"""Utilities for creating and manipulating image frames.""" import datetime import logging import subprocess as sp import threading from abc import ABC, abstractmethod from multiprocessing import resource_tracker as _mprt from multiprocessing import shared_memory as _mpshm from string import printable from typing import AnyStr, Optional import cv2 import numpy as np from unidecode import unidecode logger = logging.getLogger(__name__) def transliterate_to_latin(text: str) -> str: """ Transliterate a given text to Latin. This function uses the unidecode library to transliterate the input text to Latin. It is useful for converting texts with diacritics or non-Latin characters to a Latin equivalent. Args: text (str): The text to be transliterated. Returns: str: The transliterated text. Example: >>> transliterate_to_latin('frégate') 'fregate' """ return unidecode(text) def on_edge(box, frame_shape): if ( box[0] == 0 or box[1] == 0 or box[2] == frame_shape[1] - 1 or box[3] == frame_shape[0] - 1 ): return True def has_better_attr(current_thumb, new_obj, attr_label) -> bool: max_new_attr = max( [0] + [area(a["box"]) for a in new_obj["attributes"] if a["label"] == attr_label] ) max_current_attr = max( [0] + [ area(a["box"]) for a in current_thumb["attributes"] if a["label"] == attr_label ] ) # if the thumb has a higher scoring attr return max_new_attr > max_current_attr def is_better_thumbnail(label, current_thumb, new_obj, frame_shape) -> bool: # larger is better # cutoff images are less ideal, but they should also be smaller? # better scores are obviously better too # check face on person if label == "person": if has_better_attr(current_thumb, new_obj, "face"): return True # if the current thumb has a face attr, dont update unless it gets better if any([a["label"] == "face" for a in current_thumb["attributes"]]): return False # check license_plate on car if label == "car": if has_better_attr(current_thumb, new_obj, "license_plate"): return True # if the current thumb has a license_plate attr, dont update unless it gets better if any([a["label"] == "license_plate" for a in current_thumb["attributes"]]): return False # if the new_thumb is on an edge, and the current thumb is not if on_edge(new_obj["box"], frame_shape) and not on_edge( current_thumb["box"], frame_shape ): return False # if the score is better by more than 5% if new_obj["score"] > current_thumb["score"] + 0.05: return True # if the area is 10% larger if new_obj["area"] > current_thumb["area"] * 1.1: return True return False def draw_timestamp( frame, timestamp, timestamp_format, font_effect=None, font_thickness=2, font_color=(255, 255, 255), position="tl", ): time_to_show = datetime.datetime.fromtimestamp(timestamp).strftime(timestamp_format) # calculate a dynamic font size size = cv2.getTextSize( time_to_show, cv2.FONT_HERSHEY_SIMPLEX, fontScale=1.0, thickness=font_thickness, ) text_width = size[0][0] desired_size = max(150, 0.33 * frame.shape[1]) font_scale = desired_size / text_width # calculate the actual size with the dynamic scale size = cv2.getTextSize( time_to_show, cv2.FONT_HERSHEY_SIMPLEX, fontScale=font_scale, thickness=font_thickness, ) image_width = frame.shape[1] image_height = frame.shape[0] text_width = size[0][0] text_height = size[0][1] line_height = text_height + size[1] if position == "tl": text_offset_x = 0 text_offset_y = 0 if 0 < line_height else 0 - (line_height + 8) elif position == "tr": text_offset_x = image_width - text_width text_offset_y = 0 if 0 < line_height else 0 - (line_height + 8) elif position == "bl": text_offset_x = 0 text_offset_y = image_height - (line_height + 8) elif position == "br": text_offset_x = image_width - text_width text_offset_y = image_height - (line_height + 8) if font_effect == "solid": # make the coords of the box with a small padding of two pixels timestamp_box_coords = np.array( [ [text_offset_x, text_offset_y], [text_offset_x + text_width, text_offset_y], [text_offset_x + text_width, text_offset_y + line_height + 8], [text_offset_x, text_offset_y + line_height + 8], ] ) cv2.fillPoly( frame, [timestamp_box_coords], # inverse color of text for background for max. contrast (255 - font_color[0], 255 - font_color[1], 255 - font_color[2]), ) elif font_effect == "shadow": cv2.putText( frame, time_to_show, (text_offset_x + 3, text_offset_y + line_height), cv2.FONT_HERSHEY_SIMPLEX, fontScale=font_scale, color=(255 - font_color[0], 255 - font_color[1], 255 - font_color[2]), thickness=font_thickness, ) cv2.putText( frame, time_to_show, (text_offset_x, text_offset_y + line_height - 3), cv2.FONT_HERSHEY_SIMPLEX, fontScale=font_scale, color=font_color, thickness=font_thickness, ) def draw_box_with_label( frame, x_min, y_min, x_max, y_max, label, info, thickness=2, color=None, position="ul", ): if color is None: color = (0, 0, 255) try: display_text = transliterate_to_latin("{}: {}".format(label, info)) except Exception: display_text = "{}: {}".format(label, info) cv2.rectangle(frame, (x_min, y_min), (x_max, y_max), color, thickness) font_scale = 0.5 font = cv2.FONT_HERSHEY_SIMPLEX # get the width and height of the text box size = cv2.getTextSize(display_text, font, fontScale=font_scale, thickness=2) text_width = size[0][0] text_height = size[0][1] line_height = text_height + size[1] # set the text start position if position == "ul": text_offset_x = x_min text_offset_y = 0 if y_min < line_height else y_min - (line_height + 8) elif position == "ur": text_offset_x = x_max - (text_width + 8) text_offset_y = 0 if y_min < line_height else y_min - (line_height + 8) elif position == "bl": text_offset_x = x_min text_offset_y = y_max elif position == "br": text_offset_x = x_max - (text_width + 8) text_offset_y = y_max # make the coords of the box with a small padding of two pixels textbox_coords = ( (text_offset_x, text_offset_y), (text_offset_x + text_width + 2, text_offset_y + line_height), ) cv2.rectangle(frame, textbox_coords[0], textbox_coords[1], color, cv2.FILLED) cv2.putText( frame, display_text, (text_offset_x, text_offset_y + line_height - 3), font, fontScale=font_scale, color=(0, 0, 0), thickness=2, ) def is_label_printable(label) -> bool: """Check if label is printable.""" return not bool(set(label) - set(printable)) def calculate_region(frame_shape, xmin, ymin, xmax, ymax, model_size, multiplier=2): # size is the longest edge and divisible by 4 size = int((max(xmax - xmin, ymax - ymin) * multiplier) // 4 * 4) # dont go any smaller than the model_size if size < model_size: size = model_size # x_offset is midpoint of bounding box minus half the size x_offset = int((xmax - xmin) / 2.0 + xmin - size / 2.0) # if outside the image if x_offset < 0: x_offset = 0 elif x_offset > (frame_shape[1] - size): x_offset = max(0, (frame_shape[1] - size)) # y_offset is midpoint of bounding box minus half the size y_offset = int((ymax - ymin) / 2.0 + ymin - size / 2.0) # # if outside the image if y_offset < 0: y_offset = 0 elif y_offset > (frame_shape[0] - size): y_offset = max(0, (frame_shape[0] - size)) return (x_offset, y_offset, x_offset + size, y_offset + size) def calculate_16_9_crop(frame_shape, xmin, ymin, xmax, ymax, multiplier=1.25): min_size = 200 # size is the longest edge and divisible by 4 x_size = int((xmax - xmin) * multiplier) if x_size < min_size: x_size = min_size y_size = int((ymax - ymin) * multiplier) if y_size < min_size: y_size = min_size if frame_shape[1] / frame_shape[0] > 16 / 9 and x_size / y_size > 4: return None # calculate 16x9 using height aspect_y_size = int(9 / 16 * x_size) # if 16:9 by height is too small if aspect_y_size < y_size or aspect_y_size > frame_shape[0]: x_size = int((16 / 9) * y_size) // 4 * 4 if x_size / y_size > 1.8: return None else: y_size = aspect_y_size // 4 * 4 # x_offset is midpoint of bounding box minus half the size x_offset = int((xmax - xmin) / 2.0 + xmin - x_size / 2.0) # if outside the image if x_offset < 0: x_offset = 0 elif x_offset > (frame_shape[1] - x_size): x_offset = max(0, (frame_shape[1] - x_size)) # y_offset is midpoint of bounding box minus half the size y_offset = int((ymax - ymin) / 2.0 + ymin - y_size / 2.0) # # if outside the image if y_offset < 0: y_offset = 0 elif y_offset > (frame_shape[0] - y_size): y_offset = max(0, (frame_shape[0] - y_size)) return (x_offset, y_offset, x_offset + x_size, y_offset + y_size) def get_yuv_crop(frame_shape, crop): # crop should be (x1,y1,x2,y2) frame_height = frame_shape[0] // 3 * 2 frame_width = frame_shape[1] # compute the width/height of the uv channels uv_width = frame_width // 2 # width of the uv channels uv_height = frame_height // 4 # height of the uv channels # compute the offset for upper left corner of the uv channels uv_x_offset = crop[0] // 2 # x offset of the uv channels uv_y_offset = crop[1] // 4 # y offset of the uv channels # compute the width/height of the uv crops uv_crop_width = (crop[2] - crop[0]) // 2 # width of the cropped uv channels uv_crop_height = (crop[3] - crop[1]) // 4 # height of the cropped uv channels # ensure crop dimensions are multiples of 2 and 4 y = (crop[0], crop[1], crop[0] + uv_crop_width * 2, crop[1] + uv_crop_height * 4) u1 = ( 0 + uv_x_offset, frame_height + uv_y_offset, 0 + uv_x_offset + uv_crop_width, frame_height + uv_y_offset + uv_crop_height, ) u2 = ( uv_width + uv_x_offset, frame_height + uv_y_offset, uv_width + uv_x_offset + uv_crop_width, frame_height + uv_y_offset + uv_crop_height, ) v1 = ( 0 + uv_x_offset, frame_height + uv_height + uv_y_offset, 0 + uv_x_offset + uv_crop_width, frame_height + uv_height + uv_y_offset + uv_crop_height, ) v2 = ( uv_width + uv_x_offset, frame_height + uv_height + uv_y_offset, uv_width + uv_x_offset + uv_crop_width, frame_height + uv_height + uv_y_offset + uv_crop_height, ) return y, u1, u2, v1, v2 def yuv_crop_and_resize(frame, region, height=None): # Crops and resizes a YUV frame while maintaining aspect ratio # https://stackoverflow.com/a/57022634 height = frame.shape[0] // 3 * 2 width = frame.shape[1] # get the crop box if the region extends beyond the frame crop_x1 = max(0, region[0]) crop_y1 = max(0, region[1]) # ensure these are a multiple of 4 crop_x2 = min(width, region[2]) crop_y2 = min(height, region[3]) crop_box = (crop_x1, crop_y1, crop_x2, crop_y2) y, u1, u2, v1, v2 = get_yuv_crop(frame.shape, crop_box) # if the region starts outside the frame, indent the start point in the cropped frame y_channel_x_offset = abs(min(0, region[0])) y_channel_y_offset = abs(min(0, region[1])) uv_channel_x_offset = y_channel_x_offset // 2 uv_channel_y_offset = y_channel_y_offset // 4 # create the yuv region frame # make sure the size is a multiple of 4 # TODO: this should be based on the size after resize now size = (region[3] - region[1]) // 4 * 4 yuv_cropped_frame = np.zeros((size + size // 2, size), np.uint8) # fill in black yuv_cropped_frame[:] = 128 yuv_cropped_frame[0:size, 0:size] = 16 # copy the y channel yuv_cropped_frame[ y_channel_y_offset : y_channel_y_offset + y[3] - y[1], y_channel_x_offset : y_channel_x_offset + y[2] - y[0], ] = frame[y[1] : y[3], y[0] : y[2]] uv_crop_width = u1[2] - u1[0] uv_crop_height = u1[3] - u1[1] # copy u1 yuv_cropped_frame[ size + uv_channel_y_offset : size + uv_channel_y_offset + uv_crop_height, 0 + uv_channel_x_offset : 0 + uv_channel_x_offset + uv_crop_width, ] = frame[u1[1] : u1[3], u1[0] : u1[2]] # copy u2 yuv_cropped_frame[ size + uv_channel_y_offset : size + uv_channel_y_offset + uv_crop_height, size // 2 + uv_channel_x_offset : size // 2 + uv_channel_x_offset + uv_crop_width, ] = frame[u2[1] : u2[3], u2[0] : u2[2]] # copy v1 yuv_cropped_frame[ size + size // 4 + uv_channel_y_offset : size + size // 4 + uv_channel_y_offset + uv_crop_height, 0 + uv_channel_x_offset : 0 + uv_channel_x_offset + uv_crop_width, ] = frame[v1[1] : v1[3], v1[0] : v1[2]] # copy v2 yuv_cropped_frame[ size + size // 4 + uv_channel_y_offset : size + size // 4 + uv_channel_y_offset + uv_crop_height, size // 2 + uv_channel_x_offset : size // 2 + uv_channel_x_offset + uv_crop_width, ] = frame[v2[1] : v2[3], v2[0] : v2[2]] return yuv_cropped_frame def yuv_to_3_channel_yuv(yuv_frame): height = yuv_frame.shape[0] // 3 * 2 width = yuv_frame.shape[1] # flatten the image into array yuv_data = yuv_frame.ravel() # create a numpy array to hold all the 3 channel yuv data all_yuv_data = np.empty((height, width, 3), dtype=np.uint8) y_count = height * width uv_count = y_count // 4 # copy the y_channel all_yuv_data[:, :, 0] = yuv_data[0:y_count].reshape((height, width)) # copy the u channel doubling each dimension all_yuv_data[:, :, 1] = np.repeat( np.reshape( np.repeat(yuv_data[y_count : y_count + uv_count], repeats=2, axis=0), (height // 2, width), ), repeats=2, axis=0, ) # copy the v channel doubling each dimension all_yuv_data[:, :, 2] = np.repeat( np.reshape( np.repeat( yuv_data[y_count + uv_count : y_count + uv_count + uv_count], repeats=2, axis=0, ), (height // 2, width), ), repeats=2, axis=0, ) return all_yuv_data def copy_yuv_to_position( destination_frame, destination_offset, destination_shape, source_frame=None, source_channel_dim=None, interpolation=cv2.INTER_LINEAR, ): # get the coordinates of the channels for this position in the layout y, u1, u2, v1, v2 = get_yuv_crop( destination_frame.shape, ( destination_offset[1], destination_offset[0], destination_offset[1] + destination_shape[1], destination_offset[0] + destination_shape[0], ), ) # clear y destination_frame[ y[1] : y[3], y[0] : y[2], ] = 16 # clear u1 destination_frame[u1[1] : u1[3], u1[0] : u1[2]] = 128 # clear u2 destination_frame[u2[1] : u2[3], u2[0] : u2[2]] = 128 # clear v1 destination_frame[v1[1] : v1[3], v1[0] : v1[2]] = 128 # clear v2 destination_frame[v2[1] : v2[3], v2[0] : v2[2]] = 128 if source_frame is not None: # calculate the resized frame, maintaining the aspect ratio source_aspect_ratio = source_frame.shape[1] / (source_frame.shape[0] // 3 * 2) dest_aspect_ratio = destination_shape[1] / destination_shape[0] if source_aspect_ratio <= dest_aspect_ratio: y_resize_height = int(destination_shape[0] // 4 * 4) y_resize_width = int((y_resize_height * source_aspect_ratio) // 4 * 4) else: y_resize_width = int(destination_shape[1] // 4 * 4) y_resize_height = int((y_resize_width / source_aspect_ratio) // 4 * 4) uv_resize_width = int(y_resize_width // 2) uv_resize_height = int(y_resize_height // 4) y_y_offset = int((destination_shape[0] - y_resize_height) / 4 // 4 * 4) y_x_offset = int((destination_shape[1] - y_resize_width) / 2 // 4 * 4) uv_y_offset = y_y_offset // 4 uv_x_offset = y_x_offset // 2 # resize/copy y channel destination_frame[ y[1] + y_y_offset : y[1] + y_y_offset + y_resize_height, y[0] + y_x_offset : y[0] + y_x_offset + y_resize_width, ] = cv2.resize( source_frame[ source_channel_dim["y"][1] : source_channel_dim["y"][3], source_channel_dim["y"][0] : source_channel_dim["y"][2], ], dsize=(y_resize_width, y_resize_height), interpolation=interpolation, ) # resize/copy u1 destination_frame[ u1[1] + uv_y_offset : u1[1] + uv_y_offset + uv_resize_height, u1[0] + uv_x_offset : u1[0] + uv_x_offset + uv_resize_width, ] = cv2.resize( source_frame[ source_channel_dim["u1"][1] : source_channel_dim["u1"][3], source_channel_dim["u1"][0] : source_channel_dim["u1"][2], ], dsize=(uv_resize_width, uv_resize_height), interpolation=interpolation, ) # resize/copy u2 destination_frame[ u2[1] + uv_y_offset : u2[1] + uv_y_offset + uv_resize_height, u2[0] + uv_x_offset : u2[0] + uv_x_offset + uv_resize_width, ] = cv2.resize( source_frame[ source_channel_dim["u2"][1] : source_channel_dim["u2"][3], source_channel_dim["u2"][0] : source_channel_dim["u2"][2], ], dsize=(uv_resize_width, uv_resize_height), interpolation=interpolation, ) # resize/copy v1 destination_frame[ v1[1] + uv_y_offset : v1[1] + uv_y_offset + uv_resize_height, v1[0] + uv_x_offset : v1[0] + uv_x_offset + uv_resize_width, ] = cv2.resize( source_frame[ source_channel_dim["v1"][1] : source_channel_dim["v1"][3], source_channel_dim["v1"][0] : source_channel_dim["v1"][2], ], dsize=(uv_resize_width, uv_resize_height), interpolation=interpolation, ) # resize/copy v2 destination_frame[ v2[1] + uv_y_offset : v2[1] + uv_y_offset + uv_resize_height, v2[0] + uv_x_offset : v2[0] + uv_x_offset + uv_resize_width, ] = cv2.resize( source_frame[ source_channel_dim["v2"][1] : source_channel_dim["v2"][3], source_channel_dim["v2"][0] : source_channel_dim["v2"][2], ], dsize=(uv_resize_width, uv_resize_height), interpolation=interpolation, ) def yuv_region_2_yuv(frame, region): try: # TODO: does this copy the numpy array? yuv_cropped_frame = yuv_crop_and_resize(frame, region) return yuv_to_3_channel_yuv(yuv_cropped_frame) except: print(f"frame.shape: {frame.shape}") print(f"region: {region}") raise def yuv_region_2_rgb(frame, region): try: # TODO: does this copy the numpy array? yuv_cropped_frame = yuv_crop_and_resize(frame, region) return cv2.cvtColor(yuv_cropped_frame, cv2.COLOR_YUV2RGB_I420) except: print(f"frame.shape: {frame.shape}") print(f"region: {region}") raise def yuv_region_2_bgr(frame, region): try: yuv_cropped_frame = yuv_crop_and_resize(frame, region) return cv2.cvtColor(yuv_cropped_frame, cv2.COLOR_YUV2BGR_I420) except: print(f"frame.shape: {frame.shape}") print(f"region: {region}") raise def intersection(box_a, box_b) -> Optional[list[int]]: """Return intersection box or None if boxes do not intersect.""" if ( box_a[2] < box_b[0] or box_a[0] > box_b[2] or box_a[1] > box_b[3] or box_a[3] < box_b[1] ): return None return ( max(box_a[0], box_b[0]), max(box_a[1], box_b[1]), min(box_a[2], box_b[2]), min(box_a[3], box_b[3]), ) def area(box): return (box[2] - box[0] + 1) * (box[3] - box[1] + 1) def intersection_over_union(box_a, box_b): # determine the (x, y)-coordinates of the intersection rectangle intersect = intersection(box_a, box_b) if intersect is None: return 0.0 # compute the area of intersection rectangle inter_area = max(0, intersect[2] - intersect[0] + 1) * max( 0, intersect[3] - intersect[1] + 1 ) if inter_area == 0: return 0.0 # compute the area of both the prediction and ground-truth # rectangles box_a_area = (box_a[2] - box_a[0] + 1) * (box_a[3] - box_a[1] + 1) box_b_area = (box_b[2] - box_b[0] + 1) * (box_b[3] - box_b[1] + 1) # compute the intersection over union by taking the intersection # area and dividing it by the sum of prediction + ground-truth # areas - the intersection area iou = inter_area / float(box_a_area + box_b_area - inter_area) # return the intersection over union value return iou def clipped(obj, frame_shape): # if the object is within 5 pixels of the region border, and the region is not on the edge # consider the object to be clipped box = obj[2] region = obj[5] if ( (region[0] > 5 and box[0] - region[0] <= 5) or (region[1] > 5 and box[1] - region[1] <= 5) or (frame_shape[1] - region[2] > 5 and region[2] - box[2] <= 5) or (frame_shape[0] - region[3] > 5 and region[3] - box[3] <= 5) ): return True else: return False class FrameManager(ABC): @abstractmethod def create(self, name: str, size: int) -> AnyStr: pass @abstractmethod def write(self, name: str) -> memoryview: pass @abstractmethod def get(self, name: str, timeout_ms: int = 0): pass @abstractmethod def close(self, name: str): pass @abstractmethod def delete(self, name: str): pass @abstractmethod def cleanup(self): pass class UntrackedSharedMemory(_mpshm.SharedMemory): # https://github.com/python/cpython/issues/82300#issuecomment-2169035092 __lock = threading.Lock() def __init__( self, name: Optional[str] = None, create: bool = False, size: int = 0, *, track: bool = False, ) -> None: self._track = track # if tracking, normal init will suffice if track: return super().__init__(name=name, create=create, size=size) # lock so that other threads don't attempt to use the # register function during this time with self.__lock: # temporarily disable registration during initialization orig_register = _mprt.register _mprt.register = self.__tmp_register # initialize; ensure original register function is # re-instated try: super().__init__(name=name, create=create, size=size) finally: _mprt.register = orig_register @staticmethod def __tmp_register(*args, **kwargs) -> None: return def unlink(self) -> None: if _mpshm._USE_POSIX and self._name: _mpshm._posixshmem.shm_unlink(self._name) if self._track: _mprt.unregister(self._name, "shared_memory") class SharedMemoryFrameManager(FrameManager): def __init__(self): self.shm_store: dict[str, UntrackedSharedMemory] = {} def create(self, name: str, size) -> AnyStr: shm = UntrackedSharedMemory( name=name, create=True, size=size, ) self.shm_store[name] = shm return shm.buf def write(self, name: str) -> memoryview: try: if name in self.shm_store: shm = self.shm_store[name] else: shm = UntrackedSharedMemory(name=name) self.shm_store[name] = shm return shm.buf except FileNotFoundError: logger.info(f"the file {name} not found") return None def get(self, name: str, shape) -> Optional[np.ndarray]: try: if name in self.shm_store: shm = self.shm_store[name] else: shm = UntrackedSharedMemory(name=name) self.shm_store[name] = shm return np.ndarray(shape, dtype=np.uint8, buffer=shm.buf) except FileNotFoundError: return None def close(self, name: str): if name in self.shm_store: self.shm_store[name].close() del self.shm_store[name] def delete(self, name: str): if name in self.shm_store: self.shm_store[name].close() try: self.shm_store[name].unlink() except FileNotFoundError: pass del self.shm_store[name] else: try: shm = UntrackedSharedMemory(name=name) shm.close() shm.unlink() except FileNotFoundError: pass def cleanup(self) -> None: for shm in self.shm_store.values(): shm.close() try: shm.unlink() except FileNotFoundError: pass def create_mask(frame_shape, mask): mask_img = np.zeros(frame_shape, np.uint8) mask_img[:] = 255 if isinstance(mask, list): for m in mask: add_mask(m, mask_img) elif isinstance(mask, str): add_mask(mask, mask_img) return mask_img def add_mask(mask: str, mask_img: np.ndarray): points = mask.split(",") # masks and zones are saved as relative coordinates # we know if any points are > 1 then it is using the # old native resolution coordinates if any(x > "1.0" for x in points): raise Exception("add mask expects relative coordinates only") contour = np.array( [ [ int(float(points[i]) * mask_img.shape[1]), int(float(points[i + 1]) * mask_img.shape[0]), ] for i in range(0, len(points), 2) ] ) cv2.fillPoly(mask_img, pts=[contour], color=(0)) def get_image_from_recording( ffmpeg, # Ffmpeg Config file_path: str, relative_frame_time: float, codec: str, height: Optional[int] = None, ) -> Optional[any]: """retrieve a frame from given time in recording file.""" ffmpeg_cmd = [ ffmpeg.ffmpeg_path, "-hide_banner", "-loglevel", "warning", "-ss", f"00:00:{relative_frame_time}", "-i", file_path, "-frames:v", "1", "-c:v", codec, "-f", "image2pipe", "-", ] if height is not None: ffmpeg_cmd.insert(-3, "-vf") ffmpeg_cmd.insert(-3, f"scale=-1:{height}") process = sp.run( ffmpeg_cmd, capture_output=True, ) if process.returncode == 0: return process.stdout else: return None