Replace ElevenLabs with local STT and TTS

src/services/local-tts.ts

@@ -0,0 +1,94 @@
+import { Readable } from "node:stream";
+
+import prism from "prism-media";
+
+import type { AssistantRuntimeConfig } from "../config.js";
+import type { Logger } from "../logger.js";
+import { resolveFfmpegPath } from "../audio/ffmpeg-path.js";
+import { PythonJsonWorker } from "./python-json-worker.js";
+import type { PreparedSpeechAudio, TtsService } from "./tts.js";
+
+interface SynthesizeResult {
+  wav_base64?: string;
+}
+
+export class LocalMeloTtsService implements TtsService {
+  private readonly worker: PythonJsonWorker;
+
+  constructor(config: AssistantRuntimeConfig, logger: Logger) {
+    const resolvedFfmpegPath = resolveFfmpegPath();
+    if (resolvedFfmpegPath && !process.env.FFMPEG_PATH) {
+      process.env.FFMPEG_PATH = resolvedFfmpegPath;
+    }
+
+    this.worker = new PythonJsonWorker(config, logger, "local_tts_worker.py", "local-tts", {
+      LOCAL_TTS_LANGUAGE: config.LOCAL_TTS_LANGUAGE,
+      LOCAL_TTS_SPEAKER: config.LOCAL_TTS_SPEAKER,
+      LOCAL_TTS_DEVICE: config.LOCAL_TTS_DEVICE,
+      LOCAL_TTS_SPEED: String(config.LOCAL_TTS_SPEED),
+    });
+  }
+
+  async warmup(): Promise<void> {
+    await this.worker.request("ping", {});
+  }
+
+  async preparePlayback(text: string, signal?: AbortSignal): Promise<PreparedSpeechAudio> {
+    const result = await this.worker.request<SynthesizeResult>(
+      "synthesize",
+      {
+        text,
+      },
+      signal,
+    );
+
+    const wavBase64 = result.wav_base64;
+    if (!wavBase64) {
+      throw new Error("로컬 TTS가 빈 오디오를 반환했습니다.");
+    }
+
+    const input = Readable.from([Buffer.from(wavBase64, "base64")]);
+    const ffmpeg = new prism.FFmpeg({
+      args: [
+        "-analyzeduration",
+        "0",
+        "-loglevel",
+        "0",
+        "-i",
+        "pipe:0",
+        "-f",
+        "s16le",
+        "-ar",
+        "48000",
+        "-ac",
+        "2",
+        "pipe:1",
+      ],
+    });
+
+    if (signal) {
+      signal.addEventListener(
+        "abort",
+        () => {
+          input.destroy();
+          ffmpeg.destroy();
+        },
+        { once: true },
+      );
+    }
+
+    input.pipe(ffmpeg);
+
+    return {
+      stream: ffmpeg,
+      dispose: () => {
+        input.destroy();
+        ffmpeg.destroy();
+      },
+    };
+  }
+
+  async destroy(): Promise<void> {
+    await this.worker.destroy();
+  }
+}