Spaces:
Sleeping
Sleeping
File size: 6,581 Bytes
a92043d |
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 |
#! /usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright 2016 Google Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""MPEG processing classes.
Functions for loading MPEG files and manipulating boxes.
"""
import struct
from spatialmedia.mpeg import box
from spatialmedia.mpeg import constants
from spatialmedia.mpeg import sa3d
def load(fh, position, end):
if position is None:
position = fh.tell()
fh.seek(position)
header_size = 8
size = struct.unpack(">I", fh.read(4))[0]
name = fh.read(4)
is_box = name not in constants.CONTAINERS_LIST
# Handle the mp4a decompressor setting (wave -> mp4a).
if name == constants.TAG_MP4A and size == 12:
is_box = True
if is_box:
if name == constants.TAG_SA3D:
return sa3d.load(fh, position, end)
return box.load(fh, position, end)
if size == 1:
size = struct.unpack(">Q", fh.read(8))[0]
header_size = 16
if size < 8:
print("Error, invalid size", size, "in", name, "at", position)
return None
if (position + size) > end:
print("Error: Container box size exceeds bounds.")
return None
padding = 0
if name == constants.TAG_STSD:
padding = 8
if name in constants.SOUND_SAMPLE_DESCRIPTIONS:
current_pos = fh.tell()
fh.seek(current_pos + 8)
sample_description_version = struct.unpack(">h", fh.read(2))[0]
fh.seek(current_pos)
if sample_description_version == 0:
padding = 28
elif sample_description_version == 1:
padding = 28 + 16
elif sample_description_version == 2:
padding = 64
else:
print("Unsupported sample description version:",
sample_description_version)
new_box = Container()
new_box.name = name
new_box.position = position
new_box.header_size = header_size
new_box.content_size = size - header_size
new_box.padding = padding
new_box.contents = load_multiple(
fh, position + header_size + padding, position + size)
if new_box.contents is None:
return None
return new_box
def load_multiple(fh, position=None, end=None):
loaded = list()
while (position + 4 < end):
new_box = load(fh, position, end)
if new_box is None:
print("Error, failed to load box.")
return None
loaded.append(new_box)
position = new_box.position + new_box.size()
return loaded
class Container(box.Box):
"""MPEG4 container box contents / behaviour."""
def __init__(self, padding=0):
self.name = ""
self.position = 0
self.header_size = 0
self.content_size = 0
self.contents = list()
self.padding = padding
def resize(self):
"""Recomputes the box size and recurses on contents."""
self.content_size = self.padding
for element in self.contents:
if isinstance(element, Container):
element.resize()
self.content_size += element.size()
def print_structure(self, indent=""):
"""Prints the box structure and recurses on contents."""
size1 = self.header_size
size2 = self.content_size
print("{0} {1} [{2}, {3}]".format(indent, self.name, size1, size2))
size = len(self.contents)
for i in range(size):
next_indent = indent
next_indent = next_indent.replace("├", "│")
next_indent = next_indent.replace("└", " ")
next_indent = next_indent.replace("─", " ")
if i == (size - 1):
next_indent = next_indent + " └──"
else:
next_indent = next_indent + " ├──"
element = self.contents[i]
element.print_structure(next_indent)
def remove(self, tag):
"""Removes a tag recursively from all containers."""
new_contents = []
self.content_size = 0
for element in self.contents:
if element.name != tag:
new_contents.append(element)
if isinstance(element, Container):
element.remove(tag)
self.content_size += element.size()
self.contents = new_contents
def add(self, element):
"""Adds an element, merging with containers of the same type.
Returns:
Int, increased size of container.
"""
for content in self.contents:
if content.name == element.name:
if isinstance(content, container_leaf):
return content.merge(element)
print("Error, cannot merge leafs.")
return False
self.contents.append(element)
return True
def merge(self, element):
"""Merges structure with container.
Returns:
Int, increased size of container.
"""
assert(self.name == element.name)
assert(isinstance(element, container_box))
for sub_element in element.contents:
if not self.add(sub_element):
return False
return True
def save(self, in_fh, out_fh, delta):
"""Saves box to out_fh reading uncached content from in_fh.
Args:
in_fh: file handle, source of uncached file contents.
out_fh: file_hande, destination for saved file.
delta: int, file change size for updating stco and co64 files.
"""
if self.header_size == 16:
out_fh.write(struct.pack(">I", 1))
out_fh.write(self.name)
out_fh.write(struct.pack(">Q", self.size()))
elif self.header_size == 8:
out_fh.write(struct.pack(">I", self.size()))
out_fh.write(self.name)
if self.padding > 0:
in_fh.seek(self.content_start())
box.tag_copy(in_fh, out_fh, self.padding)
for element in self.contents:
element.save(in_fh, out_fh, delta) |