Provide guidance on creating a header for `streaming_synthesize` in streaming_tts_quickstart.py

texttospeech/snippets/streaming_tts_quickstart.py の46〜48行目付近から始め、リンク先のWAV仕様を確認してください。ヘッダーのない24,000 Hz LINEAR16レスポンスに対してヘッダーをどのように作成すべきかを判断し、その後、再生可能な音声を生成するためのガイダンスを提供するようサンプルを更新してください。ストリーミング合成をデバッグするユーザーにとって、生成された出力の処理方法が明確であることを確認してください。

From https://github.com/googleapis/google-cloud-python/issues/13405, the response to streaming_synthesize is headerless LINEAR16 audio with a sample rate of 24000.. The code sample below prints the size of the audio content but does not include the necessary header to actually play the audio.

https://github.com/GoogleCloudPlatform/python-docs-samples/blob/5e8e1788598a22f4dc7ceb13b0d62ef373406554/texttospeech/snippets/streaming_tts_quickstart.py#L46-L48

This may not be the purpose of the code sample, however having this extra information in the code sample will help with debugging customer issues such as https://github.com/googleapis/google-cloud-python/issues/13405.

I added code which includes the raw audio header, however there is likely an easier way to achieve this. We should provide guidance on how folks should create the audio header.

# This is a raw header based on the spec at https://docs.fileformat.com/audio/wav/
header = b'RIFF\x00\x00\x00\x00WAVEfmt \x10\x00\x00\x00\x01\x00\x01\x00\xc0]\x00\x00\x80\xbb\x00\x00\x02\x00\x10\x00data\x00\x00\x00\x00'

total_length = 0

with open(f"output.wav", "wb") as out:
    out.write(header)
    for response in streaming_responses:
        # calculate the length of the content
        total_length += len(response.audio_content)
        out.write(response.audio_content)
    # Position 40 - 43: Size of the data section
    out.seek(40)
    out.write(bytes([total_length & 0xFF, (total_length >> 8) & 0xFF, (total_length >> 16) & 0xFF, (total_length >> 24) & 0xFF]))

import os
file_size = os.path.getsize("output.wav")

with open(f"output.wav", "r+b") as out:
    # Position 4-7: Size of the overall file - 8 bytes, in bytes (32-bit integer). Typically, you’d fill this in after creation.
    out.seek(4)
    out.write(bytes([file_size & 0xFF, (file_size >> 8) & 0xFF, (file_size >> 16) & 0xFF, (total_length >> 24) & 0xFF]))