Presenters at the virtual SCTE-ISBE Cable-Tec Expo 2020 on Oct. 14 examined a pair of ATSC 3.0-related issues of importance to cable operators, including the technical considerations of transitioning headend operations as broadcasters begin to take on NextGen TV and the opportunities the new broadcast standard offers to deliver enhanced TV viewing experiences to audience members with visual disabilities.
During the “Developments in HDR, IP Video Workflows and ATSC 3.0 Audio Accessibility” session, Mark Francisco, Comcast technology fellow, set the stage for his discussion of descriptive audio by explaining the size of the need and the opportunity to both do good and benefit financially by better serving audience members with disabilities.
When considering the size of the audience with disabilities, 20% of Caucasians have disabilities, 25% of Blacks and 33% of American Indian and Alaskan Native, said Francisco, making the point that the audience is large and diverse. On the economic side of the equation, a third of U.S. households have a disability. Those households command $220 billion, he added.
Twenty percent of people with disabilities are over 65 years of age, and 12 million Americans 40 years and older have some sort of visual impairment, he said.
“A disability is a mismatch between the environment and an individual’s capabilities at the moment,” he said, noting the mismatch could be temporary, lifelong and shrink or grow over time.
“The win-win or elegant solutions here are the ones that can cover temporary situations in addition to the permanent ones,” said Francisco.
The cable television industry faces a thorny issue as the video experiences people have using platforms, such as streaming services, mobile phones and game devices, have advanced faster than those available via cable TV, he said.
“The current conventions of ATSC 1.0 were ratified in 1996, and they are undergoing revision, but that takes time because of the massive scale we are dealing with,” he said.
The bottom line with 1.0 is “you can’t fit so much in there” and typically that means a primary and a secondary audio service per TV channel, said Francisco. With ATSC 1.0, all of the audio accessibility services are confined to a single auxiliary service that is monaural.
Francisco described work Comcast has done with NBC for the last three Olympics during ceremonies and some events to provide live audio description in the SAP channel for those with visual impairments. He also explained audio ducking, which dips the amplitude of a commentator and other audio to enable the video descriptive audio to come in—another technique that has proven successful.
But the future of broadcast television audio is more immersive, personalized and inclusive, he said. ATSC 3.0 provides for audio multiplexing of all audio channels, including 5.1 and SAP. All of those bits are intermingled over time with headers that make it possible to pull out those channels. Audio description also can be its own substream with metadata to describe what it is, he said.
NextGen TV viewers can define their audio preferences and in the decoder—in their set-top box or television—desired audio can be reassembled from those substreams based on what viewers have told the receiver they wish to hear, such as music and effects, commentator audio and descriptive audio. Not only does 3.0 open up avenues previously unavailable to adding description at a lower cost, but it enables the more personalization of audio, he said.
GETTING TO KNOW YOU
During the “What Cable Operators Need to Know About ATSC 3.0” session, Perry Priestley, COO/CSO of Broadcast Electronics/Elenos Group, and Joonyoung Park, vice president and fellow, DigiCAP, discussed what cable operators need to understand about ATSC 3.0 signals, how they are different than 1.0 signals and what they must do to prepare for NextGen TV.
Priestly began by laying out the basic difference between 1.0 and 3.0 from a viewer’s perspective, including 3.0 support for 4K UHD, high dynamic range (HDR), wide color gamut (WCG), frame rates up to 120fps, immersive audio and enhanced emergency alerting, captioning and video description.
He repeated the comparison from a broadcaster’s point of view: 8VSB vs. OFDM, MPEG TS- vs. IP-based and encryption vs. none. Priestly laid out the benefits as well, including better OTA reception, immunity to selective fading, resilience to interference, spectrum efficiency, simpler channel equalization and support for mobile receivers.
The transition from 1.0 to 3.0 will take place in three phases, he said. During the first, a lighthouse will host the 3.0 services of full-power stations in a market while stations channel share to maintain 1.0 service. Phase 2 will see an expansion of the first phase. The final phase will see the shut off of 1.0 service, which Priestly predicted would happen no sooner than in five years.
“…[T]he cable company receiving ATSC 3.0 will have to get a new receiver that can decode and demodulate the ATSC 3.0 standard,” said Priestly. “There will be times, and this is going to be a difficult period, where you have to receive some signals from ATSC 3.0 transmissions and some from ATSC 1.0 to obtain all of the content you need.”
Cable companies may also have to select programs differently because there could be a lot of duplication resulting from 1.0 and 3.0 simulcasts. Those programs will be in different formats, and there will be added complexity because the Emergency Alerting System and program guide will be different between the two, he said.
“There will also be a lot of content that may need to be ignored like specialized data—non-real-time data as well [content] that may be being delivered for overnight storage,” he said. “So, there will be data as broadcast apps that may potentially be used by cable companies, or [data that] they would need to … ignore….”
Park described a new integrated receiver decoder that will enable cable headend systems to receive and translate ATSC 3.0 signals.
“Basically you have two functions, one is the receiver and transmux function and the other one is transcoder function,” said Park.
Showing a diagram of the IRD, Park explained the functional architecture of 3.0 conversion for cable redistribution. He pointed out how the device can translate 3.0 signaling and metadata to fit into the MPEG transport stream for 1.0 distribution.
In addition, he described the management functions that are required. “As Perry explained, there are multiple programs and duplicate programs,” said Park. “So, as you are tuning into ATSC 3.0 signals, there should be a way to control the receiver and transmux functions to receive the right programs and right channels for your cable transmission.”
Phil Kurz is contributing editor to TV Technology
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