draft-ietf-payload-tsvcis-01.txt   rfc8817.txt 
Payload Working Group Victor Demjanenko Internet Engineering Task Force (IETF) V. Demjanenko
Internet-Draft John Punaro Request for Comments: 8817 J. Punaro
Intended Status: Standards Track David Satterlee Category: Standards Track D. Satterlee
VOCAL Technologies, Ltd. ISSN: 2070-1721 VOCAL Technologies, Ltd.
Expires: April 19, 2019 October 16, 2018 August 2020
RTP Payload Format for TSVCIS Codec RTP Payload Format for Tactical Secure Voice Cryptographic
draft-ietf-payload-tsvcis-01 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 Status of This Memo
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Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
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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
for enhancing voice quality. TSVCIS augmented speech data is
processed in conjunction with its temporal matched MELP 2400 speech
data. The RTP packetization of TSVCIS and MELPe speech coder data is
described in detail.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Conventions
2. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Abbreviations
3. Payload Format . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Background
3.1. MELPe Bitstream Definitions . . . . . . . . . . . . . . . 5 3. Payload Format
3.1.1. 2400 bps Bitstream Structure . . . . . . . . . . . . . 6 3.1. MELPe Bitstream Definitions
3.1.2. 1200 bps Bitstream Structure . . . . . . . . . . . . . 6 3.1.1. 2400 bps Bitstream Structure
3.1.3. 600 bps Bitstream Structure . . . . . . . . . . . . . 7 3.1.2. 1200 bps Bitstream Structure
3.1.4. Comfort Noise Bitstream Definition . . . . . . . . . . 8 3.1.3. 600 bps Bitstream Structure
3.2. TSVCIS Bitstream Definition . . . . . . . . . . . . . . . 8 3.1.4. Comfort Noise Bitstream Definition
3.3. Multiple TSVCIS Frames in an RTP Packet . . . . . . . . . 10 3.2. TSVCIS Bitstream Definition
3.4. Congestion Control Considerations . . . . . . . . . . . . 11 3.3. Multiple TSVCIS Frames in an RTP Packet
4. Payload Format Parameters . . . . . . . . . . . . . . . . . . 11 3.4. Congestion Control Considerations
4.1. Media Type Definitions . . . . . . . . . . . . . . . . . . 11 4. Payload Format Parameters
4.2. Mapping to SDP . . . . . . . . . . . . . . . . . . . . . . 13 4.1. Media Type Definitions
4.3. Declarative SDP Considerations . . . . . . . . . . . . . . 14 4.2. Mapping to SDP
4.4. Offer/Answer SDP Considerations . . . . . . . . . . . . . 15 4.3. Declarative SDP Considerations
5. Discontinuous Transmissions . . . . . . . . . . . . . . . . . 15 4.4. Offer/Answer SDP Considerations
6. Packet Loss Concealment . . . . . . . . . . . . . . . . . . . 16 5. Discontinuous Transmissions
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 6. Packet Loss Concealment
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7. IANA Considerations
9. RFC Editor Considerations . . . . . . . . . . . . . . . . . . 17 8. Security Considerations
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 9. References
10.1. Normative References . . . . . . . . . . . . . . . . . . 17 9.1. Normative References
10.2. Informative References . . . . . . . . . . . . . . . . . 19 9.2. Informative References
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses
1. Introduction 1. Introduction
This document describes how compressed Tactical Secure Voice This document describes how compressed Tactical Secure Voice
Cryptographic Interoperability Specification (TSVCIS) speech as Cryptographic Interoperability Specification (TSVCIS) speech as
produced by the TSVCIS codec [TSVCIS] [NRLVDR] may be formatted for produced by the TSVCIS codec [TSVCIS] [NRLVDR] may be formatted for
use as an RTP payload. The TSVCIS speech coder (or TSVCIS speech use as an RTP payload. The TSVCIS speech coder (or TSVCIS speech-
aware communications equipment on any intervening transport link) may aware communications equipment on any intervening transport link) may
adjust to restricted bandwidth conditions by reducing the amount of adjust to restricted bandwidth conditions by reducing the amount of
augmented speech data and relying on the underlying MELPe speech augmented speech data and relying on the underlying MELPe speech
coder for the most constrained bandwidth links. coder for the most constrained bandwidth links.
Details are provided for packetizing the TSVCIS augmented speech data Details are provided for packetizing the TSVCIS augmented speech data
along with MELPe 2400 bps speech parameters in a RTP packet. The along with MELPe 2400 bps speech parameters in an RTP packet. The
sender may send one or more codec data frames per packet, depending sender may send one or more codec data frames per packet, depending
on the application scenario or based on transport network conditions, on the application scenario or based on transport network conditions,
bandwidth restrictions, delay requirements, and packet loss bandwidth restrictions, delay requirements, and packet loss
tolerance. tolerance.
1.1. Conventions 1.1. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC 2119 [RFC2119]. "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 Best current practices for writing an RTP payload format
specification were followed [RFC2736]. 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
LSB: Least Significant Bit
MELP: Mixed Excitation Linear Prediction
MELPe: Mixed Excitation Linear Prediction Enhanced
MSB: Most Significant Bit
MTC: Modified Count
NATO: North American Treaty Organization
NRL: Naval Research Lab
PLC: Packet Loss Concealment
SAVP: Secure Audio/Video Profile
SAVPF: Secure Audio/Video Profile Feedback
SDP: Session Description Protocol
SSRC: Synchronization Source
SRTP: Secure Real-Time Transport Protocol
TSVCIS: Tactical Secure Voice Cryptographic Interoperability
Specification
VAD: Voice Activity Detect
VDR: Variable Date Rate
2. Background 2. Background
The MELP speech coder was developed by the US military as an upgrade The MELP speech coder was developed by the US military as an upgrade
from the LPC-based CELP standard vocoder for low-bitrate from the LPC-based CELP standard vocoder for low-bitrate
communications [MELP]. ("LPC" stands for "Linear-Predictive Coding", communications [MELP]. ("LPC" stands for "Linear-Predictive Coding",
and "CELP" stands for "Code-Excited Linear Prediction".) MELP was and "CELP" stands for "Code-Excited Linear Prediction".) MELP was
further enhanced and subsequently adopted by NATO as MELPe for use by further enhanced and subsequently adopted by NATO as "MELPe" for use
its members and Partnership for Peace countries for military and by its members and Partnership for Peace countries for military and
other governmental communications as international NATO Standard other governmental communications as international NATO Standard
STANAG 4591 [MELPE]. STANAG 4591 [MELPE].
The Tactical Secure Voice Cryptographic Interoperability The Tactical Secure Voice Cryptographic Interoperability
Specification (TSVCIS) is a specification written by the Tactical Specification (TSVCIS) is a specification written by the Tactical
Secure Voice Working Group (TSVWG) for enabling all modern tactical Secure Voice Working Group (TSVWG) to enable all modern tactical
secure voice devices to be interoperable across the Department of secure voice devices to be interoperable across the US Department of
Defense [TSVCIS]. One of the most important aspects is that the Defense [TSVCIS]. One of the most important aspects is that the
voice modes defined in TSVCIS are based on a fixed rate variant of voice modes defined in TSVCIS are based on specific fixed rates of
Naval Research Lab's (NRL's) Variable Date Rate (VDR) Vocoder which the Naval Research Lab's (NRL's) Variable Date Rate (VDR) Vocoder,
uses the MELPe standard as its base [NRLVDR]. A complete TSVCIS which uses the MELPe standard as its base [NRLVDR]. A complete
speech frame consists of MELPe speech parameters and corresponding TSVCIS speech frame consists of MELPe speech parameters and
TSVCIS augmented speech data. corresponding TSVCIS augmented speech data.
In addition to the augmented speech data, the TSVCIS specification In addition to the augmented speech data, the TSVCIS specification
identifies which speech coder and framing bits are to be encrypted, identifies which speech coder and framing bits are to be encrypted
and how they are protected by forward error correction (FEC) and how they are protected by forward error correction (FEC)
techniques (using block codes). At the RTP transport layer, only the techniques (using block codes). At the RTP transport layer, only the
speech coder related bits need to be considered and are conveyed in speech coder-related bits need to be considered and are conveyed in
unencrypted form. In most IP-based network deployments, standard unencrypted form. In most IP-based network deployments, standard
link encryption methods (SRTP, VPNs, FIPS 140 link encryptors or Type link encryption methods (Secure Real-Time Transport Protocol (SRTP),
1 Ethernet encryptors) would be used to secure the RTP speech VPNs, FIPS 140 link encryptors, or Type 1 Ethernet encryptors) would
contents. Further, it is desirable to support the highest voice be used to secure the RTP speech contents.
quality between endpoint which is only possible without the overhead
of FEC.
TSVCIS augmented speech data is derived from the signal processing TSVCIS augmented speech data is derived from the signal processing
and data already performed by the MELPe speech coder. For the and data generated by the MELPe speech coder. For the purposes of
purposes of this specification, only the general parameter nature of this specification, only the general parameter nature of TSVCIS will
TSVCIS will be characterized. Depending on the bandwidth available be characterized. Depending on the bandwidth available (and FEC
(and FEC requirements), a varying number of TSVCIS specific speech requirements), a varying number of TSVCIS-specific speech coder
coder parameters need to be transported. These are first byte-packed parameters need to be transported. These are first byte-packed and
and then conveyed from encoder to decoder. then conveyed from encoder to decoder.
Byte packing of TSVCIS speech data into packed parameters is Byte packing of TSVCIS speech data into packed parameters is
processed as per the following example: processed as per the following example, where
Two-bit field: bits A and B (A is MSB, B is LSB) Three-bit field: Bits A, B, and C (A is MSB; C is LSB)
Six-bit field: bits C, D, E, F, G, and H (C is MSB, H is LSB)
Five-bit field: Bits D, E, F, G, and H (D is MSB; H is LSB)
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| H | G | F | E | D | C | B | A | | H | G | F | E | D | C | B | A |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
This packing method places the two-bit field "first" in the lowest This packing method places the three-bit field "first" in the lowest
bits followed by the next six-bit field. Parameters may be split bits followed by the next five-bit field. Parameters may be split
between octets with the most significant bits in the earlier octet. between octets with the most significant bits in the earlier octet.
Any unfilled bits in the last octet SHOULD be filled with zero. Any unfilled bits in the last octet MUST be filled with zero.
In order to accommodate a varying amount of TSVCIS augmented speech In order to accommodate a varying amount of TSVCIS augmented speech
data, it is only necessary to specify the number of octets containing data, an octet count specifies the number of octets representing the
the packed TSVCIS parameters. The encoding to do so is presented in TSVCIS packed parameters. The encoding to do so is presented in
Section 3.2. The preferred sets of TSVCIS parameters is specified in Section 3.2. TSVCIS specifically uses the NRL VDR in two
the speech coder specification [TSVCIS] and is beyond the scope of configurations with a fixed set of 15 and 35 packed octet parameters
this RFC to describe or limit. in a standardized order [TSVCIS].
3. Payload Format 3. Payload Format
The TSVCIS codec augments the standard MELP 2400, 1200 and 600 The TSVCIS codec augments the standard MELP 2400, 1200, and 600
bitrates and hence uses 22.5, 67.5, or 90 ms frames with a sampling bitrates and hence uses 22.5, 67.5, or 90 ms frames with a sampling
rate clock of 8 kHz, so the RTP timestamp MUST be in units of 1/8000 rate clock of 8 kHz, so the RTP timestamp MUST be in units of 1/8000
of a second. of a second.
The RTP payload for TSVCIS has the format shown in Figure 1. No The RTP payload for TSVCIS has the format shown in Figure 1. No
additional header specific to this payload format is needed. This additional header specific to this payload format is needed. This
format is intended for situations where the sender and the receiver format is intended for situations where the sender and the receiver
send one or more codec data frames per packet. send one or more codec data frames per packet.
0 1 2 3 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 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 | | RTP Header |
+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
| | | |
+ one or more frames of TSVCIS | + one or more frames of TSVCIS |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Packet Format Diagram Figure 1: Packet Format Diagram
The RTP header of the packetized encoded TSVCIS speech has the The RTP header of the packetized encoded TSVCIS speech has the
expected values as described in [RFC3550]. The usage of the M bit expected values as described in [RFC3550]. The usage of the M bit
SHOULD be as specified in the applicable RTP profile -- for example, SHOULD be as specified in the applicable RTP profile -- for example,
[RFC3551], where [RFC3551] specifies that if the sender does not [RFC3551] specifies that if the sender does not suppress silence
suppress silence (i.e., sends a frame on every frame interval), the (i.e., sends a frame on every frame interval), the M bit will always
M bit will always be zero. When more than one codec data frame is be zero. When more than one codec data frame is present in a single
present in a single RTP packet, the timestamp is, as always, that of RTP packet, the timestamp specified is that of the oldest data frame
the oldest data frame represented in the RTP packet. represented in the RTP packet.
The assignment of an RTP payload type for this new packet format is 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 outside the scope of this document and will not be specified here.
is expected that the RTP profile for a particular class of It is expected that the RTP profile for a particular class of
applications will assign a payload type for this encoding, or if that applications will assign a payload type for this encoding; if that is
is not done, then a payload type in the dynamic range shall be chosen not done, then a payload type in the dynamic range shall be chosen by
by the sender. the sender.
3.1. MELPe Bitstream Definitions 3.1. MELPe Bitstream Definitions
The TCVCIS speech coder includes all three MELPe coder rates used as The TSVCIS speech coder includes all three MELPe coder rates used as
base speech parameters or as speech coders for bandwidth restricted base speech parameters or as speech coders for bandwidth-restricted
links. RTP packetization of MELPe follows RFC 8130 and is repeated links. RTP packetization of MELPe follows [RFC8130] and is repeated
here for all three MELPe rates [RFC8130] which with its here for all three MELPe rates [RFC8130], with its recommendations
recommendations now regarded as requirements. The bits previously now regarded as requirements. The bits previously labeled as RSVA,
labeled as RSVA, RSVB, and RSVC in RFC 8130 SHOULD be filled with RSVB, and RSVC in [RFC8130] SHOULD be filled with rate code bits
rate coding, CODA, CODB, and CODC, as shown in Table 1 (compatible CODA, CODB, and CODC, as shown in Table 1 (compatible with Table 7 in
with Table 7 in Section 3.3 of [RFC8130]). Section 3.3 of [RFC8130]).
+-------------------+------+------+------+------+ +===============+======+======+======+========+
| Coder Bitrate | CODA | CODB | CODC |Length| | Coder Bitrate | CODA | CODB | CODC | Length |
+-------------------+------+------+------+------+ +===============+======+======+======+========+
| 2400 bps | 0 | 0 | N/A | 7 | | 2400 bps | 0 | 0 | N/A | 7 |
+-------------------+------+------+------+------+ +---------------+------+------+------+--------+
| 1200 bps | 1 | 0 | 0 | 11 | | 1200 bps | 1 | 0 | 0 | 11 |
+-------------------+------+------+------+------+ +---------------+------+------+------+--------+
| 600 bps | 0 | 1 | N/A | 7 | | 600 bps | 0 | 1 | N/A | 7 |
+-------------------+------+------+------+------+ +---------------+------+------+------+--------+
| Comfort Noise | 1 | 0 | 1 | 2 | | Comfort Noise | 1 | 0 | 1 | 2 |
+-------------------+------+------+------+------+ +---------------+------+------+------+--------+
| TSVCIS data | 1 | 1 | N/A | var. | | TSVCIS Data | 1 | 1 | N/A | var. |
+-------------------+------+------+------+------+ +---------------+------+------+------+--------+
Table 1: TSVCIS/MELPe Frame Bitrate Indicators and Frame Length Table 1: TSVCIS/MELPe Frame Bitrate
Indicators and Frame Length
The total number of bits used to describe one MELPe frame of 2400 bps The total number of bits used to describe one MELPe frame of 2400 bps
speech is 54, which fits in 7 octets (with two rate code bits). For speech is 54, which fits in 7 octets (with two rate code bits). For
MELPe 1200 bps speech, the total number of bits used is 81, which MELPe 1200 bps speech, the total number of bits used is 81, which
fits in 11 octets (with three rate code bits and four unused bits). fits in 11 octets (with three rate code bits and four unused bits).
For MELPe 600 bps speech, the total number of bits used is 54, which For MELPe 600 bps speech, the total number of bits used is 54, which
fits in 7 octets (with two rate code bits). The comfort noise frame fits in 7 octets (with two rate code bits). The comfort noise frame
consists of 13 bits, which fits in 2 octets (with three rate code consists of 13 bits, which fits in 2 octets (with three rate code
bits). TSVCIS packed parameters will use the last code combination bits). TSVCIS packed parameters will use the last code combination
in a trailing byte as discussed in Section 3.2. in a trailing byte as discussed in Section 3.2.
It should be noted that CODB for both the 2400 and 600 bps modes MAY It should be noted that CODB for MELPe 600 bps mode MAY deviate from
deviate from the values in Table 1 when bit 55 is used as an end-to- the value in Table 1 when bit 55 is used as an alternating 1/0 end-
end framing bit. Frame decoding would remain distinct as CODA being to-end framing bit. Frame decoding would remain distinct as CODA
zero on its own would indicate a 7-byte frame for either rate and the being zero on its own would indicate a 7-byte frame for either a 2400
use of 600 bps speech coding could be deduced from the RTP timestamp or 600 bps rate, and the use of 600 bps speech coding could be
(and anticipated by the SDP negotiations). deduced from the RTP timestamp (and anticipated by the Session
Description Protocol (SDP) negotiations).
3.1.1. 2400 bps Bitstream Structure 3.1.1. 2400 bps Bitstream Structure
The 2400 bps MELPe RTP payload is constructed as per Figure 2. Note The 2400 bps MELPe RTP payload is constructed as per Figure 2. Note
that CODA must be filled with 0 and CODB SHOULD be filled with 0 as that CODA MUST be filled with 0 and CODB SHOULD be filled with 0 as
per Section 3.1. CODB MAY contain an end-to-end framing bit if per Section 3.1. CODB MAY contain an end-to-end framing bit if
required by the endpoints. required by the endpoints.
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 | | B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_16 | B_15 | B_14 | B_13 | B_12 | B_11 | B_10 | B_09 | | B_16 | B_15 | B_14 | B_13 | B_12 | B_11 | B_10 | B_09 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
skipping to change at page 6, line 49 skipping to change at line 334
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_32 | B_31 | B_30 | B_29 | B_28 | B_27 | B_26 | B_25 | | B_32 | B_31 | B_30 | B_29 | B_28 | B_27 | B_26 | B_25 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_40 | B_39 | B_38 | B_37 | B_36 | B_35 | B_34 | B_33 | | B_40 | B_39 | B_38 | B_37 | B_36 | B_35 | B_34 | B_33 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_48 | B_47 | B_46 | B_45 | B_44 | B_43 | B_42 | B_41 | | B_48 | B_47 | B_46 | B_45 | B_44 | B_43 | B_42 | B_41 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| CODA | CODB | B_54 | B_53 | B_52 | B_51 | B_50 | B_49 | | CODA | CODB | B_54 | B_53 | B_52 | B_51 | B_50 | B_49 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 2: Packed MELPe 2400 bps Payload Octets Figure 2: Packed MELPe 2400 bps Payload Octets
3.1.2. 1200 bps Bitstream Structure 3.1.2. 1200 bps Bitstream Structure
The 1200 bps MELPe RTP payload is constructed as per Figure 3. Note The 1200 bps MELPe RTP payload is constructed as per Figure 3. Note
that CODA, CODB, and CODC MUST be filled with 1, 0, and 0 that CODA, CODB, and CODC MUST be filled with 1, 0, and 0,
respectively as per Section 3.1. RSV0 SHOULD be coded as 0. respectively, as per Section 3.1. RSV0 MUST be coded as 0.
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 | | B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_16 | B_15 | B_14 | B_13 | B_12 | B_11 | B_10 | B_09 | | B_16 | B_15 | B_14 | B_13 | B_12 | B_11 | B_10 | B_09 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_24 | B_23 | B_22 | B_21 | B_20 | B_19 | B_18 | B_17 | | B_24 | B_23 | B_22 | B_21 | B_20 | B_19 | B_18 | B_17 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
skipping to change at page 7, line 34 skipping to change at line 368
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_64 | B_63 | B_62 | B_61 | B_60 | B_59 | B_58 | B_57 | | B_64 | B_63 | B_62 | B_61 | B_60 | B_59 | B_58 | B_57 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_72 | B_71 | B_70 | B_69 | B_68 | B_67 | B_66 | B_65 | | B_72 | B_71 | B_70 | B_69 | B_68 | B_67 | B_66 | B_65 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_80 | B_79 | B_78 | B_77 | B_76 | B_75 | B_74 | B_73 | | B_80 | B_79 | B_78 | B_77 | B_76 | B_75 | B_74 | B_73 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| CODA | CODB | CODC | RSV0 | RSV0 | RSV0 | RSV0 | B_81 | | CODA | CODB | CODC | RSV0 | RSV0 | RSV0 | RSV0 | B_81 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 3: Packed MELPe 1200 bps Payload Octets Figure 3: Packed MELPe 1200 bps Payload Octets
3.1.3. 600 bps Bitstream Structure 3.1.3. 600 bps Bitstream Structure
The 600 bps MELPe RTP payload is constructed as per Figure 4. Note The 600 bps MELPe RTP payload is constructed as per Figure 4. Note
CODA must be filled with 0 and CODB SHOULD be filled with 1 as per CODA MUST be filled with 0 and CODB SHOULD be filled with 1 as per
Section 3.1. CODB MAY contain an end-to-end framing bit if required Section 3.1. CODB MAY contain an end-to-end framing bit if required
by the endpoints. by the endpoints.
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 | | B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_16 | B_15 | B_14 | B_13 | B_12 | B_11 | B_10 | B_09 | | B_16 | B_15 | B_14 | B_13 | B_12 | B_11 | B_10 | B_09 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
skipping to change at page 8, line 13 skipping to change at line 395
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_32 | B_31 | B_30 | B_29 | B_28 | B_27 | B_26 | B_25 | | B_32 | B_31 | B_30 | B_29 | B_28 | B_27 | B_26 | B_25 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_40 | B_39 | B_38 | B_37 | B_36 | B_35 | B_34 | B_33 | | B_40 | B_39 | B_38 | B_37 | B_36 | B_35 | B_34 | B_33 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_48 | B_47 | B_46 | B_45 | B_44 | B_43 | B_42 | B_41 | | B_48 | B_47 | B_46 | B_45 | B_44 | B_43 | B_42 | B_41 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| CODA | CODB | B_54 | B_53 | B_52 | B_51 | B_50 | B_49 | | CODA | CODB | B_54 | B_53 | B_52 | B_51 | B_50 | B_49 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 4: Packed MELPe 600 bps Payload Octets Figure 4: Packed MELPe 600 bps Payload Octets
3.1.4. Comfort Noise Bitstream Definition 3.1.4. Comfort Noise Bitstream Definition
The comfort noise MELPe RTP payload is constructed as per Figure 5. The comfort noise MELPe RTP payload is constructed as per Figure 5.
Note that CODA, CODB, and CODC MUST be filled with 1, 0, and 1 Note that CODA, CODB, and CODC MUST be filled with 1, 0, and 1,
respectively as per Section 3.1. respectively, as per Section 3.1.
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 | | B_08 | B_07 | B_06 | B_05 | B_04 | B_03 | B_02 | B_01 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| CODA | CODB | CODC | B_13 | B_12 | B_11 | B_10 | B_09 | | CODA | CODB | CODC | B_13 | B_12 | B_11 | B_10 | B_09 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 5: Packed MELPe Comfort Noise Payload Octets Figure 5: Packed MELPe Comfort Noise Payload Octets
3.2. TSVCIS Bitstream Definition 3.2. TSVCIS Bitstream Definition
The TSVCIS augmented speech data as packed parameters MUST be placed The TSVCIS augmented speech data as packed parameters MUST be placed
immediately after a corresponding MELPe 2400 bps payload in the same immediately after a corresponding MELPe 2400 bps payload in the same
RTP packet. The packed parameters are counted in octets (TC). In RTP packet. The packed parameters are counted in octets (TC). The
the preferred placement, shown in Figure 6, a single trailing octet preferred placement SHOULD be used for TSVCIS payloads with TC less
SHALL be appended to include a two-bit rate code, CODA and CODB, than or equal to 77 octets; this is shown in Figure 6. In the
(both bits set to one) and a six-bit modified count (MTC). The preferred placement, a single trailing octet SHALL be appended to
special modified count value of all ones (representing a MTC value of include a two-bit rate code, CODA and CODB (both bits set to one),
63) SHALL NOT be used for this format as it is used as the indicator and a six-bit modified count (MTC). The special modified count value
for the alternate packing format shown next. In a standard of all ones (representing an MTC value of 63) SHALL NOT be used for
implementation, the TSVCIS speech coder uses a minimum of 15 octets this format as it is used as the indicator for the alternate packing
for parameters in octet packed form. The modified count (MTC) MUST format shown next. In a standard implementation, the TSVCIS speech
be reduced by 15 from the full octet count (TC). Computed MTC = TC- coder uses a minimum of 15 octets for parameters in octet packed
15. This accommodates a maximum of 77 parameter octets (maximum form. The modified count (MTC) MUST be reduced by 15 from the full
value of MTC is 62, 77 is the sum of 62+15). octet count (TC). Computed MTC = TC-15. This accommodates a maximum
of 77 parameter octets (the maximum value of MTC is 62; 77 is the sum
of 62+15).
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
1 | T008 | T007 | T006 | T005 | T004 | T003 | T002 | T001 | 1 | T008 | T007 | T006 | T005 | T004 | T003 | T002 | T001 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 | 2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
3 | T024 | T023 | T022 | T021 | T020 | T019 | T018 | T017 | 3 | T024 | T023 | T022 | T021 | T020 | T019 | T018 | T017 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
skipping to change at page 9, line 38 skipping to change at line 470
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
14 | T112 | T111 | T110 | T109 | T108 | T107 | T106 | T105 | 14 | T112 | T111 | T110 | T109 | T108 | T107 | T106 | T105 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
15 | T120 | T119 | T118 | T117 | T116 | T115 | T114 | T113 | 15 | T120 | T119 | T118 | T117 | T116 | T115 | T114 | T113 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| . . . . | | . . . . |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+1 | CODA | CODB | modified octet count | TC+1 | CODA | CODB | modified octet count |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 6: Preferred Packed TSVCIS Payload Octets Figure 6: Preferred Packed TSVCIS Payload Octets
In order to accommodate all other NRL VDR configurations for TSVCIS, In order to accommodate all other NRL VDR configurations, an
an alternate parameter placement MUST use two trailing bytes as shown alternate parameter placement MUST use two trailing bytes as shown in
in Figure 7. The last trailing byte MUST be filled with a two-bit Figure 7. The last trailing byte MUST be filled with a two-bit rate
rate code, CODA and CODB, (both bits set to one) and its six-bit code, CODA and CODB (both bits set to one), and its six-bit count
count field MUST be filled with ones. The second to last trailing field MUST be filled with ones. The second to last trailing byte
byte MUST contain the parameter count (TC) in octets and MAY MUST contain the parameter count (TC) in octets (a value from 1 and
represent any value from one to 255. The value of zero SHALL be 255, inclusive). The value of zero SHALL be considered as reserved.
considered as reserved.
MSB LSB MSB LSB
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
1 | T008 | T007 | T006 | T005 | T004 | T003 | T002 | T001 | 1 | T008 | T007 | T006 | T005 | T004 | T003 | T002 | T001 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 | 2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| . . . . | | . . . . |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+1 | octet count | TC+1 | octet count |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+2 | CODA | CODB | 1 | 1 | 1 | 1 | 1 | 1 | TC+2 | CODA | CODB | 1 | 1 | 1 | 1 | 1 | 1 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
skipping to change at page 10, line 16 skipping to change at line 494
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 | 2 | T016 | T015 | T014 | T013 | T012 | T011 | T010 | T009 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
| . . . . | | . . . . |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+1 | octet count | TC+1 | octet count |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
TC+2 | CODA | CODB | 1 | 1 | 1 | 1 | 1 | 1 | TC+2 | CODA | CODB | 1 | 1 | 1 | 1 | 1 | 1 |
+------+------+------+------+------+------+------+------+ +------+------+------+------+------+------+------+------+
Figure 7: Length Unrestricted Packed TSVCIS Payload Octets Figure 7: Length Unrestricted Packed TSVCIS Payload Octets
3.3. Multiple TSVCIS Frames in an RTP Packet 3.3. Multiple TSVCIS Frames in an RTP Packet
A TSVCIS RTP packet MAY consist of zero or more TSVCIS coder frames A TSVCIS RTP packet payload consists of zero or more consecutive
(each consisting of MELPe and TSVCIS coder data) followed by zero or TSVCIS coder frames (each consisting of MELPe 2400 and TSVCIS coder
one MELPe comfort noise frame. The presence of a comfort noise frame data), with the oldest frame first, followed by zero or one MELPe
can be determined by its rate code bits in its last octet. comfort noise frame. The presence of a comfort noise frame can be
determined by its rate code bits in its last octet.
The default packetization interval is one coder frame (22.5, 67.5, or The default packetization interval is one coder frame (22.5, 67.5, or
90 ms) according to the coder bitrate (2400, 1200, or 600 bps). For 90 ms) according to the coder bitrate (2400, 1200, or 600 bps). For
some applications, a longer packetization interval is used to reduce some applications, a longer packetization interval is used to reduce
the packet rate. the packet rate.
A TSVCIS RTP packet comprised of no coder frame and no comfort noise A TSVCIS RTP packet without coder and comfort noise frames MAY be
frame MAY be used periodically by an endpoint to indicate used periodically by an endpoint to indicate connectivity by an
connectivity by an otherwise idle receiver. otherwise idle receiver.
TSVCIS coder frames in a single RTP packet MAY be of different coder TSVCIS coder frames in a single RTP packet MAY have varying TSVCIS
bitrates. With the exception for the variable length TSVCIS parameter octet counts. Its packed parameter octet count (length) is
parameter frames, the coder rate bits in the trailing byte identify indicated in the trailing byte(s). All MELPe frames in a single RTP
the contents and length as per Table 1. packet MUST be of the same coder bitrate. For all MELPe coder
frames, the coder rate bits in the trailing byte identify the
contents and length as per Table 1.
It is important to observe that senders have the following additional It is important to observe that senders have the following additional
restrictions: restrictions:
Senders SHOULD NOT include more TSVCIS or MELPe frames in a single * Senders SHOULD NOT include more TSVCIS or MELPe frames in a single
RTP packet than will fit in the MTU of the RTP transport protocol. RTP packet than will fit in the MTU of the RTP transport protocol.
Frames MUST NOT be split between RTP packets. * Frames MUST NOT be split between RTP packets.
It is RECOMMENDED that the number of frames contained within an RTP It is RECOMMENDED that the number of frames contained within an RTP
packet be consistent with the application. For example, in telephony packet be consistent with the application. For example, in telephony
and other real-time applications where delay is important, then the and other real-time applications where delay is important, the fewer
fewer frames per packet the lower the delay, whereas for bandwidth- frames per packet, the lower the delay. However, for bandwidth-
constrained links or delay-insensitive streaming messaging constrained links or delay-insensitive streaming messaging
applications, more than one frame per packet or many frames per applications, more than one frame per packet or many frames per
packet would be acceptable. packet would be acceptable.
Information describing the number of frames contained in an RTP Information describing the number of frames contained in an RTP
packet is not transmitted as part of the RTP payload. The way to packet is not transmitted as part of the RTP payload. The way to
determine the number of TSVCIS/MELPe frames is to identify each frame determine the number of TSVCIS/MELPe frames is to identify each frame
type and length thereby counting the total number of octets within type and length, thereby counting the total number of octets within
the RTP packet. the RTP packet.
3.4. Congestion Control Considerations 3.4. Congestion Control Considerations
The target bitrate of TSVCIS can be adjusted at any point in time, The target bitrate of TSVCIS can be adjusted at any point in time,
thus allowing congestion management. Furthermore, the amount of thus allowing congestion management. Furthermore, the amount of
encoded speech or audio data encoded in a single packet can be used encoded speech or audio data encoded in a single packet can be used
for congestion control, since the packet rate is inversely for congestion control, since the packet rate is inversely
proportional to the packet duration. A lower packet transmission proportional to the packet duration. A lower packet transmission
rate reduces the amount of header overhead but at the same time rate reduces the amount of header overhead but at the same time
increases latency and loss sensitivity, so it ought to be used increases latency and loss sensitivity, so it ought to be used with
with care. care.
Since UDP does not provide congestion control, applications that use Since UDP does not provide congestion control, applications that use
RTP over UDP SHOULD implement their own congestion control above the RTP over UDP SHOULD implement their own congestion control above the
UDP layer [RFC8085] and MAY also implement a transport circuit UDP layer [RFC8085] and MAY also implement a transport circuit
breaker [RFC8083]. Work in the RMCAT working group [RMCAT] describes breaker [RFC8083]. Work in the RMCAT Working Group [RMCAT] describes
the interactions and conceptual interfaces necessary between the the interactions and conceptual interfaces necessary between the
application components that relate to congestion control, including application components that relate to congestion control, including
the RTP layer, the higher-level media codec control layer, and the the RTP layer, the higher-level media codec control layer, and the
lower-level transport interface, as well as components dedicated to lower-level transport interface, as well as components dedicated to
congestion control functions. congestion control functions.
4. Payload Format Parameters 4. Payload Format Parameters
This RTP payload format is identified using the TSVCIS media subtype, This RTP payload format is identified using the TSVCIS media subtype,
which is registered in accordance with RFC 4855 [RFC4855] and per the which is registered in accordance with [RFC4855] and per the media
media type registration template from RFC 6838 [RFC6838]. type registration template from [RFC6838].
4.1. Media Type Definitions 4.1. Media Type Definitions
Type name: audio Type name: audio
Subtype names: TSVCIS Subtype name: TSVCIS
Required parameters: N/A Required parameters: Clock Rate (Hz): 8000
Optional parameters: Optional parameters:
ptime:
the recommended length of time (in milliseconds) represented by
the media in a packet. It SHALL use the nearest rounded-up ms
integer packet duration. For TSVCIS, this corresponds to the
following values: 23, 45, 68, 90, 112, 135, 156, and 180.
Larger values can be used as long as they are properly rounded.
See Section 6 of [RFC4566].
ptime: the recommended length of time (in milliseconds) maxptime:
represented by the media in a packet. It SHALL use the nearest the maximum length of time (in milliseconds) that can be
rounded-up ms integer packet duration. For TSVCIS, this
corresponds to the following values: 23, 45, 68, 90, 112, 135,
156, and 180. Larger values can be used as long as they are
properly rounded. See Section 6 of RFC 4566 [RFC4566].
maxptime: the maximum length of time (in milliseconds) that can be
encapsulated in a packet. It SHALL use the nearest rounded-up encapsulated in a packet. It SHALL use the nearest rounded-up
ms integer packet duration. For TSVCIS, this corresponds to ms integer packet duration. For TSVCIS, this corresponds to
the following values: 23, 45, 68, 90, 112, 135, 156, and 180. the following values: 23, 45, 68, 90, 112, 135, 156, and 180.
Larger values can be used as long as they are properly rounded. Larger values can be used as long as they are properly rounded.
See Section 6 of RFC 4566 [RFC4566]. See Section 6 of [RFC4566].
bitrate: specifies the MELPe coder bitrates supported. Possible bitrate:
values are a comma-separated list of rates from the following specifies the MELPe coder bitrates supported. Possible values
set: 2400, 1200, 600. The modes are listed in order of are a comma-separated list of rates from the following set:
preference; first is preferred. If "bitrate" is not present, 2400, 1200, 600. The modes are listed in order of preference;
the fixed coder bitrate of 2400 MUST be used. the first is preferred. If "bitrate" is not present, the fixed
coder bitrate of 2400 MUST be used.
tcmax: specifies the TSVCIS maximum value for TC supported or tcmax:
desired ranging from 1 to 255. If "tcmax" is not present, a specifies the TSVCIS maximum value for the TC supported or
desired, ranging from 1 to 255. If "tcmax" is not present, a
default value of 35 is used. default value of 35 is used.
[EDITOR NOTE - the value of 35 is suggested based on a Channels:
preferred 8kbps TSVCIS coder bitrate.] 1
Encoding considerations: This media subtype is framed and binary; see
Section 4.8 of RFC 6838 [RFC6838].
Security considerations: Please see Section 8 of RFC XXXX.
[EDITOR NOTE - please replace XXXX with the RFC number of this Encoding considerations: This media subtype is framed and binary;
document.] see Section 4.8 of [RFC6838].
Interoperability considerations: N/A Security considerations: Please see Section 8 of RFC 8817.
Published specification: N/A Interoperability considerations: N/A
Applications that use this media type: N/A Published specification: [TSVCIS]
Additional information: N/A Applications that use this media type: N/A
Deprecated alias names for this type: N/A Fragment identifier considerations: N/A
Magic number(s): N/A Additional information:
File extension(s): N/A Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): N/A
Macintosh file type code(s): N/A
Macintosh file type code(s): N/A
Person & email address to contact for further information: Person & email address to contact for further information:
Victor Demjanenko, Ph.D. <victor.demjanenko@vocal.com>
Victor Demjanenko, Ph.D. Intended usage: COMMON
VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202
Buffalo, NY 14228
United States of America
Phone: +1 716 688 4675
Email: victor.demjanenko@vocal.com
Intended usage: COMMON
Restrictions on usage: The media subtype depends on RTP framing and Restrictions on usage: The media subtype depends on RTP framing and
hence is only defined for transfer via RTP [RFC3550]. Transport hence is only defined for transfer via RTP [RFC3550]. Transport
within other framing protocols is not defined at this time. within other framing protocols is not defined at this time.
Author: Victor Demjanenko Author: Victor Demjanenko, Ph.D.
Change controller: IETF Payload working group delegated from the Change controller: IETF; contact <avt@ietf.org>
IESG.
Provisional registration? (standards tree only): No Provisional registration? (standards tree only): No
4.2. Mapping to SDP 4.2. Mapping to SDP
The mapping of the above-defined payload format media subtype and its The mapping of the above-defined payload format media subtype and its
parameters SHALL be done according to Section 3 of RFC 4855 parameters SHALL be done according to Section 3 of [RFC4855].
[RFC4855].
The information carried in the media type specification has a The information carried in the media type specification has a
specific mapping to fields in the Session Description Protocol (SDP) specific mapping to fields in the Session Description Protocol (SDP)
[RFC4566], which is commonly used to describe RTP sessions. When SDP [RFC4566], which is commonly used to describe RTP sessions. When SDP
is used to specify sessions employing the TSVCIS codec, the mapping is used to specify sessions employing the TSVCIS codec, the mapping
is as follows: is as follows:
o The media type ("audio") goes in SDP "m=" as the media name. * The media type ("audio") goes in SDP "m=" as the media name.
o The media subtype (payload format name) goes in SDP "a=rtpmap" as * The media subtype (payload format name) goes in SDP "a=rtpmap" as
the encoding name. the encoding name.
o The parameter "bitrate" goes in the SDP "a=fmtp" attribute by * The parameter "bitrate" goes in the SDP "a=fmtp" attribute by
copying it as a "bitrate=<value>" string. copying it as a "bitrate=<value>" string.
o The parameter "tcmax" goes in the SDP "a=fmtp" attribute by * The parameter "tcmax" goes in the SDP "a=fmtp" attribute by
copying it as a "tcmax=<value>" string. copying it as a "tcmax=<value>" string.
o The parameters "ptime" and "maxptime" go in the SDP "a=ptime" and * The parameters "ptime" and "maxptime" go in the SDP "a=ptime" and
"a=maxptime" attributes, respectively. "a=maxptime" attributes, respectively.
When conveying information via SDP, the encoding name SHALL be When conveying information via SDP, the encoding name SHALL be
"TSVCIS" (the same as the media subtype). "TSVCIS" (the same as the media subtype).
An example of the media representation in SDP for describing TSVCIS An example of the media representation in SDP for describing TSVCIS
might be: might be:
m=audio 49120 RTP/AVP 96 m=audio 49120 RTP/AVP 96
a=rtpmap:96 TSVCIS/8000 a=rtpmap:96 TSVCIS/8000
skipping to change at page 14, line 40 skipping to change at line 704
parameter=value pairs. The string "value" is an integer number in parameter=value pairs. The string "value" is an integer number in
the range of 1 to 255 representing the maximum number of TSVCIS the range of 1 to 255 representing the maximum number of TSVCIS
parameter octets supported. An example of the media representation parameter octets supported. An example of the media representation
in SDP for describing TSVCIS with a maximum of 101 octets supported in SDP for describing TSVCIS with a maximum of 101 octets supported
is as follows: is as follows:
m=audio 49120 RTP/AVP 96 m=audio 49120 RTP/AVP 96
a=rtpmap:96 TSVCIS/8000 a=rtpmap:96 TSVCIS/8000
a=fmtp:96 tcmax=101 a=fmtp:96 tcmax=101
Parameter "ptime" cannot be used for the purpose of specifying the The parameter "ptime" cannot be used for the purpose of specifying
TSVCIS operating mode, due to the fact that for certain values it the TSVCIS operating mode due to the fact that, for certain values,
will be impossible to distinguish which mode is about to be used it will be impossible to distinguish which mode is about to be used
(e.g., when ptime=68, it would be impossible to distinguish if the (e.g., when ptime=68, it would be impossible to distinguish whether
packet is carrying one frame of 67.5 ms or three frames of 22.5 ms). the packet is carrying one frame of 67.5 ms or three frames of 22.5
ms).
Note that the payload format (encoding) names are commonly shown in Note that the payload format (encoding) names are commonly shown in
upper case. Media subtypes are commonly shown in lower case. These upper case. Media subtypes are commonly shown in lower case. These
names are case insensitive in both places. Similarly, parameter names are case insensitive in both places. Similarly, parameter
names are case insensitive in both the media subtype name and the names are case insensitive in both the media subtype name and the
default mapping to the SDP a=fmtp attribute. default mapping to the SDP a=fmtp attribute.
4.3. Declarative SDP Considerations 4.3. Declarative SDP Considerations
For declarative media, the "bitrate" parameter specifies the possible For declarative media, the "bitrate" parameter specifies the possible
bitrates used by the sender. Multiple TSVCIS rtpmap values (such as bitrates used by the sender. Multiple TSVCIS rtpmap values (such as
97, 98, and 99, as used below) MAY be used to convey TSVCIS-coded 97, 98, and 99, as used below) MAY be used to convey TSVCIS-coded
voice at different bitrates. The receiver can then select an voice at different bitrates. The receiver can then select an
appropriate TSVCIS codec by using 97, 98, or 99. appropriate TSVCIS codec by using 97, 98, or 99.
m=audio 49120 RTP/AVP 97 98 99 m=audio 49120 RTP/AVP 97 98 99
a=rtpmap:97 TSVCIS/8000 a=rtpmap:97 TSVCIS/8000
a=fmtp:97 bitrate=2400 a=fmtp:97 bitrate=2400
a=rtpmap:98 TSVCIS/8000 a=rtpmap:98 TSVCIS/8000
skipping to change at page 15, line 19 skipping to change at line 734
m=audio 49120 RTP/AVP 97 98 99 m=audio 49120 RTP/AVP 97 98 99
a=rtpmap:97 TSVCIS/8000 a=rtpmap:97 TSVCIS/8000
a=fmtp:97 bitrate=2400 a=fmtp:97 bitrate=2400
a=rtpmap:98 TSVCIS/8000 a=rtpmap:98 TSVCIS/8000
a=fmtp:98 bitrate=1200 a=fmtp:98 bitrate=1200
a=rtpmap:99 TSVCIS/8000 a=rtpmap:99 TSVCIS/8000
a=fmtp:99 bitrate=600 a=fmtp:99 bitrate=600
For declarative media, the "tcmax" parameter specifies the maximum For declarative media, the "tcmax" parameter specifies the maximum
number of TSVCIS packed parameter octets used by the sender or the number of octets of TSVCIS packed parameters used by the sender or
sender's communications channel. the sender's communications channel.
4.4. Offer/Answer SDP Considerations 4.4. Offer/Answer SDP Considerations
In the Offer/Answer model [RFC3264], "bitrate" is a bidirectional In the Offer/Answer model [RFC3264], "bitrate" is a bidirectional
parameter. Both sides MUST use a common "bitrate" value or values. parameter. Both sides MUST use a common "bitrate" value or values.
The offer contains the bitrates supported by the offerer, listed in The offer contains the bitrates supported by the offerer, listed in
its preferred order. The answerer MAY agree to any bitrate by its preferred order. The answerer MAY agree to any bitrate by
listing the bitrate first in the answerer response. Additionally, listing the bitrate first in the answerer response. Additionally,
the answerer MAY indicate any secondary bitrate or bitrates that it the answerer MAY indicate any secondary bitrate or bitrates that it
supports. The initial bitrate used by both parties SHALL be the supports. The initial bitrate used by both parties SHALL be the
first bitrate specified in the answerer response. first bitrate specified in the answerer response.
For example, if offerer bitrates are "2400,600" and answer bitrates For example, if offerer bitrates are "2400,600" and answerer bitrates
are "600,2400", the initial bitrate is 600. If other bitrates are are "600,2400", the initial bitrate is 600. If other bitrates are
provided by the answerer, any common bitrate between the offer and provided by the answerer, any common bitrate between the offer and
answer MAY be used at any time in the future. Activation of these answer MAY be used at any time in the future. Activation of these
other common bitrates is beyond the scope of this document. other common bitrates is beyond the scope of this document.
The use of a lower bitrate is often important for a case such as when The use of a lower bitrate is often important for a case such as when
one endpoint utilizes a bandwidth-constrained link (e.g., 1200 bps one endpoint utilizes a bandwidth-constrained link (e.g., 1200 bps
radio link or slower), where only the lower coder bitrate will work. radio link or slower), where only the lower coder bitrate will work.
In the Offer/Answer model [RFC3264], "tcmax" is a bidirectional In the Offer/Answer model [RFC3264], "tcmax" is a bidirectional
parameter. Both sides SHOULD use a common "tcmax" value. The offer parameter. Both sides SHOULD use a common "tcmax" value. The offer
contains the tcmax supported by the offerer. The answerer MAY agree contains the tcmax supported by the offerer. The answerer MAY agree
to any tcmax equal or less than this value by stating the desired to any tcmax equal to or less than this value by stating the desired
tcmax in the answerer response. The answerer alternatively MAY tcmax in the answerer response. The answerer alternatively MAY
identify its own tcmax and rely on TSVCIS ignoring any augmented data identify its own tcmax and rely on TSVCIS ignoring any augmented data
it cannot use. it cannot use.
5. Discontinuous Transmissions 5. Discontinuous Transmissions
A primary application of TSVCIS is for radio communications of voice A primary application of TSVCIS is for radio communications of voice
conversations, and discontinuous transmissions are normal. When conversations, and discontinuous transmissions are normal. When
TSVCIS is used in an IP network, TSVCIS RTP packet transmissions may TSVCIS is used in an IP network, TSVCIS RTP packet transmissions may
cease and resume frequently. RTP synchronization source (SSRC) cease and resume frequently. RTP synchronization source (SSRC)
sequence number gaps indicate lost packets to be filled by PLC, while sequence number gaps indicate lost packets to be filled by Packet
abrupt loss of RTP packets indicates intended discontinuous Loss Concealment (PLC), while abrupt loss of RTP packets indicates
transmissions. intended discontinuous transmissions. Resumption of voice
transmission SHOULD be indicated by the RTP marker bit (M) set to 1.
If a TSVCIS coder so desires, it may send a MELPe comfort noise frame If a TSVCIS coder so desires, it may send a MELPe comfort noise frame
as per Appendix B of [SCIP210] prior to ceasing transmission. A as per Appendix B of [SCIP210] prior to ceasing transmission. A
receiver may optionally use comfort noise during its silence periods. receiver may optionally use comfort noise during its silence periods.
No SDP negotiations are required. No SDP negotiations are required.
6. Packet Loss Concealment 6. Packet Loss Concealment
TSVCIS packet loss concealment (PLC) uses the special properties and TSVCIS packet loss concealment (PLC) uses the special properties and
coding for the pitch/voicing parameter of the MELPe 2400 bps coder. coding for the pitch/voicing parameter of the MELPe 2400 bps coder.
The PLC erasure indication utilizes any of the errored encodings of a The PLC erasure indication utilizes any of the errored encodings of a
non-voiced frame as identified in Table 1 of [MELPE]. For the sake of non-voiced frame as identified in Table 1 of [MELPE]. For the sake
simplicity, it is preferred that a code value of 3 for the of simplicity, it is preferred that a code value of 3 for the pitch/
pitch/voicing parameter be used. Hence, set bits P0 and P1 to one voicing parameter be used. Hence, set bits P0 and P1 to one and bits
and bits P2, P3, P4, P5, and P6 to zero. P2, P3, P4, P5, and P6 to zero.
When using PLC in 1200 bps or 600 bps mode, the MELPe 2400 bps When using PLC in 1200 bps or 600 bps mode, the MELPe 2400 bps
decoder is called three or four times, respectively, to cover the decoder is called three or four times, respectively, to cover the
loss of a low bitrate MELPe frame. loss of a low bitrate MELPe frame.
7. IANA Considerations 7. IANA Considerations
This memo requests that IANA registers TSVCIS as specified in Section IANA has registered TSVCIS as specified in Section 4.1. The media
4.1. The media type is also requested to be added to the IANA type has been added to the IANA registry for "RTP Payload Format
registry for "RTP Payload Format MIME types" Media Types" (https://www.iana.org/assignments/rtp-parameters).
(http://www.iana.org/assignments/rtp-parameters).
8. Security Considerations 8. Security Considerations
RTP packets using the payload format defined in this specification RTP packets using the payload format defined in this specification
are subject to the security considerations discussed in the RTP are subject to the security considerations discussed in the RTP
specification [RFC3550] and in any applicable RTP profile such as specification [RFC3550] and in any applicable RTP profile such as
RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/AVP [RFC3551], RTP/AVPF [RFC4585], RTP/SAVP [RFC3711], or RTP/
RTP/SAVPF [RFC5124]. However, as discussed in [RFC7202], it is not SAVPF [RFC5124]. However, as discussed in [RFC7202], it is not an
an RTP payload format's responsibility to discuss or mandate what RTP payload format's responsibility to discuss or mandate what
solutions are used to meet such basic security goals as solutions are used to meet such basic security goals as
confidentiality, integrity, and source authenticity for RTP in confidentiality, integrity, and source authenticity for RTP in
general. This responsibility lies with anyone using RTP in an general. This responsibility lies with anyone using RTP in an
application. They can find guidance on available security mechanisms application. They can find guidance on available security mechanisms
and important considerations in [RFC7201]. Applications SHOULD use and important considerations in [RFC7201]. Applications SHOULD use
one or more appropriate strong security mechanisms. The rest of this one or more appropriate strong security mechanisms. The rest of this
section discusses the security-impacting properties of the payload section discusses the security-impacting properties of the payload
format itself. format itself.
This RTP payload format and the TSVCIS decoder do not exhibit any This RTP payload format and the TSVCIS decoder, to the best of our
significant non-uniformity in the receiver-side computational knowledge, do not exhibit any significant non-uniformity in the
complexity for packet processing and thus are unlikely to pose a receiver-side computational complexity for packet processing and thus
denial-of-service threat due to the receipt of pathological data. are unlikely to pose a denial-of-service threat due to the receipt of
Additionally, the RTP payload format does not contain any active pathological data. Additionally, the RTP payload format does not
content. contain any active content.
Please see the security considerations discussed in [RFC6562] Please see the security considerations discussed in [RFC6562]
regarding VAD and its effect on bitrates. regarding Voice Activity Detect (VAD) and its effect on bitrates.
9. RFC Editor Considerations 9. References
Note to RFC Editor: This section may be removed after carrying out 9.1. Normative References
all the instructions of this section.
10. References [MELP] Department of Defense, "Analog-to-Digital Conversion of
Voice by 2,400 Bit/Second Mixed Excitation Linear
Prediction (MELP)", Department of Defense
Telecommunications Standard MIL-STD-3005, December 1999.
10.1. Normative References [MELPE] North Atlantic Treaty Organization (NATO), "The 600 Bit/S,
1200 Bit/S and 2400 Bit/S NATO Interoperable Narrow Band
Voice Coder", STANAG No. 4591, October 2008.
[NRLVDR] Heide, D., Cohen, A., Lee, Y., and T. Moran, "Universal
Vocoder Using Variable Data Rate Vocoding",
DOI 10.21236/ada588068, Naval Research Lab NRL/FR/5555--
13-10, 239, June 2013,
<https://doi.org/10.21236/ada588068>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2736] Handley, M. and C. Perkins, "Guidelines for Writers of RTP [RFC2736] Handley, M. and C. Perkins, "Guidelines for Writers of RTP
Payload Format Specifications", BCP 36, RFC 2736, Payload Format Specifications", BCP 36, RFC 2736,
DOI 10.17487/RFC2736, December 1999, DOI 10.17487/RFC2736, December 1999,
<http://www.rfc-editor.org/info/rfc2736>. <https://www.rfc-editor.org/info/rfc2736>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<http://www.rfc-editor.org/info/rfc3264>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551, Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003, DOI 10.17487/RFC3551, July 2003,
<http://www.rfc-editor.org/info/rfc3551>. <https://www.rfc-editor.org/info/rfc3551>.
[RFC8130] Demjanenko, V., and D. Satterlee, "RTP Payload Format for
the Mixed Excitation Linear Prediction Enhanced (MELPe)
Codec", RFC 8130, DOI 10.tbd/RFC8130, March 2017,
<http://www.rfc-editor.org/info/rfc8130>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, DOI 10.17487/RFC3711, March 2004, RFC 3711, DOI 10.17487/RFC3711, March 2004,
<http://www.rfc-editor.org/info/rfc3711>. <https://www.rfc-editor.org/info/rfc3711>.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, DOI 10.17487/RFC4566, Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
July 2006, <http://www.rfc-editor.org/info/rfc4566>. July 2006, <https://www.rfc-editor.org/info/rfc4566>.
[RFC4855] Casner, S., "Media Type Registration of RTP Payload [RFC4855] Casner, S., "Media Type Registration of RTP Payload
Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007, Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
<http://www.rfc-editor.org/info/rfc4855>. <https://www.rfc-editor.org/info/rfc4855>.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, (RTP/SAVPF)", RFC 5124, DOI 10.17487/RFC5124, February
February 2008, <http://www.rfc-editor.org/info/rfc5124>. 2008, <https://www.rfc-editor.org/info/rfc5124>.
[RFC6562] Perkins, C. and JM. Valin, "Guidelines for the Use of [RFC6562] Perkins, C. and JM. Valin, "Guidelines for the Use of
Variable Bit Rate Audio with Secure RTP", RFC 6562, Variable Bit Rate Audio with Secure RTP", RFC 6562,
DOI 10.17487/RFC6562, March 2012, DOI 10.17487/RFC6562, March 2012,
<http://www.rfc-editor.org/info/rfc6562>. <https://www.rfc-editor.org/info/rfc6562>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013, RFC 6838, DOI 10.17487/RFC6838, January 2013,
<http://www.rfc-editor.org/info/rfc6838>. <https://www.rfc-editor.org/info/rfc6838>.
[RFC8083] Perkins, C. and V. Singh, "Multimedia Congestion Control: [RFC8083] Perkins, C. and V. Singh, "Multimedia Congestion Control:
Circuit Breakers for Unicast RTP Sessions", RFC 8083, Circuit Breakers for Unicast RTP Sessions", RFC 8083,
DOI 10.17487/RFC8083, March 2017, DOI 10.17487/RFC8083, March 2017,
<http://www.rfc-editor.org/info/rfc8083>. <https://www.rfc-editor.org/info/rfc8083>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", RFC 8085, DOI 10.17487/RFC8085, March 2017, Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
<http://www.rfc-editor.org/info/rfc8085>. March 2017, <https://www.rfc-editor.org/info/rfc8085>.
[NRLVDR] Heide, D., Cohen, A., Lee, Y., and T. Moran, "Universal [RFC8088] Westerlund, M., "How to Write an RTP Payload Format",
Vocoder Using Variable Data Rate Vocoding", Naval Research RFC 8088, DOI 10.17487/RFC8088, May 2017,
Lab, NRL/FR/5555-13-10,239, June 2013. <https://www.rfc-editor.org/info/rfc8088>.
[MELP] Department of Defense Telecommunications Standard, [RFC8130] Demjanenko, V. and D. Satterlee, "RTP Payload Format for
"Analog-to-Digital Conversion of Voice by 2,400 Bit/Second the Mixed Excitation Linear Prediction Enhanced (MELPe)
Mixed Excitation Linear Prediction (MELP)", MIL-STD-3005, Codec", RFC 8130, DOI 10.17487/RFC8130, March 2017,
December 1999. <https://www.rfc-editor.org/info/rfc8130>.
[MELPE] North Atlantic Treaty Organization (NATO), "The 600 Bit/S, [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
1200 Bit/S and 2400 Bit/S NATO Interoperable Narrow Band 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
Voice Coder", STANAG No. 4591, January 2006. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[SCIP210] National Security Agency, "SCIP Signaling Plan", SCIP-210, [SCIP210] National Security Agency, "SCIP Signaling Plan", SCIP-210,
December 2007. January 2013.
10.2. Informative References
[TSVCIS] National Security Agency, "Tactical Secure Voice 9.2. Informative References
Cryptographic Interoperability Specification (TSVCIS)
Version 2.1", NSA 09-01A, July 2012.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control "Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
DOI 10.17487/RFC4585, July 2006, DOI 10.17487/RFC4585, July 2006,
<http://www.rfc-editor.org/info/rfc4585>. <https://www.rfc-editor.org/info/rfc4585>.
[RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP [RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014, Sessions", RFC 7201, DOI 10.17487/RFC7201, April 2014,
<http://www.rfc-editor.org/info/rfc7201>. <https://www.rfc-editor.org/info/rfc7201>.
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP [RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, DOI 10.17487/RFC7202, Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
April 2014, <http://www.rfc-editor.org/info/rfc7202>. 2014, <https://www.rfc-editor.org/info/rfc7202>.
[RMCAT] IETF, RTP Media Congestion Avoidance Techniques (rmcat) [RMCAT] IETF, "RTP Media Congestion Avoidance Techniques (rmcat)
Working Group, Working Group",
<https://datatracker.ietf.org/wg/rmcat/about/>. <https://datatracker.ietf.org/wg/rmcat/about/>.
[TSVCIS] National Security Agency, "Tactical Secure Voice
Cryptographic Interoperability Specification (TSVCIS)
Version 3.1", NSA 09-01A, March 2019.
Authors' Addresses Authors' Addresses
Victor Demjanenko, Ph.D. Victor Demjanenko, Ph.D.
VOCAL Technologies, Ltd. VOCAL Technologies, Ltd.
520 Lee Entrance, Suite 202 520 Lee Entrance, Suite 202
Buffalo, NY 14228 Buffalo, NY 14228
United States of America United States of America
Phone: +1 716 688 4675 Phone: +1 716 688 4675
Email: victor.demjanenko@vocal.com Email: victor.demjanenko@vocal.com
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