The BBC has been given permission to launch its iPlayer service for television on demand.

The player takes the form of a piece of software users can download from the BBC website. Once installed, users can download programmes broadcast during the previous few days.

A trial run took place in 2006 of an early edition of the software, then known as iMP. The BBC Trust, which regulates the BBC, has demanded some changes from that version - in the full edition, users will only be able to keep programmes for 30 days, rather than the 13 weeks the corporation had requested.

Viewers will be able to 'stack' certain series, so the iPlayer downloads each episode of a series. However, this will be limited to programmes with a 'distinct run', so soaps and current affairs shows would be excluded.

One major change is the final player will be compatible with all modern computers - the trial version worked only with Windows PCs.

At the same time, the Trust has declared the BBC would not be allowed to offer future free downloads of classical music.

In 2005, the corporation gave away new recordings of all nine of Beethoven's symphonies as podcast-style downloads on its websites. The mp3 downloads, which were not protected from copying, led to protests from classical music labels, who claimed the BBC was encroaching on their territory. The Trust, agreeing with the labels' view, has said that the BBC won't be able to make similar giveaways in future.