It is easy to take a DVD to a friend’s house and watch it on his TV. But things are more complicated when digital video downloads are involved. A movie file bought from Blockbuster.com will not work on a Sony HDTV, for example, and videos from iTunes work only on devices with Apple software.

At the electronics show, a big high-tech gathering that will begin Wednesday in Las Vegas, Hollywood studios and consumer electronics makers plan to lay out some steps they are taking to simplify this digital future — and perhaps stem the worrying decline in home entertainment sales.

Hollywood and its high-tech partners are deeply concerned that their customers will rebel against some of the limitations taking shape as video moves away from physical discs.

Consumers, the industry believes, could balk at buying digital movies and TV shows until they can bring their collections with them wherever they go — by and large the same freedom people have with DVDs.

In the last year and a half, a broad alliance of high-tech companies and Hollywood studios has been trying to address this problem through an organization called the Digital Entertainment Content Ecosystem, or DECE. Five of the six major Hollywood studios (Warner Brothers, NBC Universal, Sony, Paramount and Fox, but not Walt Disney) are involved, with Microsoft, Cisco Systems, Comcast, Intel and Best Buy.

The group is setting out to create a common digital standard that would let consumers buy or rent a digital video once and then play it on any device. It might sound technical, but it could be crucial to persuading consumers to buy all the splashy new Internet-connected gear that tech companies will demonstrate at C.E.S., like HDTVs and set-top boxes that can download TV shows and films.

Under the proposed system, proof of digital purchases would be stored online in a so-called rights locker, and consumers would be permitted to play the movies they bought or rented on any DECE-compatible device.

Business travelers might find that their hotel room television could tap into their personal movie collections. Consumers could buy Blu-ray discs and have digital copies of those films accessible from all of their devices, even their mobile phones. And a PC maker could customize a new laptop for buyers by loading it with all their movies and shows — and eventually even their video games and e-books.

These advances may not be all that far off. The digital content organization plans to announce several moves that signal it is ready for companies to start building devices and services with the technology this year.

The group is announcing that it has adopted a new file format that, like the DVD, will allow any company to create a compatible device or digital video store. It is also selecting Neustar, a company based in Sterling, Va., to create the online hub that will store records of people’s digital purchases, with their permission.The group is also announcing 21 new members, pushing the effort even further toward cross-industry unity. The new companies include consumer device makers like Samsung Electronics, Nokia and Motorola, entertainment retailers like Netflix and the European chain Tesco, and the cable companies Cox Communications and Liberty Global. (NYT)