Google Inc., the world’s largest Internet-search company, will announce a new music service today at its I/O developer conference, stepping up competition with Apple Inc. and Amazon.com Inc.

Google plans to discuss a test version of the product, the company said yesterday in an e-mail. The conference, held in San Francisco, caters to programmers who design applications for Google’s platforms, including the Android phone operating system and Chrome Web browser.

The announcement follows Amazon’s decision to let consumers store digital music on its servers and stream the tracks to computers and Android smartphones. Amazon’s service relies on cloud computing, which delivers songs over the Internet rather than keeping them on local hard drives. That differs from the approach of Apple’s iTunes, the world’s biggest music seller, which offers downloadable tracks.

Google, based in Mountain View, California, is moving into new forms of entertainment to diversify its revenue, boost ad sales and keep users on its sites for longer. Yesterday, Google’s YouTube unit said it would add “The King’s Speech,” “Inception” and about 3,000 other titles to its movie-rental service. The move accelerated YouTube’s shift into Hollywood entertainment and increased its rivalry with Netflix Inc.

Google rose $2.38 to $537.68 yesterday on the Nasdaq Stock Market. The shares have fallen 9.5 percent this year.

Amazon’s service doesn’t rely on music-license rights from record companies, instead requiring users to upload their own songs to the cloud. As of March, the Internet retail giant was talking to music companies about a licensing deal. That would mean Amazon wouldn’t have to keep individual copies of each song in its data centers, making the service more efficient.