在Python中检测& 记录音频到PCM格式。

Question

我需要从树莓pi中录制PCM文件格式的音频，只要它检测到声音（通过一定的阈值），就会停止，当它安静下来时，就会停止。因此，我看到了一个以前问过的问题，并按照上面的回答，在 用Python检测& 录制音频. 但是，它保存的是WAV格式的文件，但我使用的API只能读取pcm、speex或speex-wb格式的文件。

我如何去录制pcm格式的音频，同时保持只在检测到声音时才录音的功能？

from sys import byteorder
from array import array
from struct import pack

import pyaudio
import wave

THRESHOLD = 8000
chans = 1
chunk = 4096
form_1 = pyaudio.paInt16
samp_rate = 44100
dev_index = 2 # device index found by p.get_device_info_by_index(ii)
wav_output_filename = 'test4.wav'

def is_silent(snd_data):
    "Returns 'True' if below the 'silent' threshold"
    return max(snd_data) < THRESHOLD

def normalize(snd_data):
    "Average the volume out"
    MAXIMUM = 16384
    times = float(MAXIMUM)/max(abs(i) for i in snd_data)

    r = array('h')
    for i in snd_data:
        r.append(int(i*times))
    return r

def trim(snd_data):
    "Trim the blank spots at the start and end"
    def _trim(snd_data):
        snd_started = False
        r = array('h')

        for i in snd_data:
            if not snd_started and abs(i)>THRESHOLD:
                snd_started = True
                r.append(i)

            elif snd_started:
                r.append(i)
        return r

    # Trim to the left
    snd_data = _trim(snd_data)

    # Trim to the right
    snd_data.reverse()
    snd_data = _trim(snd_data)
    snd_data.reverse()
    return snd_data

def add_silence(snd_data, seconds):
    "Add silence to the start and end of 'snd_data' of length 'seconds' (float)"
    silence = [0] * int(seconds * samp_rate)
    r = array('h', silence)
    r.extend(snd_data)
    r.extend(silence)
    return r

def record():
    """
    Record a word or words from the microphone and 
    return the data as an array of signed shorts.

    Normalizes the audio, trims silence from the 
    start and end, and pads with 0.5 seconds of 
    blank sound to make sure VLC et al can play 
    it without getting chopped off.
    """
    audio = pyaudio.PyAudio()
    stream = audio.open(format = form_1, channels=chans, rate = samp_rate,
                    input_device_index = dev_index, input = True, #output=True,
                    frames_per_buffer = chunk)

    num_silent = 0
    snd_started = False

    r = array('h')

    while 1:
        # little endian, signed short
        snd_data = array('h', stream.read(chunk, exception_on_overflow = False))
        if byteorder == 'big':
            snd_data.byteswap()
        r.extend(snd_data)

        silent = is_silent(snd_data)

        if silent and snd_started:
            num_silent += 1
        elif not silent and not snd_started:
            snd_started = True

        if snd_started and num_silent > 30:
            break

    sample_width = audio.get_sample_size(form_1)
    stream.stop_stream()
    stream.close()
    audio.terminate()

    r = normalize(r)
    r = trim(r)
    r = add_silence(r, 0.5)
    return sample_width, r

def record_to_file(path):
    "Records from the microphone and outputs the resulting data to 'path'"
    sample_width, data = record()
    data = pack('<' + ('h'*len(data)), *data)

    wf = wave.open(path, 'wb')
    wf.setnchannels(chans)
    wf.setsampwidth(sample_width) #
    wf.setframerate(samp_rate)
    wf.writeframes(data) #
    wf.close()

if __name__ == '__main__':
    print("please speak a word into the microphone")
    record_to_file(wav_output_filename)
    print("done - result written to " + wav_output_filename)

Answer 1

在将音频文件形成pcm的过程中，我找不到任何解决方案，但我发现，我能够以16k的采样率处理wav格式的音频。所以我就不说了。