import time
import psutil
import multiprocessing as mp
from multiprocessing import Process

def f(thread, duty, freq, q):
    p = psutil.Process()
    p.cpu_affinity([thread])

    while True:
        while not q.empty():
            duty = float(q.get())

        t0 = time.time()
        while time.time() - t0 < duty / freq:
            pass
        t1 = time.time()
        dest = t0 + 1 / freq
        delay = dest - t1
        if delay > 0:
            time.sleep(delay)

if __name__ == '__main__':
    p = psutil.Process()
    threads = p.cpu_affinity()
    workers = []
    ctx = mp.get_context('spawn')

    bpp = 4
    width = 16
    height = 4
    fps = 2.0
    gain = 1.0

    for thread in threads:
        q = ctx.Queue()
        duty = 1
        # Uncomment to fade from 0 to 100% from left to right
        # duty = (thread % width) / (width - 1)
        p = Process(target=f, args=(thread, duty, fps, q))
        p.start()
        workers.append({"p": p, "q": q})

    # ffmpeg -i input.mp4 -vf scale=16:4,hue=s=0 -r 2 -c:v rawvideo -pix_fmt rgb32 out.rgb
    # scale=width:height
    # -r : fps
    f = open("out.rgb", "rb")
    video = f.read()
    f.close()

    frames = len(video) // (bpp * width * height)

    for frame in range(frames):
        for j, worker in enumerate(workers):
            pixel = video[frame * bpp * width * height + j * bpp] / 256. * gain
            worker["q"].put(1.0 - pixel)
        time.sleep(1 / fps)

    for worker in workers:
        worker["p"].kill()