File size: 10,209 Bytes
18dd6ad |
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 |
# Copyright (c) OpenMMLab. All rights reserved.
import os.path as osp
from collections import OrderedDict
import cv2
from cv2 import (CAP_PROP_FOURCC, CAP_PROP_FPS, CAP_PROP_FRAME_COUNT,
CAP_PROP_FRAME_HEIGHT, CAP_PROP_FRAME_WIDTH,
CAP_PROP_POS_FRAMES, VideoWriter_fourcc)
from annotator.uniformer.mmcv.utils import (check_file_exist, mkdir_or_exist, scandir,
track_progress)
class Cache:
def __init__(self, capacity):
self._cache = OrderedDict()
self._capacity = int(capacity)
if capacity <= 0:
raise ValueError('capacity must be a positive integer')
@property
def capacity(self):
return self._capacity
@property
def size(self):
return len(self._cache)
def put(self, key, val):
if key in self._cache:
return
if len(self._cache) >= self.capacity:
self._cache.popitem(last=False)
self._cache[key] = val
def get(self, key, default=None):
val = self._cache[key] if key in self._cache else default
return val
class VideoReader:
"""Video class with similar usage to a list object.
This video warpper class provides convenient apis to access frames.
There exists an issue of OpenCV's VideoCapture class that jumping to a
certain frame may be inaccurate. It is fixed in this class by checking
the position after jumping each time.
Cache is used when decoding videos. So if the same frame is visited for
the second time, there is no need to decode again if it is stored in the
cache.
:Example:
>>> import annotator.uniformer.mmcv as mmcv
>>> v = mmcv.VideoReader('sample.mp4')
>>> len(v) # get the total frame number with `len()`
120
>>> for img in v: # v is iterable
>>> mmcv.imshow(img)
>>> v[5] # get the 6th frame
"""
def __init__(self, filename, cache_capacity=10):
# Check whether the video path is a url
if not filename.startswith(('https://', 'http://')):
check_file_exist(filename, 'Video file not found: ' + filename)
self._vcap = cv2.VideoCapture(filename)
assert cache_capacity > 0
self._cache = Cache(cache_capacity)
self._position = 0
# get basic info
self._width = int(self._vcap.get(CAP_PROP_FRAME_WIDTH))
self._height = int(self._vcap.get(CAP_PROP_FRAME_HEIGHT))
self._fps = self._vcap.get(CAP_PROP_FPS)
self._frame_cnt = int(self._vcap.get(CAP_PROP_FRAME_COUNT))
self._fourcc = self._vcap.get(CAP_PROP_FOURCC)
@property
def vcap(self):
""":obj:`cv2.VideoCapture`: The raw VideoCapture object."""
return self._vcap
@property
def opened(self):
"""bool: Indicate whether the video is opened."""
return self._vcap.isOpened()
@property
def width(self):
"""int: Width of video frames."""
return self._width
@property
def height(self):
"""int: Height of video frames."""
return self._height
@property
def resolution(self):
"""tuple: Video resolution (width, height)."""
return (self._width, self._height)
@property
def fps(self):
"""float: FPS of the video."""
return self._fps
@property
def frame_cnt(self):
"""int: Total frames of the video."""
return self._frame_cnt
@property
def fourcc(self):
"""str: "Four character code" of the video."""
return self._fourcc
@property
def position(self):
"""int: Current cursor position, indicating frame decoded."""
return self._position
def _get_real_position(self):
return int(round(self._vcap.get(CAP_PROP_POS_FRAMES)))
def _set_real_position(self, frame_id):
self._vcap.set(CAP_PROP_POS_FRAMES, frame_id)
pos = self._get_real_position()
for _ in range(frame_id - pos):
self._vcap.read()
self._position = frame_id
def read(self):
"""Read the next frame.
If the next frame have been decoded before and in the cache, then
return it directly, otherwise decode, cache and return it.
Returns:
ndarray or None: Return the frame if successful, otherwise None.
"""
# pos = self._position
if self._cache:
img = self._cache.get(self._position)
if img is not None:
ret = True
else:
if self._position != self._get_real_position():
self._set_real_position(self._position)
ret, img = self._vcap.read()
if ret:
self._cache.put(self._position, img)
else:
ret, img = self._vcap.read()
if ret:
self._position += 1
return img
def get_frame(self, frame_id):
"""Get frame by index.
Args:
frame_id (int): Index of the expected frame, 0-based.
Returns:
ndarray or None: Return the frame if successful, otherwise None.
"""
if frame_id < 0 or frame_id >= self._frame_cnt:
raise IndexError(
f'"frame_id" must be between 0 and {self._frame_cnt - 1}')
if frame_id == self._position:
return self.read()
if self._cache:
img = self._cache.get(frame_id)
if img is not None:
self._position = frame_id + 1
return img
self._set_real_position(frame_id)
ret, img = self._vcap.read()
if ret:
if self._cache:
self._cache.put(self._position, img)
self._position += 1
return img
def current_frame(self):
"""Get the current frame (frame that is just visited).
Returns:
ndarray or None: If the video is fresh, return None, otherwise
return the frame.
"""
if self._position == 0:
return None
return self._cache.get(self._position - 1)
def cvt2frames(self,
frame_dir,
file_start=0,
filename_tmpl='{:06d}.jpg',
start=0,
max_num=0,
show_progress=True):
"""Convert a video to frame images.
Args:
frame_dir (str): Output directory to store all the frame images.
file_start (int): Filenames will start from the specified number.
filename_tmpl (str): Filename template with the index as the
placeholder.
start (int): The starting frame index.
max_num (int): Maximum number of frames to be written.
show_progress (bool): Whether to show a progress bar.
"""
mkdir_or_exist(frame_dir)
if max_num == 0:
task_num = self.frame_cnt - start
else:
task_num = min(self.frame_cnt - start, max_num)
if task_num <= 0:
raise ValueError('start must be less than total frame number')
if start > 0:
self._set_real_position(start)
def write_frame(file_idx):
img = self.read()
if img is None:
return
filename = osp.join(frame_dir, filename_tmpl.format(file_idx))
cv2.imwrite(filename, img)
if show_progress:
track_progress(write_frame, range(file_start,
file_start + task_num))
else:
for i in range(task_num):
write_frame(file_start + i)
def __len__(self):
return self.frame_cnt
def __getitem__(self, index):
if isinstance(index, slice):
return [
self.get_frame(i)
for i in range(*index.indices(self.frame_cnt))
]
# support negative indexing
if index < 0:
index += self.frame_cnt
if index < 0:
raise IndexError('index out of range')
return self.get_frame(index)
def __iter__(self):
self._set_real_position(0)
return self
def __next__(self):
img = self.read()
if img is not None:
return img
else:
raise StopIteration
next = __next__
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
self._vcap.release()
def frames2video(frame_dir,
video_file,
fps=30,
fourcc='XVID',
filename_tmpl='{:06d}.jpg',
start=0,
end=0,
show_progress=True):
"""Read the frame images from a directory and join them as a video.
Args:
frame_dir (str): The directory containing video frames.
video_file (str): Output filename.
fps (float): FPS of the output video.
fourcc (str): Fourcc of the output video, this should be compatible
with the output file type.
filename_tmpl (str): Filename template with the index as the variable.
start (int): Starting frame index.
end (int): Ending frame index.
show_progress (bool): Whether to show a progress bar.
"""
if end == 0:
ext = filename_tmpl.split('.')[-1]
end = len([name for name in scandir(frame_dir, ext)])
first_file = osp.join(frame_dir, filename_tmpl.format(start))
check_file_exist(first_file, 'The start frame not found: ' + first_file)
img = cv2.imread(first_file)
height, width = img.shape[:2]
resolution = (width, height)
vwriter = cv2.VideoWriter(video_file, VideoWriter_fourcc(*fourcc), fps,
resolution)
def write_frame(file_idx):
filename = osp.join(frame_dir, filename_tmpl.format(file_idx))
img = cv2.imread(filename)
vwriter.write(img)
if show_progress:
track_progress(write_frame, range(start, end))
else:
for i in range(start, end):
write_frame(i)
vwriter.release()
|