動画の基礎知識

FAR 4:3, DAR 16:9 => 16 x 3 : 9 x 4 => 48:36 => 48/12:36/12 => 4:3
FAR 3:2, DAR 16:9 => 16 x 2 : 9 x 3 => 32:27
FAR 3:2, DAR 4:3 => 4 x 2 : 3 x 3 = 8:9

#!/usr/bin/python3

aspect = "16:9"
#aspect = "4:3"
height_min = 320
height_max = 1080

#-----

class Calc:
    def __init__(self,hmin,hmax,aspect):
        s = aspect.partition(":")
        self.ax = int(s[0])
        self.ay = int(s[2])
        self.hmin = hmin
        self.hmax = hmax
        self.done = []

    def put(self,div):
        print("--- {0:d} ---".format(div))
        for h in range(self.hmin, self.hmax+1):
            if (h & 1) or h % self.ay or h % div: continue
            
            w = h // self.ay * self.ax
            if (w & 1) or w % self.ax or w % div: continue

            flag = True
            for iw,ih in self.done:
                if iw == w and ih == h:
                    flag = False
                    break

            if flag:
                self.done.append([w,h])
                print("{0:d}x{1:d}".format(w,h))

    def run(self):
        print("{0:d}:{1:d}".format(self.ax, self.ay))
        self.put(16)
        self.put(8)
        self.put(4)

o = Calc(height_min, height_max, aspect)
o.run()