Keyboard sampler python script

main.py

import wave
from pathlib import Path
import json
import time
import sys
import keyboard
import pyaudio

writing = False
reverse = False
reverse_key = {}
paused = False
pause_time = 0.0
poses = {}
is_pressed = {}

def n_samples_to_time(n_samples, sample_rate):
	total_secs = n_samples / sample_rate
	mins = total_secs // 60
	secs = total_secs %  60
	subsecs = (secs * 100) % 100
	return f'{int(mins)}:{int(secs)}.{int(subsecs)}                     '

def pressed(key):
	if keyboard.is_pressed(key):
		if key in is_pressed and is_pressed[key]:
			return False
		else:
			# print(key)
			is_pressed[key] = True
			return True
	else:
		if key in is_pressed and is_pressed[key]:
			# print('no', key)
			is_pressed[key] = False
		return False
def num_pressed():
	for i in range(10):
		if pressed(str(i)):
			return str(i)
	return False

def reverse_audio(audio, sample_size, chunk_size):
	ret = b''
	for i in range(sample_size*chunk_size, 0, -sample_size):
		ret += audio[i-sample_size:i]
	return ret

CHUNK = 1024

if len(sys.argv) < 3:
	print(f'Plays a wave file. Usage: {sys.argv[0]} infile.wav outfile.wav')
	sys.exit(-1)

# load positions from save file
save_file_path = sys.argv[1] + '.json'
if Path(save_file_path).exists():
	with open(save_file_path, 'r') as f:
			arr = json.loads(f.read())
			for entry in arr:
				poses[entry['key']] = entry['offset']
				reverse_key[entry['key']] = entry['reverse']

out = wave.open(sys.argv[2], 'wb')

with wave.open(sys.argv[1], 'rb') as wf:
	out.setnchannels(wf.getnchannels())
	out.setsampwidth(wf.getsampwidth())
	out.setframerate(wf.getframerate())

	# Instantiate PyAudio and initialize PortAudio system resources (1)
	p = pyaudio.PyAudio()

	# Open stream (2)
	stream = p.open(format=p.get_format_from_width(wf.getsampwidth()),
					channels=wf.getnchannels(),
					rate=wf.getframerate(),
					output=True)

	# Play samples from the wave file (3)
	while True:
		print(f'\r{n_samples_to_time(wf.tell(), wf.getframerate())}', end='')
		if not paused:
			data = wf.readframes(CHUNK)
			if not len(data):
				break
			if reverse:
				data = reverse_audio(data, wf.getsampwidth()*wf.getnchannels(), CHUNK)
			stream.write(data)
			if writing:
				out.writeframes(data)

			if reverse:
				pos = wf.tell() - 2*CHUNK
				if pos < 0:
					reverse = False
					pos = 0
				wf.setpos(pos)

		if pressed('esc'):
			break
		if pressed('space'):
			if paused and writing:
				out.writeframes(b'\x00' * wf.getsampwidth() * wf.getnchannels() * round(
					wf.getframerate() * (time.time() - pause_time)
				))
			else:
				pause_time = time.time()
			paused = not paused

		if pressed('r'):
			reverse = not reverse
		if pressed('w'):
			writing = not writing
			if writing:
				print('Writing started')
			else:
				print('Writing stopped')

		seek_mul = 5 if keyboard.is_pressed('shift') else 1
		if pressed('a'):
			pos = wf.tell() - seek_mul*wf.getframerate()
			if pos < 0:
				pos = 0
			wf.setpos(pos)
		if pressed('d'):
			pos = wf.tell() + seek_mul*wf.getframerate()
			if (pos >= wf.getnframes()):
				pos = wf.getnframes() - 1
			wf.setpos(pos)

		num = num_pressed()
		if not num:
			continue
		# print('OOOOOOOOOOOOO')
		if keyboard.is_pressed('ctrl'):
			pos = wf.tell()
			print(f'poses[{num}] = {pos}')
			poses[num] = pos
			reverse_key[num] = reverse
		elif (num in poses) and poses[num]:
			reverse = reverse_key[num]
			wf.setpos(poses[num])

	# Close stream (4)
	stream.close()

	# Release PortAudio system resources (5)
	p.terminate()

out.close()

json_arr = []
for key in poses:
	json_arr.append({'key': key, 'offset': poses[key], 'reverse': reverse_key[key]})
with open(save_file_path, 'w') as f:
	f.write(json.dumps(json_arr))