Azure Cognitive Services- Speech To Text

Speech 服务是认知服务的一种，提供了语音转文本，文本转语音, 语音翻译等，今天我们实战的是语音转文本（Speech To Text）。

STT支持两种访问方式，1.是SDK，2.是REST API。

其中:

SDK方式支持 识别麦克风的语音流 和 语音文件；

REST API方式仅支持语音文件；

准备工作：创建 认知服务之Speech服务：

创建完成后，两个重要的参数可以在页面查看：

一. REST API方式将语音文件转换成文本：

Azure global的 Speech API 终结点请参考：

https://docs.microsoft.com/zh-cn/azure/cognitive-services/speech-service/rest-speech-to-text#regions-and-endpoints

Azure 中国区 的 Speech API 终结点：

截至到2020.2月，仅中国东部2区域已开通Speech服务，服务终结点为：

https://chinaeast2.stt.speech.azure.cn/speech/recognition/conversation/cognitiveservices/v1

对于Speech To Text来说，有两种身份验证方式：

其中Authorization  Token有效期为10分钟。

为了简便，本文使用了Ocp-Apim-Subscription-Key的方式。

注意：如果要实现文本转语音，按照上表，则必须使用 Authorization Token形式进行身份验证。

构建请求的其他注意事项：

1. 文件格式：
   
   
   
2. 请求头：
   
   
   需要注意的是，Key或者Authorization是二选一的关系。
   
3. 请求参数：
   
   
   

在Postman中的示例如下：

如果要在REST API中使用 Authorization Token，则需要先获得Token：

Global 获取Token的终结点：

https://docs.microsoft.com/zh-cn/azure/cognitive-services/speech-service/rest-speech-to-text#authentication

中国区获取Token的终结点：

截至2020.02，只有中国东部2有Speech服务，其Token终结点为：

https://chinaeast2.api.cognitive.azure.cn/sts/v1.0/issuetoken

Postman获取Token 参考如下：

二. SDK方式将语音文件转换成文本（Python示例）：

在官网可以看到类似的代码，但需要注意的是，该代码仅在Azure Global的Speech服务中正常工作，针对中国区，需要做特定的修改（见下文）。

import azure.cognitiveservices.speech as speechsdk
​
# Creates an instance of a speech config with specified subscription key and service region.
# Replace with your own subscription key and service region (e.g., "chinaeast2").
speech_key, service_region = "YourSubscriptionKey", "YourServiceRegion"
speech_config = speechsdk.SpeechConfig(subscription=speech_key, region=service_region)
​
# Creates an audio configuration that points to an audio file.
# Replace with your own audio filename.
audio_filename = "whatstheweatherlike.wav"
audio_input = speechsdk.AudioConfig(filename=audio_filename)
​
# Creates a recognizer with the given settings
speech_recognizer = speechsdk.SpeechRecognizer(speech_config=speech_config, audio_config=audio_input)
​
print("Recognizing first result...")
​
​
# Starts speech recognition, and returns after a single utterance is recognized. The end of a
# single utterance is determined by listening for silence at the end or until a maximum of 15
# seconds of audio is processed.  The task returns the recognition text as result. 
# Note: Since recognize_once() returns only a single utterance, it is suitable only for single
# shot recognition like command or query. 
# For long-running multi-utterance recognition, use start_continuous_recognition() instead.
result = speech_recognizer.recognize_once()
​
# Checks result.
if result.reason == speechsdk.ResultReason.RecognizedSpeech:
    print("Recognized: {}".format(result.text))
elif result.reason == speechsdk.ResultReason.NoMatch:
    print("No speech could be recognized: {}".format(result.no_match_details))
elif result.reason == speechsdk.ResultReason.Canceled:
    cancellation_details = result.cancellation_details
    print("Speech Recognition canceled: {}".format(cancellation_details.reason))
    if cancellation_details.reason == speechsdk.CancellationReason.Error:
        print("Error details: {}".format(cancellation_details.error_details))

　　

代码提供页面：

https://docs.azure.cn/zh-cn/cognitive-services/speech-service/quickstarts/speech-to-text-from-file?tabs=linux&pivots=programming-language-python#create-a-python-application-that-uses-the-speech-sdk

针对中国区，需要使用自定义终结点的方式，才能正常使用SDK：

speech_key, service_region = "Your Key", "chinaeast2"
template = "wss://{}.stt.speech.azure.cn/speech/recognition" 
               "/conversation/cognitiveservices/v1?initialSilenceTimeoutMs={:d}&language=zh-CN"
speech_config = speechsdk.SpeechConfig(subscription=speech_key,
endpoint=template.format(service_region, int(initial_silence_timeout_ms)))

中国区完整代码如下：

#!/usr/bin/env python
# coding: utf-8
​
# Copyright (c) Microsoft. All rights reserved.
# Licensed under the MIT license. See LICENSE.md file in the project root for full license information.
"""
Speech recognition samples for the Microsoft Cognitive Services Speech SDK
"""
​
import time
import wave
​
try:
    import azure.cognitiveservices.speech as speechsdk
except ImportError:
    print("""
    Importing the Speech SDK for Python failed.
    Refer to
    https://docs.microsoft.com/azure/cognitive-services/speech-service/quickstart-python for
    installation instructions.
    """)
    import sys
    sys.exit(1)
​
​
# Set up the subscription info for the Speech Service:
# Replace with your own subscription key and service region (e.g., "westus").
speech_key, service_region = "your key", "chinaeast2"
​
# Specify the path to an audio file containing speech (mono WAV / PCM with a sampling rate of 16
# kHz).
filename = "D:FFOutputspeechtotext.wav"
​
def speech_recognize_once_from_file_with_custom_endpoint_parameters():
    """performs one-shot speech recognition with input from an audio file, specifying an
    endpoint with custom parameters"""
    initial_silence_timeout_ms = 15 * 1e3
    template = "wss://{}.stt.speech.azure.cn/speech/recognition/conversation/cognitiveservices/v1?initialSilenceTimeoutMs={:d}&language=zh-CN"
    speech_config = speechsdk.SpeechConfig(subscription=speech_key,
            endpoint=template.format(service_region, int(initial_silence_timeout_ms)))
    print("Using endpoint", speech_config.get_property(speechsdk.PropertyId.SpeechServiceConnection_Endpoint))
    audio_config = speechsdk.audio.AudioConfig(filename=filename)
    # Creates a speech recognizer using a file as audio input.
    # The default language is "en-us".
    speech_recognizer = speechsdk.SpeechRecognizer(speech_config=speech_config, audio_config=audio_config)
    
    result = speech_recognizer.recognize_once()
​
    # Check the result
    if result.reason == speechsdk.ResultReason.RecognizedSpeech:
        print("Recognized: {}".format(result.text))
    elif result.reason == speechsdk.ResultReason.NoMatch:
        print("No speech could be recognized: {}".format(result.no_match_details))
    elif result.reason == speechsdk.ResultReason.Canceled:
        cancellation_details = result.cancellation_details
        print("Speech Recognition canceled: {}".format(cancellation_details.reason))
        if cancellation_details.reason == speechsdk.CancellationReason.Error:
            print("Error details: {}".format(cancellation_details.error_details))
​
​
speech_recognize_once_from_file_with_custom_endpoint_parameters()

需要注意的是，如果我们使用SDK识别麦克风中的语音，则将

speech_recognizer = speechsdk.SpeechRecognizer(speech_config=speech_config, audio_config=audio_config)，修改为：

speech_recognizer = speechsdk.SpeechRecognizer(speech_config=speech_config)