mirror of https://github.com/python/cpython.git
116 lines
2.1 KiB
Python
116 lines
2.1 KiB
Python
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import sys
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from time import millitimer
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def main():
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filename = 'film2.video'
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if sys.argv[1:]: filename = sys.argv[1]
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f = open(filename, 'r')
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line = f.readline()
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w, h = eval(line[:-1])
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w2, h2 = w/2, h/2
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size = w2 * h2
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data = data2 = t = t0 = t1 = None
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nframes = 0
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t0 = millitimer()
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while 1:
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line = f.readline()
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if not line: break
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t = eval(line[:-1])
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data = None
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data = f.read(size)
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if len(data) <> size:
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raise EOFError
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dostat(w2, h2, data)
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nframes = nframes+1
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t1 = millitimer()
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t = 0.001 * (t1-t0)
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fps = 0.1 * int(10*nframes/t)
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print nframes, 'frames in', t, 'sec. =', fps, 'frames/sec.'
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def dostat(w, h, data):
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print
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stat3(w, h, data)
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# Statistic op 1: frequencies of byte values
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def stat1(w, h, data):
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bins = [0]*256
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for c in data:
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i = ord(c)
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bins[i] = bins[i]+1
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prbins(bins)
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def prbins(bins):
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import string
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s = ''
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tot = 0
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for i in range(256):
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tot = tot + bins[i]
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s = s + string.rjust(`bins[i]`, 4)
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if len(s) >= 4*16:
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print s, string.rjust(`tot`, 7)
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s = ''
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tot = 0
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# Statistic op 2: run lengths
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def stat2(w, h, data):
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runs = []
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for y in range(h):
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count, value = 0, ord(data[y*w])
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for c in data[y*w : y*w+w]:
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i = ord(c)
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if i <> value:
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runs.append(count, value)
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count, value = 0, i
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count = count+1
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runs.append(count, value)
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print len(runs), 'runs =', 0.1 * (10*w*h/len(runs)), 'bytes/run'
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# Statistic op 3: frequencies of byte differences
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def stat3(w, h, data):
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bins = [0]*256
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prev = 0
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for c in data:
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i = ord(c)
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delta = divmod(i-prev, 256)[1]
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prev = i
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bins[delta] = bins[delta]+1
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prbins(bins)
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# Try packing
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def packblock(w, h, data):
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res = ''
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for y in range(h):
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res = res + packline(data[y*w : y*w+w])
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return res
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def packline(line):
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bytes = []
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for c in line:
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bytes.append(ord(c))
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prev = bytes[0]
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i, n = 1, len(bytes)
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while i < n:
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for pack in (0, 2, 4, 8):
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if pack = 0:
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lo, hi = 0, 0
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else:
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hi = pow(2, pack-1)-1
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lo = -hi-1
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p = prev
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j = i
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count = 0
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while j < n:
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x = bytes[j]
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delta = byte(x-p)
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if not lo <= delta <= hi:
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break
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p = x
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j = j+1
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def byte(x): return divmod(x, 256)[1]
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main()
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