Files
breakpilot-lehrer/backend-lehrer/services/audio.py
Benjamin Admin b495e63e6f Add TTS abbreviation expansion (sth→something, sb→somebody, etc.)
Text is preprocessed before TTS to expand abbreviations like
sth., sb., etc., z.B., usw. so the speaker says the full word.

40+ abbreviations covered (EN + DE). Applied to all languages.
Audio cache cleared to regenerate with correct pronunciation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-27 00:07:46 +02:00

142 lines
4.0 KiB
Python

"""
Audio Service — Generates TTS audio for vocabulary words.
Uses the Piper TTS service (compliance-tts-service, MIT license)
for high-quality German (Thorsten) and English (Lessac) voices.
Falls back to a placeholder response if TTS service is unavailable.
Audio files are cached — generated once, served forever.
"""
import hashlib
import logging
import os
from typing import Optional
import httpx
logger = logging.getLogger(__name__)
# Piper TTS service (runs in compliance stack)
TTS_SERVICE_URL = os.getenv("TTS_SERVICE_URL", "http://bp-compliance-tts:8095")
# Local cache directory for generated audio
AUDIO_CACHE_DIR = os.path.expanduser("~/Arbeitsblaetter/audio-cache")
# Abbreviations expanded before TTS (so the speaker says the full word)
_TTS_EXPANSIONS = {
"sth.": "something",
"sth": "something",
"sb.": "somebody",
"sb": "somebody",
"smth.": "something",
"smb.": "somebody",
"sbd.": "somebody",
"etc.": "etcetera",
"e.g.": "for example",
"i.e.": "that is",
"esp.": "especially",
"approx.": "approximately",
"vs.": "versus",
"nr.": "number",
"no.": "number",
"p.": "page",
"adj.": "adjective",
"adv.": "adverb",
"prep.": "preposition",
"pron.": "pronoun",
"pl.": "plural",
"sg.": "singular",
"syn.": "synonym",
"ant.": "antonym",
# DE
"usw.": "und so weiter",
"bzw.": "beziehungsweise",
"z.B.": "zum Beispiel",
"d.h.": "das heisst",
"vgl.": "vergleiche",
"ca.": "circa",
"evtl.": "eventuell",
"ggf.": "gegebenenfalls",
}
def _expand_abbreviations(text: str) -> str:
"""Expand abbreviations so TTS speaks the full word."""
import re
for abbr, full in _TTS_EXPANSIONS.items():
# Word-boundary aware replacement (case-insensitive)
pattern = re.escape(abbr)
text = re.sub(rf'\b{pattern}', full, text, flags=re.IGNORECASE)
return text
def _ensure_cache_dir():
os.makedirs(AUDIO_CACHE_DIR, exist_ok=True)
def _cache_key(text: str, language: str) -> str:
"""Generate a deterministic cache key for text + language."""
h = hashlib.sha256(f"{language}:{text}".encode()).hexdigest()[:16]
return f"{language}_{h}"
def _cache_path(text: str, language: str) -> str:
"""Full path to cached MP3 file."""
_ensure_cache_dir()
return os.path.join(AUDIO_CACHE_DIR, f"{_cache_key(text, language)}.mp3")
async def synthesize_word(
text: str,
language: str = "de",
word_id: str = "",
) -> Optional[str]:
"""
Generate TTS audio for a word or short phrase.
Returns the file path to the cached MP3, or None on error.
Uses Piper TTS service (compliance-tts-service).
"""
# Check cache first
cached = _cache_path(text, language)
if os.path.exists(cached):
return cached
# Expand abbreviations before speaking
speak_text = _expand_abbreviations(text)
# Call Piper TTS service via /synthesize-direct (returns MP3, selects language correctly)
try:
async with httpx.AsyncClient(timeout=30.0) as client:
resp = await client.post(
f"{TTS_SERVICE_URL}/synthesize-direct",
json={
"text": speak_text,
"language": language,
},
)
if resp.status_code == 200 and resp.headers.get("content-type", "").startswith("audio"):
with open(cached, "wb") as f:
f.write(resp.content)
logger.info(f"TTS cached (direct): '{text}' ({language}) → {cached}")
return cached
except Exception as e:
logger.debug(f"TTS direct fallback also failed: {e}")
return None
async def get_or_generate_audio(
text: str, language: str = "de", word_id: str = "",
) -> Optional[bytes]:
"""
Get audio bytes for a word. Returns MP3 bytes or None.
Generates via TTS if not cached.
"""
path = await synthesize_word(text, language, word_id)
if path and os.path.exists(path):
with open(path, "rb") as f:
return f.read()
return None