Following a technical trial last summer, the corporation has extended the range of downloads to include 310 radio shows and 190 hours of TV.
Users can search for shows by title, channel or subtitled programmes and download them to their own computer. Broadcasts can then be played up to seven days after the transmission date.
"iMP could just be the iTunes for the broadcast industry, enabling our audience to access our TV and radio programmes on their terms - anytime, any place, any how," said Ashley Highfield, BBC director of new media and technology.
The pilot will be used to gauge demand for different types of programme and assess any commercial impact the player may have.
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