Pepsi is expected to announce a promotion at next year's Superbowl in which it will give away a billion DRM-free music tracks from Amazon's online music store.

Five billion download codes will be hidden in Pepsi products and a billion codes will open up a free download.

The plan is a repeat of a similar partnership with iTunes in 2004, which saw five million tracks given away but with copy protection.

"Amazon will serve as the supplier for the downloads, and customers will need to visit a specific redemption store on the Amazon site to access music from participating labels," said Ed Christman of Billboard magazine.

"While all majors have been approached about participating in the offer, the price that Amazon is willing to pay appears to still be a sticking point for some labels.

"Sources say that Amazon will pay labels in the area of 40 cents per track. This compares to the 65 to 70 cents labels currently receive from Amazon for digital track sales and the 70 cents they get from Apple."

The lower economic cost of the promotion via Amazon is a factor, but the move also shows the weakening position of those music companies sticking with selling content with DRM embedded.

EMI and Universal have both started selling DRM-free material and iTunes also sells some DRM-free music.