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Checking references for intended status: Informational ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 4582 (Obsoleted by RFC 8855) Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 CLUE WG A. Romanow 3 Internet-Draft Cisco 4 Intended status: Informational S. Botzko 5 Expires: December 22, 2011 M. Duckworth 6 Polycom 7 R. Even, Ed. 8 Huawei Technologies 9 T. Eubanks 10 Iformata Communications 11 June 20, 2011 13 Use Cases for Telepresence Multi-streams 14 draft-ietf-clue-telepresence-use-cases-00.txt 16 Abstract 18 Telepresence conferencing systems seek to create the sense of really 19 being present. A number of techniques for handling audio and video 20 streams are used to create this experience. When these techniques 21 are not similar, interoperability between different systems is 22 difficult at best, and often not possible. Conveying information 23 about the relationships between multiple streams of media would allow 24 senders and receivers to make choices to allow telepresence systems 25 to interwork. This memo describes the most typical and important use 26 cases for sending multiple streams in a telepresence conference. 28 Status of this Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on December 22, 2011. 45 Copyright Notice 47 Copyright (c) 2011 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 2. Telepresence Scenarios Overview . . . . . . . . . . . . . . . 3 64 3. Use Case Scenarios . . . . . . . . . . . . . . . . . . . . . . 6 65 3.1. Point to point meeting: symmetric . . . . . . . . . . . . 6 66 3.2. Point to point meeting: asymmetric . . . . . . . . . . . . 7 67 3.3. Multipoint meeting . . . . . . . . . . . . . . . . . . . . 9 68 3.4. Presentation . . . . . . . . . . . . . . . . . . . . . . . 10 69 3.5. Heterogeneous Systems . . . . . . . . . . . . . . . . . . 11 70 3.6. Multipoint Education Usage . . . . . . . . . . . . . . . . 12 71 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13 72 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 73 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 74 7. Informative References . . . . . . . . . . . . . . . . . . . . 14 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 77 1. Introduction 79 Telepresence applications try to provide a "being there" experience 80 for conversational video conferencing. Often this telepresence 81 application is described as "immersive telepresence" in order to 82 distinguish it from traditional video conferencing, and from other 83 forms of remote presence not related to conversational video 84 conferencing, such as avatars and robots. The salient 85 characteristics of telepresence are often described as: full-sized, 86 immersive video, preserving interpersonal interaction and allowing 87 non-verbal communication. 89 Although telepresence systems are based on open standards such as RTP 90 [RFC3550], SIP [RFC3261] , H.264, and the H.323 suite of protocols, 91 they cannot easily interoperate with each other without operator 92 assistance and expensive additional equipment which translates from 93 one vendor to another. A standard way of describing the multiple 94 streams constituting the media flows and the fundamental aspects of 95 their behavior, would allow telepresence systems to interwork. 97 This draft presents a set of use cases describing typical scenarios. 98 Requirements will be derived from these use cases in a separate 99 document. The use cases are described from the viewpoint of the 100 users. They are illustrative of the user experience that needs to be 101 supported. It is possible to implement these use cases in a variety 102 of different ways. 104 Many different scenarios need to be supported. Our strategy in this 105 document is to describe in detail the most common and basic use 106 cases. These will cover most of the requirements. Additional 107 scenarios that bring new features and requirements will be added. 109 We look at telepresence conferences that are point-to-point and 110 multipoint. In some settings, the number of displays is similar at 111 all sites, in others, the number of displays differs at different 112 sites. Both cases are considered. Also included is a use case 113 describing display of presentation or content. 115 The document structure is as follows:Section 2 gives an overview of 116 the scenarios, and Section 3 describes use cases. 118 2. Telepresence Scenarios Overview 120 This section describes the general characteristics of the use cases 121 and what the scenarios are intended to show. The typical setting is 122 a business conference, which was the initial focus of telepresence. 123 Recently consumer products are also being developed. We specifically 124 do not include in our scenarios the infrastructure aspects of 125 telepresence, such as room construction, layout and decoration. 127 Telepresence systems are typically composed of one or more video 128 cameras and encoders and one or more display monitors of large size 129 (around 60"). Microphones pick up sound and audio codec(s)produce 130 one or more audio streams. The cameras used to present the 131 telepresence users we will call participant cameras (and likewise for 132 displays). There may also be other cameras, such as for document 133 display. These will be referred to as presentation or content 134 cameras, which generally have different formats, aspect ratios, and 135 frame rates from the participant cameras. The presentation videos 136 may be shown on participant screen, or on auxiliary display screens. 137 A user's computer may also serve as a virtual content camera, 138 generating an animation or playing back a video for display to the 139 remote participants. 141 We describe such a telepresence system as sending M video streams, N 142 audio streams, and D content streams to the remote system(s). (Note 143 that the number of audio streams is generally not the same as the 144 number of video streams.) 146 The fundamental parameters describing today's typical telepresence 147 scenario include: 149 1. The number of participating sites 151 2. The number of visible seats at a site 153 3. The number of cameras 155 4. The number of audio channels 157 5. The screen size 159 6. The display capabilities - such as resolution, frame rate, 160 aspect ratio 162 7. The arrangement of the displays in relation to each other 164 8. Similar or dissimilar number of primary screens at all sites 166 9. Type and number of presentation displays 168 10. Multipoint conference display strategies - for example, the 169 camera-to-display mappings may be static or dynamic 171 11. The camera viewpoint 173 12. The cameras fields of view and how they do or do not overlap 175 The basic features that give telepresence its distinctive 176 characteristics are implemented in disparate ways in different 177 systems. Currently Telepresence systems from diverse vendors 178 interoperate to some extent, but this is not supported in a standards 179 based fashion. Interworking requires that translation and 180 transcoding devices be included in the architecture. Such devices 181 increase latency, reducing the quality of interpersonal interaction. 182 Use of these devices is often not automatic; it frequently requires 183 substantial manual configuration and a detailed understanding of the 184 nature of underlying audio and video streams. This state of affairs 185 is not acceptable for the continued growth of telepresence - we 186 believe telepresence systems should have the same ease of 187 interoperability as do telephones. 189 There is no agreed upon way to adequately describe the semantics of 190 how streams of various media types relate to each other. Without a 191 standard for stream semantics to describe the particular roles and 192 activities of each stream in the conference, interoperability is 193 cumbersome at best. 195 In a multiple screen conference, the video and audio streams sent 196 from remote participants must be understood by receivers so that they 197 can be presented in a coherent and life-like manner. This includes 198 the ability to present remote participants at their true size for 199 their apparent distance, while maintaining correct eye contact, 200 gesticular cues, and simultaneously providing a spatial audio sound 201 stage that is consistent with the video presentation. 203 The receiving device that decides how to display incoming information 204 needs to understand a number of variables such as the spatial 205 position of the speaker, the field of view of the cameras; the camera 206 zoom; which media stream is related to each of the displays; etc. It 207 is not simply that individual streams must be adequately described, 208 to a large extent this already exists, but rather that the semantics 209 of the relationships between the streams must be communicated. Note 210 that all of this is still required even if the basic aspects of the 211 streams, such as the bit rate, frame rate, and aspect ratio, are 212 known. Thus, this problem has aspects considerably beyond those 213 encountered in interoperation of single-node video conferencing 214 units. 216 3. Use Case Scenarios 218 Our development of use cases is staged, initially focusing on what is 219 currently typical and important. Use cases that add future or more 220 specialized features will be added later as needed. Also, there are 221 a number of possible variants for these use cases, for example, the 222 audio supported may differ at the end points (such as mono or stereo 223 versus surround sound), etc. 225 The use cases here are intended to be hierarchical, in that the 226 earlier use cases describe basics of telepresence that will also be 227 used by later use cases. 229 Many of these systems offer a full conference room solution where 230 local participants sit on one side of a table and remote participants 231 are displayed as if they are sitting on the other side of the table. 232 The cameras and screens are typically arranged to provide a panoramic 233 (left to right from the local user view point) view of the remote 234 room. 236 The sense of immersion and non-verbal communication is fostered by a 237 number of technical features, such as: 239 1. Good eye contact, which is achieved by careful placement of 240 participants, cameras and screens. 242 2. Camera field of view and screen sizes are matched so that the 243 images of the remote room appear to be full size. 245 3. The left side of each room is presented on the right display at 246 the far end; similarly the right side of the room is presented on 247 the left display. The effect of this is that participants of 248 each site appear to be sitting across the table from each other. 249 If two participants on the same site glance at each other, all 250 participants can observe it. Likewise, if a participant on one 251 site gestures to a participant on the other site, all 252 participants observe the gesture itself and the participants it 253 includes. 255 3.1. Point to point meeting: symmetric 257 In this case each of the two sites has an identical number of 258 screens, with cameras having fixed fields of view, and one camera for 259 each screen. The sound type is the same at each end. As an example, 260 there could be 3 cameras and 3 screens in each room, with stereo 261 sound being sent and received at each end. 263 The important thing here is that each of the 2 sites has the same 264 number of screens. Each screen is paired with a corresponding 265 camera. Each camera / screen pair is typically connected to a 266 separate codec, producing a video encoded stream for transmission to 267 the remote site, and receiving a similarly encoded stream from the 268 remote site. 270 Each system has one or multiple microphones for capturing audio. In 271 some cases, stereophonic microphones are employed. In other systems, 272 a microphone may be placed in front of each participant (or pair of 273 participants). In typical systems all the microphones are connected 274 to a single codec that sends and receives the audio streams as either 275 stereo or surround sound. The number of microphones and the number 276 of audio channels are often not the same as the number of cameras. 277 Also the number of microphones is often not the same as the number of 278 loudspeakers. 280 The audio may be transmitted as multi-channel (stereo/surround sound) 281 or as distinct and separate monophonic streams. Audio levels should 282 be matched, so the sound levels at both sites are identical. 283 Loudspeaker and microphone placements are chosen so that the sound 284 "stage" (orientation of apparent audio sources) is coordinated with 285 the video. That is, if a participant on one site speaks, the 286 participants at the remote site perceive her voice as originating 287 from her visual image. In order to accomplish this, the audio needs 288 to be mapped at the received site in the same fashion as the video. 289 That is, audio received from the right side of the room needs to be 290 output from loudspeaker(s) on the left side at the remote site, and 291 vice versa. 293 3.2. Point to point meeting: asymmetric 295 In this case, each site has a different number of screens and cameras 296 than the other site. The important characteristic of this scenario 297 is that the number of displays is different between the two sites. 298 This creates challenges which are handled differently by different 299 telepresence systems. 301 This use case builds on the basic scenario of 3 screens to 3 screens. 302 Here, we use the common case of 3 screens and 3 cameras at one site, 303 and 1 screen and 1 camera at the other site, connected by a point to 304 point call. The display sizes and camera fields of view at both 305 sites are basically similar, such that each camera view is designed 306 to show two people sitting side by side. Thus the 1 screen room has 307 up to 2 people seated at the table, while the 3 screen room may have 308 up to 6 people at the table. 310 The basic considerations of defining left and right and indicating 311 relative placement of the multiple audio and video streams are the 312 same as in the 3-3 use case. However, handling the mismatch between 313 the two sites of the number of displays and cameras requires more 314 complicated maneuvers. 316 For the video sent from the 1 camera room to the 3 screen room, 317 usually what is done is to simply use 1 of the 3 displays and keep 318 the second and third displays inactive, or put up the date, for 319 example. This would maintain the "full size" image of the remote 320 side. 322 For the other direction, the 3 camera room sending video to the 1 323 screen room, there are more complicated variations to consider. Here 324 are several possible ways in which the video streams can be handled. 326 1. The 1 screen system might simply show only 1 of the 3 camera 327 images, since the receiving side has only 1 screen. Two people 328 are seen at full size, but 4 people are not seen at all. The 329 choice of which 1 of the 3 streams to display could be fixed, or 330 could be selected by the users. It could also be made 331 automatically based on who is speaking in the 3 screen room, such 332 that the people in the 1 screen room always see the person who is 333 speaking. If the automatic selection is done at the sender, the 334 transmission of streams that are not displayed could be 335 suppressed, which would avoid wasting bandwidth. 337 2. The 1 screen system might be capable of receiving and decoding 338 all 3 streams from all 3 cameras. The 1 screen system could then 339 compose the 3 streams into 1 local image for display on the 340 single screen. All six people would be seen, but smaller than 341 full size. This could be done in conjunction with reducing the 342 image resolution of the streams, such that encode/decode 343 resources and bandwidth are not wasted on streams that will be 344 downsized for display anyway. 346 3. The 3 screen system might be capable of including all 6 people in 347 a single stream to send to the 1 screen system. For example, it 348 could use PTZ (Pan Tilt Zoom) cameras to physically adjust the 349 cameras such that 1 camera captures the whole room of six people. 350 Or it could recompose the 3 camera images into 1 encoded stream 351 to send to the remote site. These variations also show all six 352 people, but at a reduced size. 354 4. Or, there could be a combination of these approaches, such as 355 simultaneously showing the speaker in full size with a composite 356 of all the 6 participants in smaller size. 358 The receiving telepresence system needs to have information about the 359 content of the streams it receives to make any of these decisions. 361 If the systems are capable of supporting more than one strategy, 362 there needs to be some negotiation between the two sites to figure 363 out which of the possible variations they will use in a specific 364 point to point call. 366 3.3. Multipoint meeting 368 In a multipoint telepresence conference, there are more than two 369 sites participating. Additional complexity is required to enable 370 media streams from each participant to show up on the displays of the 371 other participants. 373 Clearly, there are a great number of topologies that can be used to 374 display the streams from multiple sites participating in a 375 conference. 377 One major objective for telepresence is to be able to preserve the 378 "Being there" user experience. However, in multi-site conferences it 379 is often (in fact usually) not possible to simultaneously provide 380 full size video, eye contact, common perception of gestures and gaze 381 by all participants. Several policies can be used for stream 382 distribution and display: all provide good results but they all make 383 different compromises. 385 One common policy is called site switching. Let's say the speaker is 386 at site A and everyone else is at a "remote" site. When the room at 387 site A shown, all the camera images from site A are forwarded to the 388 remote sites. Therefore at each receiving remote site, all the 389 screens display camera images from site A. This can be used to 390 preserve full size image display, and also provide full visual 391 context of the displayed far end, site A. In site switching, there is 392 a fixed relation between the cameras in each room and the displays in 393 remote rooms. The room or participants being shown is switched from 394 time to time based on who is speaking or by manual control, e.g., 395 from site A to site B. 397 Segment switching is another policy choice. Still using site A as 398 where the speaker is, and "remote" to refer to all the other sites, 399 in segment switching, rather than sending all the images from site A, 400 only the speaker at site A is shown. The camera images of the 401 current speaker and previous speakers (if any) are forwarded to the 402 other sites in the conference. Therefore the screens in each site 403 are usually displaying images from different remote sites - the 404 current speaker at site A and the previous ones. This strategy can 405 be used to preserve full size image display, and also capture the 406 non-verbal communication between the speakers. In segment switching, 407 the display depends on the activity in the remote rooms - generally, 408 but not necessarily based on audio / speech detection). 410 A third possibility is to reduce the image size so that multiple 411 camera views can be composited onto one or more screens. This does 412 not preserve full size image display, but provides the most visual 413 context (since more sites or segments can be seen). Typically in 414 this case the display mapping is static, i.e., each part of each room 415 is shown in the same location on the display screens throughout the 416 conference. 418 Other policies and combinations are also possible. For example, 419 there can be a static display of all screens from all remote rooms, 420 with part or all of one screen being used to show the current speaker 421 at full size. 423 3.4. Presentation 425 In addition to the video and audio streams showing the participants, 426 additional streams are used for presentations. 428 In systems available today, generally only one additional video 429 stream is available for presentations. Often this presentation 430 stream is half-duplex in nature, with presenters taking turns. The 431 presentation video may be captured from a PC screen, or it may come 432 from a multimedia source such as a document camera, camcorder or a 433 DVD. In a multipoint meeting, the presentation streams for the 434 currently active presentation are always distributed to all sites in 435 the meeting, so that the presentations are viewed by all. 437 Some systems display the presentation video on a screen that is 438 mounted either above or below the three participant screens. Other 439 systems provide monitors on the conference table for observing 440 presentations. If multiple presentation monitors are used, they 441 generally display identical content. There is considerable variation 442 in the placement, number, and size or presentation displays. 444 In some systems presentation audio is pre-mixed with the room audio. 445 In others, a separate presentation audio stream is provided (if the 446 presentation includes audio). 448 In H.323 systems, H.239 is typically used to control the video 449 presentation stream. In SIP systems, similar control mechanisms can 450 be provided using BFCP [RFC4582] for presentation token. These 451 mechanisms are suitable for managing a single presentation stream. 453 Although today's systems remain limited to a single video 454 presentation stream, there are obvious uses for multiple presentation 455 streams. 457 1. Frequently the meeting convener is following a meeting agenda, 458 and it is useful for her to be able to show that agenda to all 459 participants during the meeting. Other participants at various 460 remote sites are able to make presentations during the meeting, 461 with the presenters taking turns. The presentations and the 462 agenda are both shown, either on separate displays, or perhaps 463 re-scaled and shown on a single display. 465 2. A single multimedia presentation can itself include multiple 466 video streams that should be shown together. For instance, a 467 presenter may be discussing the fairness of media coverage. In 468 addition to slides which support the presenter's conclusions, she 469 also has video excerpts from various news programs which she 470 shows to illustrate her findings. She uses a DVD player for the 471 video excerpts so that she can pause and reposition the video as 472 needed. Another example is an educator who is presenting a 473 multi-screen slide show. This show requires that the placement 474 of the images on the multiple displays at each site be 475 consistent. 477 There are many other examples where multiple presentation streams are 478 useful. 480 3.5. Heterogeneous Systems 482 It is common in meeting scenarios for people to join the conference 483 from a variety of environments, using different types of endpoint 484 devices. In a multi-screen immersive telepresence conference may 485 include someone on a PC-based video conferencing system, a 486 participant calling in by phone, and (soon) someone on a handheld 487 device. 489 What experience/view will each of these devices have? 491 Some may be able to handle multiple streams and others can handle 492 only a single stream. (We are not here talking about legacy systems, 493 but rather systems built to participate in such a conference, 494 although they are single stream only.) In a single video stream , 495 the stream may contain one or more compositions depending on the 496 available screen space on the device. In most cases a transcoding 497 intermediate device will be relied upon to produce a single stream, 498 perhaps with some kind of continuous presence. 500 Bit rates will vary - the handheld and phone having lower bit rates 501 than PC and multi-screen systems. 503 Layout is accomplished according to different policies. For example, 504 a handheld and PC may receive the active speaker stream. The 505 decision can either be made explicitly by the receiver or by the 506 sender if it can receive some kind of rendering hint. The same is 507 true for audio -- i. e., that it receives a mixed stream or a number 508 of the loudest speakers if mixing is not available in the network. 510 For the software conferencing participant, the user's experience 511 depends on the application. It could be single stream, similar to a 512 handheld but with a bigger screen. Or, it could be multiple streams, 513 similar to an immersive but with a smaller screen. Control for 514 manipulation of streams can be local in the software application, or 515 in another location and sent to the application over the network. 517 The handheld device is the most extreme. How will that participant 518 be viewed and heard? it should be an equal participant, though the 519 bandwidth will be significantly less than an immersive system. A 520 receiver may choose to display output coming from a handheld 521 differently based on the resolution, but that would be the case with 522 any low resolution video stream, e. g., from a powerful PC on a bad 523 network. 525 The handheld will send and receive a single video stream, which could 526 be a composite or a subset of the conference. The handheld could say 527 what it wants or could accept whatever the sender (conference server 528 or sending endpoint) thinks is best. The handheld will have to 529 signal any actions it wants to take the same way that immersive 530 signals. 532 3.6. Multipoint Education Usage 534 The importance of this example is that the multiple video streams are 535 not used to create an immersive conferencing experience with 536 panoramic views at all the site. Instead the multiple streams are 537 dynamically used to enable full participation of remote students in a 538 university class. In some instances the same video stream is 539 displayed on multiple displays in the room, in other instances an 540 available stream is not displayed at all. 542 The main site is a university auditorium which is equipped with three 543 cameras. One camera is focused on the professor at the podium. A 544 second camera is mounted on the wall behind the professor and 545 captures the class in its entirety. The third camera is co-located 546 with the second, and is designed to capture a close up view of a 547 questioner in the audience. It automatically zooms in on that 548 student using sound localization. 550 Although the auditorium is equipped with three cameras, it is only 551 equipped with two screens. One is a large screen located at the 552 front so that the class can see it. The other is located at the rear 553 so the professor can see it. When someone asks a question, the front 554 screen shows the questioner. Otherwise it shows the professor 555 (ensuring everyone can easily see her). 557 The remote sites are typical immersive telepresence room with three 558 camera/screen pairs. 560 All remote sites display the professor on the center screen at full 561 size. A second screen shows the entire classroom view when the 562 professor is speaking. However, when a student asks a question, the 563 second screen shows the close up view of the student at full size. 564 Sometimes the student is in the auditorium; sometimes the speaking 565 student is at another remote site. The remote systems never display 566 the students that are actually in that room. 568 If someone at the remote site asks a question, then the screen in the 569 auditorium will show the remote student at full size (as if they were 570 present in the auditorium itself). The display in the rear also 571 shows this questioner, allowing the professor to see and respond to 572 the student without needing to turn her back on the main class. 574 When no one is asking a question, the screen in the rear briefly 575 shows a full-room view of each remote site in turn, allowing the 576 professor to monitor the entire class (remote and local students). 577 The professor can also use a control on the podium to see a 578 particular site - she can choose either a full-room view or a single 579 camera view. 581 Realization of this use case does not require any negotiation between 582 the participating sites. Endpoint devices (and an MCU if present) - 583 need to know who is speaking and what video stream includes the view 584 of that speaker. The remote systems need some knowledge of which 585 stream should be placed in the center. The ability of the professor 586 to see specific sites (or for the system to show all the sites in 587 turn) would also require the auditorium system to know what sites are 588 available, and to be able to request a particular view of any site. 589 Bandwidth is optimized if video that is not being shown at a 590 particular site is not distributed to that site. 592 4. Acknowledgements 594 The draft has benefitted from input from a number of people including 595 Alex Eleftheriadis, Tommy Andre Nyquist, Mark Gorzynski, Charles 596 Eckel, Nermeen Ismail, Mary Barnes, Pascal Buhler, Jim Cole. 598 5. IANA Considerations 600 This document contains no IANA considerations. 602 6. Security Considerations 604 While there are likely to be security considerations for any solution 605 for telepresence interoperability, this document has no security 606 considerations. 608 7. Informative References 610 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 611 A., Peterson, J., Sparks, R., Handley, M., and E. 612 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 613 June 2002. 615 [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. 616 Jacobson, "RTP: A Transport Protocol for Real-Time 617 Applications", STD 64, RFC 3550, July 2003. 619 [RFC4582] Camarillo, G., Ott, J., and K. Drage, "The Binary Floor 620 Control Protocol (BFCP)", RFC 4582, November 2006. 622 Authors' Addresses 624 Allyn Romanow 625 Cisco 626 San Jose, CA 95134 627 US 629 Email: allyn@cisco.com 631 Stephen Botzko 632 Polycom 633 Andover, MA 01810 634 US 636 Email: stephen.botzko@polycom.com 637 Mark Duckworth 638 Polycom 639 Andover, MA 01810 640 US 642 Email: mark.duckworth@polycom.com 644 Roni Even (editor) 645 Huawei Technologies 646 Tel Aviv, 647 Israel 649 Email: even.roni@huawei.com 651 Marshall Eubanks 652 Iformata Communications 653 Dayton, Ohio 45402 654 US 656 Email: marshall.eubanks@ilformata.com