Skip to content
Find file
Fetching contributors…
Cannot retrieve contributors at this time
executable file 349 lines (274 sloc) 11.4 KB
#!/usr/bin/env python
# * Copyright 2011 Alistair Buxton <>
# *
# * License: This program is free software; you can redistribute it and/or
# * modify it under the terms of the GNU General Public License as published
# * by the Free Software Foundation; either version 3 of the License, or (at
# * your option) any later version. This program is distributed in the hope
# * that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
# * GNU General Public License for more details.
# This is the main data analyser.
import sys
import os
import numpy as np
from scipy.ndimage import gaussian_filter1d as gauss
from scipy.optimize import fminbound
import pylab
from util import paritybytes, setbyte, normalise, hammbytes, allbytes, mrag, notzero
import util
from guess import Guess
import time
import finders
import math
np.seterr(invalid= 'raise')
class Vbi(object):
'''This class represents a line of raw vbi data and all our attempts to
decode it.'''
possible_bytes = [hammbytes]*2 + [paritybytes]*40
def __init__(self, vbi, bitwidth=5.112, gauss_sd=1.1, gauss_sd_offset=2.0,
offset_low = 75.0, offset_high = 119.0,
thresh_low = 1.1, thresh_high = 2.36,
allow_unmatched = True):
# data arrays
# vbi is the raw line as an array of 2048 floats
self.vbi = vbi
# blurring amounts
self.gauss_sd = gauss_sd
self.gauss_sd_offset = gauss_sd_offset
# Offset range to check for signal drift, in samples.
# The algorithm will check with sub sample accuracy.
# The offset finder is very fast (it uses bisection)
# so this range can be relatively large. But not too
# large or you get false positives.
self.offset_low = offset_low
self.offset_high = offset_high
# black level of the signal = np.mean(self.vbi[:80])
# Threshold multipliers. The black level of the signal
# is derived from the mean of the area before the VBI
# begins. This is multiplied by the following factors
# to give the low/high thresholds. Anything outside
# this range is assumed to be a 0 or a 1. Tweaking these
# can improve results, but often at a speed cost.
self.thresh_low =*thresh_low
self.thresh_high =*thresh_high
# Allow to emitt packet 0's that don't match
# any finder? Set to false when you have finders
# for all headers in the data.
self.allow_unmatched = allow_unmatched
# vbi packet bytewise
self._mask0 = np.zeros(42, dtype=np.uint8)
self._mask1 = np.zeros(42, dtype=np.uint8)
self.g = Guess(bitwidth=bitwidth)
def find_offset_and_scale(self):
'''Tries to find the offset of the vbi data in the raw samples.'''
# Split into chunks and ensure there is something "interesting" in each
target = gauss(self.vbi, self.gauss_sd_offset)
d = [np.std(target[x:x+128]) < 5.0 for x in range(64, 1440, 128)]
if any(d):
return False
low = 64
high = 256
target = gauss(self.vbi[low:high], self.gauss_sd_offset)
def _inner(offset):
self.g.update_cri(low, high)
guess_scaled = self.g.convolved[low:high]
mask_scaled = self.g.mask[low:high]
a = guess_scaled*mask_scaled
b = np.clip(target*mask_scaled,, 256)
scale = a.std()/b.std()
b -=
b *= scale
a = np.clip(a, 0, 256*scale)
return np.sum(np.square(b-a))
offset = fminbound(_inner, self.offset_low, self.offset_high)
# call it also to set self.offset and self.scale
return (_inner(offset) < 10)
def make_guess_mask(self):
a = []
for i in range(42*8):
(low, high) = self.g.get_bit_pos(i)
mins = np.array([min(x) for x in a])
maxs = np.array([max(x) for x in a])
avgs = np.array([np.array(x).mean() for x in a])
for i in range(42):
mini = mins[i*8:(i+1)*8]
maxi = maxs[i*8:(i+1)*8]
avgi = avgs[i*8:(i+1)*8]
self._mask0[i] = 0xff
for j in range(8):
if mini[j] < self.thresh_low:
self._mask0[i] &= ~(1<<j)
if maxi[j] > self.thresh_high:
self._mask1[i] |= (1<<j)
tmp = self._mask1 & self._mask0
self._mask0 |= self._mask1
self._mask1 = tmp
def make_possible_bytes(self, possible_bytes):
def masked(b, n):
m0 = util.m0s[self._mask0[n]]
m1 = util.m1s[self._mask1[n]]
m = m0 & m1 & b
if m:
return m
mm0 = m0 & b
mm1 = m1 & b
if len(mm0) < len(mm1):
return mm0 or mm1 or b
return mm1 or mm0 or b
self.possible_bytes = [masked(b,n) for n,b in enumerate(possible_bytes)]
def _deconvolve_make_diff(self, (low, high)):
a = normalise(self.g.convolved)
diff_sq = np.square(a -
return np.sum(diff_sq)
# an interesting trick I discovered.
# bias the result towards the curent area of interest
return np.sum(diff_sq[:low]) + 2.6*np.sum(diff_sq[low:high]) + np.sum(diff_sq[high:])
def _deconvolve_pass(self, first=0, last=42):
for n in range(first, last):
nb = self.possible_bytes[n]
changed = self.g.set_update_range(n+4, 1)
if len(nb) == 100000:
self.g.set_byte(n, nb[0])
ans = []
for b1 in nb:
self.g.set_byte(n, b1)
best = min(ans)
self.g.set_byte(n, best[1])
def _deconvolve(self):
for it in range(10):
# if this iteration didn't produce a change in the answer
# then the next one won't either, so stop.
if (self.g.bytes == self._oldbytes).all():
#print it
self._oldbytes[:] = self.g.bytes
def _nzdeconvolve(self):
for it in range(10):
changed = self.g.set_update_range(4, 2)
for nb in notzero:
self.g.set_two_bytes(0, nb[0], nb[1])
best = min(ans)
self.g.set_two_bytes(0, best[1][0], best[1][1])
# if this iteration didn't produce a change in the answer
# then the next one won't either, so stop.
if (self.g.bytes == self._oldbytes).all():
#print it
self._oldbytes[:] = self.g.bytes
def deconvolve(self):
target = gauss(self.vbi, self.gauss_sd) = normalise(target)
self._oldbytes = np.zeros(42, dtype=np.uint8)
packet = "".join([chr(x) for x in self.g.bytes])
F = finders.test(finders.all_headers, packet)
if F:
sys.stderr.write("matched by finder ""\n");
packet = F.fixup()
return packet
# if the packet did not match any of the finders then it isn't
# a packet 0 (or 30). if the packet still claims to be a packet 0 it
# will mess up the page splitter. so redo the deconvolution but with
# packet 0 (and 30) header removed from possible bytes.
# note: this doesn't work. i am not sure why. a packet in 63322
# does not match the finders but still passes through this next check
# with r=0. which should be impossible.
((m,r),e) = mrag(self.g.bytes[:2])
if r == 0:
sys.stderr.write("packet falsely claimed to be packet %d\n" % r);
if not self.allow_unmatched:
packet = "".join([chr(x) for x in self.g.bytes])
# if it's a link packet, it is completely hammed
elif r == 27:
packet = "".join([chr(x) for x in self.g.bytes])
return packet
def process_file((inname, outname)):
print inname, outname
data = np.fromstring(file(inname).read(), dtype=np.uint8)
outfile = file(outname, 'wb')
for line in range(32):
offset = line*2048
vbiraw = data[offset:offset+2048]
v = Vbi(vbiraw)
tmp = v.find_offset_and_scale()
if tmp:
except IOError:
def test_file(outfile):
return os.path.isfile(outfile) and (os.path.getsize(outfile) == (42 * 32))
def list_files(inputpath, outputpath, first, count, skip):
for frame in range(first, first+count, skip):
frame = "%08d" % frame
if test_file(outputpath + '/' + frame + '.t42'):
#print "skipping %s\n" % (outputpath + '/' + frame + '.t42')
yield (inputpath + '/' + frame + '.vbi',
outputpath + '/' + frame + '.t42')
if __name__ == '__main__':
import multiprocessing
from multiprocessing.pool import IMapIterator, Pool
import cProfile
import pstats
def wrapper(func):
def wrap(self, timeout=None):
# Note: the timeout of 1 googol seconds introduces a rather subtle
# bug for Python scripts intended to run many times the age of the universe.
return func(self, timeout=timeout if timeout is not None else 1e100)
return wrap = wrapper(
path = sys.argv[1]
print "Usage:", sys.argv[0], "<path> [<first> <count>]\n"
print " path: directory with VBI files to process"
print " first: first file to process"
print " count: maximum number of files to process\n"
first = int(sys.argv[2], 10)
count = int(sys.argv[3], 10)
skip = int(sys.argv[4], 10)
first = 0
count = 10000000
skip = 1
if 1:
p = Pool(multiprocessing.cpu_count())
it = p.imap(process_file, list_files(path+'/vbi/', path+'/t42/', first, count, skip), chunksize=1)
for i in it:
else: # single thread mode for debugging
def doit():
map(process_file, list_files(path+'/vbi/', path+'/t42/', first, count, skip))'doit()', 'myprofile')
p = pstats.Stats('myprofile')
Something went wrong with that request. Please try again.