The Q plugs into TVs or speakers so its owners can listen to music or play video from their Android phones or tablets. It is similar to devices like Apple TV, Boxee, Roku and Google TV.

But the Q is much more expensive than those products and does much less. It plays music, movies and TV shows only from Google Play’s limited collection and YouTube, and can be controlled only by Android devices. It is unclear how it would work with Google TV. The Nexus 7, however, a $199 tablet computer that Google introduced on the same day, has been met with rave reviews and is selling quickly, and can be used as a remote control for TVs.

Tech companies want people to buy their devices so they will also buy their media, and vice versa. Amazon.com sells Kindles so people will buy e-books from Amazon, and Apple sells music on iTunes so people will buy iPods. Companies are racing with one another, because once people store enough media with one service, it is much harder to persuade them to switch services or devices.

Though analysts say the race is far from the finish line, a problem for Google is that most people have not purchased much in the way of music and movies from Google.

“They only extended it to people who had music inside Google Music and media purchased off Google Play which, let’s admit, was a much smaller market than Apple iTunes, Amazon and any other media outlet,” said Chris Silva, a mobile analyst at the Altimeter Group. “They want to get people using Android and using Google Play for media and they know it’s an uphill battle, which is why they’re pushing it so hard.”

Google also hoped that the Q would be the centerpiece of its fledgling efforts to connect home devices to the Internet. It has said it wants to tackle not just the entertainment space but the whole home, eventually connecting coffee pots to the Internet so they can be turned off remotely, for instance, or refrigerators so they can order milk when it is running low.