Google is working on its own version of a multimedia format pioneered by Snap, and it wants publishers to help. So Google is giving them an incentive: The search giant is paying some sites working on its new "Stamp" project, a move sources say is intended to defray the costs publishers incur as they build content and systems to accommodate the new format.

It's unclear how much Google is paying individual publishers. One executive I talked to said the fee covered the costs of "multiple expensive people" working for several months on the project. Another described the payment as "de minimus."

Google is working with multiple publishers on Stamp, which was supposed to debut this month to a small subset of mobile users but may be delayed. Sources say participating publishers include Conde Nast, Hearst, Time Inc., Mashable, Mic.com, CNN, The Washington Post and Vox Media, which owns this site.

A Google rep declined to comment.

Google has spent money to encourage content makers before. In 2011 and 2012, its YouTube service spent hundreds of millions of dollars to encourage video makers to create more "professional" content. Facebook has also paid video creators to make live and on-demand content.

Publishers who are working on Stamp describe it as multimedia slide format, optimized for phones, that's supposed to surface at the top of Google's search results but would also live on their own sites. It can accommodate video, images and text, and users can advance through slides by swiping or tapping through, similar to Snap's Discover and Instagram's Stories.

Stamp is supposed to be built on the open-source, fast-loading "AMP" mobile format Google rolled out a couple years ago. But publishers say they have needed to assign staff to create new content for the format, and also to create their own publishing systems to upload the content to Google.

I've heard mixed prognostications about the format's potential -- some publishers tell me they're hopeful that Google can use its enormous reach to push a format designed for video and images. Others remember failed Google launches like Google Plus.

In either event, it's unlikely to generate significant revenue in the near term. Launch plans call for the format to appear to a small percentage of mobile users at launch -- perhaps one or two percent -- and eventually ramp up.

But Google doesn't have any plans to sell ads for the format itself right now, so publishers will have sell it themselves. Sources say publishers will be able to keep 100 percent of the ad revenue they generate, but they won't have much inventory to sell for some time, since the format won't be widely distributed.