Merge commit 'v3.3.0' into upstream

[debian/gnuradio] / gr-atsc / src / python / atsc_utils.py

diff --git a/gr-atsc/src/python/atsc_utils.py b/gr-atsc/src/python/atsc_utils.py
new file mode 100644 (file)
index 0000000..1e74d22
--- /dev/null
+++ b/gr-atsc/src/python/atsc_utils.py
@@ -0,0 +1,74 @@
+#
+# 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 3, 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
+
+