RTP Payload Format for Tactical Secure Voice Cryptographic Interoperability Specification (TSVCIS) Codec
RFC 8817

Document Type RFC - Proposed Standard (August 2020; No errata)
Authors Victor Demjanenko  , John Punaro  , David Satterlee 
Last updated 2020-08-17
Replaces draft-demjanenko-payload-tsvcis
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Internet Engineering Task Force (IETF)                     V. Demjanenko
Request for Comments: 8817                                     J. Punaro
Category: Standards Track                                   D. Satterlee
ISSN: 2070-1721                                 VOCAL Technologies, Ltd.
                                                             August 2020

       RTP Payload Format for Tactical Secure Voice Cryptographic
             Interoperability Specification (TSVCIS) Codec

Abstract

   This document describes the RTP payload format for the Tactical
   Secure Voice Cryptographic Interoperability Specification (TSVCIS)
   speech coder.  TSVCIS is a scalable narrowband voice coder supporting
   varying encoder data rates and fallbacks.  It is implemented as an
   augmentation to the Mixed Excitation Linear Prediction Enhanced
   (MELPe) speech coder by conveying additional speech coder parameters
   to enhance voice quality.  TSVCIS augmented speech data is processed
   in conjunction with its temporally matched Mixed Excitation Linear
   Prediction (MELP) 2400 speech data.  The RTP packetization of TSVCIS
   and MELPe speech coder data is described in detail.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8817.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
     1.1.  Conventions
     1.2.  Abbreviations
   2.  Background
   3.  Payload Format
     3.1.  MELPe Bitstream Definitions
       3.1.1.  2400 bps Bitstream Structure
       3.1.2.  1200 bps Bitstream Structure
       3.1.3.  600 bps Bitstream Structure
       3.1.4.  Comfort Noise Bitstream Definition
     3.2.  TSVCIS Bitstream Definition
     3.3.  Multiple TSVCIS Frames in an RTP Packet
     3.4.  Congestion Control Considerations
   4.  Payload Format Parameters
     4.1.  Media Type Definitions
     4.2.  Mapping to SDP
     4.3.  Declarative SDP Considerations
     4.4.  Offer/Answer SDP Considerations
   5.  Discontinuous Transmissions
   6.  Packet Loss Concealment
   7.  IANA Considerations
   8.  Security Considerations
   9.  References
     9.1.  Normative References
     9.2.  Informative References
   Authors' Addresses

1.  Introduction

   This document describes how compressed Tactical Secure Voice
   Cryptographic Interoperability Specification (TSVCIS) speech as
   produced by the TSVCIS codec [TSVCIS] [NRLVDR] may be formatted for
   use as an RTP payload.  The TSVCIS speech coder (or TSVCIS speech-
   aware communications equipment on any intervening transport link) may
   adjust to restricted bandwidth conditions by reducing the amount of
   augmented speech data and relying on the underlying MELPe speech
   coder for the most constrained bandwidth links.

   Details are provided for packetizing the TSVCIS augmented speech data
   along with MELPe 2400 bps speech parameters in an RTP packet.  The
   sender may send one or more codec data frames per packet, depending
   on the application scenario or based on transport network conditions,
   bandwidth restrictions, delay requirements, and packet loss
   tolerance.

1.1.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   Best current practices for writing an RTP payload format
   specification were followed [RFC2736] [RFC8088].

1.2.  Abbreviations

   The following abbreviations are used in this document.

   AVP:      Audio/Video Profile

   AVPF:     Audio/Video Profile Feedback

   CELP:     Code-Excited Linear Prediction

   FEC:      Forward Error Correction

   LPC:      Linear-Predictive Coding
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