3 Definitions and abbreviations
26.1143GPPIP Multimedia Subsystem (IMS)Media handling and interactionMultimedia telephonyRelease 18TS
3.1 Definitions
For the purposes of the present document, the terms and definitions given in TR 21.905 [1] and the following apply:
NOTE: A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905 [1].
example: text used to clarify abstract rules by applying them literally.
360-degree video: A real-world visual scene captured by a set of cameras or a camera device with multiple lenses and sensors covering the sphere in all directions around the centre point of the camera set or camera device. The term 360-degree video may be used to include also limited 360-degree video.
Limited 360-degree video: A 360-degree video in which the visual scene does not cover the entire sphere around the center point of the camera set or camera device but only a part of it. A limited 360-degree video may be limited i) in the horizontal field to less than 360 degrees, or ii) in the vertical field to less than 180 degrees or iii) in both the vertical and horizontal fields.
AMR, AMR-NB: Both names refer to the AMR codec (TS 26.071 [11]) and are used interchangeably in this specification.
Bitstream: A bitstream that conforms to a video or audio encoding format.
bitstream: A sequence of bits that forms the representation of one or more coded video or audio sequences.
CHEM: The Coverage and Handoff Enhancements using Multimedia error robustness feature.
Codec mode: Used for the AMR and AMR-WB codecs to identify one specific bitrate. For example AMR includes 8 codec modes (excluding SID), each of different bitrate.
Constrained terminal: UE that is (i) operating in radio access capability category series "M" capable of supporting conversational services, and/or (ii) a wearable device which is constrained in size, weight or power consumption (e.g. connected watches), excluding smartphones and feature phones.
DCMTSI client: A data channel capable MTSI client supporting data channel media as defined in clause 6.2.10.
DCMTSI client in terminal: A DCMTSI client that is implemented in a terminal or UE. The term "DCMTSI client in terminal" is used in this document when entities such as MRFP, MRFC or media gateways are excluded.
Dual-mono: A variant of 2-channel stereo encoding where two instances of a mono codec are used to encode a 2-channel stereo signal.
Evolved UTRAN: Evolved UTRAN is an evolution of the 3G UMTS radio-access network towards a high-data-rate, low-latency and packet-optimized radio-access network.
EVS codec: The EVS codec includes two operational modes: EVS Primary operational mode (‘EVS Primary mode’) and EVS AMR-WB Inter-Operable (‘EVS AMR-WB IO mode’). When using EVS AMR-WB IO mode the speech frames are bitstream interoperable with the AMR-WB codec [18]. Frames generated by an EVS AMR-WB IO mode encoder can be decoded by an AMR-WB decoder, without the need for transcoding. Likewise, frames generated by an AMR-WB encoder can be decoded by an EVS AMR-WB IO mode decoder, without the need for transcoding.
EVS Primary mode: Includes 11 bit-rates for fixed-rate or multi-rate operation; 1 average bit-rate for variable bit-rate operation; and 1 bit-rate for SID (TS 26.441 [121]). The EVS Primary can encode narrowband, wideband, super-wideband and fullband signals. None of these bit-rates are interoperable with the AMR-WB codec.
EVS AMR-WB IO mode: Includes 9 codec modes and SID. All are bitstream interoperable with the AMR-WB codec (TS 26.171 [17]).
Field of View: The extent of visible area expressed with vertical and horizontal angles, in degrees in the 3GPP 3DOF reference system as defined in TS 26.118 [180].
Fisheye Video: Video captured by a wide-angle camera lens that usually captures an approximately hemispherical field of view and projects it as a circular image.
Frame Loss Rate (FLR): The percentage of speech frames not delivered to the decoder. FLR includes speech frames that are not received in time to be used for decoding.
ITT4RT client: MTSI client supporting the Immersive Teleconferencing and Telepresence for Remote Terminals (ITT4RT) feature, as defined in Annex Y.
ITT4RT-Tx client: ITT4RT client only capable of sending immersive video.
ITT4RT-Rx client: ITT4RT client only capable of receiving immersive video
ITT4RT MRF: An ITT4RT client implemented by functionality included in the MRFC and the MRFP.
ITT4RT client in terminal: An ITT4RT client that is implemented in a terminal or UE. The term "ITT4RT client in terminal" is used in this document when entities such as ITT4RT MRF is excluded.
Mode-set: Used for the AMR and AMR-WB codecs to identify the codec modes that can be used in a session. A mode-set can include one or more codec modes.
MSMTSI client: A multi-stream capable MTSI client supporting multiple streams as defined in Annex S. An MTSI client may support multiple streams, even of the same media type, without being an MSMTSI client. Such an MTSI client may, for example, add a second video to an ongoing video telephony session as shown in Annex A.11. In that case, the MTSI client is an MSMTSI client only if it is fully compliant with Annex S.
MSMTSI MRF: An MSMTSI client implemented by functionality included in the MRFC and the MRFP.
MSMTSI client in terminal: An MSMTSI client that is implemented in a terminal or UE. The term "MSMTSI client in terminal" is used in this document when entities such as MRFP, MRFC or media gateways are excluded.
MTSI client: A function in a terminal or in a network entity (e.g. a MRFP) that supports MTSI.
MTSI client in terminal: An MTSI client that is implemented in a terminal or UE. The term "MTSI client in terminal" is used in this document when entities such as MRFP, MRFC or media gateways are excluded.
MTSI media gateway (or MTSI MGW): A media gateway that provides interworking between an MTSI client and a non MTSI client, e.g. a CS UE. The term MTSI media gateway is used in a broad sense, as it is outside the scope of the current specification to make the distinction whether certain functionality should be implemented in the MGW or in the MGCF.
Omnidirectional media: Media such as image or video and its associated audio that enable rendering according to the user’s viewing orientation, if consumed with a head-mounted device, or according to user’s desired viewport, otherwise, as if the user was in the spot where and when the media was captured.
Operational mode: Used for the EVS codec to distinguish between EVS Primary mode and EVS AMR-WB IO mode.
Overlay: A piece of visual media, rendered over omnidirectional video or image, or a viewport.
Pose: Position and rotation information associated to a viewport.
Projected picture: Picture that has a representation format specified by an omnidirectional video projection format.
Projection: Inverse of the process by which the samples of a projected picture are mapped to a set of positions identified by a set of azimuth and elevation coordinates on a unit sphere.
Simulcast: Simultaneously sending different encoded representations (simulcast formats) of a single media source (e.g. originating from a single microphone or camera) in different simulcast streams.
Simulcast format: The encoded format used by a single simulcast stream, typically represented by an SDP format and all SDP attributes that apply to that particular SDP format, indicated in RTP by the RTP header payload type field.
Simulcast stream: The RTP stream carrying a single simulcast format in a simulcast.
Viewport: Region of omnidirectional image or video suitable for display and viewing by the user.
3.2 Abbreviations
For the purposes of the present document, the abbreviations given in TR 21.905 [1] and the following apply:
NOTE: An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905 [1].
3DOF 3 Degrees of freedom
5GC 5G Core Network
AC Alternating Current
AL-SDU Application Layer – Service Data Unit
AMR Adaptive Multi-Rate
AMR-NB Adaptive Multi-Rate – NarrowBand
AMR-WB Adaptive Multi-Rate – WideBand
AMR-WB IO Adaptive Multi-Rate – WideBand Inter-operable Mode, included in the EVS codec
ANBR Access Network Bitrate Recommendation
ANBRQ Access Network Bitrate Recommendation Query
APP APPlication-defined RTCP packet
ARQ Automatic repeat ReQuest
AS Application Server
ATCF Access Transfer Control Function
ATGW Access Transfer GateWay
AVC Advanced Video Coding
BFCP Binary Floor Control Protocol
CCM Codec Control Messages
CDF Cumulative Distribution Function
cDRX Connected Mode DRX
CHEM Coverage and Handoff Enhancements using Multimedia error robustness feature
CMP Cube-Map Projection
CMR Codec Mode Request
cps characters per second
CS Circuit Switched
CSCF Call Session Control Function
CTM Cellular Text telephone Modem
CVO Coordination of Video Orientation
DBI Delay Budget Information
DRB Data Radio Bearer
DRX Discontinuous Reception
DTLS Datagram Transport Layer Security
DTMF Dual Tone Multi-Frequency
DTX Discontinuous Transmission
ECN Explicit Congestion Notification
ECN-CE ECN Congestion Experienced
ECT ECN Capable Transport
eNodeB E-UTRAN Node B
ERP EquiRectangular Projection
E-UTRAN Evolved UTRAN
EVS Enhanced Voice Services
FECC Far End Camera Control
FIR Full Intra Request
FLR Frame Loss Rate
FoIP Facsimile over IP
FOV Field Of View
GIP Generic IP access
GOB Group Of Blocks
H-ARQ Hybrid – ARQ
HEVC High Efficiency Video Coding
HMD Head Mounted Display HSPA High Speed Packet Access
ICM Initial Codec Mode
IDR Instantaneous Decoding Refresh
IFP Internet Facsimile Protocol
IFT Internet Facsimile Transfer
IMS IP Multimedia Subsystem
IP Internet Protocol
IPv4 Internet Protocol version 4
IRAP Intra Random Access Point
ITT4RT Immersive Teleconferencing and Telepresence for Remote Terminals
ITU-T International Telecommunications Union – Telecommunications
JBM Jitter Buffer Management
MGCF Media Gateway Control Function
MGW Media GateWay
MIME Multipurpose Internet Mail Extensions
MO Management Object
MPEG Moving Picture Experts Group
MRFC Media Resource Function Controller
MRFP Media Resource Function Processor
MSMTSI Multi-Stream Multimedia Telephony Service for IMS
MSRP Message Session Relay Protocol
MTSI Multimedia Telephony Service for IMS
MTU Maximum Transfer Unit
NACK Negative ACKnowledgment
NNI Network-to-Network Interface
NTP Network Time Protocol
OMAF Omnidirectional MediA Format
PCM Pulse Code Modulation
PDCP Packet Data Convergence Protocol
PDP Packet Data Protocol
PLI Picture Loss Indication
PLR Packet Loss Ratio
POI Point Of Interconnect
PSTN Public Switched Telephone Network
PTZF Pan, Tilt, Zoom and Focus
QCI QoS Class Identifier
QMC QoE Measurement Collection
QoE Quality of Experience
QoS Quality of Service
QP Quantization Parameter
RoHC Robust HeaderCompression
ROI Region of Interest
RR Receiver Report
RTCP RTP Control Protocol
RTP Real-time Transport Protocol
RWP Region-Wise Packing
SB-ADPCM Sub-Band Adaptive Differential PCM
SC-VBR Source Controlled VBR
SCTP Stream Control Transmission Protocol
SDAP Service Data Adaptation Protocol
SDP Session Description Protocol
SDPCapNeg SDP Capability Negotiation
SEI Supplemental Enhancement Information
SID SIlence Descriptor
SIP Session Initiation Protocol
SR Sender Report
SRVCC Single Radio Voice Call Continuity
TFO Tandem-Free Operation
TISPAN Telecoms and Internet converged Services and Protocols for Advanced Network
TMMBN Temporary Maximum Media Bit-rate Notification
TMMBR Temporary Maximum Media Bit-rate Request
TrFO Transcoder-Free Operation
UDP User Datagram Protocol
UDPTL Facsimile UDP Transport Layer (protocol)
UE User Equipment
VDP Viewport Dependent Processing
VoIP Voice over IP
VOP Video Object Plane
VR Virtual Reality
WebRTC Web Real-Time Communication