slack-end/scripts/remove_bg.ts

// convert video to frames
// remove bg from frames
// compile frames into video
// must have ffmpeg installed

import canvas from "canvas";
import { execSync } from "child_process";
const { createCanvas, loadImage } = canvas;
import fs, { existsSync, readdirSync } from "fs";
// rmrif frames and remake
execSync(`rm -rf assets/dice/frames`, { stdio: "inherit" });
execSync(`mkdir assets/dice/frames`, { stdio: "inherit" });
if (!process.env.VIDEO_FILE)
  process.env.VIDEO_FILE = `assets/dice/green_screen_dice.mp4`;
if (!process.env.OUT_FILE)
  process.env.OUT_FILE = `assets/dice/no_green_screen_dice.mp4`;
const removeGreenScreen = async (inputPath, outputPath) => {
  const image = await loadImage(inputPath);

  const canvas = createCanvas(image.width, image.height);
  const ctx = canvas.getContext("2d");

  ctx.drawImage(image, 0, 0, image.width, image.height);

  const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
  const data = imageData.data;

  for (let i = 0; i < data.length; i += 4) {
    const red = data[i];
    const green = data[i + 1];
    const blue = data[i + 2];

    if (green > 150 && red < 100 && blue < 100) {
      data[i + 3] = 0; // Set alpha to 0 (transparent)
    }
  }

  ctx.putImageData(imageData, 0, 0);

  const buffer = canvas.toBuffer("image/png");
  fs.writeFileSync(outputPath, buffer);

  console.log(`Green screen removed and saved to ${outputPath}`);
};
execSync(
  `ffmpeg -i ${process.env.VIDEO_FILE} assets/dice/frames/frame_%04d.png`,
  { stdio: "inherit" },
);
// Usage
let frames = readdirSync("assets/dice/frames");
(async () => {
  for (const frame of frames) {
    if (!existsSync(`assets/dice/frames/cleaned_${frame}`)) {
      await removeGreenScreen(
        `assets/dice/frames/${frame}`,
        `assets/dice/frames/cleaned_${frame}`,
      );
    } else {
      console.log(`Skipping ${frame}`);
    }
  }
  console.log(`Compiling frames into video`);
  execSync(
    `ffmpeg -framerate 30 -i assets/dice/frames/cleaned_frame_%04d.png -c:v libx264 -pix_fmt yuva420p ${process.env.OUT_FILE}`,
    { stdio: "inherit" },
  );
  console.log(`Done`);
})();