Smartphones and media tablets are radically transforming the way the public consumes TV. This is raising new concerns among broadcasters over maintaining the quality of the video and audio destined for these devices, as well as over how signal preparation, conversion, and compression to support them will impact workflow.
Adding to the concerns is the latest broadcast-centric “second screen,” the standalone Mobile DTV receiver and third-party add-ons that will enable iOS and Android devices to receive MDTV signals delivered over the air.
With some 135 stations on air across the United States with MDTV channels—some with multiple channels—and the estimated 200 million smartphones and media tablets to be in the hands of U.S. consumers by 2015, delivering content to second screens at a quality level viewers enjoy will only grow in importance. Recent research reveals just how important multiple screens are to viewers: a pilot test conducted by Arbitron found that 90 percent of those measured use second and third screens to access content.
Broadcasters grappling with quality issues will find screen resolution, on-screen graphics and titles, and audio among the top concerns. Each also raises workflow issues for broadcasters choosing to serve content to multiple screens.
“One stream doesn’t fit all situations,” says Jay Adrick, VP Harris Broadcast Technology. Broadcasters seeking to maximize video quality will want to make certain they are delivering the maximum resolution possible to the device being served.
Adrick, who chairs the Mobile DTV Forum, says maximizing resolution for MDTV receiver will become particular tricky. When the MDTV system was first proposed five years ago, maximum resolution was set at 416 by 240 pixels. However, in the intervening period Apple has introduced the iPad with much higher screen resolution and devices are coming to market to allow them to receive MDTV signals.
The Advanced Television Systems Committee is working on adding higher screen resolutions and profiles to the MDTV standard to accommodate the iPad and other media tablets. While broadcasters ultimately are likely to use layered coding to support different resolutions, for the next couple of years they will most likely transmit multiple MDTV streams to accommodate different resolutions, says Adrick.
Graphics and titles are another area where quality must be considered, says John Luff, media technology consultant. The graphics and titles that are part of a commercial that looks great on a 60in HDTV set may be unreadable on a smartphone screen, he says.
In Europe, studies have been conducted on ways to read graphics overlayed onto pictures and use block-matching techniques to wipe out the graphics produced for large screens so graphics that are readable on small screens can be reinserted, Adrick explains. Another approach could involve maintaining a clean feed of source video and overlaying graphics appropriate to the screen being served.
Audio issues related to playback on small, portable devices also raise serious quality concerns for broadcasters. Broadcast television audio with a wide dynamic range and a mix intended to be heard in a relatively quiet environment, such as a living room, isn’t well suited to listening in a noisy public place where mobile devices are often used.
Broadcasters were alerted to the situation during the Open Mobile Video Coalition’s 2010 Mobile DTV Consumer Showcase in Washington, D.C. Participants in the trial found they frequently had to adjust the volume of their receivers as the ambient noise level changed as they moved from location to location. The situation highlighted the stark difference between TV and home theater speakers and tiny transducer speakers built into portable devices. It also underscored the need for broadcasters to deploy a different approach to audio loudness and management for mobile devices.
Following the showcase, two approaches were considered: one proposal called for processing of a separate audio stream intended specifically for listening on mobile devices to be done at the station; the other proposed allowing the mobile device itself to process broadcast audio. In the end, the former approach was chosen, which has implications for station workflow.
While quality and workflow issues are at the forefront of the minds of broadcasters pursuing second-screen strategies, the industry is in a period of learning and testing. Solutions will emerge, but not until enough time has passed to reveal all of the issues involved.
With the resolution of each new issue, broadcasters will get one step closer to realizing the full economic benefit of delivering their content to second-screen devices. Ultimately, that financial reward will make the effort to deliver high-quality video and sound to these devices—and the changes to workflow required to accomplish that—more than a worthwhile endeavor.
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