Initial commit

.gitignore

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+*.mp4
+*.png
+*.mp3
+*.gif
+converted-ss/
+tmp-ss/
+node_modules/

convertToAscii.js

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+module.exports = convertToAscii = async (file, dotSize = 24, verticalSpacinModifier = 4, output = __dirname + '/tmp.img.png') => {
+    const hobbitImageFile = file;
+    const density = 'Ñ@#W$9876543210?!abc;:+=-,._ ';
+
+    const { createCanvas } = require('canvas')
+    const ImageDataURI = require('image-data-uri');
+    var sizeOf = require('image-size');
+    var dimensions = sizeOf(hobbitImageFile);
+
+    const hobbit = {
+        width: dimensions.width,
+        height: dimensions.height,
+        pixels: [],
+    }
+
+    function clamp(input, min, max) {
+        return input < min ? min : input > max ? max : input;
+    }
+
+    function map(current, in_min, in_max, out_min, out_max) {
+        const mapped = ((current - in_min) * (out_max - out_min)) / (in_max - in_min) + out_min;
+        return clamp(mapped, out_min, out_max);
+    }
+
+    await new Promise((res, rej) => {
+        var PNG = require('png-js');
+        PNG.decode(hobbitImageFile, function(pixels) {
+
+            const canvas = createCanvas(hobbit.width * dotSize, hobbit.height * dotSize);
+            const ctx = canvas.getContext('2d')
+
+            hobbit.pixels = pixels;
+
+            ctx.fillStyle = 'black';
+            ctx.fillRect(0, 0, hobbit.width * dotSize, hobbit.height * dotSize);
+
+            for(let x = 0; x < hobbit.width; x++) {
+                for(let y = 0; y < hobbit.height; y++) {
+                    const pixelPosition = (x + y*hobbit.width)*4;
+                    const r = hobbit.pixels[pixelPosition + 0];
+                    const g = hobbit.pixels[pixelPosition + 1];
+                    const b = hobbit.pixels[pixelPosition + 2];
+                    const a = hobbit.pixels[pixelPosition + 3];
+                    
+                    const avg = Math.floor((r+g+b)/ 3);
+
+                    const gray = map(255 - avg, 0, 255, 0, density.length);
+                    
+                    ctx.font = (dotSize + verticalSpacinModifier) + "px Courier";
+                    ctx.textAlign = 'center';
+                    ctx.textBaseline = 'middle';
+                    ctx.fillStyle = `white`;
+                    ctx.fillText(density.charAt(gray), x*dotSize + dotSize/2, y*dotSize + dotSize/2);
+                }
+            }
+            
+            ImageDataURI.outputFile(canvas.toDataURL(), output);
+            console.log(output, 'converted');
+            res(1);
+        });
+
+    });
+}

index.js

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+/*
+
+PREREQUISITES:
+    - ffmpeg installed and added to the PATH
+
+COMMANDS TO PREPARE VIDEO FOR CONVERSION:
+    - scale video and lower fps
+        ffmpeg.exe -i .\original-video.mp4 -vf "scale=120:-2, fps=30" scaled-video.mp4
+
+COMMANDS TO BUILD VIDEO AFTER CONVERSION:
+    - extract audio from video
+        ffmpeg -i .\original-video.mp4 extracted-audio.mp3
+
+    - combine video with audio
+        ffmpeg -i .\converted-video.mp4 -i extracted-audio.mp3 -c:v copy -c:a aac finished-video.mp4
+
+    - convert video to gif (no audio)
+        ffmpeg -i .\converted-video.mp4 -f gif .\converted-video.gif
+
+*/
+
+const extractFrames = require('ffmpeg-extract-frames')
+const convertToAscii = require('./convertToAscii');
+const fs = require('fs');
+const { exec } = require("child_process");
+const fsExtra = require('fs-extra')
+
+fsExtra.emptyDirSync(__dirname + '/converted-ss')
+fsExtra.emptyDirSync(__dirname + '/tmp-ss')
+
+if (!fs.existsSync(__dirname + '/converted-ss')) {
+    fs.mkdirSync(__dirname + '/converted-ss');
+}
+if (!fs.existsSync(__dirname + '/tmp-ss')) {
+    fs.mkdirSync(__dirname + '/tmp-ss');
+}
+
+const PATH_TO_VIDEO_TO_BE_CONVERTED = __dirname + '/sponge-bob-mrs-puff-scaled.mp4';
+
+async function run() {
+    await extractFrames({
+        input: PATH_TO_VIDEO_TO_BE_CONVERTED,
+        output: __dirname + '/tmp-ss/%d.png'
+    });
+
+    let files = fs.readdirSync(__dirname + '/tmp-ss');
+
+    files = files.filter(name => name.endsWith('.png'));
+
+    for (let file of files) {
+        await convertToAscii(__dirname + '/tmp-ss/' + file, 12, 0, __dirname + '/converted-ss/' + file);
+        fs.rmSync(__dirname + '/tmp-ss/' + file);
+    }
+
+    exec('ffmpeg -framerate 10 -i ./converted-ss/%d.png -c:v libx264 -r 30 -pix_fmt yuv420p output.mp4 -y', (error, stdout, stderr) => {
+        if (error) {
+            console.log(`error: ${error.message}`);
+            return;
+        }
+        if (stderr) {
+            console.log(`stderr: ${stderr}`);
+            return;
+        }
+        console.log(`stdout: ${stdout}`);
+    });
+
+    console.log('done');
+}
+
+run();

package.json

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+{
+  "name": "virtualcanvas",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "canvas": "^2.9.0",
+    "ffmpeg-extract-frames": "^2.0.2",
+    "fs-extra": "^10.0.0",
+    "image-data-uri": "^2.0.1",
+    "image-size": "^1.0.1",
+    "png-js": "^1.0.0"
+  }
+}