Numpy

Video Barcode

A video barcode shows the change in colour and tone over time. Time is represented on the horizontal axis, while the vertical remains the vertical direction in the image.

See http://moviebarcode.tumblr.com/ for examples from Hollywood movies, and here is an example from a sunset timelapse:

The code that created this:

from PIL import Image
import numpy as np

import av
import av.datasets


container = av.open(
    av.datasets.curated("pexels/time-lapse-video-of-sunset-by-the-sea-854400.mp4")
)
container.streams.video[0].thread_type = "AUTO"  # Go faster!

columns = []
for frame in container.decode(video=0):

    print(frame)
    array = frame.to_ndarray(format="rgb24")

    # Collapse down to a column.
    column = array.mean(axis=1)

    # Convert to bytes, as the `mean` turned our array into floats.
    column = column.clip(0, 255).astype("uint8")

    # Get us in the right shape for the `hstack` below.
    column = column.reshape(-1, 1, 3)

    columns.append(column)

# Close the file, free memory
container.close()

full_array = np.hstack(columns)
full_img = Image.fromarray(full_array, "RGB")
full_img = full_img.resize((800, 200))
full_img.save("barcode.jpg", quality=85)

Generating Video

import numpy as np

import av


duration = 4
fps = 24
total_frames = duration * fps

container = av.open("test.mp4", mode="w")

stream = container.add_stream("mpeg4", rate=fps)
stream.width = 480
stream.height = 320
stream.pix_fmt = "yuv420p"

for frame_i in range(total_frames):

    img = np.empty((480, 320, 3))
    img[:, :, 0] = 0.5 + 0.5 * np.sin(2 * np.pi * (0 / 3 + frame_i / total_frames))
    img[:, :, 1] = 0.5 + 0.5 * np.sin(2 * np.pi * (1 / 3 + frame_i / total_frames))
    img[:, :, 2] = 0.5 + 0.5 * np.sin(2 * np.pi * (2 / 3 + frame_i / total_frames))

    img = np.round(255 * img).astype(np.uint8)
    img = np.clip(img, 0, 255)

    frame = av.VideoFrame.from_ndarray(img, format="rgb24")
    for packet in stream.encode(frame):
        container.mux(packet)

# Flush stream
for packet in stream.encode():
    container.mux(packet)

# Close the file
container.close()