Apple CEO Tim Cook says Apple TV is no longer being viewed as a hobby gadget given its serious revenue return and told investors he's feeling pretty confident about Apple's move into the getting-more-crowded-by-the-minute set-top box market.

The company has sold more than 20 million Apple TVs and the sale of boxes and content for 2013 hit over $1 billion.

"It didn't feel right to me to refer to something that's over $1 billion as a hobby," Cook told investors during the company's recent earnings call. "From an investment point of view, we continue to make the product better and better so it doesn't feel right from that POV either."

The news comes as big names, such as Amazon and its Fire TV, break into the burgeoning set-top box market promising to shake up an industry once dominated by cable and telecom services providers. New players are hammering out new content deals to grab consumer attention.

 "I'm feeling quite good about that business and where it can go," he said.

Industry watchers expect Apple to push out a revamped set-top box product later this year and Apple is already busy expanding content with new channels.