python get audio duration from blob

Question

my question is similar to Get.wav file length or duration .

1. use MediaRecorder in js frontend to record audio
2. send blob to backend

I want to apply a length limit of 30 seconds , but all I have is a blob, should be stored in django BinaryField .

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since in backend I don't want to create a file in each request, I only want to access the length of the audio, I am grateful for your suggestions.

Answer 1

You want to use the io package to give your in-memory data a file-like interface for other libraries (like wave ).

An example below:

from io import BytesIO

with open("sample.wav", "rb") as f:
  blob = f.read()

data = BytesIO(blob)

data can then be treated like any wav file:

import wave
import contextlib

with contextlib.closing(wave.open(data,'r')) as f:
    frames = f.getnframes()
    rate = f.getframerate()
    duration = frames / float(rate)
    print(duration)