add hermes tts playback (#541)

packages/server/src/services/hermes/tts.ts

@@ -0,0 +1,41 @@
+import { EdgeTTS } from 'node-edge-tts'
+import { tmpdir } from 'os'
+import { join } from 'path'
+import { readFile, unlink } from 'fs/promises'
+import { randomUUID } from 'crypto'
+import { logger } from '../logger'
+
+const FIXED_VOICE = 'zh-CN-XiaoxiaoNeural'
+const FIXED_RATE = '+4%'
+const FIXED_PITCH = '+12Hz'
+
+export interface TtsOptions {
+  text: string
+  lang?: string
+}
+
+export async function edgeTts(opts: TtsOptions): Promise<Buffer> {
+  const id = randomUUID()
+  const tmpFile = join(tmpdir(), `tts-${id}.mp3`)
+
+  try {
+    const tts = new EdgeTTS({
+      voice: FIXED_VOICE,
+      rate: FIXED_RATE,
+      pitch: FIXED_PITCH,
+      timeout: 15000,
+    })
+
+    await tts.ttsPromise(opts.text, tmpFile)
+    const buf = await readFile(tmpFile)
+    return buf
+  } finally {
+    unlink(tmpFile).catch(() => {})
+  }
+}
+
+export async function textToSpeech(opts: TtsOptions): Promise<{ audio: Buffer; engine: string }> {
+  const audio = await edgeTts(opts)
+  logger.debug({ engine: 'edge', voice: FIXED_VOICE, rate: FIXED_RATE, pitch: FIXED_PITCH }, 'TTS generated via Edge')
+  return { audio, engine: 'edge' }
+}