在流识别Python代码中使用生成器

Question

我很难理解与块生成器和转录过程相关的 python 脚本摘录的动态。

这是完整的代码：https://cloud.google.com/speech-to-text/docs/samples/speech-transcribe-streaming-mic#code-sample

我没有得到脚本的这一部分：

    with MicrophoneStream(RATE, CHUNK) as stream:
        audio_generator = stream.generator()
        requests = (
            speech.StreamingRecognizeRequest(audio_content=content)
            for content in audio_generator
        )

        responses = client.streaming_recognize(streaming_config, requests)

        # Now, put the transcription responses to use.
        listen_print_loop(responses)

我可以管理“audio_generator”变量接收一种函数返回（来自麦克风的音频流块）。但是，“request”变量获取多个“speech.StreamingRecognizeRequest”对象，这些对象被馈送到“client.streaming_recognize”请求中。然后，“responses”对象在“listen_print_loop”中处理以显示文本结果。但是，我不明白为什么脚本能够无限循环以及它如何通过说“退出”结束。

我尝试搜索线程解释（因为队列使用）和函数返回的“yield”，但我不明白这部分是如何工作的。

Answer 1

请参阅您发送的链接，“listen_print_loop”函数：

def listen_print_loop(responses: object) -> str:
"""Iterates through server responses and prints them.

The responses passed is a generator that will block until a response
is provided by the server.

In this case, responses are provided for interim results as well. If the
response is an interim one, print a line feed at the end of it, to allow
the next result to overwrite it, until the response is a final one. For the
final one, print a newline to preserve the finalized transcription.

Args:
    responses: List of server responses

Returns:
    The transcribed text.
"""
num_chars_printed = 0
for response in responses:
    if not response.results:
        continue

    # The `results` list is consecutive. For streaming, we only care about
    # the first result being considered, since once it's `is_final`, it
    # moves on to considering the next utterance.
    result = response.results[0]
    if not result.alternatives:
        continue

    # Display the transcription of the top alternative.
    transcript = result.alternatives[0].transcript

    # Display interim results, but with a carriage return at the end of the
    # line, so subsequent lines will overwrite them.
    #
    # If the previous result was longer than this one, we need to print
    # some extra spaces to overwrite the previous result
    overwrite_chars = " " * (num_chars_printed - len(transcript))

    if not result.is_final:
        sys.stdout.write(transcript + overwrite_chars + "\r")
        sys.stdout.flush()

        num_chars_printed = len(transcript)

    else:
        print(transcript + overwrite_chars)

        # Exit recognition if any of the transcribed phrases could be
        # one of our keywords.
        if re.search(r"\b(exit|quit)\b", transcript, re.I):
            print("Exiting..")
            break

        num_chars_printed = 0

return transcript

特别是这部分：

# Exit recognition if any of the transcribed phrases could be
        # one of our keywords.
        if re.search(r"\b(exit|quit)\b", transcript, re.I):
            print("Exiting..")
            break

如果检测到关键字“exit”或“quit”，则会中断程序的for循环并返回结果。