Method and apparatus for distributing a media content service

A method of receiving a streaming digital media content service across an electronic packet-based delivery channel, the streaming digital media content service being available in a plurality of representations each having a different bit rate, wherein each of the plurality of media content representations are transmitted as a sequence of bursts, with the bursts aligned in time such that starting transmission times for each burst of the sequence of bursts of each of the plurality of media content service representations are at the same time as a corresponding segment boundary in each of the plurality of media content service representations, wherein a segment comprises a set of frames of video content and a corresponding segment in each of the plurality of media content service representations corresponds to the same frames of video content, and wherein there is a window period between successive bursts during which media content is not transmitted, the window period comprising a duration sufficient for a multicast receiver to leave one media content representation and join a different media content representation at a different bit rate, the method comprising:

• receiving, at a subscriber apparatus, a first of the media content service representations of the media content service across the electronic packet-based delivery channel as part of a multicast of the first media content service representation;
• selecting a second of the media content service representations of the media content service for delivery across the electronic packet-based delivery channel;
• sending a request to leave the multicast of the first media content service representation;
• sending a request to join a multicast of the second media content service representation;
• and,
• receiving the second media content service representation as part of the multicast of the selected media content service representation, wherein both the leaving and joining of the respective multicasts occurs during the same one of the window periods between successive bursts during which media content is not transmitted.

Apparatus for distributing a streaming digital media content service across an electronic packet-based distribution network, the apparatus comprising:

• an interface for receiving a streaming digital media content service;
• a segmenting processor arranged to generate a plurality of segmented media content service representations for the streaming digital media content service, each of the media content representations having a different bit rate and divided into segments, wherein the segments of the plurality of media content service representations are aligned in time such that segment boundaries of each of the plurality of media content service representations are at the same time as a corresponding segment boundary in each of the plurality of media content service representations, wherein a segment comprises a set of frames of video content and a corresponding segment in each of the plurality of media content service representations corresponds to the same frames of video content;
• a transmitter arranged to transmit the segments of each of the plurality of media content service representations as a sequence of bursts, wherein the bursts of the plurality of media content service representations are aligned in time such that starting transmission times for each burst of the sequence of bursts of each of the plurality of media content service representations are at the same time as corresponding bursts in each of the plurality of media content service representations, and wherein there is a window period between successive bursts during which media content is not transmitted, the window period comprising a duration sufficient for a multicast receiver to leave one media content representation and join a different media content representation at a different bit rate,
• wherein each of the media content service representations is transmitted as a multicast, and wherein each of the received or generated media content service representations has a respective bit rate and the transmitter is arranged to transmit each of the segments at a higher bit rate to create the window period between successive bursts during which media content is not transmitted.

Apparatus for receiving a streaming digital media content service across an electronic packet-based delivery channel, the streaming digital media content service being available in a plurality of representations each having a different bit rate, wherein each of the plurality of media content representations are transmitted as a sequence of bursts, with the bursts aligned in time such that starting transmission times for each burst of the sequence of bursts of each of the plurality of media content service representations are at the same time as a corresponding segment boundary in each of the plurality of media content service representation, wherein a segment comprises a set of frames of video content and a corresponding segment in each of the plurality of media content service representations corresponds to the same frames of video content, and wherein there is a window period between successive bursts during which media content is not transmitted, the window period comprising a duration sufficient for a multicast receiver to leave one media content representation and join a different media content representation at a different bit rate, the apparatus comprising:

• a communication interface for receiving a first of the media content service representations of the streaming digital media content service across the electronic packet-based delivery channel as part of a multicast of the first media content service representation;
• a controller coupled to the communication interface which is arranged to:
• select a second of the media content service representations of the streaming digital media content service for delivery across the electronic packet-based delivery channel;
• send a request to leave the multicast of the first media content service representation;
• send a request to join a multicast of the second media content service representation;
• and,
• receive the second media content service representation as part of the multicast of the selected media content service representation,
• wherein both the leaving and joining of the respective multicasts occurs during the same one of the window periods between successive bursts during which media content is not transmitted.