def decode(self, bites):
bitbin = BitBin(bites)
self.table_id = bitbin.ashex(8)
if self.table_id != "0xfc":
to_stderr("splice info section table id should be 0xfc")
self.section_syntax_indicator = bitbin.asflag(1)
self.private = bitbin.asflag(1)
self.reserved = bitbin.ashex(2)
if self.reserved != "0x3":
to_stderr("splice info section reserved should be 0x3")
self.section_length = bitbin.asint(12)
self.protocol_version = bitbin.asint(8)
if self.protocol_version != 0:
to_stderr("splice info section protocol version should be 0")
self.encrypted_packet = bitbin.asflag(1)
self.encryption_algorithm = bitbin.asint(6)
self.pts_adjustment = bitbin.as90k(33)
self.cw_index = bitbin.ashex(8)
self.tier = bitbin.ashex(12)
self.splice_command_length = bitbin.asint(12)
self.splice_command_type = bitbin.asint(8)
self.descriptor_loop_length = 0
def decode(self):
"""
decode a segmentation descriptor
"""
bitbin = BitBin(self.bites)
self.parse_id(bitbin)
self.segmentation_event_id = bitbin.ashex(32) # 4 bytes
self.segmentation_event_cancel_indicator = bitbin.asflag(1)
bitbin.forward(7) # 1 byte
if not self.segmentation_event_cancel_indicator:
self._decode_flags(bitbin) # 1 byte
if not self.program_segmentation_flag:
self._decode_components(bitbin)
self._decode_segmentation(bitbin)
def decode(self, bites):
bitbin = BitBin(bites)
self.table_id = bitbin.ashex(8)
if self.table_id != '0xfc':
raise ValueError('splice_info_section.table_id should be 0xfc')
self.section_syntax_indicator = bitbin.asflag(1)
self.private = bitbin.asflag(1)
self.reserved = bitbin.ashex(2)
if self.reserved != '0x3':
raise ValueError('splice_info_section.reserved should be 0x3')
self.section_length = bitbin.asint(12)
self.protocol_version = bitbin.asint(8)
if self.protocol_version != 0:
raise ValueError(
'splice_info_section.protocol_version should be 0')
self.encrypted_packet = bitbin.asflag(1)
self.encryption_algorithm = bitbin.asint(6)
self.pts_adjustment = bitbin.as90k(33)
self.cw_index = bitbin.ashex(8)
self.tier = bitbin.ashex(12)
self.splice_command_length = bitbin.asint(12)
self.splice_command_type = bitbin.asint(8)
self.descriptor_loop_length = 0
class Splice:
descriptor_map = {
0: Avail_Descriptor,
1: Dtmf_Descriptor,
2: Segmentation_Descriptor,
3: Time_Descriptor,
4: Audio_Descriptor
}
command_map = {
0: Splice_Null,
4: Splice_Schedule,
5: Splice_Insert,
6: Time_Signal,
7: Bandwidth_Reservation,
255: Private_Command
}
def __init__(self, mesg):
mesg = self.mkbits(mesg)
self.bitbin = BitBin(mesg)
self.descriptors = []
self.info_section = None
self.command = None
self.do()
def do(self):
self.info_section = Splice_Info_Section()
self.info_section.decode(self.bitbin)
self.set_splice_command()
self.descriptorloop()
self.info_section.crc = self.bitbin.ashex(32)
def descriptorloop(self):
self.info_section.descriptor_loop_length = self.bitbin.asint(16)
dll = self.info_section.descriptor_loop_length
tag_plus_header_size = 2 # 1 byte for descriptor_tag, 1 byte for header?
while dll > 0:
try:
sd = self.set_splice_descriptor()
sdl = sd.descriptor_length
self.descriptors.append(sd)
except:
sdl = 0
bit_move = sdl + tag_plus_header_size
dll -= bit_move
def kvprint(self, obj):
print(f'{json.dumps(vars(obj))}')
def sectionstart(self, section_name):
print(f'{section_name}')
def mkbits(self, s):
if s[:2].lower() == '0x':
s = s[2:]
if s[:2].lower() == 'fc':
return bytes.fromhex(s)
try:
return b64decode(s)
except:
return s
def set_splice_command(self):
sct = self.info_section.splice_command_type
if sct not in self.command_map.keys():
raise ValueError('unknown splice command type')
self.command = self.command_map[sct]()
self.command.decode(self.bitbin)
def set_splice_descriptor(self):
# splice_descriptor_tag 8 uimsbf
tag = self.bitbin.asint(8)
if tag in self.descriptor_map.keys():
return self.descriptor_map[tag](self.bitbin, tag)
def show_info_section(self):
if self.info_section and self.command:
self.sectionstart('Splice Info Section')
self.kvprint(self.info_section)
else:
return False
def show_command(self):
if self.command:
self.sectionstart('Splice Command')
self.kvprint(self.command)
else:
return False
def show_descriptors(self):
if len(self.descriptors) > 0:
for d in self.descriptors:
idx = self.descriptors.index(d)
self.sectionstart(f'Splice Descriptor {idx}')
self.kvprint(d)
def show(self):
if self.info_section and self.command:
self.sectionstart('[SCTE 35 Message]')
self.show_info_section()
self.show_command()
self.show_descriptors()
else:
return False