303 lines
11 KiB
Python
303 lines
11 KiB
Python
import io
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from typing import Optional
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import aiohttp
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from google.cloud import texttospeech
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from pydub import AudioSegment
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from ..core.config import settings
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from ..core.logging import get_logger
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logger = get_logger(__name__)
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class TTSService:
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def __init__(self):
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# Initialize Google TTS (uses GOOGLE_APPLICATION_CREDENTIALS env var)
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# The same GCP credentials used for GCS also work for TTS
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try:
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self.google_client = texttospeech.TextToSpeechClient()
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logger.info("Google TTS client initialized successfully")
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except Exception as e:
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logger.warning(f"Google TTS credentials not configured: {e}")
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self.google_client = None
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# Check ElevenLabs availability
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self.elevenlabs_available = bool(settings.elevenlabs_api_key)
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async def synthesize_audio_description(
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self,
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ad_vtt_content: str,
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language_code: str = "en-US",
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voice_name: Optional[str] = None
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) -> bytes:
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"""
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Generate MP3 audio from audio description VTT content
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Synthesizes each cue separately and stitches them together with timing
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Uses Google TTS with ElevenLabs fallback
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"""
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# Try Google TTS first, fallback to ElevenLabs
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try:
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if self.google_client:
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return await self._synthesize_with_google(ad_vtt_content, language_code, voice_name)
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elif self.elevenlabs_available:
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return await self._synthesize_with_elevenlabs(ad_vtt_content, language_code, voice_name)
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else:
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raise ValueError("No TTS service configured")
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except Exception as e:
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if self.elevenlabs_available and self.google_client:
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logger.warning(f"Google TTS failed, trying ElevenLabs: {e}")
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return await self._synthesize_with_elevenlabs(ad_vtt_content, language_code, voice_name)
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raise
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async def _synthesize_with_google(
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self,
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ad_vtt_content: str,
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language_code: str = "en-US",
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voice_name: Optional[str] = None
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) -> bytes:
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"""Generate MP3 using Google TTS with 2-second pauses between passages"""
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# Parse VTT cues
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cues = self._parse_ad_cues(ad_vtt_content)
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if not cues:
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raise ValueError("No audio description cues found")
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# Synthesize each cue separately with precise timing anchoring
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audio_segments = []
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current_audio_position = 0.0 # Track actual audio timeline position
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for i, cue in enumerate(cues):
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# Calculate where this cue should start (anchored to VTT timing)
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target_start_time = cue["start_time"]
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# Add silence to reach the exact VTT start time
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if target_start_time > current_audio_position:
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silence_duration = target_start_time - current_audio_position
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silence = AudioSegment.silent(duration=int(silence_duration * 1000))
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audio_segments.append(silence)
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current_audio_position = target_start_time
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# Synthesize this cue's text
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text = cue["text"].strip()
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if text:
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# Ensure proper punctuation for natural TTS flow
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if not text.endswith(('.', '!', '?')):
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text += "."
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# Synthesize this individual cue
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audio_data = await self._synthesize_text_google(
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text, language_code, voice_name
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)
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# Convert to AudioSegment and get actual duration
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audio_segment = AudioSegment.from_file(io.BytesIO(audio_data), format="mp3")
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audio_segments.append(audio_segment)
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# Update current position based on actual audio duration (not VTT end time)
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actual_audio_duration = len(audio_segment) / 1000.0 # Convert ms to seconds
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current_audio_position += actual_audio_duration
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# Combine all segments
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if audio_segments:
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final_audio = sum(audio_segments, AudioSegment.empty())
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else:
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# Fallback to empty audio if no segments
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final_audio = AudioSegment.silent(duration=1000)
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# Export to MP3
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output_buffer = io.BytesIO()
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final_audio.export(output_buffer, format="mp3", bitrate="128k")
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return output_buffer.getvalue()
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async def _synthesize_with_elevenlabs(
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self,
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ad_vtt_content: str,
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language_code: str = "en-US",
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voice_name: Optional[str] = None
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) -> bytes:
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"""Generate MP3 using ElevenLabs TTS"""
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# Parse VTT cues
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cues = self._parse_ad_cues(ad_vtt_content)
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if not cues:
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raise ValueError("No audio description cues found")
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# Get voice ID for language
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voice_id = self._get_elevenlabs_voice(language_code, voice_name)
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# Synthesize each cue with precise timing anchoring
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audio_segments = []
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current_audio_position = 0.0 # Track actual audio timeline position
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for i, cue in enumerate(cues):
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# Calculate where this cue should start (anchored to VTT timing)
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target_start_time = cue["start_time"]
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# Add silence to reach the exact VTT start time
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if target_start_time > current_audio_position:
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silence_duration = target_start_time - current_audio_position
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silence = AudioSegment.silent(duration=int(silence_duration * 1000))
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audio_segments.append(silence)
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current_audio_position = target_start_time
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# Synthesize this cue with ElevenLabs
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text = cue["text"].strip()
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if text:
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audio_data = await self._synthesize_text_elevenlabs(text, voice_id)
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# Convert to AudioSegment and get actual duration
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audio_segment = AudioSegment.from_file(io.BytesIO(audio_data), format="mp3")
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audio_segments.append(audio_segment)
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# Update current position based on actual audio duration (not VTT end time)
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actual_audio_duration = len(audio_segment) / 1000.0 # Convert ms to seconds
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current_audio_position += actual_audio_duration
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# Combine all segments
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final_audio = sum(audio_segments, AudioSegment.empty())
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# Export to MP3
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output_buffer = io.BytesIO()
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final_audio.export(output_buffer, format="mp3", bitrate="128k")
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return output_buffer.getvalue()
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async def _synthesize_text_google(
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self,
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text: str,
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language_code: str,
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voice_name: Optional[str] = None
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) -> bytes:
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"""Synthesize a single text string to audio using Google TTS"""
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# Configure voice
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if not voice_name:
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voice_name = settings.google_tts_voices.get(language_code, "en-US-Neural2-D")
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voice = texttospeech.VoiceSelectionParams(
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language_code=language_code,
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name=voice_name
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)
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# Configure audio
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audio_config = texttospeech.AudioConfig(
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audio_encoding=texttospeech.AudioEncoding.MP3,
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speaking_rate=1.2, # Faster cadence for better flow
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pitch=0.0
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)
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# Synthesize
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synthesis_input = texttospeech.SynthesisInput(text=text)
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response = self.google_client.synthesize_speech(
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input=synthesis_input,
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voice=voice,
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audio_config=audio_config
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)
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return response.audio_content
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async def _synthesize_text_elevenlabs(self, text: str, voice_id: str) -> bytes:
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"""Synthesize text using ElevenLabs API"""
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url = f"https://api.elevenlabs.io/v1/text-to-speech/{voice_id}"
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headers = {
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"Accept": "audio/mpeg",
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"Content-Type": "application/json",
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"xi-api-key": settings.elevenlabs_api_key
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}
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data = {
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"text": text,
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"model_id": "eleven_multilingual_v2",
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"voice_settings": {
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"stability": 0.5,
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"similarity_boost": 0.5,
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"style": 0.0,
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"use_speaker_boost": True
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}
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}
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async with aiohttp.ClientSession() as session:
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async with session.post(url, json=data, headers=headers) as response:
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if response.status == 200:
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return await response.read()
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else:
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error_text = await response.text()
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raise ValueError(f"ElevenLabs TTS failed: {response.status} - {error_text}")
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def _get_elevenlabs_voice(self, language_code: str, voice_name: Optional[str] = None) -> str:
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"""Get ElevenLabs voice ID for language"""
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if voice_name:
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return voice_name
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return settings.elevenlabs_voices.get(language_code, "21m00Tcm4TlvDq8ikWAM")
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def _parse_ad_cues(self, vtt_content: str) -> list[dict]:
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"""Parse audio description VTT and extract timing + text"""
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lines = vtt_content.strip().split('\n')
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cues = []
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i = 0
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while i < len(lines):
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line = lines[i].strip()
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# Skip header and empty lines
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if line == "WEBVTT" or line == "" or line.startswith("NOTE"):
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i += 1
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continue
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# Check for timing line
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if " --> " in line:
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timing_parts = line.split(" --> ")
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start_time = self._parse_timestamp(timing_parts[0].strip())
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end_time = self._parse_timestamp(timing_parts[1].strip())
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# Get text from next line(s)
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i += 1
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text_lines = []
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while i < len(lines) and lines[i].strip() != "":
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text_lines.append(lines[i].strip())
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i += 1
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if text_lines:
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cues.append({
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"start_time": start_time,
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"end_time": end_time,
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"text": " ".join(text_lines)
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})
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else:
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i += 1
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return cues
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def _parse_timestamp(self, timestamp: str) -> float:
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"""Convert VTT timestamp to seconds"""
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# Format: HH:MM:SS.mmm or MM:SS.mmm
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parts = timestamp.split(":")
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if len(parts) == 3: # HH:MM:SS.mmm
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hours, minutes, seconds = parts
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elif len(parts) == 2: # MM:SS.mmm
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hours, minutes, seconds = "0", parts[0], parts[1]
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else:
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raise ValueError(f"Invalid timestamp format: {timestamp}")
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# Parse seconds and milliseconds
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sec_parts = seconds.split(".")
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seconds = int(sec_parts[0])
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milliseconds = int(sec_parts[1]) if len(sec_parts) > 1 else 0
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total_seconds = (
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int(hours) * 3600 +
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int(minutes) * 60 +
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seconds +
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milliseconds / 1000.0
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)
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return total_seconds
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# Global service instance
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tts_service = TTSService()
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