Inside YouTube's Master Plan to Kill Lag Dead
There is a moment between when you click on a
The Best Thing Since
One recent change, which you may have already noticed, is the way in which
Things have worked differently now ever since YouTube integrated a technique it calls Sliced Bread back in April of 2012. Now, when someone uploads a video, it still gets copied into different resolutions, but each copy is like a loaf of bread which has been sliced. So you've got your 360p loaf, your 720p loaf, your 1080p loaf, etc. This enables YouTube to serve up your video one slice at a time, and it can change the quality of the next slice of video dynamically, depending on what's happening with your internet connection.
For example, when you first click the video it might start you with a couple slices from the 480p loaf, just to get your video playing right away. Once YouTube sees that you've got a steady and fast internet connection, the next slices could come from the 1080p loaf, giving you a boost in video quality. Then, suddenly, your significant other starts download some four terabyte PDF file and you lose a bunch of bandwidth; the next few slices could come at 720p. Ideally, the transitions are seamless. You might notice variation in the
Sliced Bread has been a success, so far, reducing the rebuffering of videos by 40 percent, YouTube claims. But it's what's coming down the pipe that should really kick things into high gear.
Parallel Processing and Pre-Loading
Do Less. It's when you transition from one video to another that you start to see significant reductions. If you've already watched a video, and in doing so downloaded the video player and all of that other stuff, why download it all over again? That's how it works now, and it's a total waste of time, The YouTube of the very near future knows that. So, instead, when you click over to another video, it will download the page, and immediately request the video and begin streaming because the player is already loaded up. Now we're cooking with gas.
YouTube claims that people don't generally just watch one video and leave. They have a tendency to click the related/suggested videos. Since YouTube thinks you're likely to click on one of those videos next, it will pre-download the first slices (remember ""Sliced Bread"") of some related videos. So, when you click over to one of those videos it has started caching, it should load almost instantly. In the video above, you can see it working in a prototype version of new YouTube. The video, which took one and a quarter seconds to load in the current software, began playback in less than half a second in the prototype software. This was on
Now, it's important to mention that this last step hinges on the idea that YouTube can accurately predict what you're going to click next. Personally, I probably click on the Suggested videos mmmmaaaybe four percent of the time, but it does happen, and I'm sure it happens more for other people. Luckily, the Suggested results will get better if you're within a channel, assuming you're interested in watching other videos by the same content creator.
It's also worth mentioning that the biggest gap between hitting play and watching you video-preroll ads-aren't going away any time soon. Still, faster is as faster does.
All these speedy changes would be even more appreciated if they were on mobile devices, where data speeds can often be slow and unreliable, and thankfully that's just what's happening. Users of YouTube's
This is a fantastic feature. The only problem is that you need to have
kind of internet connection to play the videos back. It would be even better if you could load up the video at night while on your home Wi-Fi network, and then watch them while you're on the
On the mobile side of things, preloading is currently only available on Android, but it should be coming to
These are all steps in the right direction. Naturally, home network speed affects this stuff a lot, but all things being equal, the speed is one of the major determining factors of the quality of user experience. It's good to see that things are happening behind the scenes to move us toward the dream of honest-to-goodness instant.
Big thanks to Google's John Harding and Matt McLernon for their time.