| |
| 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.mmpkg.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.mmpkg.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): |
| |
| 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 |
| |
| 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. |
| """ |
| |
| 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)) |
| ] |
| |
| 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() |
|
|
