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- Digital storage media command and control (DSM-CC) is a toolkit for developing control channels associated with MPEG-1 and MPEG-2 streams. It is defined in part 6 of the MPEG-2 standard (Extensions for DSM-CC) and uses a client/server model connected via an underlying network (carried via the MPEG-2 multiplex or independently if needed). DSM-CC may be used for controlling the video reception, providing features normally found on Video Cassette Recorders (VCR) (fast-forward, rewind, pause, etc.). It may also be used for a wide variety of other purposes including packet data transport. It is defined by a series of weighty standards, principally MPEG-2 ISO/IEC 13818-6 (part 6 of the MPEG-2 standard). DSM-CC may work in conjunction with next generation packet networks, working alongside such internet protocols as RSVP, RTSP, RTP and SCP. Although DSM-CC is usually associated with video delivery (via satellite or terrestrially) and with interactive content, it is also used among audio servers and clients. The architecture describes three main parts of the system: the client, the server, and the (SRM). The server provides content and other services to the client, and both are "clients" of the SRM. The SRM allocates and manages network resources (such as channels, bandwidth, and network addresses.) By combining server and client components together onto the same platforms, peer-to-peer content access and delivery systems can be constructed. These specifications include numerous implementation options. For example, MPEG-2 video can be encoded in different ways, and a DSM-CC system can be constructed to include or exclude certain features and interfaces. Normally, an outside specification will define a profile of specific options, allowing systems built using common profiles to interoperate. DSM-CC defines or extends five distinct protocols: User-UserAllows remote access by the client to objects on the server. The User-User specification goes beyond the definition of specific server object classes to define classes local to the client, as well as some of the interaction with other parts of the system. The distributed object model is based on CORBA. Objects are accessed using the internet inter-ORB protocol (IIOP), with some optional extensions. Two subsets, "core" and "extended", are defined. In the model, some clients may also load content onto the server.User-NetworkThere are two parts to this protocol: Session and Resource. This protocol is used between the client and SRM, and between the server and SRM. The U-N Session protocol is used to establish sessions with the network, associated with resources which are allocated and released using the U-N Resource protocol.MPEG transport profilesThe specification provides profiles to the standard MPEG transport protocol (defined by ISO/IEC 13818-1) to allow transmission of event, synchronization, download, and other information in the MPEG transport stream.DownloadSeveral variations of this protocol allow transfer of content from server to client, either within the MPEG transport stream or on a separate (presumably high-speed) channel. Flow-controlled download allows the download operations to be negotiated and controlled by the client. A variation of download is an autonomous "data carousel" on the server which repeatedly downloads information; the client waits for the information without initiating the transfer. An extension to the data carousel is the "object carousel", which presents downloaded information as objects compatible with the objects defined by the User-User API. (The choice of download or IIOP protocols is embedded in the object's IOR, so the means of access is transparent to the client application.)Switched Digital Broadcast-Channel Change Protocol (SDB/CCP)Enables a client to remotely switch from channel to channel in a broadcast environment. Used to attach a client to a (CFS) or other broadcast feed. Sometimes used in pay-per-view. An implementation does not always need all of these protocols. Almost all implementations in the real world use a subset. (en)
- En inglés "Digital Storage Media Command and Control" (DSM-CC). Se trata de un marco de desarrollo para controlar los canales asociados a los flujos de datos de tipo MPEG-1 y MPEG-2 y utiliza un modelo cliente-servidor sobre una red subyacente. DSM-CC puede trabajar con la nueva generación de paquetes de red mediante protocolos como RSVP, RTSP, RTP y SCP. Aunque DSM-CC está generalmente relacionado con distribución de video (bien vía satélite o vía terrestre) y con contenido interactivo, también se usa entre servidores y clientes de audio. La arquitectura se divide en tres partes diferenciadas: el cliente, el servidor, que ofrece los contenidos y los servicios al dicho cliente, y el gestor de recursos y sesiones (SRM), que se encarga de localizar y gestionar los recursos de la red (tales como canales, ancho de banda y las direcciones Ip). Tanto el cliente como el servidor son, a su vez, “clientes” del SRM, responsable de crear una plataforma y asegurar las comunicaciones entre ellos, y construir así, sistemas de distribución mediante un acceso a los contenidos de tipo P2P (Peer to peer). Esta especificación se puede implementar con diferentes configuraciones, incluyendo o no determinadas características. Generalmente, se definen perfiles permitiendo que los sistemas que los utilicen puedan interoperar.DSM-CC define cinco protocolos distintos: (es)
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