feat: add ffmpeg music player

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/media/musicPlayer.ts

@@ -0,0 +1,70 @@
+import { spawn as nodeSpawn } from "node:child_process";
+import type { ChildProcessWithoutNullStreams } from "node:child_process";
+import { discordPlayer } from "../player";
+import type {
+  DiscordAudioPlayer,
+  MusicPlayback,
+  MusicPlayer,
+  ResolvedMediaSource,
+} from "./mediaTypes";
+
+export interface MusicPlayerDependencies {
+  spawn?: typeof nodeSpawn;
+  discordPlayer?: DiscordAudioPlayer;
+}
+
+export function createMusicPlayer(
+  dependencies: MusicPlayerDependencies = {},
+): MusicPlayer {
+  const spawn = dependencies.spawn ?? nodeSpawn;
+  const audioPlayer = dependencies.discordPlayer ?? discordPlayer;
+
+  return {
+    play(source: ResolvedMediaSource): MusicPlayback {
+      const proc = spawn("ffmpeg", buildFfmpegArgs(source.source), {
+        stdio: ["ignore", "pipe", "pipe"],
+      }) as unknown as ChildProcessWithoutNullStreams;
+
+      audioPlayer.playStream(proc.stdout);
+
+      const done = new Promise<void>((resolve, reject) => {
+        proc.on("error", reject);
+        proc.on("close", (code) => {
+          if (code === 0) {
+            resolve();
+            return;
+          }
+          reject(new Error(`ffmpeg exited with code ${code}`));
+        });
+      });
+
+      return {
+        done,
+        stop() {
+          proc.kill("SIGTERM");
+          audioPlayer.stop();
+        },
+      };
+    },
+  };
+}
+
+export function buildFfmpegArgs(source: string): string[] {
+  return [
+    "-hide_banner",
+    "-loglevel",
+    "warning",
+    "-i",
+    source,
+    "-vn",
+    "-acodec",
+    "libopus",
+    "-ar",
+    "48000",
+    "-ac",
+    "2",
+    "-f",
+    "ogg",
+    "pipe:1",
+  ];
+}

src/player.ts

@@ -29,6 +29,10 @@ export class DiscordPlayer {
     this.connection.subscribe(this.player);
   }
 
+  public isConnected(): boolean {
+    return this.connection !== null;
+  }
+
   public playStream(stream: Readable) {
     console.log("[player] Starting new audio stream...");
 

tests/media/musicPlayer.test.ts

@@ -0,0 +1,72 @@
+import { EventEmitter } from "node:events";
+import { PassThrough } from "node:stream";
+import { describe, expect, it, vi } from "vitest";
+import { createMusicPlayer } from "../../src/media/musicPlayer";
+import type { DiscordAudioPlayer } from "../../src/media/mediaTypes";
+
+class FakeProcess extends EventEmitter {
+  stdout = new PassThrough();
+  stderr = new PassThrough();
+  killed = false;
+  kill = vi.fn(() => {
+    this.killed = true;
+    this.emit("close", 0);
+    return true;
+  });
+}
+
+describe("createMusicPlayer", () => {
+  it("spawns ffmpeg as Ogg Opus and passes stdout to Discord", async () => {
+    const proc = new FakeProcess();
+    const spawn = vi.fn(() => proc);
+    const discordPlayer: DiscordAudioPlayer = {
+      isConnected: () => true,
+      playStream: vi.fn(),
+      stop: vi.fn(),
+    };
+    const player = createMusicPlayer({ spawn, discordPlayer });
+
+    const playback = player.play({
+      source: "https://example.com/song.mp3",
+      title: "song.mp3",
+      kind: "url",
+    });
+    proc.emit("close", 0);
+    await playback.done;
+
+    expect(spawn).toHaveBeenCalledWith("ffmpeg", [
+      "-hide_banner",
+      "-loglevel",
+      "warning",
+      "-i",
+      "https://example.com/song.mp3",
+      "-vn",
+      "-acodec",
+      "libopus",
+      "-ar",
+      "48000",
+      "-ac",
+      "2",
+      "-f",
+      "ogg",
+      "pipe:1",
+    ], { stdio: ["ignore", "pipe", "pipe"] });
+    expect(discordPlayer.playStream).toHaveBeenCalledWith(proc.stdout);
+  });
+
+  it("kills ffmpeg and stops Discord playback", () => {
+    const proc = new FakeProcess();
+    const discordPlayer: DiscordAudioPlayer = {
+      isConnected: () => true,
+      playStream: vi.fn(),
+      stop: vi.fn(),
+    };
+    const player = createMusicPlayer({ spawn: vi.fn(() => proc), discordPlayer });
+
+    const playback = player.play({ source: "/tmp/song.ogg", title: "song.ogg", kind: "local" });
+    playback.stop();
+
+    expect(proc.kill).toHaveBeenCalledWith("SIGTERM");
+    expect(discordPlayer.stop).toHaveBeenCalled();
+  });
+});