The MP3 format is losing marketshare to new audio codecs from Apple and Microsoft, The NPD Group reports.

The percentage of MP3-formatted songs in people's personal music collections has fallen from 82 per cent to 72 per cent in a year.

A report on divulges the new data, revealing that users tend to delete their MP3 downloads. This reflects a move from peer-to-peer file-sharing towards legal download services.

Apple's AAC format has gained share, but MP3 remains "the one necessary format for hardware and software companies," the report points out.