Google supercharges YouTube with a custom video chip



Angela Lang/CNET

To keep YouTube humming, Google has developed a custom chip to keep YouTube called Argos that’s designed to deliver the best video quality and keep you from blowing through your broadband or mobile monthly data caps.

Thousands of the chips are running in Google data centers right now, Google revealed to CNET in an exclusive interview. If you upload a video today, it’s almost certain that an Argos chip will process it so it can be streamed all over the world. One specific benefit: when it processes high-resolution 4K video, it can be available to watch in hours instead of the days it previously took.

Google detailed its Argos chips for the first time at the ASPLOS Conference on Wednesday, offering a rare glimpse into its data centers’ inner workings. A team of about 100 Google engineers designed the first-generation chips starting in 2015, said Scott Silver, the Google vice president of engineering who oversees YouTube’s massive infrastructure. In recent months, Google began phasing in its second-generation Argos chips that push video compression another step forward, too.

“Customers have to pay for bandwidth one way or another,” Silver said. “Our goal is to make sure people can get the highest quality video on whatever device they have.” Silver also detailed the Argos chip work in a blog post.

Designing a custom chip isn’t for the faint of heart. But these days, it can be an important way to get ahead. For example, Apple has seized more control over its destiny with its M1 processors, which power MacBooks and its new iPad Pro and iMacs. The M1 design let Apple improve battery life, add an AI accelerator and other circuitry the company wanted and follow Apple’s own product schedule instead of Intel’s. More akin to YouTube’s situation is Amazon Web Services’ Graviton 2 chip to reduce computing costs.

500 hours of YouTube video uploaded every minute

Handling video is a monumental task at YouTube. Each minute, we upload 500 hours of video to YouTube. That means Google has to do lots of transcoding — converting those original uploaded videos into different compression formats and adapting it for different screen sizes. That’s Argos’ job.

YouTube servers use electronic boards with dual Argos video processing chips.

YouTube servers use electronic boards with dual Argos video processing chips.


Google

Because it’s hard to improve the performance of general purpose chips, custom chips also let companies push their own computing priorities. In the case of Argos, that means Google can lower its costs, keep YouTube users happier and advance its preferred video technology.

Argos handles video 20 to 33 times more efficiently than conventional servers when you factor in the cost to design and build the chip, employ it in Google’s data centers, and pay YouTube’s colossal electricity and network usage bills.

Handling video is a monumental task at YouTube. Each minute, we upload 500 hours of video to YouTube. That means Google has to do lots of transcoding — converting those original uploaded videos into different compression formats and adapting it for different screen sizes. That’s why it’s worth it for Google to design a custom chip.

Argos, a type of chip Google calls a video coding unit (VCU ), gave YouTube a boost during our pandemic induced video binge. That’s a big help given that we’ve also been watching 25% more video during the pandemic.

Creating video variations

When you upload a video, YouTube immediately needs new versions based on your original. For example, from a 1080p video, it creates lower-resolution 720p and 360p versions. That’s because people watching on phones might not have the screen resolution or network capacity for full-res versions.

In some areas where slow mobile networks are common, YouTube also builds even lower resolution versions and videos with slower frame rates, Silver added.

All this processing is the job of the Argos chips — thus the term video coding unit. Each Argos chip has 10 modules to process video, and Google parks two Argos chips on each circuit board.

Argos chips also creates versions encoded with different compression formats. Each original turns into 10 to 15 variations, Silver said.

Boosting AV1 video compression

Those compression formats, called codecs, are an enormous point of contention in the industry. For years, the premium video codecs came from the Motion Picture Experts Group. A wide range of technology companies created the formats then licensed their patents necessary to use the codec. This is the origin of the H.264 codec, also called AVC, that powered the first explosion of video on the internet and mobile phones. More recently, the group created HEVC (High Efficiency Video Coding, also called H.265) and VVC (Versatile Video Coding, or H.266)

The patent issue proved thorny. Licencing can be costly, and restrictions are antithetical to the open-source software philosophy that Google favors. Google offered the VP8 and later VP9 codecs royalty free and as open source to try to counteract the trend.

Compared with H.264, VP9 needs about 30% less data for the same video image quality.

Google designed a chip called Argos to speed video processing at YouTube. Here’s the chip’s layout.


Google

For a successor to VP9, Google and allies like Mozilla, Cisco, Microsoft, Amazon and Netflix formed the Alliance for Open Video. They created a new codec called AV1 that won an endorsement from Apple that’s just now starting to gain traction.

AV1 offers another 30% improvement in video quality, reducing the network use or letting YouTube send a 4K stream when a network previously only would support a 1080p stream.

Cracking the chicken and egg problem

AV1 is now available in some web browsers like Chrome, Firefox, Brave, Edge and Samsung Internet, and online video giants like Netflix and Facebook now offer AV1 video. But it takes years to get codecs to catch on. Witness Qualcomm’s lack of AV1 support in its new Snapdragon 888 chip, even though AV1 fans had promised AV1 support in 2020 smartphones.

The second-generation Argos chip adds AV1 support, a major incentive for phone makers to add support.

“People who make chips or devices don’t want to add new decoders … unless streams are available,” Silver said. “What YouTube can do is break that chicken and egg problem so people can have a better experience.”



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