Conventional wisdom holds that Hollywood's fortunes go up when the economy goes down. People still crave entertainment, particularly of the escapist variety, and movies remain within the budgets of most people.

That may prove true this time around, too - ticket sales have been robust in recent weeks - but studio prosperity stopped depending on box-office results a long time ago. DVDs propel profits these days, and there is a creeping dread in the movie capital that buyers' interest is plummeting as the global economic crisis worsens.

"Every studio is claiming, 'We're O.K. so far, but we've looked at the overall competitive sales data and we have some concerns,'" said Amir Malin, a partner at Qualia Capital, a media-focused investment company with assets that include several large film libraries.

So far, total DVD sales are down about 4 percent for the year, with most of that weakness coming in October, according to data compiled by Warner Brothers, the largest distributor of DVDs.

The independent tracking service Nielsen VideoScan paints a bleaker picture, reporting a 9 percent drop in overall DVD sales during the third quarter alone and a 22 percent decline in sales of higher-priced new titles. Its data do not, however, include results from Wal-Mart Stores.

Most troubling, industrywide sales of next-generation Blu-ray discs - promoted as a high-definition technology that will restore growth to the medium - are growing but will miss sales projections for the year by 25 percent or more, according to Warner.

Weak consumer spending is not the only culprit. Media companies, desperate for revenue, are dumping more obscure titles on the market, leading to downward pricing pressure, according to Distribution Video and Audio, a home entertainment overstock company in Burbank, California.

Consumers, with their living rooms already stacked with DVDs, are being more selective. There are signs that digital downloads are cutting into sales, too.

And Blu-ray discs are still causing widespread confusion in the marketplace, with shoppers still doubtful that Blu-ray is here to stay after a lengthy format war with a rival technology. Indeed, 57 percent of standard DVD customers say they are "waiting to make sure Blu-ray is really the standard the industry will stick with," according to an industry study released this month.

"As a result, a number of consumers are sitting on the sidelines and not buying anything," Malin said.

Studio executives prefer to look on the bright side, saying that the DVD market is stronger even in decline than other media businesses, like broadcast television.