Video edition with CSS & JavaScript

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Video Editing with CSS and JavaScript Eva Ferreira – Smashing TV

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Hi! I’m Eva

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Hi! I’m Eva • Front-end Developer by day • Protector of useless creativity at night • Mozilla Tech Speaker • Organizer of CSSConf Argentina @evaferreira92

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Hi! I’m Maria Evangelina Ferreira Kuzminski • Front-end Developer by day • Protector of useless creativity at night • Mozilla Tech Speaker • Organizer of CSSConf Argentina @evaferreira92

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@evaferreira92

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Rotoscoping

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Take on me – A-ha 1985

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21st Century Breakdown – Green Day 2009

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Sheezus – Lily Allen 2014

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Hard Times – Paramore 2017

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Caught in the Middle – Paramore 2018

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Rotoscoping 1. Record a video 2. Draw on top 15 to 25 images per second @evaferreira92

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Animation on the web.

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Traditional Web • Stop Motion  Rachel Nabors • Motion Graphics  Chris Gannon @evaferreira92

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Can we go further?

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Can we make rotoscoping on the web? No.

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Interactive media Take Rotoscoping idea into the web.

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Rotoscoping = Animation above video

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With CSS or with JavaScript

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The CSS Version 1. “Normal” video 2. “Animation” video @evaferreira92

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https://vimeo.com/58933055

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https://vimeo.com/49581518

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Mix them

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Blend them

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Blend Modes

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mix-blend-mode: luminosity;

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Make it interactive

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Add clip-path and filters

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Interactive wow-ness Ok-ish browser support

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https://caniuse.com/#feat=css-mixblendmode

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Let’s try with JavaScript now

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Chroma Key

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Chroma Key • Green or blue background • Really good light @evaferreira92

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No natural light

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Chroma key with user’s camera

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Chroma key in the browser 1. Take the user’s camera input 1. Put it in a video tag 2. Copy that into a canvas 3. Process canvas 1. Remove green or blue 2. Show background image or video @evaferreira92

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1. Take the user’s camera input

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Take video input @evaferreira92 navigator.mediaDevices.getUserMedia({video: true}) .then() .catch();

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Put it in a video tag @evaferreira92

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Put it in a video tag @evaferreira92 .then(function (stream) { video.srcObject = stream; }) .catch(function (error) { console.log("Error:", error); }); navigator.mediaDevices.getUserMedia({video: true})

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@evaferreira92

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2. Copy video into canvas

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Create canvas @evaferreira92 c1 = document.getElementById("canvas"); ctx1 = this.c1.getContext("2d");

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Create the draw function @evaferreira92 function draw () { ctx1.drawImage(video, 0, 0, this.width, this.height); }

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Update the canvas function time_callback () { if (video.paused || video.ended) { return; } draw(); // Update setTimeout(function () { this.time_callback(); }, 0); };

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@evaferreira92

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3. Process the canvas Remove green or blue background

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Pixel manipulation

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What is a pixel?

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@evaferreira92

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@evaferreira92 Pixel

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RGB Format

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@evaferreira92 = 227 45 145

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Alpha Channel @evaferreira92

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Ask for pixel information (RGBa) • The red value • The green value • The blue value • The Alpha value @evaferreira92

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Ask for pixel information (RGBa) • The red value • The green value • The blue value • The Alpha value  It will always return 255  … Unless we change it @evaferreira92

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Making Chroma happen. 1. Find the green pixels 2. Remove them 1. Alpha value of 0 @evaferreira92

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Find the green pixels

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Ask for pixel data @evaferreira92 function findGreen () { // Ask for color data let frame = this.ctx1.getImageData(0, 0, this.width, this.height); ... }

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@evaferreira92

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@evaferreira92 1,228,800 640 x 480 x 4 =

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@evaferreira92

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@evaferreira92

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@evaferreira92

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@evaferreira92 Alpha value

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@evaferreira92 R G B A R G B A R G B A R G B A R G B A

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@evaferreira92 } rgba(55, 74, 86, 1)

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Find the green pixels @evaferreira92 function findGreen () { ... let allData = frame.data.length / 4; for (let i = 0; i < allData; i++) { ... } }

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@evaferreira92 // Save all the data of 1.2m pixels let allData = frame.data.length / 4; // Go through it and identify it for (let i = 0; i < allData; i++) { let r = frame.data[i * 4 + 0]; let g = frame.data[i * 4 + 1]; let b = frame.data[i * 4 + 2]; // Ask if the greatest value is green if (g > r && g > b) { // Remove opacity frame.data[i * 4 + 3] = 0; } }

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Return the updated data @evaferreira92 function findGreen () { let frame = this.ctx1.getImageData(0, 0, this.width, this.height); let l = frame.data.length / 4; for (let i = 0; i < l; i++) { ... frame.data[i * 4 + 3] = 0; } this.ctx1.putImageData(frame, 0, 0); return; }

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@evaferreira92

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Improve it 1. Better light 2. Remove only if the green is > 100 @evaferreira92 if (g > r && g > b) { if (g > 100 ) { frame.data[i * 4 + 3] = 0; } }

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@evaferreira92

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Live demo

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Invisibility Cloak

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@evaferreira92

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MOAR Pixel Manipulation

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@evaferreira92

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@evaferreira92

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Copy content into canvases @evaferreira92

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Copy content into canvases @evaferreira92 function findColor (color) { let frame1 = this.ctx1.getImageData(0, 0, this.width, this.height); let frame2 = this.ctx1.getImageData(0, 0, this.width, this.height); let frame3 = this.ctx1.getImageData(0, 0, this.width, this.height); ... this.ctx1.putImageData(frame1, 0, 0); this.ctx2.putImageData(frame2, 0, 0); this.ctx3.putImageData(frame3, 0, 0); return; }

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@evaferreira92

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Turn what’s left into pink @evaferreira92 for (let i = 0; i < l; i++) { ... if (g > r && g > b) { frame1.data[i * 4 + 3] = 0; frame2.data[i * 4 + 3] = 0; frame3.data[i * 4 + 3] = 0; } else { frame2.data[i * 4 + 0] = 200; frame3.data[i * 4 + 0] = 200; frame2.data[i * 4 + 2] = 200; frame3.data[i * 4 + 2] = 200; } } 0 = Red 1 = Green 2 = Blue 3 = Alpha

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@evaferreira92

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@evaferreira92

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@evaferreira92

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@evaferreira92

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Endless possibilities. Runs in your browser with JavaScript. No other software required.

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Protect the useless. @evaferreira92

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Thank you :) • Demos & links: https://github.com/evaferreira/smashing-tv • Green screen online: https://chroma-code.netlify.com/ • @evaferreira92