Abstract: A method of regulating sharing of a multimedia object (200) by a device (100), comprising registering usage information for the multimedia object (200) upon sharing of the multimedia object (200), and after the registering, billing a user of the device (100) for a certain amount in accordance with the registered usage information for the multimedia object (200). Registration preferably takes place in a client (101) arranged for sharing of the multimedia object (200). The usage information could for instance comprise the number of times a multimedia object has been shared, or the duration of the object. If a sufficient number of objects have been shared, or if the total time exceeds a maximum, the client (101) reports the usage information to a third party (130) for billing purposes.

Abstract: The present invention relates to a method for a service provider to distribute an audio signal to a listener. Before delivering the audio signal to the listener, the audio impression of the audio signal is personalized to the listener. The personalizing could e.g. be performed by filtering the audio signal using a set of head related transfer functions (HRTFs) defined by parameters being specific for the listener. This is for minimizing the interest of performing illegal copying of the audio signal. The invention further relates to a method of playing back a distributed audio signal and a playback device for playing back a distributed audio signal, where the personalization is detected and used as a watermark, which is identified and interpreted before playing back the distributed audio.