Seth Macfarlane is planning a 'Family Guy' movie.

The 'Ted' director has ''finally'' come up with the perfect idea to take his hit cartoon sitcom from the small screen to a feature length film and promises it will be more successful than the 2007 'The Simpsons' attempt.

He told Entertainment Weekly: ''We do know what the 'Family Guy' movie will be. 'The Simpsons' movie, I thought, was hilarious, but the one criticism I would have is that it's a story they probably could've done on TV. There could've been an episode that had that plotline.

''That's the challenge with animation. You pretty much can do any story you want, so what is the reason for the movie? We finally hit on the answer to that question, and it will be something that would be impossible to do on TV.''

The 2013 Oscars host remained coy about his upcoming project, but hinted he would be concentrating on the crude comedy series for the near future until it had run its course.

Seth teased: ''It's just a matter of when. It's hard to do that while you have the series going on at the same time; I think that's why it took 'The Simpsons' 20 seasons to figure out how to do it.''

Speaking to a disappointed crowd of UCLA students, he said of the film's core idea: ''I can't tell you what that is.''

Meanwhile, the funnyman's first foray into cinema, 'Ted' - starring Oscars - starring Mark Wahlberg and Mila Kunis - grossed almost $400 million worldwide in the box office and Universal Pictures have confirmed they want to get started on a sequel ''as soon as possible.''