Tango

Tango
Hardware-accelerate your encoding on Snapdragon™.

Tango is a free mobile video calling service that connects people around the world with family and friends wherever they are. Tango offers high-quality video calling for iPhone, iPod touch, iPad and 70+ Android™ phones and tablets. The service works over 3G, 4G, and Wi-Fi.

 "We participated in Qualcomm's booth at CTIA, and that appearance really put us on the map. The three-way collaboration among Qualcomm, Tango and Qualcomm's customers has been very powerful for us. Almost every week, we get yet more value from our relationship with them."

– Eric Setton, Founder and CTO, Tango

Technical Highlights

  • Hardware acceleration of video encoding/decoding
  • Development on Snapdragon MDP MSM8655
  • Offloading video processing to dedicated hardware frees up CPU and extends battery life
  • 2x frame-rate, 2x resolution, 3x number of pixels shown per second versus software codecs

Business Highlights

  • Four weeks’ development time to hardware-accelerated version
  • Increased exposure to OEM prospects as Qualcomm developer
  • Potential for more cooperation with Qualcomm on other technologies

If you reached your first million users within ten days of launch, wouldn’t you do everything you could to keep them happy?

Tango did.

Tango’s video calling application and service run on iOS and Android, allowing customers to connect across the two platforms. Within six months of launch, the company had over 12 million users in 190 countries and was powering millions of minutes of calling every day.

CTO Eric Setton describes the wild popularity and uptake of Tango in three words: “Because it works.” Mobile video is tricky, and mobile video calling is trickier, but Tango has made the user interaction as simple as a phone call, even integrating with the phone’s address book to find other Tango users.

Differentiating the product

“Most mobile devices incorporate cameras,” explains Setton, “and people are seeing the virtues of video calling in services like FaceTime. We’re the first platform to launch for both iOS and Android, with something that also works over 3G. There’s also a lot of flexibility with Tango: 1-way/2-way video, front/back camera, window within window. Launching with that combination put us in a strong position.”

Tango saw that every time it improved the quality of the service, there was a corresponding jump in the number of users and minutes of calling. But the biggest opportunity for Tango to differentiate its offering was in performance, because people want high-quality, smooth video, even in a free service. Tango had launched with a software codec running on the CPU and decided after a few months to process video on hardware instead, for a performance boost that would keep its users happy and distance it from the competition.

Setton determined that Snapdragon-based Android phones formed a big chunk of Tango’s user base, so his team contacted Qualcomm and began working with the Snapdragon MDP based on the company’s MSM8655 mobile processor.

Hardware acceleration payback: Double the frame-rate, double the resolution

“In the software version, we were maxing out the CPU,” says Setton. “Snapdragon dedicates all of the video processing to the H.264 hardware encoder and decoder, which frees up the CPU for better audio quality. We wanted very much to work with Qualcomm on this.

“In less than a month and with Qualcomm’s help, we had the first hardware-accelerated version of Tango ready to demonstrate. The quick turnaround speaks to a few things: the well-defined hardware interfaces, the sample code that saved us so much time, and the maturity of the MDP, which is a very accurate reference implementation of the hardware as it’s running in the real world. I was impressed that Qualcomm made so many resources available and were willing to offer advice to us, and they were pleased at seeing something demonstrable in such short order.”

The hardware-accelerated version of Tango shows big performance improvements over the software version:

  • 2x frames per second
  • 2x resolution
  • 3x number of pixels shown in a second

Also, Tango’s modular architecture played an important role in the quick turnaround. To accommodate a variety of devices, the application is designed around clearly defined interfaces for swapping modules, so it wasn’t hard to conditionally swap them in and out for Snapdragon-based phones. At run time, Tango can decide which modules to use and put together a pipeline that carries the video call.

Setton’s team is strict in defining the architecture of Tango’s modules and in conforming to that strict separation of modules. They write code as if it were a software development kit to be shared with partners, and this made the hardware acceleration easier because they could focus more on forward development than on retrofitting code.

Collaboration with Qualcomm has unexpected benefits

But if Setton and Tango were impressed by working with Qualcomm’s engineers in the lab, they were even more impressed by working with them in the booth at CTIA. The company has made valuable contacts among OEMs as a result of their collaboration with Qualcomm.

“There were about a hundred WiFi networks in our vicinity with lots of interference,” recalls Setton. “It was impossible to get a strong enough signal to demonstrate the application we had worked so hard to accelerate. William Frantz of Qualcomm found and installed synchronization software on a desktop to proxy the connection through computers and send video back and forth over a cable. He went to a lot of effort to help us get the demo off the ground. Those guys really care about the success of their developers.

“Another big advantage to working with Qualcomm is all of the other technologies in progress around the company, and we’re finding new areas of collaboration with them, especially in image processing and audio. For example, if you can use face detection in video chat, you can spend your bits accurately around the face area, which is most important. Or, in audio, we want to build echo cancellation into Tango that helps when calls go through a speakerphone. We’ve made relationships elsewhere in the company around technologies like these that could give Tango big competitive advantages.”

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