/usr/lib/python2.7/dist-packages/kaa/metadata/audio/ac3.py is in python-kaa-metadata 0.7.7+svn4596-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 | # -*- coding: iso-8859-1 -*-
# -----------------------------------------------------------------------------
# ac3.py - AC3 file parser
# -----------------------------------------------------------------------------
# $Id: ac3.py 3217 2008-03-23 17:22:49Z tack $
#
# -----------------------------------------------------------------------------
# kaa-Metadata - Media Metadata for Python
# Copyright (C) 2003-2006 Thomas Schueppel, Dirk Meyer
#
# First Edition: Thomas Schueppel <stain@acm.org>
# Maintainer: Dirk Meyer <dischi@freevo.org>
#
# Please see the file AUTHORS for a complete list of authors.
#
# 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 2 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 warranty of MER-
# CHANTABILITY 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 this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# -----------------------------------------------------------------------------
__all__ = ['Parser']
# python imports
import struct
# import kaa.metadata.audio core
import core
# http://www.atsc.org/standards/a_52a.pdf
# fscod: Sample rate code, 2 bits
# 00 48
# 01 44.1
# 10 32
# 11 reserved
FSCOD = [ 48000, 44100, 32000, 0 ]
# bsmod: Bit stream mode, 3 bits
# bsmod acmod Type of Service
# 000 any main audio service: complete main (CM)
# 001 any main audio service: music and effects (ME)
# 010 any associated service: visually impaired (VI)
# 011 any associated service: hearing impaired (HI)
# 100 any associated service: dialogue (D)
# 101 any associated service: commentary (C)
# 110 any associated service: emergency (E)
# 111 001 associated service: voice over (VO)
# 111 010 - 111 main audio service: karaoke
#
# acmod: Audio coding mode, 3 bits
# 000 1+1 2 Ch1, Ch2
# 001 1/0 1 C
# 010 2/0 2 L, R
# 011 3/0 3 L, C, R
# 100 2/1 3 L, R, S
# 101 3/1 4 L, C, R, S
# 110 2/2 4 L, R, SL, SR
# 111 3/2 5 L, C, R, SL, SR
ACMOD = [ ( '1+1', 2, 'Ch1, Ch2' ),
( '1/0', 1, 'C' ),
( '2/0', 2, 'L, R' ),
( '3/0', 3, 'L, C, R' ),
( '2/1', 3, 'L, R, S' ),
( '3/1', 4, 'L, C, R, S' ),
( '2/2', 4, 'L, R, SL, SR' ),
( '3/2', 5, 'L, C, R, SL, SR' ) ]
# dsurmod: Dolby surround mode, 2 bits
# 00 not indicated
# 01 Not Dolby Surround encoded
# 10 Dolby Surround encoded
# 11 reserved
#
# lfeon: Low frequency effects channel on, 1 bit
# This bit has a value of 1 if the lfe (sub woofer) channel is on, and a
# value of 0 if the lfe channel is off.
#
# frmsizcod:
# byte&0x3e = 0x00 \b, 32 kbit/s
# byte&0x3e = 0x02 \b, 40 kbit/s
# byte&0x3e = 0x04 \b, 48 kbit/s
# byte&0x3e = 0x06 \b, 56 kbit/s
# byte&0x3e = 0x08 \b, 64 kbit/s
# byte&0x3e = 0x0a \b, 80 kbit/s
# byte&0x3e = 0x0c \b, 96 kbit/s
# byte&0x3e = 0x0e \b, 112 kbit/s
# byte&0x3e = 0x10 \b, 128 kbit/s
# byte&0x3e = 0x12 \b, 160 kbit/s
# byte&0x3e = 0x14 \b, 192 kbit/s
# byte&0x3e = 0x16 \b, 224 kbit/s
# byte&0x3e = 0x18 \b, 256 kbit/s
# byte&0x3e = 0x1a \b, 320 kbit/s
# byte&0x3e = 0x1c \b, 384 kbit/s
# byte&0x3e = 0x1e \b, 448 kbit/s
# byte&0x3e = 0x20 \b, 512 kbit/s
# byte&0x3e = 0x22 \b, 576 kbit/s
# byte&0x3e = 0x24 \b, 640 kbit/s
FRMSIZCOD = [ 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192,
224, 256, 320, 384, 448, 512, 576, 640 ]
class AC3(core.Music):
def __init__(self,file):
core.Music.__init__(self)
if file.name.endswith('.ac3'):
# when the ending is ac3, force the detection. It may not be
# necessary the the header is at the beginning but in the first
# 2000 bytes
check_length = 1000
else:
check_length = 1
for i in range(check_length):
if file.read(2) == '\x0b\x77':
break
else:
raise core.ParseError()
info = struct.unpack('<HBBBB',file.read(6))
self.samplerate = FSCOD[info[1] >> 6]
self.bitrate = FRMSIZCOD[(info[1] & 0x3F) >> 1] * 1000
bsmod = info[2] & 0x7
channels = ACMOD[info[3] >> 5]
acmod = info[3] >> 5
self.channels = ACMOD[acmod][1]
bits = 0
if acmod & 0x01 and not acmod == 0x01:
bits += 2
if acmod & 0x04:
bits += 2
if acmod == 0x02:
bits += 2
# info is now 5 bits of info[3] and all bits of info[4] ( == 13 bits)
# 'bits' bits (0-6) bits are information we don't need, after that,
# the bit we need is lfeon.
info = (((info[3] & 0x1F) << 8) + info[4])
# now we create the mask we need (based on 'bits')
# the bit number 13 - 'bits' is what we want to read
for i in range(13 - bits - 1):
info = info >> 1
if info & 1:
# LFE channel
self.channels += 1
file.seek(-1, 2)
size = file.tell()
self.length = size * 8.0 / self.bitrate
self.codec = 0x2000 # fourcc code of ac3
self.mime = 'audio/ac3'
Parser = AC3
|