iTunes Radio is expected to arrive next month with audio ads every 15 minutes and video ads every hour.

McDonald's, Nissan, Pepsi and Proctor & Gamble are among the big brands that'll be part of the launch. They'll pay up to tens of millions of dollars to secure a 12 month advertising campaign.

In January, adverts will reportedly become widely available to buy for around $1 million. They will be available as audio ads, video ads and slate ads - interactive display ads that will take over the listener's screen. While Apple users will be able to avoid the ads by buying iTunes Match, advertisers can target across iPhones, iPads and computers loaded with iTunes, including Windows PC.

The iTunes radio service will also feature a purchase button next to every song played to encourage listeners to buy the tracks for their iTunes library. [via TNW]