Engineering and Developers Blog
What's happening with engineering and developers at YouTube
YouTube now defaults to HTML5 <video>
Tuesday, January 27, 2015
Four years ago, we wrote about YouTube’s
early support for the HTML5 <video> tag
and how it performed compared to Flash. At the time, there were limitations that held it back from becoming our preferred platform for video delivery. Most critically, HTML5 lacked support for Adaptive Bitrate (ABR) that lets us show you more videos with less buffering.
Over the last four years, we’ve worked with browser vendors and the broader community to close those gaps, and now, YouTube uses HTML5 <video> by default in Chrome, IE 11, Safari 8 and in beta versions of Firefox.
The benefits of HTML5 extend beyond web browsers, and it's now also used in smart TVs and other streaming devices. Here are a few key technologies that have enabled this critical step forward:
MediaSource Extensions
Adaptive Bitrate (ABR) streaming is critical for providing a quality video experience for viewers - allowing us to quickly and seamlessly adjust resolution and bitrate in the face of changing network conditions. ABR has reduced buffering by more than 50 percent globally and as much as 80 percent on heavily-congested networks. MediaSource Extensions also enable live streaming in game consoles like Xbox and PS4, on devices like Chromecast and in web browsers.
VP9 video codec
HTML5 lets you take advantage of the open VP9 codec, which gives you higher quality video resolution with an average bandwidth reduction of 35 percent. These smaller files allow more people to access 4K and HD at 60FPS -- and videos start 15-80 percent faster. We've already served hundreds of billions of VP9 videos, and you can look for more about VP9 in a future post.
Encrypted Media Extensions
and Common Encryption
In the past, the choice of delivery platform (Flash, Silverlight, etc) and content protection technology (Access, PlayReady) were tightly linked, as content protection was deeply integrated into the delivery platform and even the file format. Encrypted Media Extensions separate the work of content protection from delivery, enabling content providers like YouTube to use a single HTML5 video player across a wide range of platforms. Combined with Common Encryption, we can support multiple content protection technologies on different platforms with a single set of assets, making YouTube play faster and smoother.
WebRTC
YouTube enables everyone to share their videos with the world, whether uploading pre-recorded videos or
broadcasting live
. WebRTC allows us to build on the same technology that enables
plugin-free Google Hangouts
to provide broadcasting tools from within the browser.
Fullscreen
Using the new fullscreen APIs in HTML5, YouTube is able to provide an immersive fullscreen viewing experience (perfect for those
4K videos
), all with standard HTML UI.
Moving to <iframe> embeds
Given the progress we've made with HTML5 <video>, we’re now defaulting to the HTML5 player on the web. We're also deprecating the "old style" of Flash <object> embeds and our Flash API. We encourage all embedders to use the
<iframe> API
, which can intelligently use whichever technology the client supports.
These advancements have benefitted not just YouTube’s community, but the entire industry. Other content providers like Netflix and Vimeo, as well as companies like Microsoft and Apple have embraced HTML5 and been key contributors to its success. By providing an open standard platform, HTML5 has also enabled new classes of devices like Chromebooks and Chromecast. You can support HTML5 by using the
<iframe> API
everywhere you embed YouTube videos on the web.
Richard Leider, Engineering Manager, recently watched,
“Ex Hex - Waterfall.”
Accelerating YouTube Playback
Wednesday, December 1, 2010
The YouTube Players team’s goal is to make sure that watching videos online is as enjoyable an experience as possible. As a viewer, maximizing enjoyment usually involves some tradeoffs: sure, you can watch a 1080p high definition version of the newest movie trailer, but that might mean choppy playback as your computer strains to keep up with the more demanding processing required. We wanted to let you know about some changes we’re making to help minimize those tradeoffs, so that you can watch smoother, higher-quality video from your existing devices.
Adobe’s
recently announced
Flash Player 10.2 release supports a new, more efficient video display mechanism known as the Stage Video API. The full details of how and why Stage Video speeds up video display can be found in Adobe’s
technical documentation
. The Players Team will be gradually experimenting with Stage Video playbacks on YouTube.com in the coming weeks, but as a developer using the ActionScript 3 Player APIs, you can enable Stage Video playback for your embedded video right away; simply add the
wmode=direct
parameter to the player URL that you’re using to reference the YouTube video. You’ll need the
Flash Player 10.2 installed
to take advantage of the accelerated playback, but playbacks will work for users with older Flash Player versions as well.
The Players Team knows that Stage Video for Flash playbacks is just one path to take toward improving video playback performance across the web. For example, YouTube playbacks using the
new <iframe> embeds
will automatically benefit as
more
and
more
(and
more
) modern browsers add hardware acceleration for the native HTML5 <video> element.
Cheers,
-Jeff Posnick, on behalf of the YouTube Players team
(Updated 2011-02-09 to reflect the production release of Flash Player 10.2.)
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