AIMD (additive-increase, multiplicative-decrease),

AW001-PerkinsIX 5/14/03 2:01 PM Page 397 INDEX A ACK (acknowledgement) Use with RTP retransmission, 277 279 Use with TCP 292 294 ACM (Association for Computing Machinery), 26 Active content, security of, 382 additive-increase, multiplicativedecrease (AIMD), 293 294, 303 Admission control, congestion and, 288 ADUs (application data units), 52, 86-89 Advanced Encryption Standard (AES), 365, 375 Advertisement protocols, 62 AES (Advanced Encryption Standard), 365, 375 AH (Authentication Header), 379 380 AIMD (additive-increase, multiplicative-decrease), 293 294, 303 Algorithms audio error concealment. See Error concealment, audio audio format conversion, 149 audio mixing, 202 203 audio playout adaptation, 197 clock skew management, 176 180 encryption, 365 FEC. See FEC (forward error correction) IPSec, 380 jitter compensation, 185 TCP-friendly rate control, 300 305 video error concealment. See Error concealment, video video format conversion, 150 video playout adaptation, 198 AMR (Adaptive Multi-Rate) audio interleaving and, 250 loss-tolerant payload formats for, 87 partial checksums and, 274 275 AMR-WB (Adaptive Multi-Rate Wideband) audio, 250 APP (application-defined packets), RTCP, 98, 118 application data units (ADUs), 52 Application layer, OSI reference model, 18 Application-level authentication, 377 Application-level encryption, 362 363 Application-level framing, RTP design, 52 53 Application-specific multiplexing, 354 357 Applications data transport decisions, 52 GeRM, 352 353 header compression and, 334 336 TCP limitations for real-time applications, 47 ARPANET, 4 Association for Computing Machinery (ACM), 26 397

AW001-PerkinsIX 5/14/03 2:01 PM Page 398 398 INDEX Asynchronous playout, 205 Atlantic Satellite Network (SATNET), 5 ATM (Asynchronous Transfer Mode), 355 Audio capture devices, 148 149 decoding compressed media, 204 206 distortion, 228 error concealment. See Error concealment, audio lack of congestion control standards for, 298 mixing, 201 204 packet size, 37 payload formats, 60, 80 81 playout point with silence suppression, 193 196 playout point without silence suppression, 196 197 quality measurements, 228 229 RTP timestamp and, 154 separating from video, 210 211 teleconferencing, 272 Audio redundancy coding, 266 272 effect on playout buffer, 182-183 limitations of, 271 overview of, 266 267 packet format, 267 271 use of, 272 Audio/Video networking early packet voice and video experiments, 4 5 Internet and, 5 7 ITU standards, 7 8 streaming A/V, 9 Audio/Video profile, 71-74 See also RTP profiles Audio/Video transport, 45 48 requirements in packet networks, 45 48 RTP standard, 55 use of TCP, 47 use of UDP, 46 47 Audio/Video Transport group, IETF, 10, 55, 342 343 Authentication, 376 380 firewalls and, 380 IPsec, 373, 378 380 levels applied at, 377 RTP standard, 377 SRTP, 378 types of, 376 377 Authentication Header (AH), 379 380 Average packet loss, IP networks, 26 29 B Bandwidth FEC impact on, 252 253 redundant encoding and, 270 RTCP reporting interval and, 129 RTCP implementation problems and, 141 142 session information variables and, 124 TCP probing available, 44 45 TCRTP and, 347 Bidirectional optimistic mode, ROHC, 330 Bidirectional reliable mode, ROHC, 330 Book references, 395 Bridges, as one-to-one translator, 91 Buffer overflow attacks, 382 383 Buffers audio mixing, 203 205 for error correction, 284 285 playout buffer, 166 delay due to TCP, 44 video playout, 206 207 Bundling RTP packets, 340 341 BYE (membership management), RTCP overview of, 116 117 packets, 98, 165 reconsideration, 139 140 C CAIDA (Cooperative Association for Internet Data Analysis), 26 Call control protocols, 10 Call setup protocols, 62 Canonical names. See CNAME (canonical names) Capture time, 152, 217

AW001-PerkinsIX 5/14/03 2:01 PM Page 399 INDEX 399 Capture-to-playout delay, receivers, 220 Cellular networks, performance characteristics, 40 Channel coding, 273 276 overview of, 273 partial checksum and, 273 274 reference picture selection, 275 276 Checksums effects on header compression, 335-336 in CRTP, 323-324, 326 in ROHC, 328 packet corruption and, 31 32 partial checksum in channel coding, 273 274 UDP, 43 Circuit emulation, 356 357 Clock skew, 34, 175 180 algorithms for managing, 176 180 compensation strategies, 175 estimating, 175 176 nonstationary skew, 179 packet send time vs. receive time, 171 playout calculation and, 174 Clocks See also Timestamps mapping RTP media clock to sender s reference clock, 164 media clock, 80-81 RTP timing model and, 154 155 synchronization of media streams, 211 214 CNAME (canonical name) IP addresses and, 120 linking audio and video streams, 165 mapping SSRC to, 82, 214 216 member identification by, 126 privacy and, 360 361 SDES items and, 112 113 Codecs (compression-decompression) audio, 149-150, 168, 300, 335 integrated with audio capture, 151 integrated with video capture, 151 interpolation of codec state, 241 layered coding and, 306 RTP standard and, 10 See also Payload Formats separating audio and video packets, 210 211 speech, 195 video, 150, 168, 300 Collision detection, SSRC, 82 Comfort noise, 233 Components, RTCP, 96 97 Compound packets, RTCP, 118 119 Compressed RTP. See CRTP (Compressed RTP) Compression. See also Codecs (compressiondecompression); Header compression audio capture and, 147 150 context, 200 CRTP, 323 326 decoding audio, 204 206 decoding video, 206 207 ROHC, 331 334 video capture and, 150 152 video predictive coding, 242 Conferences, reference resources, 391 395 Confidentiality encryption algorithms, 375 end-to-end encryption, 375 376 IPsec, 372 375 overview of, 362 363 RTP specification, 363 366 Secure RTP profile, 367 372 Congestion bandwidth and, 253 denial-of-service attacks and, 381 detecting, 293 294 need for controlling, 287 290 Congestion avoidance, 292 Congestion collapse, 288 289 Congestion control admission control and, 288 congestion collapse and, 288 289 fair sharing of capacity, 289 290, 296 multicast, 306, 308 310 Congestion control, Internet, 290 296 detecting congestion, 293 294 OSI layers and, 290 sliding receiver window, 290, 292 stop-and-wait protocols, 290 291 TCP congestion windows, 291 throughput and, 295

AW001-PerkinsIX 5/14/03 2:01 PM Page 400 400 INDEX Congestion control, multimedia, 296 310 fair sharing of capacity, 296 layered coding, 306 310 TCP and, 296 297 TCP-friendly rate control, 300 305 TCP-like rate control, 298 300 traffic priority and, 297 298 Congestion window, TCP, 291 292 Context, compression, 200 Context, CRTP, 321 322 Context, ROHC, 328-331 Context identifiers, header compression, 322 Contributing source. See CSRC (contributing source) Control packets, RTP packet reception, 163 165 Control protocols, 56, 62. See also RTCP (RTP control protocol) Cooperative Association for Internet Data Analysis (CAIDA), 26 Coordinated Universal Time (UTC), 213 Count field, RTCP header, 164 CRTP (Compressed RTP), 319 327 compared with ROHC, 328 329 compression/decompression, 323 326 initialization and context, 321 322 overview of, 319 320 packet loss and, 326 327 standards, 318 319 Cryptography. See Encryption CSRC (contributing source), RTCP FEC packet, 257 participant database and, 127 RTP header, 83 See also Mixers Cumulative number of packets lost, 102 D DARTnet, 5 Data Encryption Standard (DES), 365, 373, 375 Data link layer, OSI reference model, 17, 19, 315 Data transfer packets. See Packets, RTP data transfer Data transfer protocol, RTP, 56 Decoding compressed media, 200 207. See also Codecs (compression-decompression) audio mixing, 201 204 audio playout, 204 206 buffers, 166 overview of, 200 201 playout and, 169 separating audio and video packets, 211 video playout, 206 207 Delay since last sender report (DLSR), 104 See also Round trip time Denial-of-service attack, 381 Dependency reduction, video error concealment, 245 246 DES (Data Encryption Standard), 365, 373, 375 Design philosophies, RTP, 51 52 application-level framing design, 52 53 end-to-end design, 53 54 flexibility, 54 Dial-up modems, 319 Differentiated Services framework prioritizing traffic flows, 290, 298 QoS, 64 65 separating audio and video packets and, 210 Digital sound, 147 148 Directory memory access (DMA), 205 206 Displays, refresh rate, 206 Distortion, audio, 228 Dither interval, 279 280 DLSR (delay since last sender report), RTCP, 104. See also Round trip time DMA (directory memory access), 205 206 DTMF tones, 60, 272 E E (Extension), FEC packet, 258 Early feedback mode, RTP retransmission, 280 Eavesdropping, preventing, 360, 376

AW001-PerkinsIX 5/14/03 2:01 PM Page 401 INDEX 401 ECMAScript, 382 EMAIL item, SDES, 113 114 Encapsulating Security Payload (ESP), 373, 378 380 Encryption algorithms, 365 application-level, 362 363 confidentiality algorithms, 375 coupling between packets and, 375 end-to-end, 375 376 IP-level, 363 key exchange, 366 nontrivial nature of encryption code, 362 RTCP packets, 121, 363 365 RTP data packets, 363 364 End-to-end delay, 170, 172 End-to-end encryption, 375 376 End-to-end principle header compression and, 340 RTP design and, 53 54 Endpoints, 53 54 Error concealment, audio, 227 241 interleaving, 247 250 interpolation of codec state, 241 measuring audio quality, 228 229 model-based repair, 241 noise substitution, 231 233 overview of, 227 228 regenerative repair, 241 repetition, 234 237 silence substitution, 229 231 timescale modification, 241 waveform substitution, 237 239 Error concealment, video, 242 250 dependency reduction, 245 246 interleaving, 247 250 motion-compensated repetition, 243 245 overview of, 242 243 spatial and temporal repairs, 245 Error correction, 251 286 channel coding, 273 276 FEC. See FEC (forward error correction) implementation considerations, 283 285 payload formats, 60 playout compensation and, 181 184 retransmission, 276 282 separating audio and video packets, 211 Error protection codes, packet reception, 164 Error resilience application level framing and, 52 multiplexing and, 342 payload headers and, 87 ESP (Encapsulating Security Payload), 373, 378 380 Exploders, as one-to-many translator, 92 Extended highest sequence number, RTCP packets, 103 Extension (E), FEC packet, 258 Extension headers. See Header extensions F FEC (forward error correction), 252 272 advantages/disadvantages, 252 254 application-level framing and, 52 audio redundancy coding. See Audio redundancy coding coupling between packets and, 375 packet schemes, 260 parity FEC. See Parity FEC (forward error correction) Reed-Solomon codes, 263 266 Feedback bidirectional and unidirectional, in ROHC, 330 modes, for RTP retransmission, 280 281 packets, for RTP retransmission, 279 Fidelity, playout buffer and, 170 File Transfer Protocol (FTP), 17 Firewalls authentication and, 380 IPsec and, 374 375 First-order compression state, ROHC, 329 Formats, packet audio redundancy, 267 271 CRTP, 323 326 GeRM, 349 352

AW001-PerkinsIX 5/14/03 2:01 PM Page 402 402 INDEX parity FEC, 255 258 retransmission, 277 279 RTCP overview of, 97 100 RTCP SR packets, 108 110 RTCP RR packets, 101 104 RTCP SDES packets, 111 112 RTCP APP packets, 118 RTCP BYE packets, 117 RTCP compound packets, 100 RTP data transfer protocol, 70 Secure RTP SRTP, 367 SRTCP, 371 IPsec ESP, 374 AH, 379 IP, 20 UDP, 42 Formats, payload AMR (Adaptive Multi-Rate) audio, 87 audio, 80 81 audio redundancy, 268 comfort noise, 233 coupling between packets and, 375 fragmentation and, 156 H.261 video, 87-88 interframe coding and, 275 list of, 72 mapping to payload type, 72-73 multiple formats, 75 multiple frames and, 88 MP3 See MPEG Audio Layer-3 (MP3), RTP, 59 60 selecting, 74 static versus dynamic, 73-74 ULP and, 264 265 video, 80 81 Forward error correction. See FEC (forward error correction) Forward reconsideration, RTCP, 134 138 Fragmentation IPv4 support for, 37 MTU and, 89 playout compensation and, 181, 184 RTP packet generation and, 155 157 Frames audio capture and, 147 150 fragmentation of, 155 157 interleaving and, 249 multiple, 88 packet reception and, 158 playout buffer and, 166 prerecorded content and, 152 153 video capture and, 150 152 Frequency repairs, video error concealment, 245 FTP (File Transfer Protocol), 17 Full header packets, CRTP, 322 G Gateways. See Routers Generic RTP Multiplexing. See GeRM (Generic RTP Multiplexing) GeRM (Generic RTP Multiplexing) application scenarios, 352 353 concepts, 349 352 future of, 353 354 IETF and, 349 packet format, 349 352 H H.245, session description, 73 H.261 video, 87 88 H.320, 7 H.323 as call setup protocol, 62 ITU standards, 8 RTP specification in, 10, 55 H.332, 7 Header compression, 315 337 applications and, 334 336 CRTP. See CRTP (Compressed RTP) local implementation, 318 multiplexing and, 339 340 overview of, 315 316 patterns, 317 318 principles, 320

AW001-PerkinsIX 5/14/03 2:01 PM Page 403 INDEX 403 robustness, 317 318 ROHC. See ROHC (Robust Header Compression) RTP, 60 scenario for use of, 316 standards, 318 Header elements, RTCP packets, 98 99, 164 Header elements, RTP packets, 71 85 contributing sources (CSRCs), 83 marker (M) bit, 83 84 padding (P) bit, 84 85 payload-specific, 157 payload type (PT) field, 71 75 sequence number, 75 78 size of, 315 synchronization source (SSRC), 82 83 timestamp, 78 82 version number, 85 Header extensions, RTP, 85 86 Header fields, FEC packets, 257 Heterogeneity of networks, 41 HMAC-MD5-96, 380 HMAC-SHA-1, 378 HMAC-SHA-96, 380 HTML (Hypertext Markup Language), 18 HTTP (Hypertext Transport Protocol), 17 I IC (item count), RTCP packets, 99 IEEE 802.11b, wireless communication, 18 IETF (Internet Engineering Task Force) Audio/Video Transport group, 10, 55, 342 343 Internet drafts, 389 390 multimedia protocol stack, 11 RTP specification, 6, 55 standards, 386 389 standards development cycle, 55 56 IKE (Internet Key Exchange), 375, 380 Immediate feedback mode, RTP retransmission, 280 Initialization, of compression context CRTP, 321 322 ROHC, 329 Input buffers, audio capture, 147 148 Input Queues, separating packet reception from playout, 162 163 Integrated layer processing, 166 Integrated Services Digital Network (ISDN), 7 Integrated Services framework see RSVP Integrity protection, 376 377 HMAC-SHA-1, 378 IPsec and, 378 replay attacks and, 380 Interarrival jitter RTCP packets, 103 104 RTP packets, 161 Interframe coding, 275 Interleaving coupling between packets and, 375 CRTP and, 335 for error concealment, 247 250 playout compensation and, 184 Internet architecture of, 23 Audio/Video networking, 5 7 congestion control, 290 296 OSI reference model and, 18 19 Internet Engineering Task Force. See IETF (Internet Engineering Task Force) Internet Key Exchange (IKE), 375, 380 Internet Protocol. See IP (Internet Protocol) Internet Weather Report, 28 Interpolation of codec state, 241 Interpretation interval, ROHC, 332 Intranets, 39 IP addresses, 113 IP datagrams, 19 IP headers, 20 IP (Internet Protocol), 19 22 abstraction provided by, 22 23 IP-to-PSTN gateways, 354 355 network layer and, 19 routers and, 21 22 services of, 19 20 TCP and UDP and, 22 IP-level authentication, 377

AW001-PerkinsIX 5/14/03 2:01 PM Page 404 404 INDEX IP-level security. See IPsec (IP Security) IP multicast benefits of, 48 packet loss and, 37 39 IP networks audio/video transport over, 9 average packet loss, 26 29 heterogeneity of, 41 intranets, 39 measuring performance, 25 26, 40 42 multicast sessions, 37 39 network technologies and, 39 40 packet corruption, 31 32 packet duplication, 30 31 packet loss patterns, 29 30 packet sizes, 37 packet transit time, 32 37 performance characteristics, 23 25 IP routers, 18 IP-to-PSTN routers, 354 355 IPsec (IP Security), 372 375 algorithms, 380 authentication, 373, 378 380 confidentiality, 373 ESP, 373 374 firewalls, 373 374 IKE, 375 modes of operation, 372 373 IPv4 fragmentation support, 37 header format, 20 ID field, 322, 324, 336 IPv6, 20 compression of, 321 ID field, lack of, 322 ISDN (Integrated Services Digital Network), 7 Item count (IC), RTCP packets, 99 ITU standards Audio/Video networking, 7 8 measuring audio quality and, 228 teleconferencing protocols, 11 See also H.245, H.320, H.323, and H.332 J Java applets, 382 Jitter buffers for removing, 166 compensating playout calculation for, 184 191 interarrival jitter in RTCP packets, 103 Interarrival jitter in RTP packets, 161 packet transit time and, 33 randomness of network-induced, 186 triggers for adaptation, 188 189 Join experiments, 308 310 Journal papers, reference resources, 391 395 K Key exchange, 366 L L2TP (Layer Two Tunneling Protocol), 343 345, 347 Last sender report (LSR) timestamp, RTCP, 104 Latency See also Playout buffer interleaving and, 250 payload data and, 89 Layered coding, congestion control, 306 310 Least-significant bit encoding (LSB), ROHC, 332 334 Length field, RTCP packets, 99 Length recovery, FEC packets, 258 Lip synchronization, 209 223 accuracy of, 222 223 mapping RTP media clock to sender reference clock, 164 overview of, 209 211 receivers, 216 222 senders, 211 216 Listening tests measuring audio quality and, 228 229 noise substitution and, 233 repetition and, 237 silence substitution and, 231 LOC item, SDES, 114

AW001-PerkinsIX 5/14/03 2:01 PM Page 405 INDEX 405 Local implementation, header compression, 318 Local timeline, mapping playout calculation to, 173 174 Loss fraction, 103, 302 303, 305 Loss packet rates, 106 107 LSB (least-significant bit encoding), ROHC, 332 334 LSR (last sender report) timestamp, RTCP, 104 M Marker (M) bit, RTP header, 83 84, 168 Mask, FEC packet, 258 Matrices, interleaving, 248 249 Maximum transmission unit. See MTU (maximum transmission unit) Mbone tools, 6 7 Mean Opinion Score (MOS), 228 229 Media capture, 147 152 audio capture and compression, 147 150 prerecorded content, 152 153 video capture and compression, 150 152 Media clocks synchronizing with reference clocks, 211 214 timestamps and, 80 81 Media decoders, 200 201. See also Decoding compressed media Media frames. See Frames; Media, real-time, 45 46 Media streams confidentiality of, 121 encrypting, 381 382 header fields and, 328 mixing, 201 multiplexing, 341 342 synchronization. See Lip synchronization Media transport layer, 10 Media transport standards, 8 Membership management. See BYE (membership management), RTCP Mergers, as one-to-many translator, 92 Message authentication, 377, 378 Metrics, packet loss, 26 MIME (Multipurpose Internet Mail Extensions), 18, 59 Mapping to payload type, 71-75 Mixers overview of, 92 94 RTP support for, 57 security of, 381 382 Mixing audio, 201 204 Mixing media streams, 201 MMX (Multimedia Extensions), 203 Model-based repair, 241 Modes of operation RTP retransmission, 280 281 ROHC, 330 331 Monitoring packet reception, 164 MOS (Mean Opinion Score), 228 229 Motion-compensated repetition, 243 245 MPEG Audio Layer-3 (MP3); See also Formats, payload interleaving and, 249 loss-tolerant payload formats for, 87 MPEG B frames, 335 MTU (maximum transmission unit) fragmentation and, 155 157 packet sizes and, 37 payload data and, 89 Multicast conferencing, 9 congestion control and, 306, 308 310 sessions, IP networks, 37 39 Multimedia congestion control, 296 310 streaming, 6 Multimedia Extensions (MMX), 203 Multimedia protocol stack, 61 62 Multimedia synchronization. See Lip synchronization Multiplexing, 339 357 advantages/disadvantages, 340 342 application-specific, 354 357 compared with bundling, 340 341 GeRM, 349 354

AW001-PerkinsIX 5/14/03 2:01 PM Page 406 406 INDEX header compression and, 339 340 RTP, 61 TCRTP, 342 348 telephony specific, 354 355 Multipurpose Internet Mail Extensions (MIME), 18, 59 Mapping to payload type, 71 75 N NACK (negative acknowledgement), 277 279 NAME item, SDES, 113 NAT (Network Address Translation) authentication, 380 IP addresses, 113 IPsec and, 374 375 RTP awareness and, 120 National Laboratory for Applied Network Research (NLANR), 26 Negative acknowledgement (NACK), 277 279 Network Address Translation. See NAT (Network Address Translation) Network layer, OSI reference model, 17, 19 Network technologies, IP networks, 39 40 Network Time Protocol (NTP), 108 109, 180, 213 Network traffic congestion control and, 287, 297 298 measurements, 24 multimedia and congestion collapse, 289 patterns, 25 prioritizing, 296 298 Network Voice Protocol (NVP), 4 5 NLANR (National Laboratory for Applied Network Research), 26 Noise substitution, 231 233 NOTE item, SDES, 114 NTP (Network Time Protocol), 108 109, 180 NTP timestamp, 108, 213 Null termination, SDES, 115 116 NVP (Network Voice Protocol), 4 5 O Open standards, vs. proprietary solutions, 4 OSI reference model, 16 23 communication between layers, 18 congestion control and, 290 difficulty of placing RTP in, 57 Internet and, 18 19 IP and, 19 22 layers of, 17 18 presentation protocols, 22 protocol layering, 16 17 session protocols, 22 transport protocols, 22 Out-of-order packets, 192 P P (padding) bit. See Padding (P) bit Packet formats. See Formats, packet Packet generation, RTP, 152 157 fragmentation, 155 157 overview of, 152 154 payload-specific headers, 157 timestamps, 154 155 Packet loss cumulative number of RTCP packets, 102 effects on CRTP, 326 327 effects on ROHC, 331 332 effects on TCRTP, 348 parity FEC and, 261 patterns, 29 30, 41 QoS and, 39 40 recovering from, 261 263 retransmission and, 276 277 ULP, 263 266 Packet networks A/V transport requirements, 45 48 voice and video experiments on, 4 5 Packet Radio Network, 4 5 Packet reception, RTP, 159 165 control packets, 163 165 data packets, 160 163 monitoring, 164 overview of, 159 160 separating from playout, 162 Packet type (PT), RTCP, 99

AW001-PerkinsIX 5/14/03 2:01 PM Page 407 INDEX 407 Packet voice experiments, 4 5 Packets average packet loss, 26 29 corruption, 31 32, 41 duplication, 30 31, 41 formats. See Formats, packet reliable delivery, 46 retransmission, 183 size, 37, 124, 129 transit times, 32 37, 41 42 validation, 89 91 Packets, RTCP application-defined, 118 BYE, 116 117 compound, 99 100 cumulative number of lost, 102 encrypting, 121 extended highest sequence number, 103 formats, 97 100 loss packet rates, 106 107 packing issues, 118 120 receiver report, 101-107 sender report, 107-110 source description, 110-116 timing rules, 128 129 transmission rules, 132 134 transport of, 97 types of, 96 validation, 122 124 Packets, RTP data transfer compensating playout calculation for packet reordering, 192 contributing sources (CSRCs), 83 format of, 70 fragmentation, 155 157 header elements, 71 header extensions, 85 86 marker (M) bit, 83 84 padding (P) bit, 84 85 parts of, 70 payload data, 88 89 payload headers, 86 88 payload type (PT) field, 71 75 reception, 160 163 sequence number, 75 78 synchronization source (SSRC), 82 83 timestamp, 78 82 version number, 85 Packing rules, compound RTCP packets, 118 119 Padding (P) bit RTCP header, 98 RTCP implementation, 142 RTP header, 84 85 Parity FEC (forward error correction) overview of, 254 255 packet format, 255 258 playout compensation and, 182 recovering from packet loss, 261 263 redundant audio and, 272 unequal error protection, 263 266 use of, 259 261 Parsing SDES packets, 115 116, 165 Participant database, 124 128 incorrect scaling, 141 member identification, 126 participant validation and, 127 per-participant data structure, 125 126 receiver-specific information in, 164 receivers maintenance of, 158 removing participants, 128 reporting interval and, 130 131 session variables, 124 125 Patterns header compression, 317 318 packet loss, 29 30, 41 Payload data, 88 89 Payload formats. See Formats, payload Payload headers audio redundancy, 268 269 FEC packet, 258 RTP data transfer packet, 86 88 RTP packet generation and, 157 Payload type (PT) field mappings, 58, 71 recovery, FEC packet, 258

AW001-PerkinsIX 5/14/03 2:01 PM Page 408 408 INDEX RTCP header, 99 RTP header, 71 75 static vs. dynamic assignment, 73 74 Per-flow validity checks, 90 Per-packet validity checks, 90 Performance TCRTP, 347 348 wireless networks, 40 Performance, IP networks average packet loss, 26 29 characteristics, 23 25 measuring, 25 26, 40 42 multicast sessions, 37 39 network technologies, 39 40 packet corruption, 31 32 packet duplication, 30 31 packet loss patterns, 29 30 packet sizes, 37 packet transit time, 32 37 PHONE item, SDES, 114 Phonemic restoration, 233 Physical layer, OSI reference model, 17, 19 Pitch cycles, speech patterns, 234 Plain-text attacks, 121 Playout buffer, 166 192 clock skew compensation, 175 180 data structures in, 167 fidelity vs. delay, 170 jitter compensation, 184 191 mapping playout calculation to local timeline, 173 174 overview of, 166 170 packet reordering compensation, 192 playout time calculation, 170 173 route change compensation, 191 192 sender behavior compensation, 180 184 separating audio and video packets, 211 separating packet reception from playout, 162 Playout point adaptation audio with silence suppression, 193 196 audio without silence suppression, 196 197 overview of, 192 video, 198 200 Playout synchronization. See Lip synchronization Playout time, receivers, 220 Ports RTCP data, 97 RTP data, 97 TCP and UDP, 22 PPP multiplexing, 343 345, 347 Predictive coding limitations of, 245 246 video loss concealment, 242 Prerecorded content media capture and, 152 153 RTP timestamp and, 154 Presentation layer, OSI reference model and, 18 Presentation protocols, 22 PRIV items, SDES, 114 Privacy, 120 122, 360 361 Protocol layering, OSI reference model, 16 17 PSTN (Public Switched Telephone Network), 354 355 PT (payload type). See Payload type (PT) field Public networks, 39 Public Switched Telephone Network (PSTN), 354 355 Q QoS (quality of service) IP networks and, 39 40 multiplexing and, 342 protocols, 63 65 separating audio and video packets and, 210 See also Differentiated Services Framework and RSVP. R Random number generators, SSRC, 82, 126 127 RAP (Rate Adaptation Protocol), 299 Rate control audio and video, 300 TCP-friendly, 300 305 TCP-like, 298 300

AW001-PerkinsIX 5/14/03 2:01 PM Page 409 INDEX 409 Real-time media, 45 46 Receive window, TCP, 291 Receiver reports. See RR (receiver reports), RTCP Receivers. See also Packet reception, RTP behavior of, 13 14, 157 159 capture time determination, 217 capture-to-playout delay, 220 clock skew and, 175 180 control packet reception, 163 165 data packet reception, 160 163 error concealment techniques and, 227 228, 247 error correction implementation, 283 284 FEC packets and, 261 identifying media streams for synchronization, 216 lip synchronization, 218 multithreaded, 163 playout time determination, 220 sender behavior compensation, 181 synchronization adaptation, 221 222 synchronization delay determination, 220 221 Reconsideration, RTCP BYE reconsideration, 139 140 forward reconsideration (step join), 134 138 reverse reconsideration (step leave), 138 139 Recovery process, FEC packets, 262 263 Redundant audio. See Audio redundancy coding Reed-Solomon codes, 263 266 Reference clocks, synchronizing with media clocks, 211 214 Reference picture selection, channel coding, 275 276 Reference resources, for this book, 385 396 books, 395 conferences and journal papers, 391 395 IETF drafts, 389 390 IETF standards, 386 389 other standards, 390 391 Refresh rate, displays, 206 Refresh state, ROHC, 329 Regenerative repair, audio error concealment, 241 Reliable delivery, packets, 46 Repetition audio error concealment, 234 237 motion-compensated in video, 243 245 Replay protection, 380 Reportee SSRC, 102 Reporting interval, RTCP, 129-131 lack of randomization in, 142 between packets, 96 Request for comments (RFCs), 386 389. See also Standards ReSerVation Protocol. See RSVP (ReSerVation Protocol) Retransmission, RTP, 276 282 applicability of, 281 282 inefficiencies, 282 modes of operation, 280 281 overview of, 276 277 packet format, 277 279 packet playout buffer, 183 timing rules, 279 280 Retransmission, TCP, 44 45 Reverse predicted video frames, 335 Reverse reconsideration, RTCP, 138 139 RFCs (request for comments), 386 389. See also Standards Robust Header Compression. See ROHC (Robust Header Compression) Robustness. See Congestion control; Error concealment; Error correction Robustness and compression efficiency, ROHC, 331 334 Robustness, header compression, 317 318 ROHC (Robust Header Compression), 327 334 compared with CRTP, 328 329 modes of operation, 330 331 overview of, 327 329 robustness and compression efficiency, 331 334 standards, 318

AW001-PerkinsIX 5/14/03 2:01 PM Page 410 410 INDEX states of operation, 329 330 Round-trip time calculation, 164 packet playout buffer and, 183 RR data and, 105 106 See also End-to-end Delay Route changes, playout compensation and, 191 192 Routers congestion control and, 289 IP, 18, 21 22 IP-to-PSTN, 354 355 QoS and, 64 RR (receiver reports), RTCP data interpretation, 105 107 packet format, 101 104 round-trip calculation and, 164 RTCP packet types, 97 RSVP (ReSerVation Protocol) prioritizing traffic flows, 290, 298 QoS and, 63 separating audio and video packets and, 210 RTCP (RTP control protocol). See also Packets, RTCP application-defined packets, 118 BYE packets, 116-117 BYE reconsideration, 139 140 common implementation problems, 141 142 components of, 96 97 compound packets, 119 120 forward reconsideration, 134 138 membership control, 116 117 overview of, 56 57 packet formats, 97 100 packet packing issues, 118 120 packet transport, 97 packet type limitations, 58 packet validation, 122 124 participant database, 124 128 privacy, 120 122 receiver report packets, 101 107 reconsideration, 141 reference clock, 213 reporting interval, 129 131 reverse reconsideration, 138 139 security, 120 122 sender report packets, 107 110 source description packets, 110 116 timing rules, 128 129 transmission rules, 132 134 RTP data transfer protocol, 67 94 CSRCs, 83 header elements, 71 header extensions, 85 86 marker (M) bit, 83 84 mixers, 92 94 overview of, 56 packet format, 70 packet validation, 89 91 padding (P) bit, 84 85 payload data, 88 89 payload formats, 59 payload headers, 86 88 payload type (PT) field, 71 75 sequence number, 75 78 sessions, 67 69 SSRC, 82 83 timestamp, 78 82 translators, 91 92 version number, 85 RTP-over-TCP encapsulation, 298 RTP (Real-time Transport Protocol), introduction, 9 14 application-level framing design, 52 53 bundling packets, 340 341 design philosophies, 51 52 development of, 6 end-to-end principle in design, 53 54 features, 9 10 flexibility of, 54 future standards, 65 header compression, 60 limitations of, 57 multiplexing, 61

AW001-PerkinsIX 5/14/03 2:01 PM Page 411 INDEX 411 payload formats, 59 60 related standards, 10 11, 61 65 RTP profiles, 58 59, 71-74, 81, 84 RTP receivers, 13 14 RTP senders, 11 12 specification, 55 57 RTP receivers. See Receivers RTP senders. See Senders RTP timestamp. See Timestamps, RTP RTSP (Real-Time Streaming Protocol) as call setup protocol, 62 key exchange and, 366 normal play time in, 79 80 RTP-over-TCP encapsulation, 298 streaming A/V, 9 RTT (round-trip time), 105 106. See also Round-trip time S SAP (Session Announcement Protocol), 6 7, 62 SATNET (Atlantic Satellite Network), 5 Saturating addition, audio mixing, 202 203 SDES (source destination), RTCP buffer overflow attacks and, 382 383 parsers, 115 116 item types, 112 115 mapping SSRC to CNAME, 214 216 overview of, 110 111 packet format, 111 112 packet reception, 165 RTCP packet types, 98 text security, 382 383 SDP (Session Description Protocol) development of, 7 overview of, 63 RTP payload formats and, 59 payload type mapping using, 72 73 Second-order compression state, ROHC, 329 Secure RTP profile. See SRTP (Secure RTP) profile Security, 359 383 active content and, 382 authentication, 376 380 confidentiality. See confidentiality denial-of-service, 381 mixers and, 381 382 overview of, 359 360 privacy, 360 361 replay protection, 380 RTCP, 120 122 SDES text items, 382 383 translators and, 381 382 Security parameter index (SPI), 373 Sender reports. See SR (sender reports), RTCP Senders behavior, 11 12, 146 147 clock skew and, 175 180 clock synchronization, 211 214 congestion detection, 293 294 error concealment techniques and, 247 error correction, 251, 285 FEC and, 252, 259 261 octet count, 110 packet count, 110 playout calculation and, 180 184 source synchronization, 214 216 Sequence number, FEC, 258, 262 Sequence number, RTCP, 103 Sequence number, RTP, 75 78 functions of, 75, 77 78 initial values of, 77 wrap-around counters and, 76 77 Serial links, CRTP, 319 Session Announcement Protocol (SAP), 6 7, 62 Session description protocols, 63. See also SDP (Session Description Protocol) Session initiation, key exchange, 366 Session Initiation Protocol. See SIP (Session Initiation Protocol) Session layer, OSI reference model, 17 Session protocols, 22 Sessions, RTP, 67 69 defined, 67 types of, 69 unicast and multicast, 68 Signal-to-noise ratio, 228

AW001-PerkinsIX 5/14/03 2:01 PM Page 412 412 INDEX Silence substitution, audio error concealment, 229 231 Silence suppression audio with, 193 196 audio without, 196 197 Simple Mail Transfer Protocol (SMTP), 17 Simulcast, 307 SIP (Session Initiation Protocol) as call setup protocol, 62 development of, 7 key exchange and, 366 as replacement for H.323, 7 Sliding receiver window, congestion control, 290, 292 Sliding window protocols, 290 Slow-start algorithm, TCP, 304 SMTP (Simple Mail Transfer Protocol), 17 SONET (Synchronous Optical Network), 355 Sound. See Audio Source destination. See SDES (source destination), RTCP Source origin authentication, 377, 378 Spatial repairs, video error concealment, 245 Specification, RTP, 55 57, 363 366 Speech codecs, 195 measuring audio quality and, 228 phonemic restoration, 233 pitch cycles, 234 repetition repair techniques, 234 237 talk spurts, 193 195 waveform substitution, 237 239 SPI (security parameter index), 373 Spikes, packet transit time, 35, 188 191 SR (sender reports), RTCP data interpretation, 110 mapping media clock to sender reference clock, 164 NTP timestamp and, 108 overview of, 107 packet format, 108 110 packet variables, 125 round-trip calculation and, 164 RTCP packet types, 97 sender s packet count, 110 SRTP (Secure RTP) profile, 367 372 AES as default for, 368 AES counter mode, 369 AES f8 mode, 370 371 authentication, 378 encryption process with, 368 369 payload encryption, 367 368 RTCP packets, 371 372 RTP packets, 367 371 senders and receivers and, 368 SSRC (synchronization source) associating sources with media time base, 214 FEC packet, 257 mapping CNAME to, 82 member identification by, 126 nonrandom, 353 RR (receiver reports) and, 101 102 RTP header, 82 83 ST (Stream Protocol), 5 Standard deviation, jitter compensation, 187 Standards future development, 65 IETF, 386 389 NIST, 390 391 RTP related, 10 11, 61 65 State information, 322 States of operation, ROHC, 329 330 Step join, RTCP reconsideration, 134 Step leave, RTCP reconsideration, 138 139 Stop-and-wait protocols, 290 291 Stream Protocol (ST), 5 Symmetric algorithms, 373 374 Synchronization. See also Lip synchronization accuracy of, 222 223 adaptation in receivers, 221 222 delay in receivers, 220 221 Synchronization source. See SSRC (synchronization source) Synchronous Optical Network (SONET), 355

AW001-PerkinsIX 5/14/03 2:01 PM Page 413 INDEX 413 T T1 lines, 355 Talk spurts, audio playout adaptation, 193 195 TCP-friendly rate control, 300 305 TCP/IP OSI reference model and, 16 22 TCP-like rate control, 298 300 TCP (Transmission Control Protocol) congestion collapse and, 289 congestion control algorithms, 290 congestion windows, 291 fair sharing of capacity, 296 297 features, 44 IP and, 22, 43 limitations for real-time applications, 47 multimedia congestion control and, 296 297 packet loss and, 25 reliability at expense of timeliness, 52, 298 slow-start algorithm, 304 as transport protocol, 43 45 TCRTP (Tunneling Multiplexed Compressed RTP), 342 348 concepts, 343 345 IETF Audio/Video group and, 342 343 implementing, 346 347 performance, 347 348 protocol stack, 343 transparency of interface, 346 TDM (Time Division Multiplexing), 355 Telephony multiplexed, 354 355 unicast voice, 54 Temporal repairs, video error concealment, 245 TESLA (Timed Efficient Stream Loss-tolerant Authentication), 378 Throughput congestion control and, 295 variations in, 295 Time Division Multiplexing (TDM), 355 Timed Efficient Stream Loss-tolerant Authentication (TESLA), 378 Timescale modification, audio error concealment, 241 Timestamps FEC packet, 258 LSR timestamp, 104 NTP timestamp, 108 109 Timestamps, RTP, 78 82 calculations, 78 79 continuity of, 80 duplication of, 80 81 function of, 78 initial values of, 78 NTP timestamp and, 109 packet generation and, 154 155 playout calculation and, 173 synchronizing media clocks with reference clocks, 213 Timing model, RTP, 154 155 Timing rules retransmission, 279 280 RTCP, 128 129 TOOL item, SDES, 114 Traffic. See Network traffic Transcoders, as one-to-one translator, 91 92 Transit time, packets, 32 37 calculating variance in, 103 factors effecting, 32 33 jitter as measurement of, 33 measuring, 33 34 periodicity in, 37 spikes, 35, 188 191 Translators classes of, 91 92 overview of, 91 RTP support for, 57 security, 381 382 Transmission FEC and, 252 problem of discontinuous, 305 RTCP rules, 132 134, 141 142 Transmission Control Protocol. See TCP (Transmission Control Protocol) Transport layer, OSI reference model, 17, 210

AW001-PerkinsIX 5/14/03 2:01 PM Page 414 414 INDEX Transport mode, IPsec, 372 373 Transport protocols OSI reference model and, 22 real-time media and, 46 TCP, 43 45 UDP, 42 43 Triple DES, 365 Troubleshooting RTCP implementation, 141 142 Tunnel mode, IPsec, 372 373 Tunneling, 343 345. See also TCRTP (Tunneling Multiplexed Compressed RTP) Tunneling Multiplexed Compressed RTP. See TCRTP (Tunneling Multiplexed Compressed RTP) U UDP checksum compression efficiency and, 335 336 disabling, 273 unpredictable header fields and, 329 UDP (User Datagram Protocol) as basis of RTP, 46 header, 42 IP and, 22, 42 43 RTP sitting on top of, 56 standard RTP ports, 97 ULP (unequal layered protection), 263 266 Unicast voice telephony, 54 Unidirectional mode, ROHC, 330 User Datagram Protocol. See UDP (User Datagram Protocol) User names, 120 UTC (Coordinated Universal Time), 213 UTF-8, 116 V Validity checks encryption confirmation, 365 RTCP packets, 122 124 RTP packets, 90 Version number (V field) RTCP header, 98 RTP header, 85 Video. codecs, 168 conferencing, 5 7 decoding compressed media, 206 207 error concealment. See Error concealment, video lack of congestion control standards for, 298 packet size, 37 payload formats, 60, 80 81 playout point, 198 200 RTP timestamp and, 154 treating separately from audio, 210 211 Virtual private networks (VPNs), 344 Voice circuit emulation, 356 Voice-over-IP, 348 VPN (virtual private networks), 344 W W-LSB (window-based least-significant bit) encoding, ROHC, 332 334 Waveform substitution, audio error concealment, 237 239 Web browsers, 18 White noise, 231 Wideband Satellite Network, 5 Window-based least-significant bit (W-LSB) encoding, 332 334 Wireless networks IEEE 802.11b, 18 performance characteristics, 40 Wiretaps, 376 Wrap-around counters, 75 76 X XOR operation, parity FEC, 254 255 ndwid