Get ready for video ads in your news feed.

Facebook is set to unveil a new video-ad product in the first half of next year in its largest attempt to date to attract big swaths of ad dollars from TV advertisers, according to several industry executives who have been briefed on the company's plans over the past few weeks.

Facebook is still debating several product features, but has decided on this much to date, these executives said: By April at the latest, it will offer video advertisers the chance to target video ads to large numbers of Facebook users in their news feeds on both the desktop version of Facebook as well as on Facebook apps on mobile phones and tablets.

Facebook is leaning toward capping the length of these video ads at 15 seconds -- a move that could push ad agencies normally reluctant to cut down their 30-second commercials to do so. That decision could also mean that 15-second video ads would become more prevalent elsewhere on the web.

'Autoplay' ads
In what's sure to be a controversial move, the visual component of the Facebook video ads will start playing automatically -- a dynamic known as "autoplay" -- according to two of the executives. Facebook is still debating whether to have the audio component of the ads activated automatically as well, one of these people said.

On the desktop version of Facebook, the video ads are expected to grab a user's attention by expanding out of the news feed into webpage real estate in both the left and right columns -- or rails -- of the screen. Facebook is also working on a way to ensure that the video ads stand out on the mobile apps as well, though it is unclear how exactly the company will accomplish this. (Some details about the video-ad plans remain vague and could change as Facebook gets more feedback from clients.)

Advertisers will be able to shows their video ads to desktop users of Facebook, but Facebook has been highlighting the mobile versions of the product in meetings with ad agencies, demonstrating the product on both tablets and mobile phones. Advertisers will be able to show the same video ad to a Facebook user up to three times a day across various devices, two of the executives said.

All of the executives interviewed view the new video ad product as a blatant attempt on Facebook's part to wrest big ad dollars from TV budgets. Ad agencies have plenty of TV spots and increasingly want to extend their reach on the web. But TV-like inventory on the web is scarce, which is why ad rates at places such as Hulu are so high.

Inventory from scratch
Adding video ads to Facebook would create a huge new trough of inventory created essentially from scratch. With Facebook's scale, advertisers could target demographics as they do on TV as well as use the gross ratings point currency, which they use for TV.

Yet questions remain. How widely will advertisers be able to distribute these TV commercials on Facebook? Will they only be able to show them to their Facebook fans, and friends of their fans, or to the Facebook user base at large?

For the most part, videos from advertisers currently only appear in a user's news feed if that person, or a friend of that person, has "liked" that advertiser's brand page on the social network and the brand has posted a video to its page. But several of the executives Ad Age interviewed are suspecting that advertisers will be able to target these video ads to Facebook users whether or not the user or his friends has any relationship on Facebook with the advertiser.

"The assumption is that these would be widespread campaigns," one of the execs said. "They are looking to grab big chunks of money ... millions of dollars."

These executives stressed that Facebook has not indicated yet whether this will be case, but they note that the product would otherwise carry much less appeal to advertisers. It is not clear how Facebook will charge for the video ads. Video-ad prices are typically higher than other forms of web advertising.

While the consensus among the executives is that advertisers have long been waiting for Facebook to open up its platform in a meaningful way to video advertising, several of the execs Ad Age spoke to are nervous about the reaction from Facebook users to the latest ad product.

At the top of the list of concerns is the autoplay function, which is often viewed as intrusive and sometimes as a source of fraud in the video-ad market, when autoplay ads count toward a view even if someone isn't watching them. Additionally, some of those interviewed said they are concerned that Facebook visitors will quickly become tired of ads from advertisers with which they or their friends have no relationship, even if advertisers tailor the ads based on information in a person's profile.

"There could be serious outrage," one of these people said.

Ad Age reached out to Facebook to inquire about the video-ad plans, and shared the details of what our reporting has uncovered. Facebook declined to comment.