#!/usr/bin/env python3 """ Gemini TTS API Server A FastAPI-based REST API for Google's Gemini Text-to-Speech service with concurrent request handling and audio format conversion. """ import os import asyncio import json import base64 import uuid from datetime import datetime from typing import Optional, List, Dict, Any from io import BytesIO import aiohttp import aiofiles from fastapi import FastAPI, HTTPException, BackgroundTasks, Request from fastapi.responses import FileResponse, JSONResponse from fastapi.middleware.cors import CORSMiddleware from pydantic import BaseModel, Field from pydub import AudioSegment import uvicorn # Pydantic models for request/response class VoiceConfig(BaseModel): voice_name: str = Field(default="Zephyr", description="Voice name (e.g., Zephyr, Puck)") class SpeakerConfig(BaseModel): speaker: str = Field(description="Speaker identifier") voice_config: VoiceConfig class TTSRequest(BaseModel): text: str = Field(description="Text to convert to speech") speakers: Optional[List[SpeakerConfig]] = Field( default=None, description="Multi-speaker configuration (optional)" ) voice_name: Optional[str] = Field( default="Zephyr", description="Single voice name (used if speakers not provided)" ) output_format: str = Field(default="wav", description="Output format: wav or mp3") speed_factor: float = Field(default=1.0, description="Speed adjustment factor") temperature: float = Field(default=1.0, description="Generation temperature") class TTSResponse(BaseModel): task_id: str status: str message: str audio_url: Optional[str] = None metadata: Optional[Dict[str, Any]] = None class TaskStatus(BaseModel): task_id: str status: str progress: Optional[str] = None error: Optional[str] = None result: Optional[Dict[str, Any]] = None # Global task storage (in production, use Redis or database) tasks: Dict[str, Dict[str, Any]] = {} # FastAPI app initialization app = FastAPI( title="Gemini TTS API", description="Text-to-Speech API using Google's Gemini model with concurrent request handling", version="1.0.0" ) # CORS middleware app.add_middleware( CORSMiddleware, allow_origins=["*"], # Configure appropriately for production allow_credentials=True, allow_methods=["*"], allow_headers=["*"], ) # Configuration def get_api_keys(): """Get API keys from environment variables""" # Support multiple formats for API keys api_keys = [] # Single API key (backward compatibility) single_key = os.getenv('GEMINI_API_KEY') if single_key: api_keys.append(single_key.strip()) # Multiple API keys (comma-separated) multi_keys = os.getenv('GEMINI_API_KEYS') if multi_keys: keys = [key.strip() for key in multi_keys.split(',') if key.strip()] api_keys.extend(keys) # Individual API keys (GEMINI_API_KEY_1, GEMINI_API_KEY_2, etc.) i = 1 while True: key = os.getenv(f'GEMINI_API_KEY_{i}') if not key: break api_keys.append(key.strip()) i += 1 # Remove duplicates while preserving order seen = set() unique_keys = [] for key in api_keys: if key not in seen: seen.add(key) unique_keys.append(key) return unique_keys GEMINI_API_KEYS = get_api_keys() MODEL_ID = "gemini-2.5-flash-preview-tts" GENERATE_CONTENT_API = "streamGenerateContent" OUTPUT_DIR = "/tmp/audio_files" MAX_CONCURRENT_REQUESTS = 10 RATE_LIMIT_RETRY_DELAY = 60 # seconds to wait after rate limit MAX_RETRIES_PER_KEY = 2 # API key management class APIKeyManager: def __init__(self, api_keys: List[str]): self.api_keys = api_keys self.current_key_index = 0 self.key_stats = {key: {"requests": 0, "failures": 0, "last_rate_limit": None} for key in api_keys} self.lock = asyncio.Lock() async def get_next_key(self) -> Optional[str]: """Get the next available API key""" async with self.lock: if not self.api_keys: return None # Try to find a key that's not rate limited for _ in range(len(self.api_keys)): key = self.api_keys[self.current_key_index] stats = self.key_stats[key] # Check if this key is currently rate limited if stats["last_rate_limit"]: time_since_limit = datetime.now().timestamp() - stats["last_rate_limit"] if time_since_limit < RATE_LIMIT_RETRY_DELAY: # Still rate limited, try next key self.current_key_index = (self.current_key_index + 1) % len(self.api_keys) continue else: # Rate limit period has passed, reset stats["last_rate_limit"] = None # This key is available stats["requests"] += 1 return key # All keys are rate limited, return the one with oldest rate limit oldest_key = min( self.api_keys, key=lambda k: self.key_stats[k]["last_rate_limit"] or 0 ) return oldest_key async def mark_rate_limited(self, api_key: str): """Mark an API key as rate limited""" async with self.lock: if api_key in self.key_stats: self.key_stats[api_key]["last_rate_limit"] = datetime.now().timestamp() self.key_stats[api_key]["failures"] += 1 async def mark_success(self, api_key: str): """Mark an API key as successful (reset failure count)""" async with self.lock: if api_key in self.key_stats: self.key_stats[api_key]["failures"] = max(0, self.key_stats[api_key]["failures"] - 1) def get_stats(self) -> dict: """Get statistics for all API keys""" return { "total_keys": len(self.api_keys), "key_stats": self.key_stats.copy() } # Initialize API key manager api_key_manager = APIKeyManager(GEMINI_API_KEYS) # Ensure output directory exists os.makedirs(OUTPUT_DIR, exist_ok=True) # Semaphore to limit concurrent requests semaphore = asyncio.Semaphore(MAX_CONCURRENT_REQUESTS) async def convert_and_adjust_audio( audio_data: bytes, output_format: str = "wav", speed_factor: float = 1.0 ) -> tuple[bytes, str]: """ Convert PCM audio data to specified format and adjust speed asynchronously """ def _convert(): # Create AudioSegment from raw PCM data audio = AudioSegment( data=audio_data, sample_width=2, # 16-bit = 2 bytes frame_rate=24000, # 24kHz channels=1 # mono ) # Adjust speed by changing frame rate if speed_factor != 1.0: new_frame_rate = int(audio.frame_rate * speed_factor) audio_speed_adjusted = audio._spawn( audio.raw_data, overrides={"frame_rate": new_frame_rate} ) audio_speed_adjusted = audio_speed_adjusted.set_frame_rate(audio.frame_rate) else: audio_speed_adjusted = audio # Export to desired format buffer = BytesIO() if output_format.lower() == "mp3": audio_speed_adjusted.export(buffer, format="mp3", bitrate="128k") return buffer.getvalue(), "mp3" else: audio_speed_adjusted.export(buffer, format="wav") return buffer.getvalue(), "wav" # Run audio processing in thread pool to avoid blocking loop = asyncio.get_event_loop() return await loop.run_in_executor(None, _convert) async def generate_tts_audio( task_id: str, text: str, speakers: Optional[List[SpeakerConfig]] = None, voice_name: str = "Zephyr", output_format: str = "wav", speed_factor: float = 1.0, temperature: float = 1.0 ): """ Generate TTS audio using Gemini API with multiple API key support and rate limit handling """ async with semaphore: # Limit concurrent requests try: # Update task status tasks[task_id]["status"] = "processing" tasks[task_id]["progress"] = "Preparing request" # Prepare request data if speakers: # Multi-speaker configuration speech_config = { "multi_speaker_voice_config": { "speaker_voice_configs": [ { "speaker": speaker.speaker, "voice_config": { "prebuilt_voice_config": { "voice_name": speaker.voice_config.voice_name } } } for speaker in speakers ] } } else: # Single voice configuration speech_config = { "voice_config": { "prebuilt_voice_config": { "voice_name": voice_name } } } request_data = { "contents": [ { "role": "user", "parts": [{"text": text}] } ], "generationConfig": { "responseModalities": ["audio"], "temperature": temperature, "speech_config": speech_config } } # API endpoint url = f"https://generativelanguage.googleapis.com/v1beta/models/{MODEL_ID}:{GENERATE_CONTENT_API}" tasks[task_id]["progress"] = "Calling Gemini API" # Try multiple API keys with rate limit handling last_error = None attempts = 0 max_total_attempts = len(GEMINI_API_KEYS) * MAX_RETRIES_PER_KEY if GEMINI_API_KEYS else 1 while attempts < max_total_attempts: current_api_key = await api_key_manager.get_next_key() if not current_api_key: raise HTTPException(status_code=500, detail="No API keys available") attempts += 1 tasks[task_id]["progress"] = f"Attempting API call (attempt {attempts}/{max_total_attempts})" try: # Make async API request async with aiohttp.ClientSession() as session: async with session.post( url, headers={"Content-Type": "application/json"}, params={"key": current_api_key}, json=request_data, timeout=aiohttp.ClientTimeout(total=120) # 2 minute timeout ) as response: # Handle different HTTP status codes if response.status == 200: # Success! Mark key as successful and proceed await api_key_manager.mark_success(current_api_key) response_data = await response.json() break elif response.status == 429: # Rate limit exceeded error_text = await response.text() await api_key_manager.mark_rate_limited(current_api_key) last_error = f"Rate limit exceeded for API key: {error_text}" print(f"Rate limit hit for key ending in ...{current_api_key[-4:]}, trying next key") continue elif response.status in [403, 401]: # Auth errors error_text = await response.text() await api_key_manager.mark_rate_limited(current_api_key) # Temporarily disable this key last_error = f"Authentication error: {error_text}" print(f"Auth error for key ending in ...{current_api_key[-4:]}: {error_text}") continue else: # Other HTTP errors error_text = await response.text() last_error = f"HTTP {response.status}: {error_text}" # Don't mark as rate limited for other errors, but still try next key continue except asyncio.TimeoutError: last_error = "Request timeout" continue except aiohttp.ClientError as e: last_error = f"Client error: {str(e)}" continue except Exception as e: last_error = f"Unexpected error: {str(e)}" continue else: # All attempts failed raise HTTPException( status_code=500, detail=f"All API keys exhausted. Last error: {last_error}" ) tasks[task_id]["progress"] = "Processing audio data" # Extract audio data if response_data and len(response_data) > 0: candidates = response_data[0].get("candidates", []) if not candidates: raise HTTPException(status_code=500, detail="No candidates in response") parts = candidates[0].get("content", {}).get("parts", []) audio_data_b64 = None for part in parts: if "inlineData" in part: audio_data_b64 = part["inlineData"].get("data", "") break if not audio_data_b64: raise HTTPException(status_code=500, detail="No audio data found in response") # Decode base64 audio data audio_data = base64.b64decode(audio_data_b64) tasks[task_id]["progress"] = "Converting audio format" # Convert and adjust audio converted_audio, file_ext = await convert_and_adjust_audio( audio_data, output_format, speed_factor ) # Generate filename timestamp = datetime.now().strftime("%Y%m%d_%H%M%S") filename = f"gemini_audio_{task_id}_{timestamp}.{file_ext}" filepath = os.path.join(OUTPUT_DIR, filename) # Save audio file async with aiofiles.open(filepath, "wb") as f: await f.write(converted_audio) # Update task with results tasks[task_id].update({ "status": "completed", "progress": "Completed", "result": { "filename": filename, "filepath": filepath, "format": output_format.upper(), "speed_factor": speed_factor, "original_size": len(audio_data), "converted_size": len(converted_audio), "audio_url": f"/audio/{filename}" } }) except Exception as e: tasks[task_id].update({ "status": "failed", "error": str(e) }) # API Endpoints @app.get("/") async def root(): """Root endpoint with API information""" return { "message": "Gemini TTS API Server", "version": "1.0.0", "endpoints": { "POST /tts": "Generate TTS audio", "GET /status/{task_id}": "Get task status", "GET /audio/{filename}": "Download audio file", "GET /tasks": "List all tasks" } } @app.post("/tts", response_model=TTSResponse) async def create_tts_task( request: TTSRequest, background_tasks: BackgroundTasks ): """ Create a new TTS generation task """ if not GEMINI_API_KEYS: raise HTTPException(status_code=500, detail="No GEMINI_API_KEYs configured. Please set GEMINI_API_KEY, GEMINI_API_KEYS, or GEMINI_API_KEY_1, GEMINI_API_KEY_2, etc.") # Generate unique task ID task_id = str(uuid.uuid4()) # Initialize task tasks[task_id] = { "task_id": task_id, "status": "queued", "created_at": datetime.now().isoformat(), "request": request.dict() } # Start background task background_tasks.add_task( generate_tts_audio, task_id, request.text, request.speakers, request.voice_name, request.output_format, request.speed_factor, request.temperature ) return TTSResponse( task_id=task_id, status="queued", message="TTS generation task created successfully" ) @app.get("/status/{task_id}", response_model=TaskStatus) async def get_task_status(task_id: str): """ Get the status of a TTS generation task """ if task_id not in tasks: raise HTTPException(status_code=404, detail="Task not found") task = tasks[task_id] return TaskStatus( task_id=task_id, status=task["status"], progress=task.get("progress"), error=task.get("error"), result=task.get("result") ) @app.get("/audio/{filename}") async def download_audio(filename: str): """ Download generated audio file """ filepath = os.path.join(OUTPUT_DIR, filename) if not os.path.exists(filepath): raise HTTPException(status_code=404, detail="Audio file not found") return FileResponse( filepath, media_type="application/octet-stream", filename=filename ) @app.get("/tasks") async def list_tasks(): """ List all tasks with their current status """ return {"tasks": list(tasks.values())} @app.delete("/tasks/{task_id}") async def delete_task(task_id: str): """ Delete a task and its associated audio file """ if task_id not in tasks: raise HTTPException(status_code=404, detail="Task not found") task = tasks[task_id] # Delete audio file if it exists if task.get("result") and task["result"].get("filepath"): filepath = task["result"]["filepath"] if os.path.exists(filepath): os.remove(filepath) # Remove task from memory del tasks[task_id] return {"message": "Task deleted successfully"} @app.get("/health") async def health_check(): """ Health check endpoint with API key status """ api_stats = api_key_manager.get_stats() return { "status": "healthy", "timestamp": datetime.now().isoformat(), "active_tasks": len([t for t in tasks.values() if t["status"] in ["queued", "processing"]]), "total_tasks": len(tasks), "api_keys": { "total_configured": api_stats["total_keys"], "available_keys": len([ key for key, stats in api_stats["key_stats"].items() if not stats["last_rate_limit"] or (datetime.now().timestamp() - stats["last_rate_limit"]) > RATE_LIMIT_RETRY_DELAY ]), "rate_limited_keys": len([ key for key, stats in api_stats["key_stats"].items() if stats["last_rate_limit"] and (datetime.now().timestamp() - stats["last_rate_limit"]) <= RATE_LIMIT_RETRY_DELAY ]) } } @app.get("/api-keys/stats") async def get_api_key_stats(): """ Get detailed statistics for all API keys """ stats = api_key_manager.get_stats() # Mask API keys for security (show only last 4 characters) masked_stats = {} for key, data in stats["key_stats"].items(): masked_key = f"***{key[-4:]}" if len(key) > 4 else "***" masked_stats[masked_key] = { **data, "is_rate_limited": ( data["last_rate_limit"] and (datetime.now().timestamp() - data["last_rate_limit"]) <= RATE_LIMIT_RETRY_DELAY ) if data["last_rate_limit"] else False, "time_until_available": max(0, RATE_LIMIT_RETRY_DELAY - ( datetime.now().timestamp() - data["last_rate_limit"] )) if data["last_rate_limit"] else 0 } return { "total_keys": stats["total_keys"], "key_statistics": masked_stats, "rate_limit_settings": { "retry_delay_seconds": RATE_LIMIT_RETRY_DELAY, "max_retries_per_key": MAX_RETRIES_PER_KEY } } # Cleanup old files periodically (you might want to implement this with a proper scheduler) async def cleanup_old_files(): """ Clean up old audio files and completed tasks """ # This is a simple implementation - consider using APScheduler for production pass if __name__ == "__main__": # Configuration for running the server uvicorn.run( "gemini_tts_api:app", host="0.0.0.0", port=8000, reload=False, # Set to False in production workers=4 # Use multiple workers in production with proper task storage )