1、 ANSI/CEA Standard Remote Control Command Pass-through Standard for Home Networking ANSI/CEA-931-C R-2012 December 2007 NOTICE Consumer Electronics Association (CEA) Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings
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9、ion of this document by any means. Organizations may obtain permission to reproduce a limited number of copies by entering into a license agreement. Requests to reproduce text, data, charts, figures or other material should be made to CEA. (Formulated under the cognizance of the CEA R7 Home Networks
10、 Committee.) Published by CONSUMER ELECTRONICS ASSOCIATION 2012 Technology others take in A/V data and process it for output or 1While the commands are specified here in terms of protocols built on the IEEE-1394 standard and on HTTP over IP, the commands could be transported via other standards incl
11、uding other physical layer protocols as they travel from source device to receiving device in the network. 2IR Blasters involve infrared emitters on or connected to one device that are programmed to emit infrared pulses emulating the remote control codes recognized by another device. The emitter is
12、placed in proximity of the device to be controlled. Functions such as tuning and operation of a recording device can be performed using an IR Blaster approach. 1 CEA-931-Cdisplay (visual or audio). Some devices in the network may function only to control different devices in the network. The current
13、 standard specifies certain commands sent from one A/V device to another in the home network that represents the kinds of functions that are so basic they are often associated with dedicated keys on the remote control unit. The kinds of functions considered here include such things as power on/off,
14、channel up/down, volume up/down, direct entry of channel numbers, and media playback and record controls (play, pause, stop, fast forward and rewind, record). Operations considered for inclusion here communicate simple user intent across the network, ideally in response to a single, simple user acti
15、on. The operation is one of a set of operations that enable a remote control associated with any device on the network with video display capability to perform basic functions on any device in the network. In the protocols described in this standard, the controller device (the one issuing the comman
16、d) can know whether the target device has implemented the particular function, and whether it was able to perform the indicated action. In some situations, it is up to the user to know whether the action that was performed was actually the desired action, for example, by visual or audio feedback. Th
17、e functions specified here have an effect on the target device that is defined by the manufacturer of that device. As an example, the “POWER” control function corresponds to the behavior that would occur if the user hit the Power key on the target devices native remote. A particular target device ma
18、y use the Power key as “enter low-power standby” or it may be a power toggle. These functions are used in conjunction with visual feedback to the user, for example via an on-screen display or front panel. A source device can create on-screen displays by embedding text and graphics into its video out
19、put. Or, if CEA-775-A 6 graphics are used, the on-screen display can be created from bitmaps delivered across the 1394 bus. This standard does not specify the method a controller device might use to determine which target device on the network should be the recipient of a given command. Typically fo
20、r example, controllers would send video playback-related command to the networked device currently selected as the video source and audio-related commands (mute, volume control) to the device designated as the audio subsystem associated with that source device. As several different a/v devices in th
21、e room may receive infrared pulses from a given remote control unit, and a controller device may translate these pulses into a network command, a given device may receive both a network-delivered command and that same command in the form of infrared pulses. This standard does not specify design requ
22、irements to avoid command duplication in such cases3. In summary, this standard involves network-communicated remote control unit (RCU) commands that convey a simple user intent, usually in response to a single, simple user action; does not specify specific behavior required of the target device in
23、response to any given function, although guidance on expected behavior is provided (exact behavior is at the discretion of the device manufacturer); and may be used to build a remote control unit that is capable of operating any compliant device in the home network. 3It is recommended that in the ca
24、se a target device determines that the same command has been received both via infrared pulses and via the network, it should reply to the PASS-THROUGH command with the ACCEPTED response (even if the infrared pulses arrived first). 2 CEA-931-C2.1 Example Scenarios Figure 1 shows an example network w
25、here the DTV acts as the “controller” device. In this simple scenario, the user has selected the Personal Video Recorder (PVR) on the right as the input source. Using the protocol specified in this standard, a PLAY key on the DTV remote is interpreted by the DTV as indicating a desire on the part of
26、 the user to start playback of the recorded or paused video content. The DTV recognizes the IR pulses, which may be emitted using a proprietary format, as being the PLAY key. The DTV then creates a command delivered on the Home Network backbone to the PVR, indicating “perform your PLAY operation.” P
27、VRDTVRCURoom to RoomInterface (opt.)NetworkInterconnectIR pulses(proprietaryformat)“PLAY”command“PLAY”keyFigure 1 Example Operational Scenario The figure shows that the PVR may or may not be in the same room as the DTV receiveroptionally, a room-to-room network interface may separate the two. If the
28、 DTV and PVR are in the same room, the protocol defined in this standard offers the features of a “universal remote” in that an RCU from one manufacturer can control a device made by another manufacturer. The conversion between proprietary IR pulse formats and a standard command on the bus makes thi
29、s possible. Figure 2 illustrates commands used to interact with and control a source device via a Graphical User Interface the source provides over video or via bitmaps per CEA-775-A 6. A GUI generated within the source device could be MPEG-2 encoded and delivered across the network bus as compresse
30、d video, or CEA-775-A bitmaps could be supplied for the DTV to mix with video. The user can interact with the source devices GUI using the DTVs RCU as long as the GUI uses only the basic navigational keys: the numeric keys (0-9), the arrow keys (up, down, left, right), Enter (or “OK”), and Cancel, a
31、nd those keys are provided on the DTV remote. 3 CEA-931-CDevice UnderControlDTVRCUIR pulses(proprietaryformat)GUI in VIdeo(or EIA-775A bitmaps)commands0-9, , Enter, CancelFigure 2 Example Navigation using GUI in Video 2.2 Revision History Revision A incorporates Version 1.21 of the AV/C Panel Subuni
32、t specification, which added the operation_id values corresponding to “deterministic functions,” values 6016through 6A16. Annex A includes this update of the AV/C document. Informative Section 4.5 in the present revision discusses deterministic functions. Section 4 was expanded to describe requireme
33、nts for both target and controller devices. Support of the AV/C POWER control commands is now mandatory. Informative Annex B was added to describe an IR Blaster scenario and an example application of CEA-931 in a digital networked environment. Revision B defines the CEA-931 URI and specifies normati
34、ve requirements for devices supporting HTTP 1.1 over IP. This fully backward-compatible extension to CEA-931-A is designed to allow devices networked via IP protocols to communicate the same set of RCU key codes and deterministic functions as those defined for the AV/C-based method. Section B.3 in A
35、nnex B was added to illustrate an example usage scenario for this option. Revision C adds references to L3 Bridged 1394/COAX and FCP over IPv4 2, AV/C Panel Subunit specification 1.23 3. In addition Hostport and path_segments was added to the HTTP command sequence to allow for addressing logical uni
36、ts as defined in CEA-2027-B 9. Added optional allowance for the procedure extension type and the connection ID to appear in the HTTP command sequence (additional examples were added in Section 4.2.6). 4 CEA-931-C3. GENERAL 3.1 Normative References The following standards contain provisions that, thr
37、ough reference in this text, constitute normative provisions of the appropriate sections of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibil
38、ity of applying for the most recent editions of the standards listed in Section 3.1.1. 3.1.1 Normative Reference List 1. AV/C Digital Interface Command Set General Specification, Version 4.1, TA Document 2002012, 1394 Trade Association, December 11, 2001. 2. IEEE 1394 Bridged over Coaxial Cable Part
39、 3: FCP and CMP over IPv4, TA Document 2006021, Revision d0.5, 1394 Trade Association, March 19, 2007. 3. AV/C Panel Subunit Specification 1.23, TA Document 2007001, 1394Trade Association, January 2007. 4. RFC 2616, Hypertext Transfer Protocol HTTP 1.1, The Internet Society, June 1999. 5. RFC 2396,
40、Uniform Resource Identifiers (URI): Generic Syntax, The Internet Society, August 1998. 3.1.2 Normative Reference Acquisition 1394 Trade Association Documents Contact the 1394 Trade Association, 1111 South Main Street, Suite 100, Grapevine, TX, USA; Phone: 817-410-5750; Fax: 817-410-5752; Internet: h
41、ttp:/www.1394ta.org. RFC Documents Contact the World Wide Web Consortia (W3C), 32 Vassar Street, Room 32-G515, Cambridge, MA 02139 USA; Phone: 617-253-2613; Fax: 617.258.5999; Internet www.w3.org. Contact the Internet Society (ISOC), 1775 Wiehle Ave., Suite 102, Reston, VA 20190 USA; Phone: 703-326-
42、9880; Fax: 703-326-9881; Internet: www.isocisoc.org. 3.2 Informative References 3.2.1 Informative Reference List 6. CEA-775-A, DTV 1394 Interface Specification, April 2000. 7. CEA-775.1, Web-Enhanced DTV 1394 Interface Specification, March 2000. 8. ECMAScript Language Specification, Standard ECMA-26
43、2, 3rdEdition, December 1999. 9. CEA-2027-B, A User Interface Specification for Home Networks Using Web-Based Protocols, July 2007. 5 CEA-931-C3.2.2 Informative Reference Acquisition CEA Standards: Global Engineering Documents, World Headquarters, 15 Inverness Way East, Englewood, CO USA 80112-5776;
44、 Phone: 800-854-7179; Fax: 303-397-2740; Internet: http:/; E-mail: . ECMA Standards: ECMA International, 114 Rue du Rhne - CH-1204 Geneva Switzerland; Internet: http:/www.ecma-international.org. 3.3 Definitions For the purposes of this document, the following definitions apply. Controller As defined
45、 in 1, a device at a serial bus node that sends AV/C commands to control a remote AV/C target device. direct mode A data transfer mode of the Panel Subunit defined in 3. In direct mode, the Panel Subunit is responsible for creating the on-screen user interface based on information provided by the ta
46、rget device. User operations are processed in the controller device, and when a UI object (such as a button) is activated, that fact is communicated across the network bus to the target. For details, refer to Section 4.4 of 3. indirect mode A data transfer mode of the Panel Subunit defined in 3. All
47、ows the Panel Subunit to receive user manipulations but the Panel Subunit is not responsible for display of UI data on the controller screen. The GUI image might be transmitted to the display device as part of the video data transmitted from the target device (e.g. using EIA-799 bitmaps). The Panel
48、Subunit controller conveys user operations to the target by only AV/C PASS-THROUGH commands, and works simply like a remote commander of the target device. For details, refer to Section 4.5 of 3. Subunit A uniquely identifiable and addressable entity contained within a unit. The Panel Subunit is a t
49、ype of subunit defined in 3. target As defined in 1, a device at a serial bus node that receives and responds to AV/C commands from a remote controller device. Unit The instantiation of an AV/C device. A unit is addressable in a specific way using AV/C commands. A unit may contain zero or more subunits. 3.4 Symbols and Abbreviations ANSI American National Standards Institute A/V Audio/Video AV/C Audio/Video Control CEA Consumer Electronics Association DTV Digital Television 6 CEA-931-CDV Digital Vide
