在python中生成正弦波声音

Question

我一直在尝试使用下面的代码生成正弦波，并在我的扬声器中播放，但听起来很可怕。有人知道为什么吗？它听起来不像正弦波

       dur = int(FS * float(duration) / 1000)
       for i in range(dur):
         a = frequency * i * 2 * math.pi / FS
         y = math.sin(a)
         outbuf[i] = y * 0.2

p = pyaudio.PyAudio()
stream = p.open(format=pyaudio.paFloat32, channels=1, rate=44100, output=True)
stream.write(outbuf)
stream.stop_stream()
stream.close()
p.terminate()

play_sound("sine", 1000, 1, 1000)

Answer 1

音频缓冲区必须打包成二进制，以便python3使用b''.join(struct.pack 通过将角度θ增量常数移动到回路外部，简化了正弦曲线合成

import pyaudio
import numpy as np
import math
import struct

FS = 44100  #  frames per second, samples per second or sample rate

def play_sound(type, frequency, volume, duration):

   generate_sound(type, frequency, volume, duration)

def generate_sound(type, frequency, volume, duration):

    outbuf = np.random.normal(loc=0, scale=1, size=int(float(duration / 1000.0)*FS))

    if type == "sine":
        dur = int(FS * float(duration / 1000.0))
        theta = 0.0
        incr_theta = frequency * 2 * math.pi / FS # frequency increment normalized for sample rate
        for i in range(dur):
            outbuf[i] = volume * math.sin(theta)
            theta += incr_theta

    p = pyaudio.PyAudio()
    stream = p.open(format=pyaudio.paFloat32, channels=1, rate=FS, output=True)
    data = b''.join(struct.pack('f', samp) for samp in outbuf) # must pack the binary data
    stream.write(data)
    stream.stop_stream()
    stream.close()
    p.terminate()

play_sound("sine", 220, 0.8, 1000)  #  duration in milliseconds

上面提到的python在我的Ubuntu笔记本电脑上的各种版本（包括Ubuntu20.04）都可以正常运行。。。然而，当我运行上面的代码时，下面是输出到终端的。。。只需忽略下面的消息，这些都是正常的

python generate_sin_wave_sound.py 

ALSA lib pcm.c:2642:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2642:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2642:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_route.c:869:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:869:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:869:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:869:(find_matching_chmap) Found no matching channel map
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_oss.c:377:(_snd_pcm_oss_open) Unknown field port
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
ALSA lib pcm_usb_stream.c:486:(_snd_pcm_usb_stream_open) Invalid type for card
Cannot connect to server socket err = No such file or directory
Cannot connect to server request channel
jack server is not running or cannot be started
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock
JackShmReadWritePtr::~JackShmReadWritePtr - Init not done for -1, skipping unlock