A method and apparatus for controlling a group of the client devices to switch at least one client device of the group of client devices from a first conditional access system to a second conditional access system is disclosed. In one embodiment, the method comprises generating a group identifier identifying the group of the client devices, transmitting a first client device signaling message having the group identifier only to each client device of the identified group of the client devices, and transmitting a second client device signaling message to the plurality of client devices, the second client device signaling message comprising the group identifier and signaling each client device having the group identifier stored in the non-volatile memory to switch from the first system client to the second system client.

A display apparatus transmits a picture acquisition request for getting picture information to an external image apparatus connected through a predetermined interface to the display apparatus from the external image apparatus at predetermined intervals and gets a plurality of pieces of picture information from the external image apparatus to be displayed. The plurality of pictures may be switched at predetermined intervals, for example, to be displayed, so that the plurality of pictures may be displayed in a so-called slide show manner. A plurality of pictures for thumbnail may be produced from the plurality of pieces of picture information and be arranged together to be displayed in one picture screen of a display device.

A content viewing method uses a viewing system including a content distribution server distributing contents, a mobile information terminal, and a viewing device reproducing a content. The mobile information terminal transmits user identification information and a user password to the content distribution server. The content distribution server authenticates the mobile information terminal based on the user identification information and the user password. The mobile information terminal transmits an account issue request requesting an account for reproducing a desired content to the content distribution server. The content distribution server issues the account based on the account issue request and transmits the account to the mobile information terminal. The mobile information terminal stores the account. The mobile information terminal transmits the account by short-range wireless communication. The viewing device stores the account received by short-range wireless communication. The viewing device reproduces the desired content using the stored account.

A display apparatus transmits a picture acquisition request for getting picture information to an external image apparatus connected through a predetermined interface to the display apparatus from the external image apparatus at predetermined intervals and gets a plurality of pieces of picture information from the external image apparatus to be displayed. The plurality of pictures may be switched at predetermined intervals, for example, to be displayed, so that the plurality of pictures may be displayed in a so-called slide show manner. A plurality of pictures for thumbnail may be produced from the plurality of pieces of picture information and be arranged together to be displayed in one picture screen of a display device.

A method and a device for processing a multimedia file are provided. In some embodiments, for a multimedia file to be processed, payload data in the multimedia file is acquired, and the payload data includes multi-frame data forming the multimedia file. Some pieces of frame data are selected from the payload data as frame data to be encrypted, and the frame data to be encrypted is encrypted. New payload data is formed by the encrypted frame data and unencrypted frame data, and the new payload data is encoded to obtain an encoded multimedia file. Therefore, the protection of the copyrights of the multimedia file is achieved.

Provided is a relay device for transferring a protocol data unit (PDU) transmitted from a server device to a terminal device, receiving content information that pertains to content stored in the PDU, and controlling a transfer in the PDU transfer step on the basis of the content information. The terminal device receives, via the relay device, the PDU transmitted from the server device, and transmits the content information that pertains to the content stored in the PDU to the relay device.

A display apparatus transmits a picture acquisition request for getting picture information to an external image apparatus connected through a predetermined interface to the display apparatus from the external image apparatus at predetermined intervals and gets a plurality of pieces of picture information from the external image apparatus to be displayed. The plurality of pictures may be switched at predetermined intervals, for example, to be displayed, so that the plurality of pictures may be displayed in a so-called slide show manner. A plurality of pictures for thumbnail may be produced from the plurality of pieces of picture information and be arranged together to be displayed in one picture screen of a display device.

A display apparatus transmits a picture acquisition request for getting picture information to an external image apparatus connected through a predetermined interface to the display apparatus from the external image apparatus at predetermined intervals and gets a plurality of pieces of picture information from the external image apparatus to be displayed. The plurality of pictures may be switched at predetermined intervals, for example, to be displayed, so that the plurality of pictures may be displayed in a so-called slide show manner. A plurality of pictures for thumbnail may be produced from the plurality of pieces of picture information and be arranged together to be displayed in one picture screen of a display device.

A configuration is realized in which block encryption MMT format data is reproduced by applying a time stamp. An MMT format stream file and a reproduction control information file are generated and recorded in a medium. The stream file includes encryption block data to which an encryption key generated by using an additional header in which copy control information of a block unit is stored, as a seed, is applied, and the additional header. Position identification information capable of determining a position of reproduction data, a position of the seed to be applied to decoding of the reproduction data, a position of the time stamp, and a position of the seed to be applied to decoding of the time stamp is recorded in the reproduction control information file. Data decoding, and reproduction to which the time stamp is applied are performed by using recording information.

A system for facilitating a virtual screening is disclosed. The system identifies a user for participating in a virtual screening of media content. The system generates a unique link for the user to facilitate access to the media content. When the user interacts with the link, the system prompts the user to authenticate with the system and determines whether the authentication was successful. If authentication is successful, the link is associated with an identifier of the user and/or a user device. A request for a key for decrypting the media content and a request for a digitally signed file accessing the media content pursuant to parameters are made. If the digitally signed file is valid, the system applies a watermark to the media content to track the use of the media content and streams the media content to the user. Feedback on the media content is obtained from the user.