Stabilize German XTTS speech output

platform/docker/tts-gateway/test_tts_gateway.py

@@ -1,6 +1,7 @@
 import importlib.util
 import pathlib
 import unittest
+from array import array
 
 
 MODULE_PATH = pathlib.Path(__file__).with_name("tts_gateway.py")
@@ -10,6 +11,12 @@ SPEC.loader.exec_module(gateway)
 
 
 class LanguageSegmentationTests(unittest.TestCase):
+    def setUp(self):
+        self.original_code_switch = gateway.CODE_SWITCH_ENABLED
+
+    def tearDown(self):
+        gateway.CODE_SWITCH_ENABLED = self.original_code_switch
+
     def test_german_only(self):
         self.assertEqual(
             gateway.segment_languages("Guten Abend, wie warm ist es heute?"),
@@ -21,6 +28,7 @@ class LanguageSegmentationTests(unittest.TestCase):
         self.assertEqual(gateway.segment_languages(text), [("en", text)])
 
     def test_mixed_compounds(self):
+        gateway.CODE_SWITCH_ENABLED = True
         text = "Ich öffne das Unraid-Dashboard und prüfe die Docker-Container."
         self.assertEqual(
             gateway.segment_languages(text),
@@ -33,6 +41,43 @@ class LanguageSegmentationTests(unittest.TestCase):
             ],
         )
 
+    def test_operational_vocabulary_is_not_read_as_german(self):
+        gateway.CODE_SWITCH_ENABLED = True
+        text = (
+            "31 von 60 Containern laufen, alle sind up und healthy. "
+            "Die Health-Checks zeigen keine Crashes oder Restart-Loops. "
+            "Immich meldet unsupported image format und premature end of JPEG."
+        )
+        segments = gateway.segment_languages(text)
+        english = [part.lower() for language, part in segments if language == "en"]
+        self.assertIn("containern", english)
+        self.assertIn("up", english)
+        self.assertIn("healthy", english)
+        self.assertIn("health-checks", english)
+        self.assertIn("crashes", english)
+        self.assertIn("restart-loops", english)
+        self.assertIn("unsupported image format", english)
+        self.assertIn("premature end of jpeg", english)
+        prepared = gateway.prepare_segments(text)
+        self.assertTrue(all(any(char.isalnum() for char in part) for _, part in prepared))
+
+    def test_long_text_is_cleaned_and_chunked(self):
+        text = "✅ **Status**\n" + ("Ein langer deutscher Diagnosesatz. " * 30)
+        segments = gateway.prepare_segments(text)
+        self.assertTrue(segments)
+        self.assertTrue(all(len(part) <= gateway.CHUNK_CHARS for _, part in segments))
+        self.assertNotIn("✅", "".join(part for _, part in segments))
+
+    def test_inflected_container_has_english_pronunciation(self):
+        gateway.CODE_SWITCH_ENABLED = True
+        prepared = gateway.prepare_segments("Ich prüfe die Containern.")
+        self.assertIn(("en", "containers."), prepared)
+
+    def test_code_switch_is_disabled_by_default(self):
+        gateway.CODE_SWITCH_ENABLED = False
+        text = "Docker-Container laufen, die Health-Checks melden healthy."
+        self.assertEqual(gateway.segment_languages(text), [("de", text)])
+
 
 class FallbackTests(unittest.TestCase):
     def setUp(self):
@@ -55,5 +100,24 @@ class FallbackTests(unittest.TestCase):
         )
 
 
+class AudioJoinTests(unittest.TestCase):
+    @staticmethod
+    def pcm(values):
+        samples = array("h", values)
+        return samples.tobytes()
+
+    def test_trim_removes_long_silent_edges(self):
+        pcm = self.pcm(([0] * 1000) + ([500] * 100) + ([0] * 1000))
+        trimmed = gateway._trim_pcm(pcm)
+        self.assertLess(len(trimmed), len(pcm))
+        self.assertGreater(len(trimmed), 100 * 2)
+
+    def test_join_inserts_pause_only_after_sentence(self):
+        spoken = self.pcm([500] * 1000)
+        inline = gateway._join_pcm([("Docker", spoken), ("Container", spoken)])
+        sentence = gateway._join_pcm([("Fertig.", spoken), ("Weiter", spoken)])
+        self.assertGreater(len(sentence), len(inline))
+
+
 if __name__ == "__main__":
     unittest.main()

platform/docker/tts-gateway/tts_gateway.py

@@ -14,9 +14,11 @@ import re
 import subprocess
 import threading
 import time
+import unicodedata
 import urllib.error
 import urllib.request
 import wave
+from array import array
 from http import HTTPStatus
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 
@@ -28,13 +30,19 @@ PIPER_URL = os.getenv("PIPER_URL", "http://piper:8085").rstrip("/")
 VOICE_ALIAS = os.getenv("TTS_VOICE_ALIAS", "alloy")
 XTTS_SPEAKER = os.getenv("XTTS_SPEAKER", "Annmarie Nele")
 DEFAULT_LANGUAGE = os.getenv("TTS_DEFAULT_LANGUAGE", "de")
+CODE_SWITCH_ENABLED = os.getenv("TTS_CODE_SWITCH_ENABLED", "false").lower() \
+    in {"1", "true", "yes", "on"}
 MAX_TEXT_CHARS = int(os.getenv("TTS_MAX_TEXT_CHARS", "8000"))
 MAX_REQUEST_BYTES = int(os.getenv("TTS_MAX_REQUEST_BYTES", "65536"))
 MAX_AUDIO_BYTES = int(os.getenv("TTS_MAX_AUDIO_BYTES", str(64 * 1024 * 1024)))
 XTTS_TIMEOUT = float(os.getenv("XTTS_TIMEOUT", "120"))
 PIPER_TIMEOUT = float(os.getenv("PIPER_TIMEOUT", "120"))
 QUEUE_TIMEOUT = float(os.getenv("XTTS_QUEUE_TIMEOUT", "15"))
-SILENCE_MS = int(os.getenv("XTTS_SEGMENT_SILENCE_MS", "20"))
+CHUNK_CHARS = int(os.getenv("XTTS_CHUNK_CHARS", "220"))
+TRIM_THRESHOLD = int(os.getenv("XTTS_TRIM_THRESHOLD", "90"))
+TRIM_PADDING_MS = int(os.getenv("XTTS_TRIM_PADDING_MS", "18"))
+CROSSFADE_MS = int(os.getenv("XTTS_CROSSFADE_MS", "8"))
+SENTENCE_PAUSE_MS = int(os.getenv("XTTS_SENTENCE_PAUSE_MS", "65"))
 
 SYNTHESIS_LOCK = threading.Lock()
 STATE_LOCK = threading.Lock()
@@ -50,16 +58,27 @@ STATE = {
 # Prefer full compounds to isolated terms. This keeps switches infrequent and
 # avoids making mixed-language speech sound like a sequence of separate clips.
 ENGLISH_TERMS = (
+    "unsupported image format", "premature end of JPEG", "incomplete scan",
+    "Docker Containers", "Docker-Containers", "Docker Containern",
+    "Docker-Containern", "Health Checks", "Health-Checks",
+    "Restart Loops", "Restart-Loops", "False Positive", "Delivery Errors",
+    "DeliveryErrors", "Ack Problem", "Ack-Problem", "I/O timeout",
+    "Parity Check", "Parity-Check", "Disk disabled", "Disk invalid",
     "Home Assistant", "Open WebUI", "OpenWebUI", "Unraid Dashboard",
     "Unraid-Dashboard", "Docker Container", "Docker-Container",
     "Server Log", "Server-Log", "GitHub Repository", "GitHub Repo",
     "WireGuard Tunnel", "Cron Job", "Cronjob", "Home Server",
     "API Key", "Tool Calling", "Context Window", "Prompt Injection",
-    "Unraid", "Docker", "Container", "Dashboard", "Server", "Log",
+    "Unraid", "Docker", "Containern", "Containers", "Container",
+    "Crashes", "healthy", "disabled", "invalid", "Dashboard", "Server",
+    "Logs", "Log", "Matches", "up",
     "OpenAI", "GitHub", "WireGuard", "Linux", "Debian", "Frontend",
     "Backend", "Router", "Browser", "Web", "Token", "Prompt", "Context",
     "Model", "Image", "Tool", "Workflow", "Benchmark", "Streaming",
     "SSH", "MCP", "API", "CPU", "GPU", "VRAM", "RAM", "HTTP", "HTTPS",
+    "HomeAssistant", "ESPHome", "iGotify", "Immich", "Vaultwarden",
+    "UniFi", "UptimeKuma", "go2rtc", "Zigbee", "SONOFF", "eWeLink",
+    "RTSP", "JPEG", "NVMe", "GiB",
 )
 TERM_PATTERN = re.compile(
     r"(?<![\w])(" + "|".join(
@@ -77,6 +96,26 @@ ENGLISH_MARKERS = {
     "of", "on", "or", "please", "the", "this", "to", "with", "you",
 }
 
+ENGLISH_PRONUNCIATIONS = {
+    "containern": "containers",
+    "docker containern": "Docker containers",
+    "docker-containern": "Docker containers",
+    "docker-container": "Docker container",
+    "docker-containers": "Docker containers",
+    "health-checks": "health checks",
+    "restart-loops": "restart loops",
+    "deliveryerrors": "delivery errors",
+    "ack-problem": "ack problem",
+    "i/o timeout": "I O timeout",
+    "parity-check": "parity check",
+    "homeassistant": "Home Assistant",
+    "openwebui": "Open Web U I",
+    "rtsp": "R T S P",
+    "jpeg": "J peg",
+    "nvme": "N V M E",
+    "gib": "gigabytes",
+}
+
 
 def _request(url: str, *, payload: dict | None = None,
              timeout: float = 10) -> tuple[bytes, str]:
@@ -124,6 +163,8 @@ def segment_languages(text: str) -> list[tuple[str, str]]:
         return [("en", text)]
     if DEFAULT_LANGUAGE != "de":
         return [(DEFAULT_LANGUAGE, text)]
+    if not CODE_SWITCH_ENABLED:
+        return [("de", text)]
 
     segments: list[tuple[str, str]] = []
     cursor = 0
@@ -149,6 +190,79 @@ def segment_languages(text: str) -> list[tuple[str, str]]:
     return merged
 
 
+def clean_for_speech(text: str) -> str:
+    """Remove visual markup that makes long TTS output unstable or noisy."""
+    text = re.sub(r"```.*?```", " Code block. ", text, flags=re.DOTALL)
+    text = re.sub(r"`([^`]+)`", r"\1", text)
+    text = re.sub(r"!\[([^]]*)\]\([^)]+\)", r"\1", text)
+    text = re.sub(r"\[([^]]+)\]\([^)]+\)", r"\1", text)
+    text = re.sub(r"(?m)^\s{0,3}#{1,6}\s*", "", text)
+    text = re.sub(r"(?m)^\s*[-*+]\s+", "", text)
+    text = text.replace("→", ". ").replace("←", ". ")
+    text = text.replace("–", " - ").replace("—", " - ")
+    text = "".join(
+        char for char in text
+        if unicodedata.category(char) not in {"So", "Cs"}
+    )
+    text = re.sub(r"[ \t]+", " ", text)
+    text = re.sub(r"\s*\n+\s*", ". ", text)
+    text = re.sub(r"(?:\.\s*){2,}", ". ", text)
+    return text.strip()
+
+
+def _split_chunk(text: str, limit: int = CHUNK_CHARS) -> list[str]:
+    """Split at natural pauses and keep every XTTS request comfortably short."""
+    text = text.strip()
+    if not text:
+        return []
+    if len(text) <= limit:
+        return [text]
+
+    pieces = re.split(r"(?<=[.!?;:])\s+|\s+(?=\d+[.)]\s)", text)
+    chunks: list[str] = []
+    current = ""
+    for piece in pieces:
+        piece = piece.strip()
+        if not piece:
+            continue
+        if len(piece) > limit:
+            words = piece.split()
+            for word in words:
+                candidate = f"{current} {word}".strip()
+                if current and len(candidate) > limit:
+                    chunks.append(current)
+                    current = word
+                else:
+                    current = candidate
+            continue
+        candidate = f"{current} {piece}".strip()
+        if current and len(candidate) > limit:
+            chunks.append(current)
+            current = piece
+        else:
+            current = candidate
+    if current:
+        chunks.append(current)
+    return chunks
+
+
+def prepare_segments(text: str) -> list[tuple[str, str]]:
+    """Prepare short, deterministic German/English XTTS requests."""
+    prepared: list[tuple[str, str]] = []
+    for language, segment in segment_languages(clean_for_speech(text)):
+        if not re.search(r"\w", segment, flags=re.UNICODE):
+            if prepared:
+                previous_language, previous_text = prepared[-1]
+                prepared[-1] = (previous_language, previous_text + segment.strip())
+            continue
+        spoken = segment
+        if language == "en":
+            spoken = ENGLISH_PRONUNCIATIONS.get(segment.strip().lower(), segment)
+        for chunk in _split_chunk(spoken):
+            prepared.append((language, chunk))
+    return prepared
+
+
 def _speaker_conditioning() -> dict:
     global SPEAKER_CONDITIONING
     with SPEAKER_LOCK:
@@ -180,6 +294,70 @@ def _xtts_pcm(text: str, language: str, conditioning: dict) -> bytes:
     return audio[44:]
 
 
+def _trim_pcm(pcm: bytes) -> bytes:
+    """Trim generated edge silence while retaining a small safety padding."""
+    samples = array("h")
+    samples.frombytes(pcm)
+    if not samples:
+        return pcm
+    first = next((i for i, value in enumerate(samples)
+                  if abs(value) >= TRIM_THRESHOLD), 0)
+    last = next((i for i in range(len(samples) - 1, -1, -1)
+                 if abs(samples[i]) >= TRIM_THRESHOLD), len(samples) - 1)
+    padding = int(24000 * max(0, TRIM_PADDING_MS) / 1000)
+    first = max(0, first - padding)
+    last = min(len(samples) - 1, last + padding)
+    return samples[first:last + 1].tobytes()
+
+
+def _fade_edge(pcm: bytes, *, fade_in: bool = False,
+               fade_out: bool = False) -> bytes:
+    samples = array("h")
+    samples.frombytes(pcm)
+    count = min(len(samples), int(24000 * max(0, CROSSFADE_MS) / 1000))
+    if count <= 1:
+        return pcm
+    if fade_in:
+        for index in range(count):
+            samples[index] = int(samples[index] * index / (count - 1))
+    if fade_out:
+        start = len(samples) - count
+        for index in range(count):
+            samples[start + index] = int(
+                samples[start + index] * (count - 1 - index) / (count - 1))
+    return samples.tobytes()
+
+
+def _join_pcm(parts: list[tuple[str, bytes]]) -> bytes:
+    """Join clips without clicks; pause only at real sentence boundaries."""
+    if not parts:
+        return b""
+    output = bytearray()
+    sentence_silence = b"\x00\x00" * int(
+        24000 * max(0, SENTENCE_PAUSE_MS) / 1000)
+    for index, (text, pcm) in enumerate(parts):
+        pcm = _trim_pcm(pcm)
+        previous_ends_sentence = index > 0 and bool(
+            re.search(r"[.!?;:]\s*$", parts[index - 1][0]))
+        if index == 0:
+            output.extend(_fade_edge(pcm, fade_in=True))
+        elif previous_ends_sentence:
+            if output:
+                faded = _fade_edge(bytes(output), fade_out=True)
+                output[:] = faded
+            output.extend(sentence_silence)
+            output.extend(_fade_edge(pcm, fade_in=True))
+        else:
+            # Language switches inside a sentence get no artificial pause.
+            # Small fades remove the discontinuity that otherwise sounds like
+            # a high click or beep between independently generated clips.
+            if output:
+                faded = _fade_edge(bytes(output), fade_out=True)
+                output[:] = faded
+            output.extend(_fade_edge(pcm, fade_in=True))
+    return bytes(output)
+
+
 def _wav(pcm: bytes) -> bytes:
     output = io.BytesIO()
     with wave.open(output, "wb") as wav_file:
@@ -211,19 +389,14 @@ def _convert(wav_bytes: bytes, output_format: str, speed: float) -> tuple[bytes,
 def synthesize_xtts(text: str, output_format: str,
                     speed: float) -> tuple[bytes, str]:
     conditioning = _speaker_conditioning()
-    pcm_parts: list[bytes] = []
-    silence = b"\x00\x00" * int(24000 * max(0, SILENCE_MS) / 1000)
-    for language, segment in segment_languages(text):
+    pcm_parts: list[tuple[str, bytes]] = []
+    for language, segment in prepare_segments(text):
         if not segment.strip():
             continue
-        pcm_parts.append(_xtts_pcm(segment, language, conditioning))
-        if silence:
-            pcm_parts.append(silence)
-    if pcm_parts and silence:
-        pcm_parts.pop()
+        pcm_parts.append((segment, _xtts_pcm(segment, language, conditioning)))
     if not pcm_parts:
         raise RuntimeError("no speech segments generated")
-    return _convert(_wav(b"".join(pcm_parts)), output_format, speed)
+    return _convert(_wav(_join_pcm(pcm_parts)), output_format, speed)
 
 
 def synthesize_piper(text: str, output_format: str,