主播大秀

The 主播大秀 have been providing interactive TV services for the past 40 years, from Ceefax, to the Broadcast Red Button service. Now the TV & Mobile Platforms department, part of 主播大秀 Digital, are introducing the internet connected service.

To continue supporting this vision the 主播大秀 has been working closely with TV manufacturers for the past 3 years to certify and approve connected devices, such as Smart TVs and PVRs to build the Red Button+ service. During that time the department has published our which we use to develop services for these devices, allowing us to bring streamed video content, and present interactive interfaces that showcase a much larger set of 主播大秀 content.

The migration challenge

We have taken care to migrate our audience over to Red Button+ without restricting access to the existing service they know and love.

Even with standards and a certification process in place, it has been a challenge providing a mechanism to allow users to switch between the new and the old services. At one stage in development it looked like there would be no way to perform a back journey from the HTML engine back to the MHEG layer.

To explain a bit more; all Smart TVs and Smart PVRs are basically equipped with a variant of a web browser and a broadcast presentation engine called MHEG. To launch a web browser from broadcast (on Freesat and Freeview), part of the MHEG-IC spec (also known as MHEG-5) includes a command known as ApL (Application Launch). This enables the event listener for the Red button press on the remote control to launch a HTML based application running in a borderless web browser. Without the ability to pass information back from the HTML layer to the MHEG layer, there would be no way for a user to switch back to the original service.

Our approach

One theory was that by uniquely identifying devices, we could use Cloud based storage to pass messages between our HTML apps and MHEG. If both layers could talk to the internet, then they could use external memory to exchange messages. This was quickly dubbed by our team as "coexistence" and a few days were set aside to investigate. Core to this investigation was making use of specific persistence features in the MHEG spec had never been validated by the department in order to build a working prototype.

To prove the theory, we developed a test harness in MHEG, and spiked out how direct launch would work across our technology stack. With the test harness, it was possible to physically check devices to see if they supported coexistence, and prove that a direct launch could be combined with preference setting for the user to switch between the Red Button and Red Button+ services. We have to work with a fragmented set of devices, with hybrid devices produced for international markets, and it is not always possible to get a full set of features on every device. Using the MHEG harness we were able to gain a high level of confidence that devices would perform as expected despite their differences. This meant we could couple them to a web-based message passing service to act as external memory.

The solution

The eventual solution required a few more leaps and innovations from the engineering team; particularly around handling heavy traffic. For big events such as F1, Sports Day, Wimbledon, Glastonbury, and the Olympics, the Red Button service can receive tens-of-thousands of interactions within a very short period of time, usually as a result of on-screen messages or call-to-actions from presenters. To cope with this traffic we opted to host the message passing service in the Cloud so that it could be scaled in advance of large events.

We also focused on maximising cache hits, increasing the number of generic calls to our services, to minimise the load on shared resources, and to help cope with really heavy traffic. The result seems bafflingly simple - there is a Settings page that lets you choose between Red Button, and Red Button+. The next time you press Red, the option you chose is launched.

Send us your feedback

As an engineering team, we're committed to improving the service based on your feedback. If you have a Smart TV or PVR with access to the service, please take a look at the new RB+ service and let us know what you think. I hope you've enjoyed this article, and given you a better idea about what goes on under the hood when pressing Red.