RTP Payload Format for the Enhanced Variable Rate Wideband Codec (EVRC-WB) and the Media Subtype Updates for EVRC-B Codec
RFC 5188
| Document | Type |
RFC - Proposed Standard
(February 2008; No errata)
Updates RFC 4788
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-hdesinen-avt-rtp-evrc-wb | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 5188 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Cullen Jennings | ||
| Send notices to | (None) | ||
Network Working Group H. Desineni
Request for Comments: 5188 Qualcomm
Updates: 4788 Q. Xie
Category: Standards Track Motorola
February 2008
RTP Payload Format for
the Enhanced Variable Rate Wideband Codec (EVRC-WB)
and the Media Subtype Updates for EVRC-B Codec
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.
Abstract
This document specifies Real-time Transport Protocol (RTP) payload
formats to be used for the Enhanced Variable Rate Wideband Codec
(EVRC-WB) and updates the media type registrations for EVRC-B codec.
Several media type registrations are included for EVRC-WB RTP payload
formats. In addition, a file format is specified for transport of
EVRC-WB speech data in storage mode applications such as email.
Desineni & Xie Standards Track [Page 1]
RFC 5188 EVRC-WB RTP Payload Format February 2008
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. EVRC-WB Codec . . . . . . . . . . . . . . . . . . . . . . . . 3
5. RTP Header Usage . . . . . . . . . . . . . . . . . . . . . . . 4
6. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Congestion Control Considerations . . . . . . . . . . . . . . 5
8. Storage Format for the EVRC-WB Codec . . . . . . . . . . . . . 5
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9.1. Media Type Registrations . . . . . . . . . . . . . . . . . 5
9.1.1. Registration of Media Type audio/EVRCWB . . . . . . . 6
9.1.2. Registration of Media Type audio/EVRCWB0 . . . . . . . 8
9.1.3. Registration of Media Type audio/EVRCWB1 . . . . . . . 9
9.1.4. Updated Registration of Media Type audio/EVRCB . . . . 11
9.1.5. Updated Registration of Media Type audio/EVRCB0 . . . 13
10. SDP Mode Attributes for EVRC-WB and EVRC-B . . . . . . . . . . 15
11. EVRC-B Interoperability with Legacy Implementations (RFC 4788) 15
12. Mapping EVRC-WB Media Type Parameters into SDP . . . . . . . . 16
13. Mapping EVRC-B Media Type Parameters into SDP . . . . . . . . 16
14. Offer-Answer Model Considerations for EVRC-WB . . . . . . . . 16
15. Offer-Answer Model Considerations for EVRC-B . . . . . . . . . 18
16. Declarative SDP Considerations . . . . . . . . . . . . . . . . 18
17. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
18. Security Considerations . . . . . . . . . . . . . . . . . . . 22
19. Changes to RFC 4788 . . . . . . . . . . . . . . . . . . . . . 22
20. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
20.1. Normative References . . . . . . . . . . . . . . . . . . . 22
20.2. Informative References . . . . . . . . . . . . . . . . . . 23
Desineni & Xie Standards Track [Page 2]
RFC 5188 EVRC-WB RTP Payload Format February 2008
1. Introduction
This document specifies the payload formats for packetization of
EVRC-WB encoded speech signals into the Real-time Transport Protocol
(RTP). It defines support for the header-free, interleaved/bundled,
and compact bundle packet formats for the EVRC-WB codec as well as
discontinuous transmission (DTX) support for EVRC-WB encoded speech
transported via RTP. The EVRC-WB codec offers better speech quality
than the EVRC and EVRC-B codecs. EVRC-WB belongs to the EVRC family
of codecs. This document also updates the media type registrations
for the EVRC-B codec.
2. Conventions
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 RFC 2119 [1].
3. Background
EVRC-WB is a wideband extension of the EVRC-B [4] speech codec
developed in the Third Generation Partnership Project 2 (3GPP2) with
support for discontinuous transmission (DTX). It provides enhanced
(wideband) voice quality.
The EVRC-WB codec operates on 20-ms frames, and the default sampling
rate is 16 kHz. Input and output at an 8-kHz sampling rate are also
supported. The EVRC-WB codec can operate in three modes (0, 4, and
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