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#
# Copyright 2006 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio 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 2, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
import random
import sys
MPEG_SYNC_BYTE = 0x47
def make_fake_transport_stream_packet(npkts):
"""
Return a sequence of 8-bit ints that represents an MPEG Transport Stream packet.
@param npkts: how many 188-byte packets to return
FYI, each ATSC Data Frame contains two Data Fields, each of which contains
312 data segments. Each transport stream packet maps to a data segment.
"""
r = [0] * (npkts * 188)
i = 0
for j in range(npkts):
r[i+0] = MPEG_SYNC_BYTE
r[i+1] = random.randint(0, 127) # top bit (transport error bit) clear
i = i + 2
for n in range(186):
r[i + n] = random.randint(0, 255)
i = i + 186
return r
def pad_stream(src, sizeof_total, sizeof_pad):
sizeof_valid = sizeof_total - sizeof_pad
assert sizeof_valid > 0
assert (len(src) % sizeof_valid) == 0
npkts = len(src) // sizeof_valid
dst = [0] * (npkts * sizeof_total)
for i in range(npkts):
src_s = i * sizeof_valid
dst_s = i * sizeof_total
dst[dst_s:dst_s + sizeof_valid] = src[src_s:src_s + sizeof_valid]
return dst
def depad_stream(src, sizeof_total, sizeof_pad):
sizeof_valid = sizeof_total - sizeof_pad
assert sizeof_valid > 0
assert (len(src) % sizeof_total) == 0
npkts = len(src) // sizeof_total
dst = [0] * (npkts * sizeof_valid)
for i in range(npkts):
src_s = i * sizeof_total
dst_s = i * sizeof_valid
dst[dst_s:dst_s + sizeof_valid] = src[src_s:src_s + sizeof_valid]
return dst
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