Resample type Pitch Shift Effect

pitch_shift_resample.py

from pydub import AudioSegment
import numpy as np
from pydub.playback import play

buflen = 2000
crossfadelen = 100
rate = 2.0
buf = np.zeros(buflen)

sound = AudioSegment.from_file("input.wav", "wav")
samples = np.array(sound.get_array_of_samples())
sample = samples[::sound.channels]

rpf = 0
rp1 = 0
rp2 = 0
wp = 0
result = np.zeros(len(sample))
gain1 = 1.0#gain for buffer line 1
gain2 = 0.0#gain for buffer line 2

#Processing loop
for i in range(len(sample)):
    buf[wp] = sample[i] #Write sample to the ring buffer
    out1 = buf[rp1] #Read sample from the ring buffer (pointer 1)
    out2 = buf[rp2] #Read sample from the ring buffer (pointer 2)
    #Calculate distance between write pointer and read pointer
    posdiff1 = wp - rp1
    posdiff2 = wp - rp2
    if rate <= 1.0:
        posdiff1 = -1.0 * posdiff1
        posdiff2 = -1.0 * posdiff2
    #Crossfade
    if 0 <= posdiff1 <= crossfadelen:
        sgain = np.sin(abs(posdiff1) * np.pi * 0.5/crossfadelen)
        cgain = np.cos(abs(posdiff1) * np.pi * 0.5/crossfadelen)
        gain1 = sgain * sgain
        gain2 = cgain * cgain
    if 0 <= posdiff2 <= crossfadelen:
        sgain = np.sin(abs(posdiff2) * np.pi * 0.5/crossfadelen)
        cgain = np.cos(abs(posdiff2) * np.pi * 0.5/crossfadelen)
        gain1 = cgain * cgain
        gain2 = sgain * sgain
    result[i] = round(out1*gain1 + out2*gain2)

    #Update write pointer and read pointer
    wp = (wp + 1) % buflen
    rpf = rpf + rate
    rp1 = int(round(rpf)) % buflen
    rp2 = (rp1 + buflen//2) % buflen

test = AudioSegment(result.real.astype("int16").tobytes(), sample_width=sound.sample_width, frame_rate=sound.frame_rate, channels = 1)
test.export("output.wav", format="wav")
play(test)