In Video-Streaming Rat Race, Fast Is Never Fast Enough

Jan 10, 2013
Originally published on January 11, 2013 11:55 am

On average, YouTube streams 4 billion hours of video per month. That's a lot of video, but it's only a fraction of the larger online-streaming ecosystem. For video-streaming services, making sure clips always load properly is extremely challenging, and a new study reveals that it's important to video providers, too.

Maybe this has happened to you: You're showing a friend some hilarious video that you found online. And right before you get to the punch line, a little loading dial pops up in the middle of the screen.

Buffering kills comedic timing, and according to a study published by University of Massachusetts professor Ramesh Sitaraman, it kills attention spans, too

"What we found was that people are pretty patient for up to two seconds," Sitaraman says. "If you start out with, say, 100 users — if the video hasn't started in five seconds, about one-quarter of those viewers are gone, and if the video doesn't start in 10 seconds, almost half of those viewers are gone."

If a video doesn't load in time, people get frustrated and click away. This may not come as a shock, but until now it hadn't come as an empirically supported fact, either.

"This is really the first large-scale study of its kind that tries to relate video-streaming quality to viewer behavior," Sitaraman says.

The study looked at close to 6.7 million viewers who watched almost 23 million videos play. That's around 216 million minutes of video time.

The threshold of unbearable loading time depends on the device.

"We found that people who had a lot of connectivity had also a lot of expectation potentially, and so they abandoned much sooner," Sitaraman says.

For about half of the people who used a high-speed, fiber-optic connection, five seconds is too long. Mobile users will wait longer. For a business that serves an ad base of 800 million people a month, every second counts — the more users who click away, the bigger the problem.

"When we started to look into this problem, we found that the existing player we had was not up to the task," says Andy Berkheimer, an engineering manager for YouTube.

For the past two years, Berkheimer's team has been working on a project to make sure that those punch lines are delivered without the pauses.

"We had to rewrite our whole player to give us more flexibility in how we handled network conditions," Berkheimer says.

The problem, for YouTube and video providers alike it, has to do with bandwidth. Think of streaming video as being like a stream of liquid information. Bandwidth is the size of the pipe.

"No matter where you are, no matter what type of device you're using, no matter what type of network you're on — at any time while you're watching a video, bandwidth can change," Berkheimer says.

So if that bandwidth, or pipe, constricts too much, the video stops playing. To solve this problem, YouTube's engineers chop the video into a bunch of tiny pieces. From moment to moment, depending on how much bandwidth is available, they swap these pieces in and out as the video streams.

If there's a ton of bandwidth, a high-definition piece flows down the pipe. But if that pipe constricts, even for a second, a lower-quality piece is swapped in.

Switching around different versions of video shortens load time, Berkheimer says. And less load time means more video, more eyeballs and more money for ads. But what's the cost?

Some films aren't always seen in their best light. Filmmaker Gregory Wilson used state-of-the-art camera equipment to film a cheetah running full speed in superslow motion. HD captures every stunning detail of the cat's fluid motion. But when you watch his video online, who knows how it will look?

"I would hope that the quality could be the best that it could be and that it would be more on par with what I had originally captured," Wilson says.

Since businesses need that video to run no matter what it looks like, the rest of us will likely see grainy cheetahs rather than stuttering punch lines.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

STEVE INSKEEP, HOST:

On a Thursday, it's MORNING EDITION from NPR News. I'm Steve Inskeep.

RENEE MONTAGNE, HOST:

And I'm Renee Montagne.

Who hasn't been driven crazy trying to watch a video online only to have it freeze, then start, then freeze again. The smooth loading of video clips, though, is not just important to viewers.

As NPR's Sami Yenigun reports, video providers also see it as critical.

(SOUNDBITE OF VIDEO)

UNIDENTIFIED MAN: Knock, knock.

SAMI YENIGUN, BYLINE: You may have heard this one already.

(SOUNDBITE OF VIDEO)

UNIDENTIFIED WOMAN: Who's there?

YENIGUN: You're showing a friend some hilarious video that you found online.

(SOUNDBITE OF VIDEO)

UNIDENTIFIED MAN: Dwayne.

YENIGUN: And right before you get the punchline...

(SOUNDBITE OF VIDEO)

UNIDENTIFIED WOMAN: Dwayne who?

YENIGUN: A little loading dial pops up in the middle of the screen.

(SOUNDBITE OF VIDEO)

UNIDENTIFIED MAN: ...bathtub. I'm drowning.

YENIGUN: Buffering kills comedic timing, and according to a study published by UMass professor Ramesh Sitaraman, it kills attention spans too.

RAMESH SITARAMAN: What we found was that people are pretty patient for up to two seconds.

YENIGUN: That's a really nice way of saying people are pretty impatient.

SITARAMAN: If you start out with, say, 100 users, if the video hasn't started in five seconds, about one-quarter of those viewers are gone, and if the video doesn't start up in 10 seconds, almost half the viewers are gone.

YENIGUN: If a video doesn't load in time, people get frustrated and click away. This may not come as a shock, but until now it hadn't come as an empirically supported fact either.

SITARAMAN: This is really the first large-scale study of this kind, that tries to relate video-streaming quality to viewer behavior.

YENIGUN: And when Professor Sitaraman says large scale, he means it. The study looked at close to 6.7 million viewers who watched almost 23 million videos played. So how long is too long? Depends on the device.

SITARAMAN: We found that people who had a lot of connectivity had also a lot of expectation potentially, and so they abandoned much sooner.

YENIGUN: For about half of the people who used a high speed fiber optic connection, five seconds is too long to wait. Mobile users will wait longer. For a business that serves an ad base of 800 million people a month, every second counts. The more users that click away, the bigger the problem.

ANDY BERKHEIMER: When we started to look into this problem, we found that kind of the existing player we had was not up to the task.

YENIGUN: That's Andy Berkheimer, engineering manager for YouTube. For the past two years, his team has been working on a project that makes sure your knock-knock jokes are delivered without the pauses.

(SOUNDBITE OF VIDEO)

UNIDENTIFIED MAN: Dwayne, the bathtub.

BERKHEIMER: And so we had to rewrite our entire player to give us more flexibility in how we handled network conditions.

YENIGUN: The need for flexibility has to do with bandwidth. Think of streaming video as being like a stream of liquid information. Bandwidth is the size of the pipe.

No matter where you are, no matter what type of device you're using, no matter what type of network you're on - at any time while you're watching a video, bandwidth can change.

So if that bandwidth, or pipe, constricts too much...

(SOUNDBITE OF WATER)

YENIGUN: ...the video stops playing. Here's how YouTube is solving this problem. They chop the video into a bunch of tiny pieces. From moment to moment, depending on how much bandwidth is available, they swap these pieces in and out as the video streams.

So if there's a ton of bandwidth, a high definition piece flows down the pipe, but if that pipe constricts, even for a second, a lower quality piece is swapped in.

SITARAMAN: And that way we can keep the data flowing uninterrupted, and we can choose a quality level that is right for the bandwidth conditions at that moment.

YENIGUN: And less load time means more video, more eyeballs, and more money for ads. But what's the cost?

(SOUNDBITE OF MUSIC)

YENIGUN: Some films aren't always seen in their best light. For example, filmmaker Gregory Wilson just used state of the art camera equipment to film a Cheetah running full speed in super-slow motion. HD captures every stunning detail of the cat's fluid motion. But when you watch it online, who knows how it will look.

GREGORY WILSON: I would hope that, you know, the quality could be the best that it could be and be more on par with what I had originally captured.

YENIGUN: But since businesses need that video to run no matter what it looks like, the rest of us will likely see grainy cheetahs rather than stuttering punch lines.

Sami Yenigun, NPR News. Transcript provided by NPR, Copyright NPR.