Adaptive control of layer count of layered media stream

A method of controlling the number of an active one or more of original layers within a layered media stream received from a media delivery server,

• wherein the media stream is structured to have a maximum number “M” of layers that include “m (0<m<M)” video layers and an audio layer,
• the method comprising:
• receiving the media stream received from the media delivery server;
• transferring the received media stream to a destination;
• from the destination, receiving quality information indicative of audio quality of the audio layer received at the destination;
• based on the received quality information, estimating a value of subjective quality of the received audio layer at the destination;
• and
• based on the estimated value of subjective quality of the received audio layer, in combination with a ratio m/M of one of more number of video layers “m” that are being transmitted to the destination to the maximum number “M” of layers, controlling one or more number of active video layers that are to be subsequently transmitted within the media stream to the destination, such that the number of active video layers increases as a product of the estimated value and the ratio m/M increases.