Dolby and TDF are Making DTT Sound as Good as it Looks

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Broadcast television has some big changes coming. It’ll look great and sound great too. We’re currently helping conduct experiments intended to upgrade digital terrestrial television (DTT).

One of the companies we’re helping is broadcasting leader TDF, which aims to deliver high-quality sound that’s as good as the high-quality UHD (ultra-high-definition) images it offers.

The trial project with TDF, a neutral and open infrastructure operator, uses AC-4 to deliver digital terrestrial television in UHD on multiplexes across the cities of Paris, Nantes, and Toulouse. Viewers with a recent television set* can take full advantage of UHD and Dolby AC-4 on DTT channels 81, 82, and 83.

In addition to the superior picture quality that has already been tested on these three channels by TDF over the past few years, TDF and Dolby are working to deliver amazing sound. One thing I’ve noticed when working in media is that picture quality gets a lot of focus. A sharp, detailed picture really grabs people’s attention. It makes a great first impression. But sound quality can reinforce that great first impression or ruin it. That’s why this experiment with TDF is so exciting.

The integration of Dolby AC-4 audio makes it possible to carry several different audio streams in different configurations (stereo, 5.1 surround, and immersive audio, for example) and it gives viewers control over new possibilities, such as choosing an alternative language, playing a secondary narration, or listening to isolated elements and sound objects, such as the musical score with no dialogue. This content is being broadcast to test the DTT signals planned for the launch of UHD with different configurations of audio services and their combined sequencing. All these features are possible because the more efficient Dolby AC-4 format allows room for multiple options in the broadcast audio stream.


The future of DTT

These tests are a precursor to the full-scale rollout of UHD DTT. The data gathered and lessons learned will help modernise DTT as requested by the Conseil Supérieur de l'Audiovisuel (CSA) in its roadmap. TDF and the rest of the industry are working hard to deliver this improved standard to an eager public. Of the 7.1 million UHD TV sets sold in France in 2019, nearly 90 per cent of TV sets larger than 43"—and these larger sets represent more than 60 per cent of the market—were UHD-compatible. Customer enthusiasm for improved television has increased during the recent lockdowns around the world, which brought an increase in consumption of TV and multimedia content at home.

Franck Langrand, Managing Director of TDF’s Audiovisual business unit, is enthusiastic about these tests, and it’s great to work with a partner who believes in making DTT better. “I am delighted with the collaboration with Dolby, which marks a major step forward for the arrival of UHD on DTT,” he says. “In terms of sound, we are achieving the desired quality that will be offered to the general public by 2024. These are essential innovations needed to modernise digital terrestrial television.”

I agree with Franck. This experimental phase allows us to give viewers a glimpse of what tomorrow’s television will look and sound like – with sound that is more immersive, more personalised, and more accessible than ever before via broadcast television. Thanks to this partnership, TVs will be able to flawlessly play content encoded in Dolby AC-4, taking advantage of all the benefits the format offers. Whether it’s enjoying an immersive audio experience or just an improvement in the clarity of dialogue, viewers will have choices. What we’re doing now with audio quality will be on our TV sets in the near future.

If you’d like to check out the work we’re doing, it is available on the following channels:

Ch. 81: The Explorers trailer in UHD HDR10 with stereo audio encoded in Dolby AC-4
Ch. 82: A succession of video sequences, including:

  • on the city of Dinard in HDR10 in UHD or HD formats with Dolby Atmos immersive audio encoded in Dolby AC-4 in two languages French and English
  • on the city of Paris in HDR10 in UHD or HD formats with stereo audio encoded in Dolby AC-4 stereo

Ch. 83: Film Aphorism in 1080p HDR10 with immersive Dolby Atmos audio encoded in Dolby AC-4 in French and German

*TVs with DVB-T2 reception, Ultra HD resolution, HDR10, and Dolby AC-4-compatible (with or without Dolby Atmos).