app_unsynced.py 文件源码

def __seek_calib_limit(self, video, frame_range, max_miss_count=3, verbose=True):
        frame_range_signed_length = frame_range[1] - frame_range[0]
        sample_interval_frames = frame_range_signed_length // 2
        failed_attempts = 0
        while sample_interval_frames != 0:
            miss_count = 0
            try:
                if verbose:
                    if sample_interval_frames < 0:
                        print("\nSampling every {:d} frames within {:s}, backwards."
                              .format(-sample_interval_frames, str((frame_range[1], frame_range[0]))))
                    else:
                        print("\nSampling every {:d} frames within {:s}.".format(sample_interval_frames,
                                                                                 str(frame_range)))
                for i_frame in range(frame_range[0], frame_range[1], sample_interval_frames):
                    video.read_at_pos(i_frame)
                    if verbose:
                        print('.', end="", flush=True)
                    if video.try_approximate_corners(self.board_dims):
                        frame_range[0] = i_frame
                        miss_count = 0
                    else:
                        miss_count += 1
                        if miss_count > max_miss_count:
                            # too many frames w/o calibration board, highly unlikely those are all bad frames,
                            # go to finer scan
                            frame_range[1] = i_frame
                            break
                sample_interval_frames = round(sample_interval_frames / 2)
            except cv2.error as e:
                failed_attempts += 1
                if failed_attempts > 2:
                    raise RuntimeError("Too many failed attempts. Frame index: " + str(i_frame))
                print("FFmpeg hickup, attempting to reopen video.")
                video.reopen()  # workaround for ffmpeg AVC/H.264 bug
        return frame_range[0]