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