Does MPEG-4 meet creator's vision?

Does MPEG-4 meet creator's vision?
It's been eight years since MPEG-4 started as a speculative gleam in the eyes of engineers across the world, the ISO/IEC standard for creating, distributing and playing back rich media is finally gaining a foothold in the marketplace. As a result, over the next two to three years, MPEG-4 shows every sign of becoming what its creators envisioned: a ubiquitous standard that will impact content delivery over the Internet, cable and satellite TV, packaged media and enterprise and educational networks.

MPEG-4 has filled a gaping hole by defining the description, coding and presentation of audio and visual content–and by enabling the types of experiences at the heart of interactive TV, distance education and other applications that have been known more for their abstract promise than reality. Although it grew out of a perceived need for greater compression efficiency for content delivery, it inevitably expanded to embrace a greater understanding of object-based coding. And that has led to more robust interactivity by creating dynamic relationships between media objects.

MPEG-7 formally named "Multimedia Content Description Interface," now in the Final Committee Draft (FCD) stage, aims to define a standard for describing multimedia content. It offers a comprehensive set of tools to create content descriptions that form the basis for applications enabling content tagging, identification, filtering, search, access and retrieval. And, the vision for MPEG-21 is to define a multimedia infrastructure to enable the creation, delivery and consumption of multimedia content across a wide range of networks and devices within diverse communities. MPEG-21 aims to complete the "big MPEG picture" of how various elements are connected in the chain for the creation, storage, protection, delivery and consumption of interactive content.

MPEG-4 systems define a rich set of nodes to describe two-dimensional and three-dimensional scene components and provides support for enabling user interaction and object-object interaction via sensor nodes and routes. The MPEG-4 system tools allow for the description, delivery and presentation of multiple streams of audio-visual content along with user interactivity.

The MPEG-4 Visual standard is comprised of a rich set of tools for very efficient compression of natural video content over a wide range of bit rates, from 64 kbits/second to potentially 38 Mbits/s. Scalability and error resiliency features provide a high degree of robustness at the video stream level against packet losses. Unlike the previous video coding standards, the MPEG-4 Visual standard also enables the efficient coding of arbitrarily shaped video content. With support for efficient coding of still images as well as synthetically generated mesh and texture content, the MPEG-4 Visual standard provides a fairly comprehensive package for the efficient coding of natural and synthetic visual content.

Speech and wideband audio coding are handled by the MPEG-4 Audio coding specifications. The speech coding tools enable coding of speech signals at bit rates from 2 kbits/s up to 24 kbits/s. The wideband audio coding tools support very high-quality encoding of multi-channel audio signals from bit rates ranging from 6 kbits/s to over 384 kbits/s. In addition, this set of specifications describes tools for the coding of synthesized speech and audio content.

Additions to the MPEG-4 Systems contain definitions and descriptions for new sensor nodes in support of advanced interactivity and content animation features. Node descriptions for audio processing and spatialization will provide for enhanced user experiences. Advanced tools for synthetic content description, parameterization, animation and rendering are being developed and will be integrated into the overall MPEG-4 framework. Digital rights management (DRM) has become a key ingredient in the proliferation of digital content. Cognizant of this, the MPEG groups, in general, are in the process of specifying architectures and messaging mechanisms to put an Intellectual Property Management and Protection structure in place.

Augmentations to the MPEG-4 Visual standard include improvements in video compression (joint work with ITU-T), the introduction of fine granularity scalability (FGS) tools (combinations of spatial, temporal and bit rate scalability features), to mention a few. The FGS set of tools provides a scalable video-coding framework suitable for multicast applications over existing IP networks and supporting a wide range of bandwidth variation scenarios.

Error resiliency tools, bit rate and bandwidth scalability features and audio spatialization features and tools for a more seamless presentation of synthetic and natural audio enrich the MPEG-4 Audio tool set.

Expect MPEG-4 to succeed only to the extent that it supports new and/or more robust commercial applications and services. The wireless community, for example, has adopted MPEG-4 video compression tools and integrated them into existing networks. To start, services likely will deliver a single stream of video associated with a single stream of audio, with nominal bandwidths ranging initially from 64 kbits/s to 128 kbits/s, and expanding to 384 kbits/s with the advent of advanced wireless infrastructures (3G). Among the more promising commercial applications are video e-mail, streaming short video clips, and downloading other video content. Error resilience tools and scalability tools are highly essential here to deliver high-quality audio-visual experiences to end-users.

Within the wider context of broadband applications, expect everything from the presentation of traditional audio-video content to highly interactive audio-visual experiences, mostly over IP networks. Potential users include education institutions and corporate communications, with initial delivery via download and playback, followed by streaming.

The DRM infrastructure becomes very important in these applications. Various architectures are being posited in order to provide tool downloads, tool authentications and content protection. MPEG-4-enabled authoring tools are just beginning to be made available but the industry can look forward to a plethora of such tools in the near future.

Other applications under consideration include interactive DVDs, with MPEG-4 used to extend the interactive capabilities and storage capacity of the format, content-on-demand services and MPEG-4 personal content recorders. To facilitate the widespread implementation and usage of the MPEG-4 standards, industrial consortia, to name but a few, have been formed to cogitate over and converge on useful subsets of the MPEG-4 standard for specific applications.