1 files changed, 115 insertions, 0 deletions
diff --git a/Demo/sgi/video/statit.py b/Demo/sgi/video/statit.py
new file mode 100755
index 0000000..360e49e
--- /dev/null
+++ b/Demo/sgi/video/statit.py
@@ -0,0 +1,115 @@
+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()