Example: 50-Arduino-Boards/Nano-RP2040/52-Audio/audio_fft.py

# 本作品采用MIT许可证授权。
# 版权所有 (c) 2013-2023 OpenMV LLC。保留所有权利。
# https://github.com/openmv/openmv/blob/master/LICENSE
#
import image
import audio
from ulab import numpy as np
from ulab import utils

CHANNELS = 1
FREQUENCY = 32000
N_SAMPLES = 32 if FREQUENCY == 16000 else 64
SCALE = 1
SIZE = (N_SAMPLES * SCALE) // CHANNELS

raw_buf = None
fb = image.Image(SIZE + (50 * SCALE), SIZE, image.RGB565, copy_to_fb=True)
audio.init(channels=CHANNELS, frequency=FREQUENCY, gain_db=16, overflow=False)


def audio_callback(buf):
    # 注意：不要调用任何分配内存的函数。
    global raw_buf
    if raw_buf is None:
        raw_buf = buf


# 开始音频流
audio.start_streaming(audio_callback)


def draw_fft(img, fft_buf):
    fft_buf = (fft_buf / max(fft_buf)) * SIZE
    fft_buf = np.log10(fft_buf + 1) * 20
    color = (0xFF, 0x0F, 0x00)
    for i in range(0, len(fft_buf)):
        img.draw_line(
            i * SCALE, SIZE, i * SCALE, SIZE - int(fft_buf[i]) * SCALE, color, SCALE
        )


def draw_audio_bar(img, level, offset):
    blk_size = SIZE // 10
    color = (0xFF, 0x00, 0xF0)
    blk_space = blk_size // 4
    for i in range(0, int(round(level / 10))):
        fb.draw_rectangle(
            SIZE + offset,
            SIZE - ((i + 1) * blk_size) + blk_space,
            20 * SCALE,
            blk_size - blk_space,
            color,
            1,
            True,
        )


while True:
    if raw_buf is not None:
        pcm_buf = np.frombuffer(raw_buf, dtype=np.int16)
        raw_buf = None

        if CHANNELS == 1:
            fft_buf = utils.spectrogram(pcm_buf)
            l_lvl = int((np.mean(abs(pcm_buf[1::2])) / 32768) * 100)
        else:
            fft_buf = utils.spectrogram(pcm_buf[0::2])
            l_lvl = int((np.mean(abs(pcm_buf[1::2])) / 32768) * 100)
            r_lvl = int((np.mean(abs(pcm_buf[0::2])) / 32768) * 100)

        fb.clear()
        draw_fft(fb, fft_buf)
        draw_audio_bar(fb, l_lvl, 0)
        draw_audio_bar(fb, l_lvl, 25 * SCALE)
        if CHANNELS == 2:
            draw_audio_bar(fb, r_lvl, 25 * SCALE)
        fb.flush()

# 停止流
audio.stop_streaming()