GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc3557

Network Working Group Q. Xie, Ed. Request for Comments: 3557 Motorola, Inc. Category: Standards Track July 2003

                       RTP Payload Format for

European Telecommunications Standards Institute (ETSI) European Standard

         ES 201 108 Distributed Speech Recognition Encoding

Status of this Memo

 This document specifies an Internet standards track protocol for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "Internet
 Official Protocol Standards" (STD 1) for the standardization state
 and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

 This document specifies an RTP payload format for encapsulating
 European Telecommunications Standards Institute (ETSI) European
 Standard (ES) 201 108 front-end signal processing feature streams for
 distributed speech recognition (DSR) systems.

Xie Standards Track [Page 1] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

Table of Contents

 1.  Conventions and Acronyms . . . . . . . . . . . . . . . . . . .  2
 2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
     2.1.  ETSI ES 201 108 DSR Front-end Codec. . . . . . . . . . .  3
     2.2.  Typical Scenarios for Using DSR Payload Format . . . . .  4
 3.  ES 201 108 DSR RTP Payload Format. . . . . . . . . . . . . . .  5
     3.1.  Consideration on Number of FPs in Each RTP Packet. . . .  6
     3.2.  Support for Discontinuous Transmission . . . . . . . . .  6
 4.  Frame Pair Formats . . . . . . . . . . . . . . . . . . . . . .  7
     4.1.  Format of Speech and Non-speech FPs. . . . . . . . . . .  7
     4.2.  Format of Null FP. . . . . . . . . . . . . . . . . . . .  8
     4.3.  RTP header usage . . . . . . . . . . . . . . . . . . . .  8
 5.  IANA Considerations. . . . . . . . . . . . . . . . . . . . . .  9
     5.1.  Mapping MIME Parameters into SDP . . . . . . . . . . . . 10
 6.  Security Considerations. . . . . . . . . . . . . . . . . . . . 11
 7.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11
 8.  Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 11
 9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.1.  Normative References . . . . . . . . . . . . . . . . . . 11
     9.2.  Informative References . . . . . . . . . . . . . . . . . 12
 10. IPR Notices. . . . . . . . . . . . . . . . . . . . . . . . . . 12
 11. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 13
 12. Editor's Address . . . . . . . . . . . . . . . . . . . . . . . 14
 13. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 15

1. Conventions and Acronyms

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in [RFC2119].
 The following acronyms are used in this document:
 DSR  - Distributed Speech Recognition
 ETSI - the European Telecommunications Standards Institute
 FP   - Frame Pair
 DTX  - Discontinuous Transmission

2. Introduction

 Motivated by technology advances in the field of speech recognition,
 voice interfaces to services (such as airline information systems,
 unified messaging) are becoming more prevalent.  In parallel, the
 popularity of mobile devices has also increased dramatically.

Xie Standards Track [Page 2] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

 However, the voice codecs typically employed in mobile devices were
 designed to optimize audible voice quality and not speech recognition
 accuracy, and using these codecs with speech recognizers can result
 in poor recognition performance.  For systems that can be accessed
 from heterogeneous networks using multiple speech codecs, recognition
 system designers are further challenged to accommodate the
 characteristics of these differences in a robust manner.  Channel
 errors and lost data packets in these networks result in further
 degradation of the speech signal.
 In traditional systems as described above, the entire speech
 recognizer lies on the server.  It is forced to use incoming speech
 in whatever condition it arrives after the network decodes the
 vocoded speech.  To address this problem, we use a distributed speech
 recognition (DSR) architecture.  In such a system, the remote device
 acts as a thin client, also known as the front-end, in communication
 with a speech recognition server, also called a speech engine.  The
 remote device processes the speech, compresses the data, and adds
 error protection to the bitstream in a manner optimal for speech
 recognition.  The speech engine then uses this representation
 directly, minimizing the signal processing necessary and benefiting
 from enhanced error concealment.
 To achieve interoperability with different client devices and speech
 engines, a common format is needed.  Within the "Aurora" DSR working
 group of the European Telecommunications Standards Institute (ETSI),
 a payload has been defined and was published as a standard [ES201108]
 in February 2000.
 For voice dialogues between a caller and a voice service, low latency
 is a high priority along with accurate speech recognition.  While
 jitter in the speech recognizer input is not particularly important,
 many issues related to speech interaction over an IP-based connection
 are still relevant.  Therefore, it is desirable to use the DSR
 payload in an RTP-based session.

2.1 ETSI ES 201 108 DSR Front-end Codec

 The ETSI Standard ES 201 108 for DSR [ES201108] defines a signal
 processing front-end and compression scheme for speech input to a
 speech recognition system.  Some relevant characteristics of this
 ETSI DSR front-end codec are summarized below.
 The coding algorithm, a standard mel-cepstral technique common to
 many speech recognition systems, supports three raw sampling rates: 8
 kHz, 11 kHz, and 16 kHz.  The mel-cepstral calculation is a frame-
 based scheme that produces an output vector every 10 ms.

Xie Standards Track [Page 3] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

 After calculation of the mel-cepstral representation, the
 representation is first quantized via split-vector quantization to
 reduce the data rate of the encoded stream.  Then, the quantized
 vectors from two consecutive frames are put into an FP, as described
 in more detail in Section 4.1.

2.2 Typical Scenarios for Using DSR Payload Format

 The diagrams in Figure 1 show some typical use scenarios of the ES
 201 108 DSR RTP payload format.
 +--------+                     +----------+
 |IP USER |  IP/UDP/RTP/DSR     |IP SPEECH |
 |TERMINAL|-------------------->|  ENGINE  |
 |        |                     |          |
 +--------+                     +----------+
   a) IP user terminal to IP speech engine
 +--------+  DSR over      +-------+                +----------+
 | Non-IP |  Circuit link  |       | IP/UDP/RTP/DSR |IP SPEECH |
 |  USER  |:::::::::::::::>|GATEWAY|--------------->|  ENGINE  |
 |TERMINAL|  ETSI payload  |       |                |          |
 +--------+  format        +-------+                +----------+
   b) non-IP user terminal to IP speech engine via a gateway
 +--------+                  +-------+  DSR over       +----------+
 |IP USER |  IP/UDP/RTP/DSR  |       |  circuit link   |  Non-IP  |
 |TERMINAL|----------------->|GATEWAY|::::::::::::::::>|  SPEECH  |
 |        |                  |       |  ETSI payload   |  ENGINE  |
 +--------+                  +-------+  format         +----------+
   c) IP user terminal to non-IP speech engine via a gateway
       Figure 1: Typical Scenarios for Using DSR Payload Format.
 For the different scenarios in Figure 1, the speech recognizer always
 resides in the speech engine.  A DSR front-end encoder inside the
 User Terminal performs front-end speech processing and sends the
 resultant data to the speech engine in the form of "frame pairs"
 (FPs).  Each FP contains two sets of encoded speech vectors
 representing 20ms of original speech.

Xie Standards Track [Page 4] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

3. ES 201 108 DSR RTP Payload Format

 An ES 201 108 DSR RTP payload datagram consists of a standard RTP
 header [RFC3550] followed by a DSR payload.  The DSR payload itself
 is formed by concatenating a series of ES 201 108 DSR FPs (defined in
 Section 4).
 FPs are always packed bit-contiguously into the payload octets
 beginning with the most significant bit.  For ES 201 108 front-end,
 the size of each FP is 96 bits or 12 octets (see Sections 4.1 and
 4.2).  This ensures that a DSR payload will always end on an octet
 boundary.
 The following example shows a DSR RTP datagram carrying a DSR payload
 containing three 96-bit-long FPs (bit 0 is the MSB):
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 \                                                               \
 /                    RTP header in [RFC3550]                    /
 \                                                               \
 +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
 |                                                               |
 +                                                               +
 |                         FP #1 (96 bits)                       |
 +                                                               +
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 +                                                               +
 |                         FP #2 (96 bits)                       |
 +                                                               +
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 +                                                               +
 |                         FP #3 (96 bits)                       |
 +                                                               +
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        Figure 2. An example of an ES 201 108 DSR RTP payload.

Xie Standards Track [Page 5] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

3.1 Consideration on Number of FPs in Each RTP Packet

 The number of FPs per payload packet should be determined by the
 latency and bandwidth requirements of the DSR application using this
 payload format.  In particular, using a smaller number of FPs per
 payload packet in a session will result in lowered bandwidth
 efficiency due to the RTP/UDP/IP header overhead, while using a
 larger number of FPs per packet will cause longer end-to-end delay
 and hence increased recognition latency.  Furthermore, carrying a
 larger number of FPs per packet will increase the possibility of
 catastrophic packet loss; the loss of a large number of consecutive
 FPs is a situation most speech recognizers have difficulty dealing
 with.
 It is therefore RECOMMENDED that the number of FPs per DSR payload
 packet be minimized, subject to meeting the application's
 requirements on network bandwidth efficiency.  RTP header compression
 techniques, such as those defined in [RFC2508] and [RFC3095], should
 be considered to improve network bandwidth efficiency.

3.2 Support for Discontinuous Transmission

 The DSR RTP payloads may be used to support discontinuous
 transmission (DTX) of speech, which allows that DSR FPs are sent only
 when speech has been detected at the terminal equipment.
 In DTX a set of DSR frames coding an unbroken speech segment
 transmitted from the terminal to the server is called a transmission
 segment.  A DSR frame inside such a transmission segment can be
 either a speech frame or a non-speech frame, depending on the nature
 of the section of the speech signal it represents.
 The end of a transmission segment is determined at the sending end
 equipment when the number of consecutive non-speech frames exceeds a
 pre-set threshold, called the hangover time.  A typical value used
 for the hangover time is 1.5 seconds.
 After all FPs in a transmission segment are sent, the front-end
 SHOULD indicate the end of the current transmission segment by
 sending one or more Null FPs (defined in Section 4.2).

Xie Standards Track [Page 6] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

4. Frame Pair Formats

4.1 Format of Speech and Non-speech FPs

 The following mel-cepstral frame MUST be used, as defined in
 [ES201108]:
 As defined in [ES201108], pairs of the quantized 10ms mel-cepstral
 frames MUST be grouped together and protected with a 4-bit CRC,
 forming a 92-bit long FP:
  0                   1                   2                   3
  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                      Frame #1  (44 bits)                      |
 +                       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                       |          Frame #2 (44 bits)           |
 +-+-+-+-+-+-+-+-+-+-+-+-+                       +-+-+-+-+-+-+-+-+
 |                                               | CRC   |0|0|0|0|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 The length of each frame is 44 bits representing 10ms of voice. The
 following mel-cepstral frame formats MUST be used when forming an FP:
 Frame #1 in FP:
 ===============
     (MSB)                                     (LSB)
       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    :  idx(2,3) |            idx(0,1)               |    Octet 1
    +-----+-----+-----+-----+-----+-----+-----+-----+
    :       idx(4,5)        |     idx(2,3) (cont)   :    Octet 2
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |             idx(6,7)              |idx(4,5)(cont)  Octet 3
    +-----+-----+-----+-----+-----+-----+-----+-----+
     idx(10,11) |              idx(8,9)             |    Octet 4
    +-----+-----+-----+-----+-----+-----+-----+-----+
    :       idx(12,13)      |   idx(10,11) (cont)   :    Octet 5
    +-----+-----+-----+-----+-----+-----+-----+-----+
                            |   idx(12,13) (cont)   :    Octet 6/1
                            +-----+-----+-----+-----+

Xie Standards Track [Page 7] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

 Frame #2 in FP:
 ===============
     (MSB)                                     (LSB)
       0     1     2     3     4     5     6     7
    +-----+-----+-----+-----+
    :        idx(0,1)       |                            Octet 6/2
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |              idx(2,3)             |idx(0,1)(cont)  Octet 7
    +-----+-----+-----+-----+-----+-----+-----+-----+
    :  idx(6,7) |              idx(4,5)             |    Octet 8
    +-----+-----+-----+-----+-----+-----+-----+-----+
    :        idx(8,9)       |      idx(6,7) (cont)  :    Octet 9
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |          idx(10,11)               |idx(8,9)(cont)  Octet 10
    +-----+-----+-----+-----+-----+-----+-----+-----+
    |                   idx(12,13)                  |    Octet 11
    +-----+-----+-----+-----+-----+-----+-----+-----+
 Therefore, each FP represents 20ms of original speech.  Note, as
 shown above, each FP MUST be padded with 4 zeros to the end in order
 to make it aligned to the 32-bit word boundary.  This makes the size
 of an FP 96 bits, or 12 octets.  Note, this padding is separate from
 padding indicated by the P bit in the RTP header.
 The 4-bit CRC MUST be calculated using the formula defined in 6.2.4
 in [ES201108]. The definition of the indices and the determination of
 their value are also described in [ES201108].

4.2 Format of Null FP

 A Null FP for the ES 201 108 front-end codec is defined by setting
 the content of the first and second frame in the FP to null (i.e.,
 filling the first 88 bits of the FP with 0's).  The 4-bit CRC MUST be
 calculated the same way as described in 6.2.4 in [ES201108], and 4
 zeros MUST be padded to the end of the Null FP to make it 32-bit word
 aligned.

4.3 RTP header usage

 The format of the RTP header is specified in [RFC3550].  This payload
 format uses the fields of the header in a manner consistent with that
 specification.
 The RTP timestamp corresponds to the sampling instant of the first
 sample encoded for the first FP in the packet.  The timestamp clock
 frequency is the same as the sampling frequency, so the timestamp
 unit is in samples.

Xie Standards Track [Page 8] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

 As defined by ES 201 108 front-end codec, the duration of one FP is
 20 ms, corresponding to 160, 220, or 320 encoded samples with
 sampling rate of 8, 11, or 16 kHz being used at the front-end,
 respectively. Thus, the timestamp is increased by 160, 220, or 320
 for each consecutive FP, respectively.
 The DSR payload for ES 201 108 front-end codes is always an integral
 number of octets.  If additional padding is required for some other
 purpose, then the P bit in the RTP in the header may be set and
 padding appended as specified in [RFC3550].
 The RTP header marker bit (M) should be set following the general
 rules defined in [RFC3551].
 The assignment of an RTP payload type for this new packet format is
 outside the scope of this document, and will not be specified here.
 It is expected that the RTP profile under which this payload format
 is being used will assign a payload type for this encoding or specify
 that the payload type is to be bound dynamically.

5. IANA Considerations

 One new MIME subtype registration is required for this payload type,
 as defined below.
 This section also defines the optional parameters that may be used to
 describe a DSR session.  The parameters are defined here as part of
 the MIME subtype registration.  A mapping of the parameters into the
 Session Description Protocol (SDP) [RFC2327] is also provided in 5.1
 for those applications that use SDP.
 Media Type name: audio
 Media subtype name: dsr-es201108
 Required parameters: none
 Optional parameters:
 rate: Indicates the sample rate of the speech.  Valid values include:
    8000, 11000, and 16000.  If this parameter is not present, 8000
    sample rate is assumed.
 maxptime: The maximum amount of media which can be encapsulated in
    each packet, expressed as time in milliseconds.  The time shall be
    calculated as the sum of the time the media present in the packet
    represents.  The time SHOULD be a multiple of the frame pair size
    (i.e., one FP <-> 20ms).

Xie Standards Track [Page 9] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

    If this parameter is not present, maxptime is assumed to be 80ms.
    Note, since the performance of most speech recognizers are
    extremely sensitive to consecutive FP losses, if the user of the
    payload format expects a high packet loss ratio for the session,
    it MAY consider to explicitly choose a maxptime value for the
    session that is shorter than the default value.
 ptime: see RFC2327 [RFC2327].
 Encoding considerations : This type is defined for transfer via RTP
    [RFC3550] as described in Sections 3 and 4 of RFC 3557.
 Security considerations : See Section 6 of RFC 3557.
 Person & email address to contact for further information:
    Qiaobing.Xie@motorola.com
 Intended usage: COMMON.  It is expected that many VoIP applications
    (as well as mobile applications) will use this type.
 Author/Change controller:
    Qiaobing.Xie@motorola.com
    IETF Audio/Video transport working group

5.1 Mapping MIME Parameters into SDP

 The information carried in the MIME media type specification has a
 specific mapping to fields in the Session Description Protocol (SDP)
 [RFC2327], which is commonly used to describe RTP sessions.  When SDP
 is used to specify sessions employing ES 201 018 DSR codec, the
 mapping is as follows:
 o  The MIME type ("audio") goes in SDP "m=" as the media name.
 o  The MIME subtype ("dsr-es201108") goes in SDP "a=rtpmap" as the
    encoding name.
 o  The optional parameter "rate" also goes in "a=rtpmap" as clock
    rate.
 o  The optional parameters "ptime" and "maxptime" go in the SDP
    "a=ptime" and "a=maxptime" attributes, respectively.

Xie Standards Track [Page 10] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

 Example of usage of ES 201 108 DSR:
    m=audio 49120 RTP/AVP 101
    a=rtpmap:101 dsr-es201108/8000
    a=maxptime:40

6. Security Considerations

 Implementations using the payload defined in this specification are
 subject to the security considerations discussed in the RTP
 specification [RFC3550] and the RTP profile [RFC3551].  This payload
 does not specify any different security services.

7. Contributors

 The following individuals contributed to the design of this payload
 format and the writing of this document: Q. Xie (Motorola), D. Pearce
 (Motorola), S. Balasuriya (Motorola), Y. Kim (VerbalTek), S. H. Maes
 (IBM), and, Hari Garudadri (Qualcomm).

8. Acknowledgments

 The design presented here benefits greatly from an earlier work on
 DSR RTP payload design by Jeff Meunier and Priscilla Walther.  The
 authors also wish to thank Brian Eberman, John Lazzaro, Magnus
 Westerlund, Rainu Pierce, Priscilla Walther, and others for their
 review and valuable comments on this document.

9. References

9.1 Normative References

 [ES201108]   European Telecommunications Standards Institute (ETSI)
              Standard ES 201 108, "Speech Processing, Transmission
              and Quality Aspects (STQ); Distributed Speech
              Recognition; Front-end Feature Extraction Algorithm;
              Compression Algorithms," Ver. 1.1.2, April 11, 2000.
 [RFC3550]    Schulzrinne, H., Casner, S., Jacobson, V. and R.
              Frederick, "RTP: A Transport Protocol for Real-Time
              Applications", RFC 3550, July 2003.
 [RFC2026]    Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.
 [RFC2119]    Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

Xie Standards Track [Page 11] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

 [RFC2327]    Handley, M. and V. Jacobson, "SDP: Session Description
              Protocol", RFC 2327, April 1998.

9.2 Informative References

 [RFC3551]    Schulzrinne, H. and S. Casner, "RTP Profile for Audio
              and Video Conferences with Minimal Control", RFC 3551,
              July 2003.
 [RFC2508]    Casner, S. and V. Jacobson, "Compressing IP/UDP/RTP
              Headers for Low-Speed Serial Links", RFC 2508, February
              1999.
 [RFC3095]    Bormann, C., Burmeister, C., Degermark, M., Fukushima,
              H., Hannu, H., Jonsson, L-E, Hakenberg, R., Koren, T.,
              Le, K., Liu, Z., Martensson, A., Miyazaki, A., Svanbro,
              K., Wiebke, T., Yoshimura, T. and H. Zheng, "RObust
              Header Compression (ROHC): Framework and four profiles",
              RFC 3095, July 2001.

10. IPR Notices

 The IETF takes no position regarding the validity or scope of any
 intellectual property or other rights that might be claimed to
 pertain to the implementation or use of the technology described in
 this document or the extent to which any license under such rights
 might or might not be available; neither does it represent that it
 has made any effort to identify any such rights.  Information on the
 IETF's procedures with respect to rights in standards-track and
 standards-related documentation can be found in BCP-11.  Copies of
 claims of rights made be made available, or the result of an attempt
 made to obtain a general license or permission for the use of such
 proprietary rights by implementors or users of this specification can
 be obtained from the IETF Secretariat.
 The IETF invites any interested party to bring to its attention any
 copyrights, patents or patent applications, or other proprietary
 rights which may cover technology that may be required to practice
 this standard.  Please address the information to the IETF Executive
 Director.

Xie Standards Track [Page 12] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

11. Authors' Addresses

 David Pearce
 Motorola Labs
 UK Research Laboratory
 Jays Close
 Viables Industrial Estate
 Basingstoke, HANTS, RG22 4PD
 Phone: +44 (0)1256 484 436
 EMail: bdp003@motorola.com
 Senaka Balasuriya
 Motorola, Inc.
 600 U.S Highway 45
 Libertyville, IL 60048, USA
 Phone: +1-847-523-0440
 EMail: Senaka.Balasuriya@motorola.com
 Yoon Kim
 VerbalTek, Inc.
 2921 Copper Rd.
 Santa Clara, CA 95051
 Phone: +1-408-768-4974
 EMail: yoonie@verbaltek.com
 Stephane H. Maes, PhD,
 Oracle
 500 Oracle Parkway, M/S 4op634
 Redwood City, CA 94065 USA
 Phone: +1-650-607-6296.
 EMail: stephane.maes@oracle.com
 Hari Garudadri
 Qualcomm Inc.
 5775, Morehouse Dr.
 San Diego, CA 92121-1714, USA
 Phone: +1-858-651-6383
 EMail: hgarudad@qualcomm.com

Xie Standards Track [Page 13] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

12. Editor's Address

 Qiaobing Xie
 Motorola, Inc.
 1501 W. Shure Drive, 2-F9
 Arlington Heights, IL 60004, USA
 Phone: +1-847-632-3028
 EMail: Qiaobing.Xie@motorola.com

Xie Standards Track [Page 14] RFC 3557 RTP Payload Format for DSR ES 201 108 July 2003

13. Full Copyright Statement

 Copyright (C) The Internet Society (2003).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Xie Standards Track [Page 15]

/data/webs/external/dokuwiki/data/pages/rfc/rfc3557.txt · Last modified: 2003/07/14 19:16 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki