{"database": "24ways", "rows": [[80, "HTML5 Video Bumpers", "Video is a bigger part of the web experience than ever before. With native browser support for HTML5 video elements freeing us from the tyranny of plugins, and the availability of faster internet connections to the workplace, home and mobile networks, it\u2019s now pretty straightforward to publish video in a way that can be consumed in all sorts of ways on all sorts of different web devices.\n\nI recently worked on a project where the client had shot some dedicated video shorts to publish on their site. They also had some five-second motion graphics produced to top and tail the videos with context and branding. This pretty common requirement is a great idea on the web, where a user might land at your video having followed a link and be viewing a page without much context.\n\nKnown as bumpers, these short introduction clips help brand a video and make it look a lot more professional.\n\n\n\nAdding bumpers to a video\n\nThe simplest way to add bumpers to a video would be to edit them on to the start and end of the video file itself. Cooking the bumpers into the video file is easy, but should you ever want to update them it can become a real headache. If the branding needs updating, for example, you\u2019d need to re-edit and re-encode all your videos. Not a fun task.\n\nWhat if the bumpers could be added dynamically? That would enable you to use the same bumper for multiple videos (decreasing download time for users who might watch more than one) and to update the bumpers whenever you wanted. You could change them seasonally, update them for special promotions, run different advertising slots, perform multivariate testing, or even target different bumpers to different users.\n\nThe trade-off, of course, is that if you dynamically add your bumpers, there\u2019s a chance that a user in a given circumstance might not see the bumper. For example, if the main video feature was uploaded to YouTube, you\u2019d have no way to control the playback. As always, you need to weigh up the pros and cons and make your choice.\n\nHTML5 bumpers\n\nIf you wanted to dynamically add bumpers to your HTML5 video, how would you go about it? That was the question I found myself needing to answer for this particular client project.\n\nMy initial thought was to treat it just like an image slideshow. If I were building a slideshow that moved between images, I\u2019d use CSS absolute positioning with z-index to stack the images up on top of each other in a pile, with the first image on top. To transition to the second image, I\u2019d use JavaScript to fade the top image out, revealing the second image beneath it.\n\n\n\nNow that video is just a native object in the DOM, just like an image, why not do the same? Stack the videos up with the opening bumper on top, listen for the video\u2019s onended event, and fade it out to reveal the main feature behind. Good idea, right?\n\nWrong\n\nRemember that this is the web. It\u2019s never going to be that easy. The problem here is that many non-desktop devices use native, dedicated video players. Think about watching a video on a mobile phone \u2013 when you play the video, the phone often goes full-screen in its native player, leaving the web page behind. There\u2019s no opportunity to fade or switch z-index, as the video isn\u2019t being viewed in the page. Your page is left powerless. Powerless!\n\n\n\nSo what can we do? What can we control?\n\nThose of us with particularly long memories might recall a time before CSS, when we\u2019d have to use JavaScript to perform image rollovers. As CSS background images weren\u2019t a practical reality, we would use lots of <img> elements, and perform a rollover by modifying the src attribute of the image. \n\nTurns out, this old trick of modifying the source can help us out with video, too. In most cases, modifying the src attribute of a <video> element, or perhaps more likely the src attribute of a source element, will swap from one video to another.\n\nSwappin\u2019 it\n\nLet\u2019s take a deliberately simple example of a super-basic video tag:\n\n<video src=\"mycat.webm\" controls>no fallback coz i is lame, innit.</video>\n\nWe could very simply write a script to find all video tags and give them a new src to show our bumper.\n\n<script>\n\tvar videos, i, l;\n\tvideos = document.getElementsByTagName('video');\n\tfor(i=0, l=videos.length; i<l; i++) {\n\t\tvideos[i].setAttribute('src', 'bumper-in.webm');\n\t}\n</script>\n\nView the example in a browser with WebM support. You\u2019ll see that the video is swapped out for the opening bumper. Great!\n\nBeefing it up\n\nOf course, we can\u2019t just publish video in one format. In practical use, you need a <video> element with multiple <source> elements containing your different source formats.\n\n<video controls>\n    <source src=\"mycat.mp4\" type=\"video/mp4\" />\n    <source src=\"mycat.webm\" type=\"video/webm\" />\n    <source src=\"mycat.ogv\" type=\"video/ogg\" />\n</video>\n\nThis time, our script needs to loop through the sources, not the videos. We\u2019ll use a regular expression replacement to swap out the file name while maintaining the correct file extension.\n\n<script>\n    var sources, i, l, orig;\n    sources = document.getElementsByTagName('source');\n    for(i=0, l=sources.length; i<l; i++) {\n        orig = sources[i].getAttribute('src');\n        sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));\n        // reload the video\n        sources[i].parentNode.load();\n    }\n</script>\n\nThe difference this time is that when changing the src of a <source> we need to call the .load() method on the video to get it to acknowledge the change.\n\nSee the code in action, this time in a wider range of browsers.\n\nBut, my video!\n\nI guess we should get the original video playing again. Keeping the same markup, we need to modify the script to do two things:\n\n\n\tStore the original src in a data- attribute so we can access it later\n\tAdd an event listener so we can detect the end of the bumper playing, and load the original video back in\n\n\nAs we need to loop through the videos this time to add the event listener, I\u2019ve moved the .load() call into that loop. It\u2019s a bit more efficient to call it only once after modifying all the video\u2019s sources.\n\n<script>\nvar videos, sources, i, l, orig;\nsources = document.getElementsByTagName('source');\nfor(i=0, l=sources.length; i<l; i++) {\n    orig = sources[i].getAttribute('src');\n    sources[i].setAttribute('data-orig', orig);\n    sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));\n}\nvideos = document.getElementsByTagName('video');\nfor(i=0, l=videos.length; i<l; i++) {\n    videos[i].load();\n    videos[i].addEventListener('ended', function(){\n        sources = this.getElementsByTagName('source');\n        for(i=0, l=sources.length; i<l; i++) {\n            orig = sources[i].getAttribute('data-orig');\n            if (orig) {\n                sources[i].setAttribute('src', orig);\n            }\n            sources[i].setAttribute('data-orig','');\n        }\n        this.load();\n        this.play();\n    });\n}\n</script>\n\nAgain, view the example to see the bumper play, followed by our spectacular main feature. (That\u2019s my cat, Widget. His interests include sleeping and internet marketing.)\n\nTidying things up\n\nThe final thing to do is add our closing bumper after the main video has played. This involves the following changes:\n\n\n\tWe need to keep track of whether the src has been changed, so we only play the video if it\u2019s changed. I\u2019ve added the modified variable to track this, and it stops us getting into a situation where the video just loops forever.\n\tAdd an else to the event listener, for when the orig is false (so the main feature has been playing) to load in the end bumper. We also check that we\u2019re not already playing the end bumper. Because looping.\n\n\n<script>\nvar videos, sources, i, l, orig, current, modified;\nsources = document.getElementsByTagName('source');\nfor(i=0, l=sources.length; i<l; i++) {\n   orig = sources[i].getAttribute('src');\n   sources[i].setAttribute('data-orig', orig);\n   sources[i].setAttribute('src', orig.replace(/(w+).(w+)/, 'bumper-in.$2'));\n}\nvideos = document.getElementsByTagName('video');\nfor(i=0, l=videos.length; i<l; i++) {\n   videos[i].load();\n   modified = false;\n   videos[i].addEventListener('ended', function(){\n      sources = this.getElementsByTagName('source');\n      for(i=0, l=sources.length; i<l; i++) {\n         orig = sources[i].getAttribute('data-orig');\n         if (orig) {\n            sources[i].setAttribute('src', orig);\n            modified = true;\n         }else{\n            current = sources[i].getAttribute('src');\n            if (current.indexOf('bumper-out')==-1) {\n               sources[i].setAttribute('src', current.replace(/([w]+).(w+)/, 'bumper-out.$2'));\n               modified = true;\n            }else{\n               this.pause();\n               modified = false;\n            }\n         }\n         sources[i].setAttribute('data-orig','');\n      }\n      if (modified) {\n         this.load();\n         this.play();\n      }\n   });\n}\n</script>\n\nYo ho ho, that\u2019s a lot of JavaScript. See it in action \u2013 you should get a bumper, the cat video, and an end bumper.\n\nOf course, this code works fine for demonstrating the principle, but it\u2019s very procedural. Nothing wrong with that, but to do something similar in production, you\u2019d probably want to make the code more modular to ease maintainability. Besides, you may want to use a framework, rather than basic JavaScript. \n\nThe end credits\n\nOne really important principle here is that of progressive enhancement. If the browser doesn\u2019t support JavaScript, the user won\u2019t see your bumper, but they will get the main video. If the browser supports JavaScript but doesn\u2019t allow you to modify the src (as was the case with older versions of iOS), the user won\u2019t see your bumper, but they will get the main video.\n\nIf a search engine or social media bot grabs your page and looks for content, they won\u2019t see your bumper, but they will get the main video \u2013 which is absolutely what you want.\n\nThis means that if the bumper is absolutely crucial, you may still need to cook it into the video. However, for many applications, running it dynamically can work quite well.\n\nAs always, it comes down to three things:\n\n\n\tMeasure your audience: know how people access your site\n\tTest the solution: make sure it works for your audience\n\tPlan for failure: it\u2019s the web and that\u2019s how things work \u2018round these parts\n\n\nBut most of all play around with it, have fun and build something awesome.", "2012", "Drew McLellan", "drewmclellan", "2012-12-01T00:00:00+00:00", "https://24ways.org/2012/html5-video-bumpers/", "code"]], "truncated": false, "columns": ["rowid", "title", "contents", "year", "author", "author_slug", "published", "url", "topic"], "query": {"sql": "select rowid, * from articles where \"author\" = :p0 and \"year\" = :p1 order by rowid limit 101", "params": {"p0": "Drew McLellan", "p1": "2012"}}, "query_ms": 1.6918182373046875}