Music Beta, which Google is offering by invitation only while in its trial state, will allow users to store 20,000 songs at no charge and stream them to Android phones, tablets and other devices. As with Amazon’s Cloud Drive, the company does not need special licenses as long as it stores each user’s files separately and then streams them back only to that user, intellectual property lawyers say.

But to sell music, or to operate a master jukebox of every available song and then matching users’ collections to it — widely viewed as the most efficient form of cloud music — Google would need licenses from the labels. Google’s plans were described by many record label executives who have been in discussions with them but spoke on condition of anonymity because their talks were private.

Google and Amazon have not been the only companies negotiating with the labels for cloud music services. Apple is preparing its own, and Spotify, a popular European subscription service, has been locked in talks for two years over American distribution rights. In most of these cases the disagreements are over lump upfront payments or concerns that a service that charges users too little could cannibalize other sales and devalue music overall, executives say.

Ted Cohen, a consultant and former major-label executive, said that when both sides of such negotiations have bad faith, customers suffer. “Neither side is playing fair with the other,” he said. “They go into the negotiations believing that the other side of dishonorable. It’s rare that both sides see that the common goal is to create a consumer experience that people value and are willing to pay for. Things don’t come to market because of this.”

But whether Google and Amazon have abandoned their bigger plans or were just scaling them back temporarily was unclear. In an interview, Ms. Levine denied that the abrupt introduction of Music Beta was a negotiating tactic. But music executives said that since Amazon introduced Cloud Drive — with almost no advance notice to the labels — it has been in discussions over licenses, and these executives, speaking anonymously, said they expected Google to eventually return to the negotiating table.

A more robust digital music service would attract more users to Google. But Mr. Goldring said that it was the labels that really needed to strike a deal.

“At the end of the day they’re clearly hurting themselves,” he said, “because they’re leaving money on the table.”