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SickGear/lib/enzyme/mpeg.py

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Change bump to major version 3.xx to signal that this branch supports Python3+ only. Initial SickGear for Python 3.
2023-01-12 01:04:47 +00:00
# -*- coding: utf-8 -*-
# enzyme - Video metadata parser
# Copyright 2011-2012 Antoine Bertin <diaoulael@gmail.com>
# Copyright 2003-2006 Thomas Schueppel <stain@acm.org>
# Copyright 2003-2006 Dirk Meyer <dischi@freevo.org>
#
# This file is part of enzyme.
#
# enzyme 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.
#
# enzyme 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 enzyme. If not, see <http://www.gnu.org/licenses/>.
__all__ = ['Parser']
import os
import struct
import logging
import stat
from .exceptions import ParseError
from . import core
from six import byte2int, indexbytes
# get logging object
log = logging.getLogger(__name__)
# #------------------------------------------------------------------------
# # START_CODE
# #
# # Start Codes, with 'slice' occupying 0x01..0xAF
# #------------------------------------------------------------------------
START_CODE = {
0x00: 'picture_start_code',
0xB0: 'reserved',
0xB1: 'reserved',
0xB2: 'user_data_start_code',
0xB3: 'sequence_header_code',
0xB4: 'sequence_error_code',
0xB5: 'extension_start_code',
0xB6: 'reserved',
0xB7: 'sequence end',
0xB8: 'group of pictures',
}
for i in range(0x01, 0xAF):
START_CODE[i] = 'slice_start_code'
# #------------------------------------------------------------------------
# # START CODES
# #------------------------------------------------------------------------
PICTURE = 0x00
USERDATA = 0xB2
SEQ_HEAD = 0xB3
SEQ_ERR = 0xB4
EXT_START = 0xB5
SEQ_END = 0xB7
GOP = 0xB8
SEQ_START_CODE = 0xB3
PACK_PKT = 0xBA
SYS_PKT = 0xBB
PADDING_PKT = 0xBE
AUDIO_PKT = 0xC0
VIDEO_PKT = 0xE0
PRIVATE_STREAM1 = 0xBD
PRIVATE_STREAM2 = 0xBf
TS_PACKET_LENGTH = 188
TS_SYNC = 0x47
# #------------------------------------------------------------------------
# # FRAME_RATE
# #
# # A lookup table of all the standard frame rates. Some rates adhere to
# # a particular profile that ensures compatibility with VLSI capabilities
# # of the early to mid 1990s.
# #
# # CPB
# # Constrained Parameters Bitstreams, an MPEG-1 set of sampling and
# # bitstream parameters designed to normalize decoder computational
# # complexity, buffer size, and memory bandwidth while still addressing
# # the widest possible range of applications.
# #
# # Main Level
# # MPEG-2 Video Main Profile and Main Level is analogous to MPEG-1's
# # CPB, with sampling limits at CCIR 601 parameters (720x480x30 Hz or
# # 720x576x24 Hz).
# #
# #------------------------------------------------------------------------
FRAME_RATE = [
0,
24000.0 / 1001, # # 3-2 pulldown NTSC (CPB/Main Level)
24, # # Film (CPB/Main Level)
25, # # PAL/SECAM or 625/60 video
30000.0 / 1001, # # NTSC (CPB/Main Level)
30, # # drop-frame NTSC or component 525/60 (CPB/Main Level)
50, # # double-rate PAL
60000.0 / 1001, # # double-rate NTSC
60, # # double-rate, drop-frame NTSC/component 525/60 video
]
# #------------------------------------------------------------------------
# # ASPECT_RATIO -- INCOMPLETE?
# #
# # This lookup table maps the header aspect ratio index to a float value.
# # These are just the defined ratios for CPB I believe. As I understand
# # it, a stream that doesn't adhere to one of these aspect ratios is
# # technically considered non-compliant.
# #------------------------------------------------------------------------
ASPECT_RATIO = (None, # Forbidden
1.0, # 1/1 (VGA)
4.0 / 3, # 4/3 (TV)
16.0 / 9, # 16/9 (Widescreen)
2.21 # (Cinema)
)
class MPEG(core.AVContainer):
"""
Parser for various MPEG files. This includes MPEG-1 and MPEG-2
program streams, elementary streams and transport streams. The
reported length differs from the length reported by most video
players but the provides length here is correct. An MPEG file has
no additional metadata like title, etc; only codecs, length and
resolution is reported back.
"""
def __init__(self, file):
core.AVContainer.__init__(self)
self.sequence_header_offset = 0
self.mpeg_version = 2
self.get_time = None
self.audio = []
self.video = []
self.start = None
self.__seek_size__ = None
self.__sample_size__ = None
self.__search__ = None
self.filename = None
self.length = None
self.audio_ok = None
# detect TS (fast scan)
if not self.isTS(file):
# detect system mpeg (many infos)
if not self.isMPEG(file):
# detect PES
if not self.isPES(file):
# Maybe it's MPEG-ES
if self.isES(file):
# If isES() succeeds, we needn't do anything further.
return
if file.name.lower().endswith('mpeg') or \
file.name.lower().endswith('mpg'):
# This has to be an mpeg file. It could be a bad
# recording from an ivtv based hardware encoder with
# same bytes missing at the beginning.
# Do some more digging...
if not self.isMPEG(file, force=True) or \
not self.video or not self.audio:
# does not look like an mpeg at all
raise ParseError()
else:
# no mpeg at all
raise ParseError()
self.mime = 'video/mpeg'
if not self.video:
self.video.append(core.VideoStream())
if self.sequence_header_offset <= 0:
return
self.progressive(file)
for vi in self.video:
vi.width, vi.height = self.dxy(file)
vi.fps, vi.aspect = self.framerate_aspect(file)
vi.bitrate = self.bitrate(file)
if self.length:
vi.length = self.length
if not self.type:
self.type = 'MPEG Video'
# set fourcc codec for video and audio
vc, ac = 'MP2V', 'MP2A'
if self.mpeg_version == 1:
vc, ac = 'MPEG', 0x0050
for v in self.video:
v.codec = vc
for a in self.audio:
if not a.codec:
a.codec = ac
def dxy(self, file):
"""
get width and height of the video
"""
file.seek(self.sequence_header_offset + 4, 0)
v = file.read(4)
x = struct.unpack('>H', v[:2])[0] >> 4
y = struct.unpack('>H', v[1:3])[0] & 0x0FFF
return x, y
def framerate_aspect(self, file):
"""
read framerate and aspect ratio
"""
file.seek(self.sequence_header_offset + 7, 0)
v = struct.unpack('>B', file.read(1))[0]
try:
fps = FRAME_RATE[v & 0xf]
except IndexError:
fps = None
if v >> 4 < len(ASPECT_RATIO):
aspect = ASPECT_RATIO[v >> 4]
else:
aspect = None
return fps, aspect
def progressive(self, file):
"""
Try to find out with brute force if the mpeg is interlaced or not.
Search for the Sequence_Extension in the extension header (01B5)
"""
file.seek(0)
buffer = ''
count = 0
while 1:
if len(buffer) < 1000:
count += 1
if count > 1000:
break
buffer += file.read(1024)
if len(buffer) < 1000:
break
pos = buffer.find('\x00\x00\x01\xb5')
if pos == -1 or len(buffer) - pos < 5:
buffer = buffer[-10:]
continue
ext = (indexbytes(buffer, pos + 4) >> 4)
if ext == 8:
pass
elif ext == 1:
if (indexbytes(buffer, pos + 5) >> 3) & 1:
self._set('progressive', True)
else:
self._set('interlaced', True)
return True
else:
log.debug(u'ext: %r' % ext)
buffer = buffer[pos + 4:]
return False
# #------------------------------------------------------------------------
# # bitrate()
# #
# # From the MPEG-2.2 spec:
# #
# # bit_rate -- This is a 30-bit integer. The lower 18 bits of the
# # integer are in bit_rate_value and the upper 12 bits are in
# # bit_rate_extension. The 30-bit integer specifies the bitrate of the
# # bitstream measured in units of 400 bits/second, rounded upwards.
# # The value zero is forbidden.
# #
# # So ignoring all the variable bitrate stuff for now, this 30 bit integer
# # multiplied times 400 bits/sec should give the rate in bits/sec.
# #
# # TODO: Variable bitrates? I need one that implements this.
# #
# # Continued from the MPEG-2.2 spec:
# #
# # If the bitstream is a constant bitrate stream, the bitrate specified
# # is the actual rate of operation of the VBV specified in annex C. If
# # the bitstream is a variable bitrate stream, the STD specifications in
# # ISO/IEC 13818-1 supersede the VBV, and the bitrate specified here is
# # used to dimension the transport stream STD (2.4.2 in ITU-T Rec. xxx |
# # ISO/IEC 13818-1), or the program stream STD (2.4.5 in ITU-T Rec. xxx |
# # ISO/IEC 13818-1).
# #
# # If the bitstream is not a constant rate bitstream the vbv_delay
# # field shall have the value FFFF in hexadecimal.
# #
# # Given the value encoded in the bitrate field, the bitstream shall be
# # generated so that the video encoding and the worst case multiplex
# # jitter do not cause STD buffer overflow or underflow.
# #
# #
# # ------------------------------------------------------------------------
# # Some parts in the code are based on mpgtx (mpgtx.sf.net)
def bitrate(self, file):
"""
read the bitrate (most of the time broken)
"""
file.seek(self.sequence_header_offset + 8, 0)
t, b = struct.unpack('>HB', file.read(3))
vrate = t << 2 | b >> 6
return vrate * 400
@staticmethod
def ReadSCRMpeg2(buffer):
"""
read SCR (timestamp) for MPEG2 at the buffer beginning (6 Bytes)
"""
if len(buffer) < 6:
return None
highbit = (byte2int(buffer) & 0x20) >> 5
low4Bytes = ((int(byte2int(buffer)) & 0x18) >> 3) << 30
low4Bytes |= (byte2int(buffer) & 0x03) << 28
low4Bytes |= indexbytes(buffer, 1) << 20
low4Bytes |= (indexbytes(buffer, 2) & 0xF8) << 12
low4Bytes |= (indexbytes(buffer, 2) & 0x03) << 13
low4Bytes |= indexbytes(buffer, 3) << 5
low4Bytes |= (indexbytes(buffer, 4)) >> 3
sys_clock_ref = (indexbytes(buffer, 4) & 0x3) << 7
sys_clock_ref |= (indexbytes(buffer, 5) >> 1)
return (int(highbit * (1 << 16) * (1 << 16)) + low4Bytes) / 90000
@staticmethod
def ReadSCRMpeg1(buffer):
"""
read SCR (timestamp) for MPEG1 at the buffer beginning (5 Bytes)
"""
if len(buffer) < 5:
return None
highbit = (byte2int(buffer) >> 3) & 0x01
low4Bytes = ((int(byte2int(buffer)) >> 1) & 0x03) << 30
low4Bytes |= indexbytes(buffer, 1) << 22
low4Bytes |= (indexbytes(buffer, 2) >> 1) << 15
low4Bytes |= indexbytes(buffer, 3) << 7
low4Bytes |= indexbytes(buffer, 4) >> 1
return (int(highbit) * (1 << 16) * (1 << 16) + low4Bytes) / 90000
@staticmethod
def ReadPTS(buffer):
"""
read PTS (PES timestamp) at the buffer beginning (5 Bytes)
"""
high = ((byte2int(buffer) & 0xF) >> 1)
med = (indexbytes(buffer, 1) << 7) + (indexbytes(buffer, 2) >> 1)
low = (indexbytes(buffer, 3) << 7) + (indexbytes(buffer, 4) >> 1)
return ((int(high) << 30) + (med << 15) + low) / 90000
def ReadHeader(self, buffer, offset):
"""
Handle MPEG header in buffer on position offset
Return None on error, new offset or 0 if the new offset can't be scanned
"""
if buffer[offset:offset + 3] != '\x00\x00\x01':
return None
_id = indexbytes(buffer, offset + 3)
if _id == PADDING_PKT:
return offset + (indexbytes(buffer, offset + 4) << 8) + \
indexbytes(buffer, offset + 5) + 6
if _id == PACK_PKT:
if indexbytes(buffer, offset + 4) & 0xF0 == 0x20:
self.type = 'MPEG-1 Video'
self.get_time = self.ReadSCRMpeg1
self.mpeg_version = 1
return offset + 12
elif (indexbytes(buffer, offset + 4) & 0xC0) == 0x40:
self.type = 'MPEG-2 Video'
self.get_time = self.ReadSCRMpeg2
return offset + (indexbytes(buffer, offset + 13) & 0x07) + 14
else:
# I have no idea what just happened, but for some DVB
# recordings done with mencoder this points to a
# PACK_PKT describing something odd. Returning 0 here
# (let's hope there are no extensions in the header)
# fixes it.
return 0
if 0xC0 <= _id <= 0xDF:
# code for audio stream
for a in self.audio:
if a.id == _id:
break
else:
self.audio.append(core.AudioStream())
self.audio[-1]._set('id', _id)
return 0
if 0xE0 <= _id <= 0xEF:
# code for video stream
for v in self.video:
if v.id == _id:
break
else:
self.video.append(core.VideoStream())
self.video[-1]._set('id', _id)
return 0
if _id == SEQ_HEAD:
# sequence header, remember that position for later use
self.sequence_header_offset = offset
return 0
if _id in [PRIVATE_STREAM1, PRIVATE_STREAM2]:
# private stream. we don't know, but maybe we can guess later
add = indexbytes(buffer, offset + 8)
# if (indexbytes(buffer, offset+6) & 4) or 1:
# id = indexbytes(buffer, offset+10+add)
if buffer[offset + 11 + add:offset + 15 + add].find('\x0b\x77') != -1:
# AC3 stream
for a in self.audio:
if a.id == _id:
break
else:
self.audio.append(core.AudioStream())
self.audio[-1]._set('id', _id)
self.audio[-1].codec = 0x2000 # AC3
return 0
if _id == SYS_PKT:
return 0
if _id == EXT_START:
return 0
return 0
# Normal MPEG (VCD, SVCD) ========================================
def isMPEG(self, file, force=False):
"""
This MPEG starts with a sequence of 0x00 followed by a PACK Header
http://dvd.sourceforge.net/dvdinfo/packhdr.html
"""
file.seek(0, 0)
buffer = file.read(10000)
offset = 0
# seek until the 0 byte stop
while offset < len(buffer) - 100 and buffer[offset] == '\0':
offset += 1
offset -= 2
# test for mpeg header 0x00 0x00 0x01
header = '\x00\x00\x01%s' % chr(PACK_PKT)
if offset < 0 or not buffer[offset:offset + 4] == header:
if not force:
return 0
# brute force and try to find the pack header in the first
# 10000 bytes somehow
offset = buffer.find(header)
if offset < 0:
return 0
# scan the 100000 bytes of data
buffer += file.read(100000)
# scan first header, to get basic info about
# how to read a timestamp
self.ReadHeader(buffer, offset)
# store first timestamp
self.start = self.get_time(buffer[offset + 4:])
while len(buffer) > offset + 1000 and \
buffer[offset:offset + 3] == '\x00\x00\x01':
# read the mpeg header
new_offset = self.ReadHeader(buffer, offset)
# header scanning detected error, this is no mpeg
if new_offset is None:
return 0
if new_offset:
# we have a new offset
offset = new_offset
# skip padding 0 before a new header
while len(buffer) > offset + 10 and \
not indexbytes(buffer, offset + 2):
offset += 1
else:
# seek to new header by brute force
offset += buffer[offset + 4:].find('\x00\x00\x01') + 4
# fill in values for support functions:
self.__seek_size__ = 1000000
self.__sample_size__ = 10000
self.__search__ = self._find_timer_
self.filename = file.name
# get length of the file
self.length = self.get_length()
return 1
@staticmethod
def _find_timer_(buffer):
"""
Return position of timer in buffer or None if not found.
This function is valid for 'normal' mpeg files
"""
pos = buffer.find('\x00\x00\x01%s' % chr(PACK_PKT))
if pos == -1:
return None
return pos + 4
# PES ============================================================
def ReadPESHeader(self, offset, buffer, id=0):
"""
Parse a PES header.
Since it starts with 0x00 0x00 0x01 like 'normal' mpegs, this
function will return (0, None) when it is no PES header or
(packet length, timestamp position (maybe None))
http://dvd.sourceforge.net/dvdinfo/pes-hdr.html
"""
if not buffer[0:3] == '\x00\x00\x01':
return 0, None
packet_length = (indexbytes(buffer, 4) << 8) + indexbytes(buffer, 5) + 6
align = indexbytes(buffer, 6) & 4
header_length = indexbytes(buffer, 8)
# PES ID (starting with 001)
if indexbytes(buffer, 3) & 0xE0 == 0xC0:
id = id or indexbytes(buffer, 3) & 0x1F
for a in self.audio:
if a.id == id:
break
else:
self.audio.append(core.AudioStream())
self.audio[-1]._set('id', id)
elif indexbytes(buffer, 3) & 0xF0 == 0xE0:
id = id or indexbytes(buffer, 3) & 0xF
for v in self.video:
if v.id == id:
break
else:
self.video.append(core.VideoStream())
self.video[-1]._set('id', id)
# new mpeg starting
if buffer[header_length + 9:header_length + 13] == \
'\x00\x00\x01\xB3' and not self.sequence_header_offset:
# yes, remember offset for later use
self.sequence_header_offset = offset + header_length + 9
elif indexbytes(buffer, 3) == 189 or indexbytes(buffer, 3) == 191:
# private stream. we don't know, but maybe we can guess later
id = id or indexbytes(buffer, 3) & 0xF
if align and \
buffer[header_length + 9:header_length + 11] == '\x0b\x77':
# AC3 stream
for a in self.audio:
if a.id == id:
break
else:
self.audio.append(core.AudioStream())
self.audio[-1]._set('id', id)
self.audio[-1].codec = 0x2000 # AC3
else:
# unknown content
pass
ptsdts = indexbytes(buffer, 7) >> 6
if ptsdts and ptsdts == indexbytes(buffer, 9) >> 4:
if indexbytes(buffer, 9) >> 4 != ptsdts:
log.warning(u'WARNING: bad PTS/DTS, please contact us')
return packet_length, None
# timestamp = self.ReadPTS(buffer[9:14])
high = ((indexbytes(buffer, 9) & 0xF) >> 1)
med = (indexbytes(buffer, 10) << 7) + (indexbytes(buffer, 11) >> 1)
low = (indexbytes(buffer, 12) << 7) + (indexbytes(buffer, 13) >> 1)
return packet_length, 9
return packet_length, None
def isPES(self, file):
log.info(u'trying mpeg-pes scan')
file.seek(0, 0)
buffer = file.read(3)
# header (also valid for all mpegs)
if not buffer == '\x00\x00\x01':
return 0
self.sequence_header_offset = 0
buffer += file.read(10000)
offset = 0
while offset + 1000 < len(buffer):
pos, timestamp = self.ReadPESHeader(offset, buffer[offset:])
if not pos:
return 0
if timestamp is not None and not hasattr(self, 'start'):
self.get_time = self.ReadPTS
bpos = buffer[offset + timestamp:offset + timestamp + 5]
self.start = self.get_time(bpos)
if self.sequence_header_offset and hasattr(self, 'start'):
# we have all informations we need
break
offset += pos
if offset + 1000 < len(buffer) < 1000000 or 1:
# looks like a pes, read more
buffer += file.read(10000)
if not self.video and not self.audio:
# no video and no audio?
return 0
self.type = 'MPEG-PES'
# fill in values for support functions:
self.__seek_size__ = 10000000 # 10 MB
self.__sample_size__ = 500000 # 500 k scanning
self.__search__ = self._find_timer_PES_
self.filename = file.name
# get length of the file
self.length = self.get_length()
return 1
def _find_timer_PES_(self, buffer):
"""
Return position of timer in buffer or -1 if not found.
This function is valid for PES files
"""
pos = buffer.find('\x00\x00\x01')
offset = 0
if pos == -1 or offset + 1000 >= len(buffer):
return None
retpos = -1
ackcount = 0
while offset + 1000 < len(buffer):
pos, timestamp = self.ReadPESHeader(offset, buffer[offset:])
if timestamp is not None and retpos == -1:
retpos = offset + timestamp
if pos == 0:
# Oops, that was a mpeg header, no PES header
offset += buffer[offset:].find('\x00\x00\x01')
retpos = -1
ackcount = 0
else:
offset += pos
if retpos != -1:
ackcount += 1
if ackcount > 10:
# looks ok to me
return retpos
return None
# Elementary Stream ===============================================
def isES(self, file):
file.seek(0, 0)
try:
header = struct.unpack('>LL', file.read(8))
except (struct.error, IOError):
return False
if header[0] != 0x1B3:
return False
# Is an mpeg video elementary stream
self.mime = 'video/mpeg'
video = core.VideoStream()
video.width = header[1] >> 20
video.height = (header[1] >> 8) & 0xfff
if header[1] & 0xf < len(FRAME_RATE):
video.fps = FRAME_RATE[header[1] & 0xf]
if (header[1] >> 4) & 0xf < len(ASPECT_RATIO):
# FIXME: Empirically the aspect looks like PAR rather than DAR
video.aspect = ASPECT_RATIO[(header[1] >> 4) & 0xf]
self.video.append(video)
return True
# Transport Stream ===============================================
def isTS(self, file):
file.seek(0, 0)
buffer = file.read(TS_PACKET_LENGTH * 2)
c = 0
while c + TS_PACKET_LENGTH < len(buffer):
if indexbytes(buffer, c) == indexbytes(buffer, c + TS_PACKET_LENGTH) == TS_SYNC:
break
c += 1
else:
return 0
buffer += file.read(10000)
self.type = 'MPEG-TS'
while c + TS_PACKET_LENGTH < len(buffer):
start = indexbytes(buffer, c + 1) & 0x40
# maybe load more into the buffer
if c + 2 * TS_PACKET_LENGTH > len(buffer) and c < 500000:
buffer += file.read(10000)
# wait until the ts payload contains a payload header
if not start:
c += TS_PACKET_LENGTH
continue
tsid = ((indexbytes(buffer, c + 1) & 0x3F) << 8) + indexbytes(buffer, c + 2)
adapt = (indexbytes(buffer, c + 3) & 0x30) >> 4
offset = 4
if adapt & 0x02:
# meta info present, skip it for now
adapt_len = indexbytes(buffer, c + offset)
offset += adapt_len + 1
if not indexbytes(buffer, c + 1) & 0x40:
# no new pes or psi in stream payload starting
pass
elif adapt & 0x01:
# PES
timestamp = self.ReadPESHeader(c + offset, buffer[c + offset:],
tsid)[1]
if timestamp is not None:
if not hasattr(self, 'start'):
self.get_time = self.ReadPTS
timestamp = c + offset + timestamp
self.start = self.get_time(buffer[timestamp:timestamp + 5])
elif not hasattr(self, 'audio_ok'):
timestamp = c + offset + timestamp
start = self.get_time(buffer[timestamp:timestamp + 5])
if start is not None and self.start is not None and \
abs(start - self.start) < 10:
# looks ok
self.audio_ok = True
else:
# timestamp broken
del self.start
log.warning(u'Timestamp error, correcting')
if hasattr(self, 'start') and self.start and \
self.sequence_header_offset and self.video and self.audio:
break
c += TS_PACKET_LENGTH
if not self.sequence_header_offset:
return 0
# fill in values for support functions:
self.__seek_size__ = 10000000 # 10 MB
self.__sample_size__ = 100000 # 100 k scanning
self.__search__ = self._find_timer_TS_
self.filename = file.name
# get length of the file
self.length = self.get_length()
return 1
def _find_timer_TS_(self, buffer):
c = 0
while c + TS_PACKET_LENGTH < len(buffer):
if indexbytes(buffer, c) == indexbytes(buffer, c + TS_PACKET_LENGTH) == TS_SYNC:
break
c += 1
else:
return None
while c + TS_PACKET_LENGTH < len(buffer):
start = indexbytes(buffer, c + 1) & 0x40
if not start:
c += TS_PACKET_LENGTH
continue
tsid = ((indexbytes(buffer, c + 1) & 0x3F) << 8) + indexbytes(buffer, c + 2)
adapt = (indexbytes(buffer, c + 3) & 0x30) >> 4
offset = 4
if adapt & 0x02:
# meta info present, skip it for now
offset += indexbytes(buffer, c + offset) + 1
if adapt & 0x01:
timestamp = self.ReadPESHeader(c + offset, buffer[c + offset:], tsid)[1]
if timestamp is None:
# this should not happen
log.error(u'bad TS')
return None
return c + offset + timestamp
c += TS_PACKET_LENGTH
return None
# Support functions ==============================================
def get_endpos(self):
"""
get the last timestamp of the mpeg, return -1 if this is not possible
"""
if not hasattr(self, 'filename') or not hasattr(self, 'start'):
return None
length = os.stat(self.filename)[stat.ST_SIZE]
if length < self.__sample_size__:
return
file = open(self.filename)
file.seek(length - self.__sample_size__)
buffer = file.read(self.__sample_size__)
end = None
while 1:
pos = self.__search__(buffer)
if pos is None:
break
end = self.get_time(buffer[pos:]) or end
buffer = buffer[pos + 100:]
file.close()
return end
def get_length(self):
"""
get the length in seconds, return -1 if this is not possible
"""
end = self.get_endpos()
if end is None or self.start is None:
return None
if self.start > end:
return int(((int(1) << 33) - 1) / 90000) - self.start + end
return end - self.start
def seek(self, end_time):
"""
Return the byte position in the file where the time position
is 'pos' seconds. Return 0 if this is not possible
"""
if not hasattr(self, 'filename') or not hasattr(self, 'start'):
return 0
file = open(self.filename)
seek_to = 0
while 1:
file.seek(self.__seek_size__, 1)
buffer = file.read(self.__sample_size__)
if len(buffer) < 10000:
break
pos = self.__search__(buffer)
if pos is not None:
# found something
nt = self.get_time(buffer[pos:])
if nt is not None and nt >= end_time:
# too much, break
break
# that wasn't enough
seek_to = file.tell()
file.close()
return seek_to
def __scan__(self):
"""
scan file for timestamps (may take a long time)
"""
if not hasattr(self, 'filename') or not hasattr(self, 'start'):
return 0
file = open(self.filename)
log.debug(u'scanning file...')
while 1:
file.seek(self.__seek_size__ * 10, 1)
buffer = file.read(self.__sample_size__)
if len(buffer) < 10000:
break
pos = self.__search__(buffer)
if pos is None:
continue
log.debug(u'buffer position: %r' % self.get_time(buffer[pos:]))
file.close()
log.debug(u'done scanning file')
Parser = MPEG
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