Flask调用Azure文本转语音REST API返回空音频文件问题排查

问题现象 #

直接通过Postman调用Azure Text to Speech REST API可获取正常播放的音频文件，但通过Flask接口转发调用时，返回空音频文件，同时触发以下报错：

<Response [200]>
Debugging middleware caught exception in streamed response at a point where response headers were already sent.
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.10/lib/python3.10/site-packages/werkzeug/wsgi.py", line 576, in __next__
    data = self.file.read(self.buffer_size)
AttributeError: 'Response' object has no attribute 'read'

报错原因 #

Flask的send_file()函数要求传入类文件对象（支持read()方法）或文件路径，但代码中直接传入了requests库的Response对象，该对象本身不具备read()方法，导致无法正确读取音频数据返回给客户端。

修复方案 #

1. 从requests响应中提取二进制音频数据（response.content）
2. 将二进制数据包装为BytesIO对象（该对象支持read()方法，符合send_file()的要求）
3. 可选：添加响应状态码检查，确保Azure API调用成功

修改后的代码示例 #

from flask import send_file
from io import BytesIO
import requests

def call_azure_cognitive_api(text):
    token = get_token()
    cognitive_service_url = 'https://eastus.tts.speech.microsoft.com/cognitiveservices/v1'
    headers = {
        'Authorization': 'Bearer %s' % token,
        'X-Microsoft-OutputFormat': 'audio-16khz-32kbitrate-mono-mp3',
        'Content-Type': 'application/ssml+xml'
    }
    
    data = """<speak version='1.0' xml:lang='en-US'><voice xml:lang='en-US' xml:gender='Male' name='en-US-ChristopherNeural'> Microsoft Speech Service Text-to-Speech API </voice></speak>"""
   
    response = requests.post(cognitive_service_url, data=data, headers=headers)
    print(response)

    # 检查Azure API调用是否成功
    if response.status_code != 200:
        # 可根据需求返回错误响应，比如return "API调用失败", 500
        pass

    # 将音频二进制数据包装为BytesIO对象
    audio_io = BytesIO(response.content)
    # 设置文件指针到起始位置
    audio_io.seek(0)
    
    return send_file(audio_io, mimetype="audio/mpeg", download_name="ajinkya.mp3")

内容的提问来源于stack exchange，提问作者Ajinkya Gadgil