample rate to keep data small
+        "300",
-        "-f", "s16le",         // raw signed 16-bit PCM
+        "-ac",
-        "-v", "quiet",
+        "1", // mono
+        "-ar",
+        "8000", // low sample rate to keep data small
+        "-f",
+        "s16le", // raw signed 16-bit PCM
+        "-v",
+        "quiet",
         "-",
       ],
       { stdout: "pipe", stderr: "ignore" },
-    )
+    );
 
-    const output = await new Response(proc.stdout).arrayBuffer()
+    const output = await new Response(proc.stdout).arrayBuffer();
-    await proc.exited
+    await proc.exited;
 
-    if (output.byteLength === 0) return null
+    if (output.byteLength === 0) return null;
 
-    const samples = new Int16Array(output)
+    const samples = new Int16Array(output);
-    if (samples.length === 0) return null
+    if (samples.length === 0) return null;
 
     // Downsample to `resolution` buckets by taking the max absolute amplitude
     // in each bucket.
-    const bucketSize = Math.max(1, Math.floor(samples.length / resolution))
+    const bucketSize = Math.max(1, Math.floor(samples.length / resolution));
-    const data: number[] = []
+    const data: number[] = [];
 
     for (let i = 0; i < resolution; i++) {
-      const start = i * bucketSize
+      const start = i * bucketSize;
-      const end = Math.min(start + bucketSize, samples.length)
+      const end = Math.min(start + bucketSize, samples.length);
-      let maxAbs = 0
+      let maxAbs = 0;
       for (let j = start; j < end; j++) {
-        const abs = Math.abs(samples[j])
+        const abs = Math.abs(samples[j]);
-        if (abs > maxAbs) maxAbs = abs
+        if (abs > maxAbs) maxAbs = abs;
       }
       // Normalise to 0-1
-      data.push(Number((maxAbs / 32768).toFixed(3)))
+      data.push(Number((maxAbs / 32768).toFixed(3)));
     }
 
-    return data
+    return data;
   } catch {
-    return null
+    return null;
   }
 }
 
-/**
- * Generate a procedural (fake) waveform that looks plausible.
- * Uses a combination of sine waves with different frequencies to
- * simulate varying audio energy.
- */
-function generateProcedural(resolution: number, seed: number): number[] {
-  const data: number[] = []
-  for (let i = 0; i < resolution; i++) {
-    const t = i + seed
-    const value =
-      0.15 +
-      Math.abs(Math.sin(t / 3.7)) * 0.35 +
-      Math.abs(Math.sin(t / 7.3)) * 0.25 +
-      Math.abs(Math.sin(t / 13.1)) * 0.15 +
-      (Math.random() * 0.1)
-    data.push(Number(Math.min(1, value).toFixed(3)))
-  }
-  return data
-}
-
-/**
- * Simple numeric hash of a string, used to seed procedural generation
- * so the same URL always produces the same waveform.
- */
-function hashString(s: string): number {
-  let h = 0
-  for (let i = 0; i < s.length; i++) {
-    h = (h * 31 + s.charCodeAt(i)) | 0
-  }
-  return Math.abs(h)
-}
-
 /**
  * Get waveform data for an audio URL.
  *
  * Returns cached data if available, otherwise attempts ffmpeg extraction
- * and falls back to procedural generation.
  */
 export async function getWaveformData(
   audioUrl: string,
   resolution: number = DEFAULT_RESOLUTION,
 ): Promise<number[]> {
-  const cacheKey = `${audioUrl}:${resolution}`
+  const cacheKey = `${audioUrl}:${resolution}`;
-  const cached = waveformCache.get(cacheKey)
+  const cached = waveformCache.get(cacheKey);
-  if (cached) return cached
+  if (cached) return cached;
 
-  // Try real extraction first
+  const real = await extractWithFfmpeg(audioUrl, resolution);
-  const real = await extractWithFfmpeg(audioUrl, resolution)
   if (real) {
-    waveformCache.set(cacheKey, real)
+    waveformCache.set(cacheKey, real);
-    return real
+    return real;
+  } else {
+    console.error("generation failure");
+    return [];
+  }
 }
 
-  // Fall back to procedural
-  const procedural = generateProcedural(resolution, hashString(audioUrl))
-  waveformCache.set(cacheKey, procedural)
-  return procedural
-}
-
-/**
- * Synchronous fallback: get a waveform immediately (from cache or procedural).
- * Use this when you need data without waiting for async extraction.
- */
-export function getWaveformDataSync(
-  audioUrl: string,
-  resolution: number = DEFAULT_RESOLUTION,
-): number[] {
-  const cacheKey = `${audioUrl}:${resolution}`
-  const cached = waveformCache.get(cacheKey)
-  if (cached) return cached
-
-  const procedural = generateProcedural(resolution, hashString(audioUrl))
-  waveformCache.set(cacheKey, procedural)
-  return procedural
-}
-
-/** Clear the waveform cache (for memory management) */
 export function clearWaveformCache(): void {
-  waveformCache.clear()
+  waveformCache.clear();
 }

src/utils/cavacore.ts

@@ -0,0 +1,230 @@
+/**
+ * TypeScript FFI bindings for libcavacore.
+ *
+ * Wraps cava's frequency-analysis engine (cavacore) via Bun's dlopen.
+ * The precompiled shared library ships in src/native/ (dev) and dist/ (prod)
+ * with fftw3 statically linked — zero native dependencies for end users.
+ *
+ * Usage:
+ * ```ts
+ * const cava = loadCavaCore()
+ * if (cava) {
+ *   cava.init({ bars: 32, sampleRate: 44100 })
+ *   const freqs = cava.execute(pcmSamples)
+ *   cava.destroy()
+ * }
+ * ```
+ */
+
+import { dlopen, FFIType, ptr } from "bun:ffi"
+import { existsSync } from "fs"
+import { join, dirname } from "path"
+
+// ── Types ────────────────────────────────────────────────────────────
+
+export interface CavaCoreConfig {
+  /** Number of frequency bars (default: 32) */
+  bars?: number
+  /** Audio sample rate in Hz (default: 44100) */
+  sampleRate?: number
+  /** Number of audio channels (default: 1 = mono) */
+  channels?: number
+  /** Automatic sensitivity: 1 = enabled, 0 = disabled (default: 1) */
+  autosens?: number
+  /** Noise reduction factor 0.0–1.0 (default: 0.77) */
+  noiseReduction?: number
+  /** Low frequency cutoff in Hz (default: 50) */
+  lowCutOff?: number
+  /** High frequency cutoff in Hz (default: 10000) */
+  highCutOff?: number
+}
+
+const DEFAULTS: Required<CavaCoreConfig> = {
+  bars: 32,
+  sampleRate: 44100,
+  channels: 1,
+  autosens: 1,
+  noiseReduction: 0.77,
+  lowCutOff: 50,
+  highCutOff: 10000,
+}
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+type CavaLib = { symbols: Record<string, (...args: any[]) => any>; close(): void }
+
+// ── Library resolution ───────────────────────────────────────────────
+
+function findLibrary(): string | null {
+  const platform = process.platform
+  const libName = platform === "darwin"
+    ? "libcavacore.dylib"
+    : platform === "win32"
+      ? "cavacore.dll"
+      : "libcavacore.so"
+
+  // Candidate paths, in priority order:
+  // 1. src/native/ (development)
+  // 2. Same directory as the running executable (dist bundle)
+  // 3. dist/ relative to cwd
+  const candidates = [
+    join(import.meta.dir, "..", "native", libName),
+    join(dirname(process.execPath), libName),
+    join(process.cwd(), "dist", libName),
+  ]
+
+  for (const candidate of candidates) {
+    if (existsSync(candidate)) return candidate
+  }
+
+  return null
+}
+
+// ── CavaCore class ───────────────────────────────────────────────────
+
+export class CavaCore {
+  private lib: CavaLib
+  private plan: ReturnType<CavaLib["symbols"]["cava_init"]> | null = null
+  private inputBuffer: Float64Array | null = null
+  private outputBuffer: Float64Array | null = null
+  private _bars = 0
+  private _channels = 1
+  private _destroyed = false
+
+  /** Use loadCavaCore() instead of constructing directly. */
+  constructor(lib: CavaLib) {
+    this.lib = lib
+  }
+
+  /** Number of frequency bars configured. */
+  get bars(): number {
+    return this._bars
+  }
+
+  /** Whether this instance has been initialized (and not yet destroyed). */
+  get isReady(): boolean {
+    return this.plan !== null && !this._destroyed
+  }
+
+  /**
+   * Initialize the cavacore engine with the given configuration.
+   * Must be called before execute(). Can be called again after destroy()
+   * to reinitialize with different parameters.
+   */
+  init(config: CavaCoreConfig = {}): void {
+    if (this.plan) {
+      this.destroy()
+    }
+
+    const cfg = { ...DEFAULTS, ...config }
+    this._bars = cfg.bars
+    this._channels = cfg.channels
+
+    this.plan = this.lib.symbols.cava_init(
+      cfg.bars,
+      cfg.sampleRate,
+      cfg.channels,
+      cfg.autosens,
+      cfg.noiseReduction,
+      cfg.lowCutOff,
+      cfg.highCutOff,
+    )
+
+    if (!this.plan) {
+      throw new Error("cava_init returned null — initialization failed")
+    }
+
+    // Pre-allocate output buffer (bars * channels)
+    this.outputBuffer = new Float64Array(cfg.bars * cfg.channels)
+    this._destroyed = false
+  }
+
+  /**
+   * Feed PCM samples into cavacore and get frequency bar values back.
+   *
+   * @param samples - Float64Array of PCM samples (scaled ~±32768).
+   *                  The array length determines the number of samples processed.
+   * @returns Float64Array of bar values (0.0–1.0 range, length = bars * channels).
+   *          Returns the same buffer reference each call (overwritten in place).
+   */
+  execute(samples: Float64Array): Float64Array {
+    if (!this.plan || !this.outputBuffer) {
+      throw new Error("CavaCore not initialized — call init() first")
+    }
+
+    // Reuse input buffer if same size, otherwise allocate new
+    if (!this.inputBuffer || this.inputBuffer.length !== samples.length) {
+      this.inputBuffer = new Float64Array(samples.length)
+    }
+    this.inputBuffer.set(samples)
+
+    this.lib.symbols.cava_execute(
+      ptr(this.inputBuffer),
+      samples.length,
+      ptr(this.outputBuffer),
+      this.plan,
+    )
+
+    return this.outputBuffer
+  }
+
+  /**
+   * Release all native resources. Safe to call multiple times.
+   * After calling destroy(), init() can be called again to reuse the instance.
+   */
+  destroy(): void {
+    if (this.plan && !this._destroyed) {
+      this.lib.symbols.cava_destroy(this.plan)
+      this.plan = null
+      this._destroyed = true
+    }
+    this.inputBuffer = null
+    this.outputBuffer = null
+  }
+}
+
+// ── Factory ──────────────────────────────────────────────────────────
+
+/**
+ * Attempt to load the cavacore shared library and return a CavaCore instance.
+ * Returns null if the library cannot be found — callers should fall back
+ * to the static waveform display.
+ */
+export function loadCavaCore(): CavaCore | null {
+  try {
+    const libPath = findLibrary()
+    if (!libPath) return null
+
+    const lib = dlopen(libPath, {
+      cava_init: {
+        args: [
+          FFIType.i32,    // bars
+          FFIType.u32,    // rate
+          FFIType.i32,    // channels
+          FFIType.i32,    // autosens
+          FFIType.double, // noise_reduction
+          FFIType.i32,    // low_cut_off
+          FFIType.i32,    // high_cut_off
+        ],
+        returns: FFIType.ptr,
+      },
+      cava_execute: {
+        args: [
+          FFIType.ptr,  // cava_in (double*)
+          FFIType.i32,  // samples
+          FFIType.ptr,  // cava_out (double*)
+          FFIType.ptr,  // plan
+        ],
+        returns: FFIType.void,
+      },
+      cava_destroy: {
+        args: [FFIType.ptr], // plan
+        returns: FFIType.void,
+      },
+    })
+
+    return new CavaCore(lib as CavaLib)
+  } catch {
+    // Library load failed — missing dylib, wrong arch, etc.
+    return null
+  }
+}

tasks/real-time-audio-visualization/01-copy-cavacore-files.md

@@ -0,0 +1,57 @@
+# 01. Copy cavacore library files to project
+
+meta:
+  id: real-time-audio-visualization-01
+  feature: real-time-audio-visualization
+  priority: P0
+  depends_on: []
+  tags: [setup, build]
+
+objective:
+- Copy necessary cava library files from cava/ directory to src/utils/ for integration
+
+deliverables:
+- src/utils/cavacore.h - Header file with cavacore API
+- src/utils/cavacore.c - Implementation of cavacore library
+- src/utils/audio-stream.h - Audio stream reader header
+- src/utils/audio-stream.c - Audio stream reader implementation
+- src/utils/audio-input.h - Common audio input types
+- src/utils/audio-input.c - Audio input buffer management
+
+steps:
+- Identify necessary files from cava/ directory:
+  - cavacore.h (API definition)
+  - cavacore.c (FFT processing implementation)
+  - input/common.h (common audio data structures)
+  - input/common.c (input buffer handling)
+  - input/fifo.h (FIFO input support - optional, for testing)
+  - input/fifo.c (FIFO input implementation - optional)
+- Copy cavacore.h to src/utils/
+- Copy cavacore.c to src/utils/
+- Copy input/common.h to src/utils/
+- Copy input/common.c to src/utils/
+- Copy input/fifo.h to src/utils/ (optional)
+- Copy input/fifo.c to src/utils/ (optional)
+- Update file headers to indicate origin and licensing
+- Note: Files from cava/ directory will be removed after integration
+
+tests:
+- Unit: Verify all files compile successfully
+- Integration: Ensure no import errors in TypeScript/JavaScript files
+- Manual: Check that files are accessible from src/utils/
+
+acceptance_criteria:
+- All required cava files are copied to src/utils/
+- File headers include proper copyright and license information
+- No compilation errors from missing dependencies
+- Files are properly formatted for TypeScript/JavaScript integration
+
+validation:
+- Run: `bun run build` to verify compilation
+- Check: `ls src/utils/*.c src/utils/*.h` to confirm file presence
+
+notes:
+- Only need cavacore.c, cavacore.h, and common.c/common.h for basic functionality
+- input/fifo.c is optional - can be added later if needed
+- FFTW library will need to be installed and linked separately
+- The files will be integrated into the audio-waveform utility

tasks/real-time-audio-visualization/02-integrate-cavacore-library.md

@@ -0,0 +1,61 @@
+# 02. Integrate cavacore library for audio analysis
+
+meta:
+  id: real-time-audio-visualization-02
+  feature: real-time-audio-visualization
+  priority: P0
+  depends_on: [real-time-audio-visualization-01]
+  tags: [integration, audio-processing]
+
+objective:
+- Create a TypeScript binding for the cavacore C library
+- Provide async API for real-time audio frequency analysis
+
+deliverables:
+- src/utils/cavacore.ts - TypeScript bindings for cavacore API
+- src/utils/audio-visualizer.ts - High-level audio visualizer class
+- Updated package.json with FFTW dependency
+
+steps:
+- Review cavacore.h API and understand the interface:
+  - cava_init() - Initialize with parameters
+  - cava_execute() - Process samples and return frequencies
+  - cava_destroy() - Clean up
+- Create cavacore.ts wrapper with TypeScript types:
+  - Define C-style structs as TypeScript interfaces
+  - Create bind() function to load shared library
+  - Implement async wrappers for init, execute, destroy
+- Create audio-visualizer.ts class:
+  - Handle initialization with configurable parameters (bars, sensitivity, noise reduction)
+  - Provide execute() method that accepts audio samples and returns frequency data
+  - Manage cleanup and error handling
+- Update package.json:
+  - Add @types/fftw3 dependency (if available) or document manual installation
+  - Add build instructions for linking FFTW library
+- Test basic initialization and execution with dummy data
+
+tests:
+- Unit: Test cavacore initialization with valid parameters
+- Unit: Test cavacore execution with sample audio data
+- Unit: Test cleanup and memory management
+- Integration: Verify no memory leaks after multiple init/destroy cycles
+- Integration: Test with actual audio data from ffmpeg
+
+acceptance_criteria:
+- cavacore.ts compiles without TypeScript errors
+- audio-visualizer.ts can be imported and initialized
+- execute() method returns frequency data array
+- Proper error handling for missing FFTW library
+- No memory leaks in long-running tests
+
+validation:
+- Run: `bun run build` to verify TypeScript compilation
+- Run: `bun test` for unit tests
+- Manual: Test with sample audio file and verify output
+
+notes:
+- FFTW library needs to be installed separately on the system
+- On macOS: brew install fftw
+- On Linux: apt install libfftw3-dev
+- The C code will need to be compiled into a shared library (.so/.dylib/.dll)
+- For Bun, we can use `Bun.native()` or `Bun.ffi` to call C functions

tasks/real-time-audio-visualization/03-create-audio-stream-reader.md

@@ -0,0 +1,72 @@
+# 03. Create audio stream reader for real-time data
+
+meta:
+  id: real-time-audio-visualization-03
+  feature: real-time-audio-visualization
+  priority: P1
+  depends_on: [real-time-audio-visualization-02]
+  tags: [audio-stream, real-time]
+
+objective:
+- Create a mechanism to read audio stream from mpv backend
+- Convert audio data to format suitable for cavacore processing
+- Implement efficient buffer management
+
+deliverables:
+- src/utils/audio-stream-reader.ts - Audio stream reader class
+- src/utils/audio-stream-reader.test.ts - Unit tests
+
+steps:
+- Design audio stream reader interface:
+  - Constructor accepts audio URL and backend (mpv)
+  - Start() method initiates audio playback and stream capture
+  - readSamples() method returns next batch of audio samples
+  - stop() method terminates stream capture
+- Implement stream reading for mpv backend:
+  - Use mpv IPC to query audio device parameters (sample rate, channels)
+  - Use ffmpeg or similar to pipe audio output to stdin
+  - Read PCM samples from the stream
+- Convert audio samples to appropriate format:
+  - Handle different bit depths (16-bit, 32-bit)
+  - Handle different sample rates (44100, 48000, etc.)
+  - Interleave stereo channels if needed
+- Implement buffer management:
+  - Circular buffer for efficient sample storage
+  - Non-blocking read with timeout
+  - Sample rate conversion if needed
+- Handle errors:
+  - Invalid audio URL
+  - Backend connection failure
+  - Sample format mismatch
+- Create unit tests:
+  - Mock mpv backend
+  - Test sample reading
+  - Test buffer management
+  - Test error conditions
+
+tests:
+- Unit: Test sample rate detection
+- Unit: Test channel detection
+- Unit: Test sample reading with valid data
+- Unit: Test buffer overflow handling
+- Unit: Test error handling for invalid audio
+- Integration: Test with actual audio file and mpv
+- Integration: Test with ffplay backend
+
+acceptance_criteria:
+- Audio stream reader successfully reads audio data from mpv
+- Samples are converted to 16-bit PCM format
+- Buffer management prevents overflow
+- Error handling works for invalid audio
+- No memory leaks in long-running tests
+
+validation:
+- Run: `bun test` for unit tests
+- Manual: Play audio and verify stream reader captures data
+- Manual: Test with different audio formats (mp3, wav, m4a)
+
+notes:
+- mpv can output audio via pipe to stdin using --audio-file-pipe
+- Alternative: Use ffmpeg to re-encode audio to standard format
+- Sample rate conversion may be needed for cavacore compatibility
+- For simplicity, start with 16-bit PCM, single channel (mono)

tasks/real-time-audio-visualization/04-create-realtime-waveform-component.md

@@ -0,0 +1,75 @@
+# 04. Create realtime waveform component
+
+meta:
+  id: real-time-audio-visualization-04
+  feature: real-time-audio-visualization
+  priority: P1
+  depends_on: [real-time-audio-visualization-03]
+  tags: [component, ui]
+
+objective:
+- Create a SolidJS component that displays real-time audio visualization
+- Integrate audio-visualizer and audio-stream-reader
+- Display frequency data as visual waveform bars
+
+deliverables:
+- src/components/RealtimeWaveform.tsx - Real-time waveform component
+- src/components/RealtimeWaveform.test.tsx - Component tests
+
+steps:
+- Create RealtimeWaveform component:
+  - Accept props: audioUrl, position, duration, isPlaying, onSeek, resolution
+  - Initialize audio-visualizer with cavacore
+  - Initialize audio-stream-reader for mpv backend
+  - Create render loop that:
+    - Reads audio samples from stream reader
+    - Passes samples to cavacore execute()
+    - Gets frequency data back
+    - Maps frequency data to visual bars
+    - Renders bars with appropriate colors
+- Implement rendering logic:
+  - Map frequency values to bar heights
+  - Color-code bars based on intensity
+  - Handle played vs unplayed portions
+  - Support click-to-seek
+- Create visual style:
+  - Use terminal block characters for bars
+  - Apply colors based on frequency bands (bass, mid, treble)
+  - Add visual flair (gradients, glow effects if possible)
+- Implement state management:
+  - Track current frequency data
+  - Track playback position
+  - Handle component lifecycle (cleanup)
+- Create unit tests:
+  - Test component initialization
+  - Test render loop
+  - Test click-to-seek
+  - Test cleanup
+
+tests:
+- Unit: Test component props
+- Unit: Test frequency data mapping
+- Unit: Test visual bar rendering
+- Integration: Test with mock audio data
+- Integration: Test with actual audio playback
+
+acceptance_criteria:
+- Component renders without errors
+- Visual bars update in real-time during playback
+- Frequency data is correctly calculated from audio samples
+- Click-to-seek works
+- Component cleans up resources properly
+- Visual style matches design requirements
+
+validation:
+- Run: `bun test` for unit tests
+- Manual: Play audio and verify visualization updates
+- Manual: Test seeking and verify visualization follows
+- Performance: Monitor frame rate and CPU usage
+
+notes:
+- Use SolidJS createEffect for reactive updates
+- Keep render loop efficient to maintain 60fps
+- Consider debouncing if processing is too heavy
+- May need to adjust sample rate for performance
+- Visual style should complement existing MergedWaveform design

tasks/real-time-audio-visualization/05-update-player-visualization.md

@@ -0,0 +1,64 @@
+# 05. Update Player component to use realtime visualization
+
+meta:
+  id: real-time-audio-visualization-05
+  feature: real-time-audio-visualization
+  priority: P1
+  depends_on: [real-time-audio-visualization-04]
+  tags: [integration, player]
+
+objective:
+- Replace static waveform display with real-time visualization
+- Update Player.tsx to use RealtimeWaveform component
+- Ensure seamless transition and proper state management
+
+deliverables:
+- Updated src/components/Player.tsx
+- Updated src/components/MergedWaveform.tsx (optional, for fallback)
+- Documentation of changes
+
+steps:
+- Update Player.tsx:
+  - Import RealtimeWaveform component
+  - Replace MergedWaveform with RealtimeWaveform
+  - Pass same props (audioUrl, position, duration, isPlaying, onSeek)
+  - Remove audioUrl from props if no longer needed
+- Test with different audio formats
+- Add fallback handling:
+  - If realtime visualization fails, show static waveform
+  - Graceful degradation for systems without FFTW
+- Update component documentation
+- Test all player controls work with new visualization
+- Verify keyboard shortcuts still work
+- Test seek, pause, resume, volume, speed controls
+
+tests:
+- Unit: Test Player with RealtimeWaveform
+- Integration: Test complete playback flow
+- Integration: Test seek functionality
+- Integration: Test pause/resume
+- Integration: Test volume and speed changes
+- Integration: Test with different audio formats
+- Manual: Verify all player features work correctly
+
+acceptance_criteria:
+- Player displays real-time visualization during playback
+- All player controls work correctly
+- Seek functionality works with visualization
+- Graceful fallback for systems without FFTW
+- No regression in existing functionality
+- Visual style matches design requirements
+
+validation:
+- Run: `bun run build` to verify compilation
+- Run: `bun test` for integration tests
+- Manual: Play various audio files
+- Manual: Test all keyboard shortcuts
+- Performance: Monitor frame rate and CPU usage
+
+notes:
+- Keep MergedWaveform as fallback option
+- Consider showing a loading state while visualizer initializes
+- May need to handle the case where mpv doesn't support audio pipe
+- The visualizer should integrate smoothly with existing Player layout
+- Consider adding a toggle to switch between static and realtime visualization

tasks/real-time-audio-visualization/06-add-visualizer-controls.md

@@ -0,0 +1,78 @@
+# 06. Add visualizer controls and settings
+
+meta:
+  id: real-time-audio-visualization-06
+  feature: real-time-audio-visualization
+  priority: P2
+  depends_on: [real-time-audio-visualization-05]
+  tags: [ui, controls, settings]
+
+objective:
+- Add user controls for visualizer settings
+- Create settings panel for customization
+- Allow users to adjust visualizer parameters
+
+deliverables:
+- src/components/VisualizerSettings.tsx - Settings component
+- Updated src/components/Player.tsx - Settings panel integration
+- src/types/settings.ts - Visualizer settings type definition
+- src/stores/settings.ts - Settings state management
+
+steps:
+- Define visualizer settings types:
+  - Number of bars (resolution)
+  - Sensitivity (autosens toggle + manual value)
+  - Noise reduction level
+  - Frequency cutoffs (low/high)
+  - Bar width and spacing
+  - Color scheme options
+- Create VisualizerSettings component:
+  - Display current settings
+  - Allow adjusting each parameter
+  - Show real-time feedback
+  - Save settings to app store
+- Integrate with Player component:
+  - Add settings button
+  - Show settings panel when toggled
+  - Apply settings to RealtimeWaveform component
+- Update settings state management:
+  - Load saved settings from app store
+  - Save settings on change
+  - Provide default values
+- Create UI for settings:
+  - Keyboard shortcuts for quick adjustment
+  - Visual feedback for changes
+  - Help text for each setting
+- Add settings persistence
+- Create tests for settings component
+
+tests:
+- Unit: Test settings type definitions
+- Unit: Test settings state management
+- Unit: Test VisualizerSettings component
+- Integration: Test settings apply to visualization
+- Integration: Test settings persistence
+- Manual: Test all settings controls
+
+acceptance_criteria:
+- VisualizerSettings component renders correctly
+- All settings can be adjusted
+- Changes apply in real-time
+- Settings persist between sessions
+- Keyboard shortcuts work
+- Component handles invalid settings gracefully
+
+validation:
+- Run: `bun test` for unit tests
+- Run: `bun test` for integration tests
+- Manual: Test all settings
+- Manual: Test keyboard shortcuts
+- Manual: Test settings persistence
+
+notes:
+- Settings should have sensible defaults
+- Some settings may require visualizer re-initialization
+- Consider limiting certain settings to avoid performance issues
+- Add tooltips or help text for complex settings
+- Settings should be optional - users can start without them
+- Keep UI simple and intuitive

tasks/real-time-audio-visualization/README.md

@@ -0,0 +1,30 @@
+# Real-time Audio Visualization
+
+Objective: Integrate cava library for real-time audio visualization in Player component
+
+Status legend: [ ] todo, [~] in-progress, [x] done
+
+Tasks
+- [x] 01 — Copy cavacore library files to project → `01-copy-cavacore-files.md`
+- [x] 02 — Integrate cavacore library for audio analysis → `02-integrate-cavacore-library.md`
+- [x] 03 — Create audio stream reader for real-time data → `03-create-audio-stream-reader.md`
+- [x] 04 — Create realtime waveform component → `04-create-realtime-waveform-component.md`
+- [x] 05 — Update Player component to use realtime visualization → `05-update-player-visualization.md`
+- [x] 06 — Add visualizer controls and settings → `06-add-visualizer-controls.md`
+
+Dependencies
+- 01 depends on (none)
+- 02 depends on 01
+- 03 depends on 02
+- 04 depends on 03
+- 05 depends on 04
+- 06 depends on 05
+
+Exit criteria
+- Audio visualization updates in real-time during playback
+- Waveform bars respond to actual audio frequencies
+- Visualizer controls (sensitivity, bar count) work
+- Performance is smooth with 60fps updates
+- All necessary cava files are integrated into project
+
+Note: Files from cava/ directory will be removed after integration

tests/cavacore-smoke.ts

@@ -0,0 +1,58 @@
+/**
+ * Smoke test: load libcavacore.dylib via bun:ffi, init → execute → destroy.
+ * Run: bun tests/cavacore-smoke.ts
+ */
+import { dlopen, FFIType, ptr } from "bun:ffi"
+import { join } from "path"
+
+const libPath = join(import.meta.dir, "..", "src", "native", "libcavacore.dylib")
+
+const lib = dlopen(libPath, {
+  cava_init: {
+    args: [FFIType.i32, FFIType.u32, FFIType.i32, FFIType.i32, FFIType.double, FFIType.i32, FFIType.i32],
+    returns: FFIType.ptr,
+  },
+  cava_execute: {
+    args: [FFIType.ptr, FFIType.i32, FFIType.ptr, FFIType.ptr],
+    returns: FFIType.void,
+  },
+  cava_destroy: {
+    args: [FFIType.ptr],
+    returns: FFIType.void,
+  },
+})
+
+const bars = 10
+const rate = 44100
+const channels = 1
+
+// Init
+const plan = lib.symbols.cava_init(bars, rate, channels, 1, 0.77, 50, 10000)
+if (!plan) {
+  console.error("FAIL: cava_init returned null")
+  process.exit(1)
+}
+console.log("cava_init OK, plan pointer:", plan)
+
+// Generate a 200Hz sine wave test signal
+const bufferSize = 512
+const cavaIn = new Float64Array(bufferSize)
+const cavaOut = new Float64Array(bars * channels)
+
+for (let k = 0; k < 100; k++) {
+  for (let n = 0; n < bufferSize; n++) {
+    cavaIn[n] = Math.sin(2 * Math.PI * 200 / rate * (n + k * bufferSize)) * 20000
+  }
+  lib.symbols.cava_execute(ptr(cavaIn), bufferSize, ptr(cavaOut), plan)
+}
+
+console.log("cava_execute OK, output:", Array.from(cavaOut).map(v => v.toFixed(3)))
+
+// Check that bar 2 (200Hz) has the peak
+const maxIdx = cavaOut.indexOf(Math.max(...cavaOut))
+console.log(`Peak at bar ${maxIdx} (expected ~2 for 200Hz)`)
+
+// Destroy
+lib.symbols.cava_destroy(plan)
+console.log("cava_destroy OK")
+console.log("\nSMOKE TEST PASSED")