From 1f295fb9270a913327e0751b16803318f02a09b4 Mon Sep 17 00:00:00 2001
From: AE <98699388+A-EDev@users.noreply.github.com>
Date: Sat, 24 Oct 2026 19:52:43 +0300
Subject: [PATCH 1/2] fix(music): stream AAC on macOS once the equalizer or
 crossfade is in use

---
 src/lib/audio/musicAudioEngine.eq.test.ts     | 42 +++++++++--
 src/lib/audio/musicAudioEngine.test.ts        | 14 ++--
 src/lib/audio/musicAudioEngine.ts             | 69 ++++++++++++++-----
 src/lib/audio/musicAudioSettings.ts           |  1 +
 src/lib/audio/webAudioFormats.test.ts         | 23 +++++++
 src/lib/audio/webAudioFormats.ts              | 11 +++
 src/lib/musicPreload.ts                       |  4 +-
 src/lib/musicStreamResolution.ts              |  7 +-
 .../useMusicPlayerStore.playback.test.ts      | 23 +++++++
 src/store/useMusicPlayerStore.queue.test.ts   |  9 ++-
 src/store/useMusicPlayerStore.ts              | 27 ++++++--
 11 files changed, 189 insertions(+), 41 deletions(-)
 create mode 100644 src/lib/audio/webAudioFormats.test.ts
 create mode 100644 src/lib/audio/webAudioFormats.ts

diff --git a/src/lib/audio/musicAudioEngine.eq.test.ts b/src/lib/audio/musicAudioEngine.eq.test.ts
index 075d27a6..c24ab307 100644
--- a/src/lib/audio/musicAudioEngine.eq.test.ts
+++ b/src/lib/audio/musicAudioEngine.eq.test.ts
@@ -4,6 +4,14 @@ import { graphSpec, EQ_GRAPH_OFF } from "./eq/graphPlan";
 import { defaultEqState, selectPreset } from "./eq/stateOps";
 import { musicAudioEngine } from "./musicAudioEngine";
 
+const platform = vi.hoisted(() => ({ macos: false }));
+vi.mock("../platform", () => ({
+  IS_LINUX_RUNTIME: false,
+  get IS_MACOS_RUNTIME() {
+    return platform.macos;
+  },
+}));
+
 // A minimal WebAudio stand-in: enough to see which nodes exist and what they were told.
 class FakeParam {
   constructor(public value = 0) {}
@@ -92,6 +100,7 @@ beforeEach(() => {
 });
 
 afterEach(() => {
+  platform.macos = false;
   vi.useRealTimers();
   vi.unstubAllGlobals();
 });
@@ -124,8 +133,8 @@ describe("music EQ graph", () => {
     expect(ctx.biquads[0]!.gain.value).toBe(rock.bands[0]!.gain);
     expect(ctx.biquads[5]!.gain.value).toBe(0);
 
-    await musicAudioEngine.load("http://127.0.0.1/stream/a");
-    musicAudioEngine.preload("b", "http://127.0.0.1/stream/b", null);
+    await musicAudioEngine.load("http://127.0.0.1/stream/a", null);
+    musicAudioEngine.preload("b", "http://127.0.0.1/stream/b", null, null);
     Object.defineProperty(pair[1], "readyState", { value: HTMLMediaElement.HAVE_FUTURE_DATA, configurable: true });
     expect(musicAudioEngine.activatePreloaded("b")).toBe(true);
 
@@ -138,6 +147,27 @@ describe("music EQ graph", () => {
     expect(ctx.biquads.every((f) => f.gain.value === 0)).toBe(true);
   });
 
+  it("asks for AAC on macOS, and keeps a WebM song it cannot hear on the element's volume", async () => {
+    platform.macos = true;
+    const pair = elements();
+    musicAudioEngine.attach(pair);
+    musicAudioEngine.setEq(EQ_GRAPH_OFF, false);
+    expect(musicAudioEngine.wantsAac()).toBe(false);
+    musicAudioEngine.setEq(rock, true);
+    expect(musicAudioEngine.wantsAac()).toBe(true);
+
+    await musicAudioEngine.load("http://127.0.0.1/stream/opus", 'audio/webm; codecs="opus"');
+    await musicAudioEngine.play();
+    musicAudioEngine.setLoudness(null, true);
+    musicAudioEngine.setVolume(0.5);
+    expect(musicAudioEngine.activeBypassesGraph()).toBe(true);
+    expect(pair[0].volume).toBeCloseTo(0.25, 2);
+
+    await musicAudioEngine.load("http://127.0.0.1/stream/aac", 'audio/mp4; codecs="mp4a.40.2"');
+    expect(musicAudioEngine.activeBypassesGraph()).toBe(false);
+    expect(pair[0].volume).toBe(1);
+  });
+
   it("starts the element even when the context will not resume", async () => {
     vi.useFakeTimers();
     const pair = elements();
@@ -175,8 +205,8 @@ describe("music EQ graph", () => {
     Object.defineProperty(pair[0], "paused", { value: false, configurable: true });
     musicAudioEngine.setCrossfadeEnabled(true);
     const ctx = lastContext();
-    await musicAudioEngine.load("http://127.0.0.1/stream/a");
-    musicAudioEngine.preload("b", "http://127.0.0.1/stream/b", null);
+    await musicAudioEngine.load("http://127.0.0.1/stream/a", null);
+    musicAudioEngine.preload("b", "http://127.0.0.1/stream/b", null, null);
     Object.defineProperty(pair[1], "readyState", { value: HTMLMediaElement.HAVE_FUTURE_DATA, configurable: true });
 
     musicAudioEngine.armCrossfade(4);
@@ -205,8 +235,8 @@ describe("crossfade without WebAudio", () => {
     engine.setCrossfadeEnabled(true);
     expect(engine.isEqAvailable()).toBe(false);
 
-    await engine.load("http://127.0.0.1/stream/a");
-    engine.preload("b", "http://127.0.0.1/stream/b", null);
+    await engine.load("http://127.0.0.1/stream/a", null);
+    engine.preload("b", "http://127.0.0.1/stream/b", null, null);
     Object.defineProperty(pair[1], "readyState", { value: HTMLMediaElement.HAVE_FUTURE_DATA, configurable: true });
     Object.defineProperty(pair[0], "paused", { value: false, configurable: true });
     engine.armCrossfade(2);
diff --git a/src/lib/audio/musicAudioEngine.test.ts b/src/lib/audio/musicAudioEngine.test.ts
index 085178c3..fcd879a4 100644
--- a/src/lib/audio/musicAudioEngine.test.ts
+++ b/src/lib/audio/musicAudioEngine.test.ts
@@ -28,8 +28,8 @@ beforeEach(() => {
 
 describe("gapless standby element", () => {
   it("buffers the next track on the element that is not playing", async () => {
-    await musicAudioEngine.load("http://127.0.0.1/stream/current");
-    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", -4);
+    await musicAudioEngine.load("http://127.0.0.1/stream/current", null);
+    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", -4, null);
 
     expect(musicAudioEngine.getActiveElement()).toBe(pair[0]);
     expect(pair[1].getAttribute("src")).toBe("http://127.0.0.1/stream/next");
@@ -38,8 +38,8 @@ describe("gapless standby element", () => {
   });
 
   it("swaps only for the track it holds, and empties the one that played", async () => {
-    await musicAudioEngine.load("http://127.0.0.1/stream/current");
-    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", -4);
+    await musicAudioEngine.load("http://127.0.0.1/stream/current", null);
+    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", -4, null);
     bufferedEnough(pair[1]);
 
     expect(musicAudioEngine.activatePreloaded("other")).toBe(false);
@@ -53,15 +53,15 @@ describe("gapless standby element", () => {
   });
 
   it("never swaps in a preload that has no audio to play yet", async () => {
-    await musicAudioEngine.load("http://127.0.0.1/stream/current");
-    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", null);
+    await musicAudioEngine.load("http://127.0.0.1/stream/current", null);
+    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", null, null);
 
     expect(musicAudioEngine.activatePreloaded("next")).toBe(false);
     expect(musicAudioEngine.getActiveElement()).toBe(pair[0]);
   });
 
   it("reports and drops what the standby element held", () => {
-    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", null);
+    musicAudioEngine.preload("next", "http://127.0.0.1/stream/next", null, null);
     expect(musicAudioEngine.clearPreload()).toBe("next");
     expect(pair[1].getAttribute("src")).toBeNull();
     expect(musicAudioEngine.clearPreload()).toBeNull();
diff --git a/src/lib/audio/musicAudioEngine.ts b/src/lib/audio/musicAudioEngine.ts
index 34ad9921..60d8f523 100644
--- a/src/lib/audio/musicAudioEngine.ts
+++ b/src/lib/audio/musicAudioEngine.ts
@@ -1,10 +1,11 @@
 import { loudnessFactor, MUSIC_MAX_CUT_DB } from "../loudness";
-import { IS_LINUX_RUNTIME } from "../platform";
+import { IS_LINUX_RUNTIME, IS_MACOS_RUNTIME } from "../platform";
 import { createAudioContext, keepRunning, resumeWithin, webAudioSupported } from "./audioContext";
 import { fadeInGain, fadeOutGain, resetFade, scheduleFade, steppedFade } from "./crossfadeRamp";
 import { EQ_GRAPH_OFF, type EqGraphSpec } from "./eq/graphPlan";
 import { EqChain, RAMP_TIME_CONSTANT } from "./eqChain";
 import { volumeGain } from "./volumeCurve";
+import { webAudioHears } from "./webAudioFormats";
 
 /**
  * One of the two <audio> elements. While one plays, the other can hold the next
@@ -20,6 +21,8 @@ interface Slot {
   /** The same share when WebAudio is not in use, applied to the element's volume. */
   fade: number;
   loudnessDb: number | null;
+  /** The loaded file's MIME type, which decides whether WebAudio can hear it. */
+  mime: string | null;
   /** The track a standby slot holds, so a swap only ever plays the right one. */
   key: string | null;
 }
@@ -31,6 +34,7 @@ const emptySlot = (): Slot => ({
   fadeGain: null,
   fade: 1,
   loudnessDb: null,
+  mime: null,
   key: null,
 });
 
@@ -59,6 +63,7 @@ class MusicAudioEngine {
   private graphReady = false;
   private webAudioFailed = false;
   private availabilityListeners = new Set<(available: boolean) => void>();
+  private graphListeners = new Set<() => void>();
 
   private volume = 1;
   private muted = false;
@@ -145,6 +150,7 @@ class MusicAudioEngine {
       this.chain.apply(this.eqSpec);
       // Turned on mid-song: the context has to run for the element to be heard.
       if (this.active.el && !this.active.el.paused) void resumeWithin(ctx);
+      for (const listener of this.graphListeners) listener();
     } catch (err) {
       console.warn("[musicAudioEngine] WebAudio graph unavailable, playing without the equalizer", err);
       this.webAudioFailed = true;
@@ -155,10 +161,12 @@ class MusicAudioEngine {
 
   // --- transport ----------------------------------------------------------
 
-  async load(url: string): Promise<void> {
+  async load(url: string, mime: string | null): Promise<void> {
     const el = this.active.el;
     if (!el) return;
     this.active.key = null;
+    this.active.mime = mime;
+    this.applyGain();
     el.src = url;
     try {
       el.load();
@@ -171,11 +179,12 @@ class MusicAudioEngine {
    * take over the moment the current track ends. A no-op when it already holds
    * that track, or while it is still fading out the last one.
    */
-  preload(key: string, url: string, loudnessDb: number | null): void {
+  preload(key: string, url: string, loudnessDb: number | null, mime: string | null): void {
     const slot = this.standby;
     if (!slot.el || slot.key === key || this.fading) return;
     slot.key = key;
     slot.loudnessDb = loudnessDb;
+    slot.mime = mime;
     slot.el.src = url;
     try {
       slot.el.load();
@@ -235,6 +244,7 @@ class MusicAudioEngine {
     if (slot.el) unload(slot.el);
     slot.key = null;
     slot.loudnessDb = null;
+    slot.mime = null;
   }
 
   // The two elements play together while their gains move in opposite directions; the one
@@ -242,7 +252,7 @@ class MusicAudioEngine {
   private startFade(previous: Slot, seconds: number): void {
     const next = this.active;
     let cancelSteps: (() => void) | null = null;
-    if (this.graphReady && this.ctx && previous.fadeGain && next.fadeGain) {
+    if (this.ctx && this.routes(previous) && this.routes(next) && previous.fadeGain && next.fadeGain) {
       const t = this.ctx.currentTime;
       scheduleFade(previous.fadeGain.gain, "out", t, seconds);
       scheduleFade(next.fadeGain.gain, "in", t, seconds);
@@ -436,26 +446,30 @@ class MusicAudioEngine {
   private applyGain(): void {
     const vol = (this.muted ? 0 : volumeGain(this.volume)) * this.fadeLevel;
 
-    if (this.graphReady && this.ctx && this.volGain) {
-      const t = this.ctx.currentTime;
-      this.volGain.gain.setTargetAtTime(vol, t, RAMP_TIME_CONSTANT);
-      for (const slot of this.slots) {
-        slot.normGain?.gain.setTargetAtTime(this.normalizationFactor(slot.loudnessDb), t, RAMP_TIME_CONSTANT);
-        if (slot.el) {
-          slot.el.volume = 1;
-          slot.el.muted = false;
-        }
-      }
-    } else {
-      for (const slot of this.slots) {
-        if (!slot.el) continue;
-        const norm = this.normalizationFactor(slot.loudnessDb);
+    const t = this.ctx?.currentTime ?? 0;
+    if (this.graphReady && this.volGain) this.volGain.gain.setTargetAtTime(vol, t, RAMP_TIME_CONSTANT);
+    // A scheduled crossfade owns the fade gains until it ends; a stepped one moves `slot.fade`.
+    const scheduledFade = !!this.fading && !this.fading.cancelSteps;
+    for (const slot of this.slots) {
+      if (!slot.el) continue;
+      const norm = this.normalizationFactor(slot.loudnessDb);
+      if (this.routes(slot)) {
+        slot.normGain?.gain.setTargetAtTime(norm, t, RAMP_TIME_CONSTANT);
+        if (!scheduledFade) slot.fadeGain?.gain.setTargetAtTime(slot.fade, t, RAMP_TIME_CONSTANT);
+        slot.el.volume = 1;
+        slot.el.muted = false;
+      } else {
         slot.el.volume = Math.max(0, Math.min(1, vol * norm * slot.fade));
         slot.el.muted = this.muted;
       }
     }
   }
 
+  /** Whether `slot` plays through the graph, rather than past it on its own volume. */
+  private routes(slot: Slot): boolean {
+    return this.graphReady && !!slot.source && webAudioHears(slot.mime);
+  }
+
   // --- crossfade ----------------------------------------------------------
 
   /** Crossfades are timed on the audio clock, so turning them on brings WebAudio in. */
@@ -489,6 +503,25 @@ class MusicAudioEngine {
     if (this.needsGraph() && this.active.el && !this.active.el.paused) this.ensureGraph();
   }
 
+  /**
+   * Whether streams should come as AAC: on macOS only MP4 audio reaches the graph, and once the
+   * graph is in use every song plays through it.
+   */
+  wantsAac(): boolean {
+    return IS_MACOS_RUNTIME && (this.graphReady || this.needsGraph());
+  }
+
+  /** Whether the song playing bypasses the graph, so the equalizer cannot be heard on it. */
+  activeBypassesGraph(): boolean {
+    return this.graphReady && !!this.active.el?.getAttribute("src") && !this.routes(this.active);
+  }
+
+  /** Called once the graph is built, when songs loaded before it may need loading again. */
+  onGraphReady(listener: () => void): () => void {
+    this.graphListeners.add(listener);
+    return () => this.graphListeners.delete(listener);
+  }
+
   /** False once WebAudio failed here, so the equalizer cannot be heard. */
   isEqAvailable(): boolean {
     return !this.webAudioFailed && webAudioSupported();
diff --git a/src/lib/audio/musicAudioSettings.ts b/src/lib/audio/musicAudioSettings.ts
index e2c21663..527c13c6 100644
--- a/src/lib/audio/musicAudioSettings.ts
+++ b/src/lib/audio/musicAudioSettings.ts
@@ -63,6 +63,7 @@ export function bindMusicAudioSettings(): void {
       (preview !== null && graphChangesSound(graphSpec(state, false, preview), REFERENCE_SAMPLE_RATE));
     musicAudioEngine.setEq(spec, engaged);
   };
+  musicAudioEngine.onGraphReady(() => useMusicPlayerStore.getState()._reloadForWebAudio());
   applyEq();
   useEqStore.subscribe((state, previous) => {
     if (state.state !== previous.state || state.bypass !== previous.bypass || state.preview !== previous.preview) {
diff --git a/src/lib/audio/webAudioFormats.test.ts b/src/lib/audio/webAudioFormats.test.ts
new file mode 100644
index 00000000..b3528337
--- /dev/null
+++ b/src/lib/audio/webAudioFormats.test.ts
@@ -0,0 +1,23 @@
+import { describe, expect, it } from "vitest";
+
+import { webAudioHears } from "./webAudioFormats";
+
+describe("webAudioHears", () => {
+  it("hears MP4 audio on macOS", () => {
+    expect(webAudioHears('audio/mp4; codecs="mp4a.40.2"', true)).toBe(true);
+    expect(webAudioHears("audio/mpeg", true)).toBe(true);
+  });
+
+  it("does not hear WebM or Ogg on macOS", () => {
+    expect(webAudioHears('audio/webm; codecs="opus"', true)).toBe(false);
+    expect(webAudioHears("audio/ogg", true)).toBe(false);
+  });
+
+  it("hears every format elsewhere", () => {
+    expect(webAudioHears('audio/webm; codecs="opus"', false)).toBe(true);
+  });
+
+  it("assumes an unknown format is heard", () => {
+    expect(webAudioHears(null, true)).toBe(true);
+  });
+});
diff --git a/src/lib/audio/webAudioFormats.ts b/src/lib/audio/webAudioFormats.ts
new file mode 100644
index 00000000..2f456c73
--- /dev/null
+++ b/src/lib/audio/webAudioFormats.ts
@@ -0,0 +1,11 @@
+import { IS_MACOS_RUNTIME } from "../platform";
+
+/**
+ * Whether WebAudio hears an element playing `mime`. macOS WebKit plays WebM and Ogg through its
+ * own player, which never feeds a MediaElementAudioSourceNode: the node gets silence while the
+ * element keeps playing straight to the speakers, so filters and gains in the graph do nothing.
+ */
+export function webAudioHears(mime: string | null, macos = IS_MACOS_RUNTIME): boolean {
+  return !macos || mime === null || !/webm|ogg|opus/i.test(mime);
+}
+
diff --git a/src/lib/musicPreload.ts b/src/lib/musicPreload.ts
index b64bd360..22a1dbee 100644
--- a/src/lib/musicPreload.ts
+++ b/src/lib/musicPreload.ts
@@ -34,8 +34,8 @@ export async function preloadTrack(
   preloading = videoId;
   recordPlayerEvent(`music preload start: ${videoId}`);
   try {
-    const info = await resolveMusicStream(videoId, quality);
-    if (stillUpcoming(videoId)) musicAudioEngine.preload(videoId, info.audioUrl, info.loudnessDb);
+    const info = await resolveMusicStream(videoId, quality, { preferAac: musicAudioEngine.wantsAac() });
+    if (stillUpcoming(videoId)) musicAudioEngine.preload(videoId, info.audioUrl, info.loudnessDb, info.mimeType);
   } catch {
     // Speculative: if it fails, the track resolves again when it is played.
   } finally {
diff --git a/src/lib/musicStreamResolution.ts b/src/lib/musicStreamResolution.ts
index 74c01509..e65a7875 100644
--- a/src/lib/musicStreamResolution.ts
+++ b/src/lib/musicStreamResolution.ts
@@ -29,7 +29,7 @@ const MUSIC_STREAM_TIMEOUT_MS = 15_000;
 const MAX_CACHED_TRACKS = 8;
 
 export interface MusicStreamOptions {
-  /** Ask for AAC over Opus, after the element could not decode the first answer. */
+  /** Ask for AAC over Opus: after the element could not decode the first answer, or for WebAudio. */
   preferAac?: boolean;
 }
 
@@ -120,11 +120,12 @@ export function resolveMusicStream(
 export function prefetchMusicStream(
   videoId: string | null | undefined,
   quality: MusicAudioQuality,
+  options?: MusicStreamOptions,
 ) {
   if (!videoId) return;
-  const key = keyFor(videoId, quality);
+  const key = keyFor(videoId, quality, options);
   if (readCache(key) || walks.has(key)) return;
-  void request(videoId, quality).catch(() => {
+  void request(videoId, quality, options).catch(() => {
     // A speculative resolve that fails costs nothing — playing the track will
     // resolve it again and surface the real error then.
   });
diff --git a/src/store/useMusicPlayerStore.playback.test.ts b/src/store/useMusicPlayerStore.playback.test.ts
index ec7b3ce0..67cc963e 100644
--- a/src/store/useMusicPlayerStore.playback.test.ts
+++ b/src/store/useMusicPlayerStore.playback.test.ts
@@ -32,6 +32,9 @@ const { engine, resolveMusicStream, getMusicWatchQueue } = vi.hoisted(() => ({
     getContextState: vi.fn(() => "running"),
     getBufferedEnd: vi.fn(() => 10),
     getErrorCode: vi.fn((): number | null => null),
+    wantsAac: vi.fn(() => false),
+    activeBypassesGraph: vi.fn(() => false),
+    getCurrentTime: vi.fn(() => 0),
   },
   resolveMusicStream: vi.fn(),
   getMusicWatchQueue: vi.fn(),
@@ -106,6 +109,26 @@ describe("starting a track", () => {
   });
 });
 
+describe("the equalizer starting on macOS", () => {
+  it("loads the song playing again as AAC from where it is", async () => {
+    await useMusicPlayerStore.getState().playTrack(song("opus"));
+    engine.wantsAac.mockReturnValue(true);
+    engine.activeBypassesGraph.mockReturnValue(true);
+    engine.getCurrentTime.mockReturnValue(42);
+
+    useMusicPlayerStore.getState()._reloadForWebAudio();
+
+    await vi.waitFor(() =>
+      expect(resolveMusicStream).toHaveBeenLastCalledWith("opus", expect.anything(), { preferAac: true }),
+    );
+    await vi.waitFor(() => expect(engine.seekWhenReady).toHaveBeenLastCalledWith(42));
+    expect(engine.clearPreload).toHaveBeenCalled();
+    engine.wantsAac.mockReturnValue(false);
+    engine.activeBypassesGraph.mockReturnValue(false);
+    engine.getCurrentTime.mockReturnValue(0);
+  });
+});
+
 describe("recovering from a playback error", () => {
   const MEDIA_ERR_NETWORK = 2;
   const MEDIA_ERR_DECODE = 3;
diff --git a/src/store/useMusicPlayerStore.queue.test.ts b/src/store/useMusicPlayerStore.queue.test.ts
index 84a6a061..b34cad4c 100644
--- a/src/store/useMusicPlayerStore.queue.test.ts
+++ b/src/store/useMusicPlayerStore.queue.test.ts
@@ -23,7 +23,14 @@ const page = (items: SongItem[], continuation: string | null = null) => ({
 });
 
 const { engine, getMusicWatchQueue, getMusicQueueContinuation } = vi.hoisted(() => ({
-  engine: { clearPreload: vi.fn(() => null), pause: vi.fn(), stop: vi.fn(), seek: vi.fn(), play: vi.fn(async () => {}) },
+  engine: {
+    clearPreload: vi.fn(() => null),
+    pause: vi.fn(),
+    stop: vi.fn(),
+    seek: vi.fn(),
+    play: vi.fn(async () => {}),
+    wantsAac: vi.fn(() => false),
+  },
   getMusicWatchQueue: vi.fn(),
   getMusicQueueContinuation: vi.fn(),
 }));
diff --git a/src/store/useMusicPlayerStore.ts b/src/store/useMusicPlayerStore.ts
index ad6105ce..c12d88d2 100644
--- a/src/store/useMusicPlayerStore.ts
+++ b/src/store/useMusicPlayerStore.ts
@@ -296,6 +296,8 @@ interface MusicPlayerState {
   _loadIndex: (index: number, options?: { resumeAt?: number; autoplay?: boolean }) => Promise<void>;
   _prefetchUpcoming: () => void;
   _preloadUpcoming: () => void;
+  /** Loads the song playing again as AAC once WebAudio is in use, when it cannot hear it. */
+  _reloadForWebAudio: () => void;
   _onPreloadError: () => void;
   _syncTime: (progress: number, duration: number) => void;
   _reflectPlaying: (isPlaying: boolean) => void;
@@ -470,7 +472,10 @@ export const useMusicPlayerStore = create<MusicPlayerState>((set, get) => ({
     musicAudioEngine.clearPreload();
 
     const audioQuality = getMusicAudioQualitySetting();
-    const lookup = () => resolveMusicStream(videoId, audioQuality, { preferAac: recovery.prefersAac(videoId) });
+    const lookup = () =>
+      resolveMusicStream(videoId, audioQuality, {
+        preferAac: recovery.prefersAac(videoId) || musicAudioEngine.wantsAac(),
+      });
 
     try {
       // The downloads library is a SQLite read and resolution is a network round
@@ -500,7 +505,7 @@ export const useMusicPlayerStore = create<MusicPlayerState>((set, get) => ({
               : {}),
           });
           musicAudioEngine.setLoudness(offline.loudnessDb, get().normalizationEnabled);
-          await musicAudioEngine.load(offline.url);
+          await musicAudioEngine.load(offline.url, offline.contentType);
           musicAudioEngine.seekWhenReady(resumeAt);
           await start();
           afterStart();
@@ -527,7 +532,7 @@ export const useMusicPlayerStore = create<MusicPlayerState>((set, get) => ({
 
       set({ loudnessDb: info.loudnessDb, loadingStreamId: null });
       musicAudioEngine.setLoudness(info.loudnessDb, get().normalizationEnabled);
-      await musicAudioEngine.load(info.audioUrl);
+      await musicAudioEngine.load(info.audioUrl, info.mimeType);
       musicAudioEngine.seekWhenReady(resumeAt);
       await start();
       afterStart();
@@ -620,7 +625,7 @@ export const useMusicPlayerStore = create<MusicPlayerState>((set, get) => ({
     const upcomingId = videoIdOf(upcoming);
     // A downloaded track plays from disk; resolving it would be a wasted request.
     if (findDownloadedRecord(upcomingId, "audio")) return;
-    prefetchMusicStream(upcomingId, getMusicAudioQualitySetting());
+    prefetchMusicStream(upcomingId, getMusicAudioQualitySetting(), { preferAac: musicAudioEngine.wantsAac() });
   },
 
   // Buffers the next track's audio on the standby element near the end of the
@@ -637,6 +642,19 @@ export const useMusicPlayerStore = create<MusicPlayerState>((set, get) => ({
     });
   },
 
+  // On macOS WebAudio cannot hear Opus, so a song loaded before the graph existed loads again as
+  // AAC from where it is, and a next song buffered as Opus is dropped to be buffered again.
+  _reloadForWebAudio: () => {
+    if (!musicAudioEngine.wantsAac()) return;
+    musicAudioEngine.clearPreload();
+    const { currentTrack, currentIndex, loadingStreamId, isPlaying } = get();
+    if (!currentTrack || loadingStreamId !== null || !musicAudioEngine.activeBypassesGraph()) return;
+    const videoId = videoIdOf(currentTrack);
+    if (findDownloadedRecord(videoId, "audio")) return;
+    recordPlayerEvent(`music reloading as AAC for the equalizer: ${videoId}`);
+    void get()._loadIndex(currentIndex, { resumeAt: musicAudioEngine.getCurrentTime(), autoplay: isPlaying });
+  },
+
   _onPreloadError: () => {
     // The standby element refused its link; forget both so the track resolves
     // afresh when it is reached.
@@ -983,3 +1001,4 @@ useMusicPlayerStore.subscribe((state, previous) => {
     state._prefetchUpcoming();
   }
 });
+

From 3cb62cb31bca67b7d39321d401129b7610e2243a Mon Sep 17 00:00:00 2001
From: AE <98699388+A-EDev@users.noreply.github.com>
Date: Sat, 24 Oct 2026 19:52:43 +0300
Subject: [PATCH 2/2] docs(changelog): note the macOS equalizer fix

---
 changelog/v0.1.0-beta3.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/changelog/v0.1.0-beta3.txt b/changelog/v0.1.0-beta3.txt
index 2b7257a1..2cec3b8b 100644
--- a/changelog/v0.1.0-beta3.txt
+++ b/changelog/v0.1.0-beta3.txt
@@ -71,6 +71,8 @@ MACOS
 - Flow uses the native macOS window controls and titlebar again. Closing the window hides it and keeps playback and downloads running until you quit, and clicking the Dock icon brings it back.
 - The window background now follows your theme. A Tauri bug was clearing it, which showed a mismatched color around the app while resizing.
 - On 120 Hz ProMotion screens Flow now draws at 120 frames per second. WebKit was holding every animation, scroll and lyric line to 60.
+- The music equalizer and crossfade are now heard on macOS. WebKit cannot pass Opus songs through audio processing, so once either is on, songs stream as AAC and the song playing reloads once from where it is.
+- The volume slider keeps working on a downloaded Opus song while the equalizer is on.
 
 LINUX
 - The AppImage is built on Ubuntu 24.04 with a newer WebKitGTK that no longer crashes on color emoji fonts, the cause of the freeze on Fedora 44 and Bazzite. It needs glibc 2.39 or newer, so on Ubuntu 22.04, Mint 21 or Debian 12 use the .deb instead.