SVG in Mobile DTV (ATSC-M/H)


Table of Contents

Introduction to Mobile DTV
The Case for an Application Framework
OMA-RME
3GPP DIMS and SVG Tiny 1.2
MPEG-4 LASeR
MobiTV's Role
RTP for Transport
OMA-RME for Application Framework
Video Element Constraint
ECMAScript Extensions
Use Cases and Business Models
NAB Show Demonstrations
NAB Show 2008
NAB Show 2009

The U.S. standard for digital broadcast television is ATSC, which is really a standards body. The ATSC group has established a new standard, A/153, to address the mobile space named ATSC-M/H (mobile/handheld). Mobile DTV is the new "consumer friendly" way to refer to ATSC-M/H. It's meaning is more obvious, and it is easier to remember.

It has been extremely difficult to receive the existing terrestrial ATSC broadcasts while moving. The mobile stream contains massive amounts of error protection and correction. In addition, it is not reasonable to expect handheld devices such as mobile phones and personal media players to decode and scale down HD video to the small screen sizes. The mobile broadcast provides a widescreen 416x240 resolution. Furthermore, this new broadcast signal is backwards compatible with all existing ATSC tuners.

To be competitive with the current and future mobile entertainment landscape, mobile TV must expand beyond the mobile playback of video and audio. Part 5 of the A/153 1.0 standard specifies an Application Framework, which will provide a new set of tools for Web-like personalization and interaction. Interactive television will allow for the ATSC-M/H viewer to engage in real-time with the television program. Real-time mobile commerce will generate new and novel revenue opportunities. Interactive advertising will increase CPM. Real-time audience measurement data can be provided via the application framework. Surveys, usage and other data go directly to the broadcaster.

The Open Mobile Alliance (OMA), a standards body that develops open standards for the mobile phone industry, has developed a Rich Media Environment (RME) specification. The ATSC has adopted this standard for its application framework.

The OMA-RME specification adds a few things to the the 3GPP DIMS standard. Namely, it adds URI support, screen orientation events, and keyboard identifiers for the "D" pad and soft keys. Most importantly, it adds the sceneCommandGroup element to make multiple 3GPP DIMS scene commands into a single, well-formed XML document.

The first to bring live television to the mobile platform, MobiTV continues to shape the mobile media landscape by consistently introducing innovations to the market. As such, MobiTV is always looking for new ways to improve the mobile media experience, one of which is Mobile DTV.

Our principle is that Mobile DTV will help accelerate the overall use of mobile video, which in turn benefits MobiTV. We also believe a hybrid approach integrating Mobile DTV into a combined broadcast and unicast delivery model will provide the best possible user experience, while addressing a potential business model for Mobile DTV.

The technology benefits of Mobile DTV cannot be ignored, including excellent image and sound quality.

MobiTV has the technology to combine these aspects of Mobile DTV with the best principles of unicast delivery, including interactivity, personalization, audience measurement, dynamic ad insertion, and premium on-demand content with DVR-like capabilities.

As the leader in mobile media delivery, providing more content to more subscribers than anyone in the industry, MobiTV is well positioned to address an application framework for Mobile DTV with the necessary technology platform and managed services it requires.

Unfortunately, the the SMIL video element adopted by SVG Tiny 1.2 presented challenges. The broadcast audio/video is continuously live independent of the scene. The application framework is optional in the broadcast and user agent; it does not make sense for the optional component to define the lifetime of the core components (audio and video). Poorly authored scenes or user agent implementations must not interfere with the audio and video user experience. It creates a different tuning model for the RME vs. non-RME channels making things more complicated and impacting channel change time. Finally, it makes development of the user agent very difficult especially on resource-constrained mobile devices thereby hindering adoption.

Consequently, we recommended a layered model for the presentation of SVG Tiny distinct from the broadcast video. In this model the video window and the SVG canvas are the same size and origin. The SVG canvas is a layer with a transparent background above the video. The user agent may optionally support alpha-blended compositing of the canvas layer with the video layer; however, it must at least be able to perform non-blended compositing after converting the alpha channel to a bitmask.

Mobile device with video appearing underneath SVG graphics overlay

In the image above, the size of the SVG drawing is the same as the video size: 416x240. Only the graphics in the top, right corner come from SVG. The graphics in the lower, left corner are of a logo that was composited with the video prior to encoding and transmission. The positioning of the visible SVG graphics are controlled within the SVG and not any external means. The position, size, and source of the video are not controlled by the SVG.

As of September, 2009, MobiTV has not announced any concrete plans or agreements to provide a service or product for ATSC-M/H.