audio, video and canvas in HTML5 - standards>next Manchester 29.09.2010
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Part II of the standards-next.org workshop on HTML5 with Bruce Lawson, concentrating on audio, video and canvas (plus hints of additional HTML5 API niceness)
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audio, video and canvas in HTML5 - standards>next Manchester 29.09.2010
- 1. audio, video and canvas in HTML5 NATIVE MULTIMEDIA SUPPORT Patrick H. Lauke / standards>next / Manchester / 29 September 2010
- 3. “...extending the language to better support Web applications [...] This puts HTML in direct competition with other technologies[...] , in particular Flash and Silverlight.” Ian Hickson, Editor of HTML5 http://lists.w3.org/Archives/Public/public-html/2009Jan/0215.html
- 4. making your site Fonzie compliant...
- 5. <video>
- 6. Adobe Flash currently most common video delivery mechanism
- 7. <object width="425" height="344"> <param name="movie" value="http://www.youtube.com/v/9sEI1AUFJKw&hl=en &fs=1&"></param> <param name="allowFullScreen" value="true"></param> <param name="allowscriptaccess" value="always"></param> <embed src="http://www.youtube.com/v/9sEI1AUFJKw&hl=en&f s=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed> </object>
- 9. <video src="video.webm" controls Autoplay Loop preload="none" poster="poster.jpg" width="320" height="240"> <a href="video.webm">Download movie</a> </video>
- 10. video as native object ● “plays nice” with rest of the page ● keyboard accessibility built-in
- 11. video formats the big debate
- 12. MP4 / H.264 ubiquitous, patent encumbered, licensing/royalties
- 13. Ogg Theora “free and open”, no licensing/royalties not many tools for it, not web optimised
- 15. WebM open and royalty-free, web optimised
- 18. providing multiple sources <video controls autoplay poster="…" width="…" height="…"> <source src="movie.webm" type="video/webm" /> <source src="movie.ogv" type="video/ogg" /> <source src="movie.mp4" type="video/mp4" /> <!-- fallback content --> </video>
- 19. still include fallback for old browsers http://camendesign.com/code/video_for_everybody
- 20. <video controls autoplay poster="…" width="…" height="…"> <source src="movie.webm" type="video/webm" /> <source src="movie.ogv" type="video/ogg" /> <source src="movie.mp4" type="video/mp4" /> <object width="…" height="…" type="application/x- shockwave-flash" data="player.swf"> <param name="movie" value="player.swf" /> <param name="flashvars" value=" … file=movie.mp4" /> <!-- fallback content --> </object> </video>
- 21. powerful (simple) API to script your own controls
- 24. controlling a <video> element var v = document.getElementById('player'); v.play(); v.pause(); v.volume = … ; v.currentTime = … ; …
- 25. events fired by <video> element var v = document.getElementById('player'); v.addEventListener('loadeddata', function() { … }, true) v.addEventListener('play', function() { … }, true) v.addEventListener('pause', function() { … }, true) v.addEventListener('timeupdate', function() { … }, true) v.addEventListener('ended', function() { … }, true) …
- 26. <audio>
- 27. audio exactly the same as video <audio src=”music.mp3” controls autoplay></audio> [...] <audio controls autoplay> <source src="music.mp3" type="audio/mpeg" /> <source src="music.oga" type="audio/ogg" /> <!-- fallback content --> </audio> same format debacle: MP3 vs Ogg Vorbis (vs WAV)
- 28. <canvas>
- 29. canvas = “scriptable images” <canvas width="…" height="…"></canvas>
- 30. canvas has standard API methods for drawing ctx = canvas.getContext("2d"); ctx.fillRect(x, y, width, height); ctx.beginPath(); ctx.moveTo(x, y); ctx.lineTo(x, y); ctx.bezierCurveTo(x1, y1, x2, y2, c1, c2);
- 31. canvas drawing ready-made images ctx = canvas.getContext("2d"); var logo = new Image(); logo.src = 'logo.png'; ctx.drawImage(logo,x1,y1,w1,h1,x2,y2,w2,h2); or call in an existing image already on the page
- 32. canvas access to image data array ctx = canvas.getContext("2d"); canvasData = ctx.getImageData(x,y,w,h); [R,G,B,A,R,G,B,A,R,G,B,A,R,G,B,A, … ]
- 33. canvas exporting image data as data:uri ctx = canvas.getContext("2d"); … canvas.toDataURL("image/png"); // returns "data:image/png;base64,…" canvas.toDataURL("image/jpg"); // returns "data:image/jpeg;base64,…" Note: do it on the canvas, not the context!
- 34. canvas also works with video ctx = canvas.getContext("2d"); v = document.getElementById('player'); ctx.drawImage(v,x1,y1,w1,h2,x2,y2,w2,h2); grab currently displayed frame (update as appropriate)
- 38. video, audio and canvas on any device without plugins (Java / Flash / Silverlight not ubiquitous)
- 41. HTML5 (and friends) has lots more APIs for developers (for powerful client-side apps)
- 43. geolocation navigator.geolocation.getCurrentPosition(success, error); navigator.geolocation.watchCurrentPosition(success, error); function success(position) { /* where's Wally? */ var lat = position.coords.latitude; var long = position.coords.longitude; ... }
- 44. offline detection... window.addEventListener('online', function(){ … }, true); window.addEventListener('offline', function(){ … }, true); and application cache <html manifest=”blah.manifest”> CACHE MANIFEST # send this with correct text/cache-manifest MIME images/sprites.png scripts/common.js scripts/jquery.js styles/global.css data.xml and many more... (even beyond HTML5)
- 45. is it all safe to use, right now?
- 46. don't do browser sniffing http://www.flickr.com/photos/timdorr/2096272747/
- 48. feature-detection progressive enhancement, graceful degradation – or use shims http://diveintohtml5.org/everything.html
- 49. feature-detection for audio/video if (!!document.createElement('video').canPlayType;) { … } if (!!document.createElement('audio').canPlayType;) { … }
- 50. feature-detection for audio/video codecs var v = document.createElement('video'); if (!!(v.canPlayType)&& ((v.canPlayType('video/webm;codecs="vp8,vorbis"') == 'probably') || (v.canPlayType('video/webm;codecs="vp8, vorbis"') == 'maybe'))) { … }
- 51. ready-made HTML5 audio/video players (for the lazy)
- 52. sublimevideo.net
- 53. videojs.com
- 56. not a question of HTML5 replacing Flash...
- 57. giving developers a choice!