Created
March 9, 2013 22:39
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multiply video via canvas
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| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>video - wall</title> | |
| <style> | |
| body { | |
| padding: 0; | |
| margin: 0; | |
| } | |
| #video { | |
| display: none; | |
| } | |
| canvas { | |
| padding: 0; | |
| margin: 0 0 -5px 0; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <video id="video" width="1280px" height="720px" /> | |
| <script> | |
| // flags | |
| var done = false; | |
| var video = document.getElementById('video'); | |
| // create canvas contexts | |
| var ctxs = times(4, function(){ | |
| var el = document.createElement('canvas'); | |
| el.width = video.width; | |
| el.height = video.height; | |
| document.documentElement.appendChild(el); | |
| return el.getContext('2d'); | |
| }); | |
| // buffer | |
| video.addEventListener('canplaythrough', onstart, true); | |
| // stop | |
| video.addEventListener('ended', onend, true); | |
| // load | |
| video.preload = 'auto'; | |
| video.src = '/earth.mp4'; | |
| // draw when buffered | |
| function onstart(){ | |
| video.play(); | |
| draw(video); | |
| } | |
| // animation frames | |
| function draw(what){ | |
| if (done) return; | |
| var pending = ctxs.length; | |
| requestAnimationFrame(function(){ | |
| ctxs.forEach(function(ctx, idx){ | |
| ctx.drawImage(what, 0, 0); | |
| --pending || draw(what); | |
| }); | |
| }); | |
| } | |
| // sets the "done" flag | |
| function onend(){ | |
| done = true; | |
| } | |
| // calls `fn` `x` times | |
| function times(x, fn){ | |
| var ret = []; | |
| while (--x >= 0) ret.push(fn()); | |
| return ret; | |
| } | |
| </script> | |
| </body> | |
| </html> |
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