azure-speech-to-text-rest-py

# Azure Speech to Text REST API for Short Audio Simple REST API for speech-to-text transcription of short audio files (up to 60 seconds). No SDK required - just HTTP requests. ## Prerequisites 1. **Azure subscription** - [Create one free](https://azure.microsoft.com/free/) 2. **Speech resource** - Create in [Azure Portal](https://portal.azure.com/#create/Microsoft.CognitiveServicesSpeechServices) 3. **Get credentials** - After deployment, go to resource > Keys and Endpoint ## Environment Variables ```bash # Required AZURE_SPEECH_KEY=<your-speech-resource-key> AZURE_SPEECH_REGION=<region> # e.g., eastus, westus2, westeurope # Alternative: Use endpoint directly AZURE_SPEECH_ENDPOINT=https://<region>.stt.speech.microsoft.com ``` ## Installation ```bash pip install requests ``` ## Quick Start ```python import os import requests def transcribe_audio(audio_file_path: str, language: str = "en-US") -> dict: """Transcribe short audio file (max 60 seconds) using REST API.""" region = os.environ["AZURE_SPEECH_REGION"] api_key = os.environ["AZURE_SPEECH_KEY"] url = f"https://{region}.stt.speech.microsoft.com/speech/recognition/conversation/cognitiveservices/v1" headers = { "Ocp-Apim-Subscription-Key": api_key, "Content-Type": "audio/wav; codecs=audio/pcm; samplerate=16000", "Accept": "application/json" } params = { "language": language, "format": "detailed" # or "simple" } with open(audio_file_path, "rb") as audio_file: response = requests.post(url, headers=headers, params=params, data=audio_file) response.raise_for_status() return response.json() # Usage result = transcribe_audio("audio.wav", "en-US") print(result["DisplayText"]) ``` ## Audio Requirements | Format | Codec | Sample Rate | Notes | |--------|-------|-------------|-------| | WAV | PCM | 16 kHz, mono | **Recommended** | | OGG | OPUS | 16 kHz, mono | Smaller file size | **Limitations:** - Maximum 60 seconds of audio - For pronunciation assessment: maximum 30 seconds - No partial/interim results (final only) ## Content-Type Headers ```python # WAV PCM 16kHz "Content-Type": "audio/wav; codecs=audio/pcm; samplerate=16000" # OGG OPUS "Content-Type": "audio/ogg; codecs=opus" ``` ## Response Formats ### Simple Format (default) ```python params = {"language": "en-US", "format": "simple"} ``` ```json { "RecognitionStatus": "Success", "DisplayText": "Remind me to buy 5 pencils.", "Offset": "1236645672289", "Duration": "1236645672289" } ``` ### Detailed Format ```python params = {"language": "en-US", "format": "detailed"} ``` ```json { "RecognitionStatus": "Success", "Offset": "1236645672289", "Duration": "1236645672289", "NBest": [ { "Confidence": 0.9052885, "Display": "What's the weather like?", "ITN": "what's the weather like", "Lexical": "what's the weather like", "MaskedITN": "what's the weather like" } ] } ``` ## Chunked Transfer (Recommended) For lower latency, stream audio in chunks: ```python import os import requests def transcribe_chunked(audio_file_path: str, language: str = "en-US") -> dict: """Stream audio in chunks for lower latency.""" region = os.environ["AZURE_SPEECH_REGION"] api_key = os.environ["AZURE_SPEECH_KEY"] url = f"https://{region}.stt.speech.microsoft.com/speech/recognition/conversation/cognitiveservices/v1" headers = { "Ocp-Apim-Subscription-Key": api_key, "Content-Type": "audio/wav; codecs=audio/pcm; samplerate=16000", "Accept": "application/json", "Transfer-Encoding": "chunked", "Expect": "100-continue" } params = {"language": language, "format": "detailed"} def generate_chunks(file_path: str, chunk_size: int = 1024): with open(file_path, "rb") as f: while chunk := f.read(chunk_size): yield chunk response = requests.post( url, headers=headers, params=params, data=generate_chunks(audio_file_path) ) response.raise_for_status() return response.json() ``` ## Authentication Options ### Option 1: Subscription Key (Simple) ```python headers = { "Ocp-Apim-Subscription-Key": os.environ["AZURE_SPEECH_KEY"] } ``` ### Option 2: Bearer Token ```python import requests import os def get_access_token() -> str: """Get access token from the token endpoint.""" region = os.environ["AZURE_SPEECH_REGION"] api_key = os.environ["AZURE_SPEECH_KEY"] token_url = f"https://{region}.api.cognitive.microsoft.com/sts/v1.0/issueToken" response = requests.post( token_url, headers={ "Ocp-Apim-Subscription-Key": api_key, "Content-Type": "application/x-www-form-urlencoded", "Content-Length": "0" } ) response.raise_for_status() return response.text # Use token in requests (valid for 10 minutes) token = get_access_token() headers = { "Authorization": f"Bearer {token}", "Content-Type": "audio/wav; codecs=audio/pcm; samplerate=16000", "Accept": "application/json" } ``` ## Query Parameters | Parameter | Required | Values | Description | |-----------|----------|--------|-------------| | `language` | **Yes** | `en-US`, `de-DE`, etc. | Language of speech | | `format` | No | `simple`, `detailed` | Result format (default: simple) | | `profanity` | No | `masked`, `removed`, `raw` | Profanity handling (default: masked) | ## Recognition Status Values | Status | Description | |--------|-------------| | `Success` | Recognition succeeded | | `NoMatch` | Speech detected but no words matched | | `InitialSilenceTimeout` | Only silence detected | | `BabbleTimeout` | Only noise detected | | `Error` | Internal service error | ## Profanity Handling ```python # Mask profanity with asterisks (default) params = {"language": "en-US", "profanity": "masked"} # Remove profanity entirely params = {"language": "en-US", "profanity": "removed"} # Include profanity as-is params = {"language": "en-US", "profanity": "raw"} ``` ## Error Handling ```python import requests def transcribe_with_error_handling(audio_path: str, language: str = "en-US") -> dict | None: """Transcribe with proper error handling.""" region = os.environ["AZURE_SPEECH_REGION"] api_key = os.environ["AZURE_SPEECH_KEY"] url = f"https://{region}.stt.speech.microsoft.com/speech/recognition/conversation/cognitiveservices/v1" try: with open(audio_path, "rb") as audio_file: response = requests.post( url, headers={ "Ocp-Apim-Subscription-Key": api_key, "Content-Type": "audio/wav; codecs=audio/pcm; samplerate=16000", "Accept": "application/json" }, params={"language": language, "format": "detailed"}, data=audio_file ) if response.status_code == 200: result = response.json() if result.get("RecognitionStatus") == "Success": return result else: print(f"Recognition failed: {result.get('RecognitionStatus')}") return None elif response.status_code == 400: print(f"Bad request: Check language code or audio format") elif response.status_code == 401: print(f"Unauthorized: Check API key or token") elif response.status_code == 403: print(f"Forbidden: Missing authorization header") else: print(f"Error {response.status_code}: {response.text}") return None except requests.exceptions.RequestException as e: print(f"Request failed: {e}") return None ``` ## Async Version ```python import os import aiohttp import asyncio async def transcribe_async(audio_file_path: str, language: str = "en-US") -> dict: """Async version using aiohttp.""" region = os.environ["AZURE_SPEECH_REGION"] api_key = os.environ["AZURE_SPEECH_KEY"] url = f"https://{region}.stt.speech.microsoft.com/speech/recognition/conversation/cognitiveservices/v1" headers = { "Ocp-Apim-Subscription-Key": api_key, "Content-Type": "audio/wav; codecs=audio/pcm; samplerate=16000", "Accept": "application/json" } params = {"language": language, "format": "detailed"} async with aiohttp.ClientSession() as session: with open(audio_file_path, "rb") as f: audio_data = f.read() async with session.post(url, headers=headers, params=params, data=audio_data) as response: response.raise_for_status() return await response.json() # Usage result = asyncio.run(transcribe_async("audio.wav", "en-US")) print(result["DisplayText"]) ``` ## Supported Languages Common language codes (see [full list](https://learn.microsoft.com/azure/ai-services/speech-service/language-support)): | Code | Language | |------|----------| | `en-US` | English (US) | | `en-GB` | English (UK) | | `de-DE` | German | | `fr-FR` | French | | `es-ES` | Spanish (Spain) | | `es-MX` | Spanish (Mexico) | | `zh-CN` | Chinese (Mandarin) | | `ja-JP` | Japanese | | `ko-KR` | Korean | | `pt-BR` | Portuguese (Brazil) | ## Best Practices 1. **Use WAV PCM 16kHz mono** for best compatibility 2. **Enable chunked transfer** for lower latency 3. **Cache access tokens** for 9 minutes (valid for 10) 4. **Specify the correct language** for accurate recognition 5. **Use detailed format** when you need confidence scores 6. **Handle all RecognitionStatus values** in production code ## When NOT to Use This API Use the Speech SDK or Batch Transcription API instead when you need: - Audio longer than 60 seconds - Real-time streaming transcription - Partial/interim results - Speech translation - Custom speech models - Batch transcription of many files ## Reference Files | File | Contents | |------|----------|