[PYTHON] Code snippets often used when processing videos with Google Colaboratory

Mount Google Drive

gdrive_path = "/content/gdrive" #Mounted path

from google.colab import drive
drive.mount(gdrive_path)

Iteration

Loop any range at any interval

for a in range(0, 1280, 10):
  print(a)

List image files under a specific directory

import glob
files = glob.glob("/content/gdrive/My Drive/ColabExp/*.png ") #Only files with the extension png
files.sort() #Sort the files found

Create a temporary directory and work

import tempfile
with tempfile.TemporaryDirectory() as tmpdir:
  #Write the file to tmpdir

Or

import tempfile
tmpdir = tempfile.TemporaryDirectory().name

Get the file name from the file path

import os
os.path.basename(files[i])

Display the progress of processing

from tqdm import tqdm
for i, file in enumerate(tqdm(src_files)):
  #processing

Image processing

Make a canvas with PIL

from PIL import Image
img = Image.new('RGB', (1280, 720), (255, 255, 255)) # 1280 x 720px

Draw a shape with PIL

from PIL import ImageDraw

draw = ImageDraw.Draw(img)

draw.rectangle(((x0, y0), (x1, y1)), fill=(255, 0, 0)) #Rectangle

Save images with OpenCV

import cv2
cv2.imwrite(save_path, image)

Save images with PIL / Pillow

img.save(path)

Make an array of images into a video

!ffmpeg -framerate 30 -i "$dst_img_dir/%06d.png " -vcodec h264 -pix_fmt yuv420p -vf "scale=trunc(iw/2)*2:trunc(ih/2)*2" "$dst_mov_dir/out.mp4"

CSV

Read CSV from file (DataFrame)

df = pd.read_csv(filepath)

Embed and read CSV (DataFrame)

CSV_DATA = StringIO("""x,y
10.0, 20.0
15.0, 30.0
20.0, 45.0
35.0, 80.0
""")

df = pd.read_csv(CSV_DATA, sep=",")

Save the contents of the DataFrame to a CSV file

df.to_csv("out.csv")

Times of Day

Timestamp of the current time in seconds

from datetime import datetime
now_ts = int(datetime.now().timestamp())