Digital storage media command and control (DSM-CC) is a toolkit for developing control channels associated with
MPEG-1
MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making ...
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
Multiplex may refer to:
* Multiplex (automobile), a former American car make
* Multiplex (comics), a DC comic book supervillain
* Multiplex (company), a global contracting and development company
* Multiplex (assay), a biological assay which measu ...
or independently if needed).
DSM-CC may be used for controlling the video reception, providing features normally found on Video Cassette Recorders (
VCR
A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and analog video from broadcast television or other source on a removable, magnetic tape videocassette, and can play back the recording. ...
) (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
ISO is the most common abbreviation for the International Organization for Standardization.
ISO or Iso may also refer to: Business and finance
* Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007
* Iso ...
/
IEC
The International Electrotechnical Commission (IEC; in French: ''Commission électrotechnique internationale'') is an international standards organization that prepares and publishes international standards for all electrical, electronic and r ...
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
RSVP is an initialism derived from the French phrase ''Répondez s'il vous plaît'', literally meaning "Respond, if you please", or just "Please respond", to require confirmation of an invitation. The initialism "RSVP" is no longer used much in ...
,
RTSP
The Real Time Streaming Protocol (RTSP) is an application-level network protocol designed for multiplexing and packetizing multimedia transport streams (such as interactive media, video and audio) over a suitable transport protocol. RTSP i ...
,
RTP and
SCP
SCP may refer to:
Organizations Political parties
* Soviet Communist Party, the leading political party in the former Soviet Union
* Syrian Communist Party
* Sudanese Communist Party
* Scottish Christian Party
Companies
* Seattle Computer Produ ...
. Although DSM-CC is usually associated with video delivery (via
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...
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
Client(s) or The Client may refer to:
* Client (business)
* Client (computing), hardware or software that accesses a remote service on another computer
* Customer or client, a recipient of goods or services in return for monetary or other valuabl ...
, the
server
Server may refer to:
Computing
*Server (computing), a computer program or a device that provides functionality for other programs or devices, called clients
Role
* Waiting staff, those who work at a restaurant or a bar attending customers and su ...
, and the
session resource manager (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
Channel, channels, channeling, etc., may refer to:
Geography
* Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water.
Australia
* Channel Country, region of outback Austral ...
,
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
, and
network address
A network address is an identifier for a node or host on a telecommunications network. Network addresses are designed to be unique identifiers across the network, although some networks allow for local, private addresses, or locally administer ...
es.) By combining server and client components together onto the same platforms,
peer-to-peer
Peer-to-peer (P2P) computing or networking is a distributed application architecture that partitions tasks or workloads between peers. Peers are equally privileged, equipotent participants in the network. They are said to form a 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-User: Allows 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
The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between s ...
. Objects are accessed using the internet inter-ORB protocol (
IIOP
In distributed computing, General Inter-ORB Protocol (GIOP) is the message protocol by which object request brokers (ORBs) communicate in CORBA. Standards associated with the protocol are maintained by the Object Management Group (OMG). The curre ...
), with some optional extensions. Two subsets, "core" and "extended", are defined. In the model, some clients may also load content onto the server.
;User-Network: There 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 profiles: The 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.
;Download: Several 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
download carousel 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
continuous-feed session (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.
Extension
Delivery Multimedia Integration Framework (DMIF) expands upon the MPEG-2 DSM-CC standard (ISO/IEC 13818-6:1998) to enable the convergence of interactive, broadcast and conversational multimedia into one specification which will be applicable to set tops, desktops and mobile stations. The DSM-CC work was extended as part of the ISO/IEC 14496-6 (
MPEG-4 Part 6), with the ''DSM-CC Multimedia Integration Framework (DMIF)''.
References
External links
ISO/IEC 13818-6:1998 - Information technology -- Generic coding of moving pictures and associated audio information - Part 6: Extensions for DSM-CCHow To Become An Expert In DSM-CC- DSM-CC from the perspective of IDTV
OpenCaster free GPL licensed software for transport stream broadcasting supporting DSM-CC
{{MPEG
Audio codecs
Video codecs
MPEG