Ratio or code selection for lmcs

Abstract

Systems, methods, and instrumentalities may be configured for coding tree unit (CTU) grid shifting. An example video decoding device may receive a picture that is encoded based on a ratio value. The device may receive the ratio value corresponding to the picture. The device may decode the picture based on the ratio value. The ratio value may correspond to the picture corresponding to a maximal gain. Decoding the picture based on the ratio value may include decoding the picture based on the maximal gain.

Description

RATIO OR CODE SELECTION FOR LMCSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of EP provisional patent application No.23306573.9, filedSeptember 21 , 2023, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Video coding systems may be used to compress digital video signals, e.g., to reduce the storage and / or transmission bandwidth needed for such signals. Video coding systems may include, for example, block-based, wavelet-based, and / or object-based systems.SUMMARY

[0003] Systems, methods, and instrumentalities may be configured for ratio or code selection for luma mapping with chroma scaling (LMCS). An example video encoding device may determine candidate ratio values associated with a video picture. The device may determine respective coding gains associated with the candidate ratio values. The device may select a ratio value from the candidate ratio values based on their respective associated coding gains. The device may, based on the selected ratio value, adjust a number of code words of a mapping function that is associated with the video picture. The device may encode the video picture based on the mapping function.

[0004] The device may partition a range of luma sample values of the video picture into luma sample value pieces, and the luma sample value pieces may correspond to respective subranges of luma values. The device may, based on the selected ratio value, determine the number of code words for the luma sample value pieces. The device may map the luma sample value pieces to updated luma sample values based on the determined number of code words for the luma sample value pieces. The device may generate the mapping function based on the mapped luma sample value pieces. The device may include an indication of the selected ratio value in video data, and the video picture may be encoded based further on the indication.

[0005] The device may determine whether to signal code words individually or whether the code words are associated with pre-defined codes, and the indication of the selected ratio value may be included in video data based on determining that the code words are associated with pre-defined codes.

[0006] The device may determine that a code word is associated with a pre-defined code. The device may include an index associated with the code word in video data, and the video picture may be encoded based further on the code word.

[0007] The device may determine at least one feature from mapped video picture samples associated with the video picture using at least one ratio value from the candidate ratio values, and the coding gain may be determined based on the determined at least one feature. The at least one feature may include at least one of a minimum value of the mapped video picture samples, a maximum value of mapped video picture samples, a histogram of the mapped video picture samples per piece, a variance of the mapped video picture samples per piece, or a temporal variance between the mapped video picture samples and samples of a second video picture that is distinct from the video picture.

[0008] The device may apply a gradient boosting decision tree algorithm to the candidate ratio values, and the coding gain may be determined based on applying the gradient boosting decision tree algorithm to the candidate ratio values.

[0009] An example video decoding device may be configured to receive a video picture. The device may receive an indication of a ratio value corresponding to the video picture. The device may, based on the ratio value, adjust a number of code words of a mapping function that is associated with the video picture. The device may decode the video picture based on the mapping function.

[0010] The device may partition a range of luma sample values of the video picture into luma sample value pieces, and the luma sample value pieces may correspond to respective subranges of luma values. The device may, based on the selected ratio value, determine the number of code words for the luma sample value pieces. The device may map the luma sample value pieces to updated luma sample values based on the determined number of code words for the luma sample value pieces. The device may generate the mapping function based on the mapped luma sample value pieces.

[0011] The device may apply the mapping function to inter predicted luma samples. The device may decode the video picture based further on applying the mapping function to the inter predicted luma samples. The device may determine that codewords belong to predefined code words, and the indication of the ratio value may be received based on determining that the codewords belong to predefined code words.

[0012] An example video decoding device may receive a picture (e.g., a video frame) that is encoded based on a ratio value. The device may receive the ratio value corresponding to the picture. The device may decode the picture based on the ratio value. The ratio value may correspond to the picture corresponding to a maximal gain. Decoding the picture based on the ratio value may include decoding the picture based on the maximal gain.

[0013] An example video decoding device may receive a picture and an index. The device may determine a best code word (CW) for a segment of a video (CODE) from a predetermined set of candidate CODEs based on the index. The device may decode the picture based on the CODE.

[0014] An example video encoding device may include receiving a picture . The device may estimate multiple encoding gains based on multiple ratio values. The device may determine a maximal gain from the encoding gains. The device may encode the picture based on the maximal gain. Estimating the encoding gains may include testing a ratio value from the ratio values on the picture. The device may determine that the ratio value corresponds to the maximal gain. Encoding the picture based on the maximal gain may include encoding the picture with the ratio value that corresponds to the maximal gain.

[0015] An example video encoding device may receive a picture. The device may evaluate multiple candidate CODEs. The device may calculate a feature using a machine-learning model to predict an encoding efficiency (e.g., gain) of the candidate CODEs. The device may compare the encoding efficiency of the candidate CODEs against a maximum gain. If the encoding efficiency of a candidate CODE is more efficient than the maximum gain, the device may select a CODE, from the candidate CODES, with the highest gain. The device may select an index corresponding to the selected CODE. The device may encode the picture based on the index.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 A is a system diagram illustrating an example communications system in which one or more disclosed embodiments may be implemented.

[0017] FIG. 1 B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0018] FIG. 1C is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communications system illustrated in FIG. 1A according to an embodiment.

[0019] FIG. 1 D is a system diagram illustrating a further example RAN and a further example CN that may be used within the communications system illustrated in FIG. 1 A according to an embodiment.

[0020] FIG. 2 illustrates an example video encoder.

[0021] FIG. 3 illustrates an example video decoder.

[0022] FIG. 4 illustrates an example of a system in which various aspects and examples may be implemented.

[0023] FIG. 5 illustrates an example flowchart of interference for a ratio selection.

[0024] FIG. 6 illustrates an example flowchart of inference for a set of CODES (e.g., a best set of codewords (CWs) per piece for a segment of video).

[0025] FIG. 7 illustrates an example flowchart of inference with a feature computed based on mapped video.DETAILED DESCRIPTION

[0026] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings.

[0027] FIG. 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0028] As shown in FIG. 1A, the communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, a RAN 104 / 113, a ON 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a "station” and / or a "STA,” may be configured to transmit and / or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably referred to as a UE.

[0029] The communications systems 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or the other networks 112. By way of example, thebase stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0030] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be in licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for a wireless service to a specific geographical area that may be relatively fixed or that may change over time. The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0031] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0032] More specifically, as noted above, the communications system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink (DL) Packet Access (HSDPA) and / or High-Speed UL Packet Access (HSUPA).

[0033] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0034] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access, which may establish the air interface 116 using New Radio (NR).

[0035] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., an eNB and a gNB).

[0036] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0037] The base station 114b in FIG. 1A may be a wireless router, Home Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a localized area, such as a place of business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0038] The RAN 104 / 113 may be in communication with the CN 106 / 115, which may be any type of network configured to provide voice, data, applications, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106 / 115 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may be utilizing a NRradio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

[0039] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or the other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and / or the internet protocol (IP) in the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communications networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0040] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0041] FIG. 1 B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1 B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138, among others. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0042] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. While FIG. 1 B depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0043] The transmit / receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0044] Although the transmit / receive element 122 is depicted in FIG. 1 B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0045] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit / receive element 122 and to demodulate the signals that are received by the transmit / receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11 , for example.

[0046] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and / or the removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0047] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium- ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0048] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable locationdetermination method while remaining consistent with an embodiment.

[0049] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a Virtual Reality and / or Augmented Reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, the sensors may be one or more of a gyroscope, an accelerometer, a hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor; a geolocation sensor; an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0050] The WTRU 102 may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and downlink (e.g., for reception) may be concurrent and / or simultaneous. The full duplex radio may include an interference management unit to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., a separate processor (not shown) or via processor 118). In an embodiment, the WRTU 102 may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0051] FIG. 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the CN 106.

[0052] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implementM IMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a.

[0053] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, and the like. As shown in FIG. 1 C, the eNode-Bs 160a, 160b, 160c may communicate with one another over an X2 interface.

[0054] The CN 106 shown in FIG. 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements are depicted as part of the CN 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0055] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0056] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0057] The SGW 164 may be connected to the PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0058] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers.

[0059] Although the WTRU is described in FIGS. 1A-1 D as a wireless terminal, it is contemplated that in certain representative embodiments that such a terminal may use (e.g., temporarily or permanently) wired communication interfaces with the communication network.

[0060] In representative embodiments, the other network 112 may be a WLAN.

[0061] A WLAN in Infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have an access or an interface to a Distribution System (DS) or another type of wired / wireless network that carries traffic in to and / or out of the BSS. Traffic to STAs that originates from outside the BSS may arrive through the AP and may be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may deliver the traffic to the destination STA. The traffic between STAs within a BSS may be considered and / or referred to as peer-to- peer traffic. The peer-to-peer traffic may be sent between (e.g., directly between) the source and destination STAs with a direct link setup (DLS). In certain representative embodiments, the DLS may use an 802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad-hoc” mode of communication.

[0062] When using the 802.11ac infrastructure mode of operation or a similar mode of operations, the AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz wide bandwidth) or a dynamically set width via signaling. The primary channel may be the operating channel of the BSS and may be used by the STAs to establish a connection with the AP. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented, for example in in 802.11 systems. For CSMA / CA, the STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0063] High Throughput (HT) STAs may use a 40 MHz wide channel for communication, for example, via a combination of the primary 20 MHz channel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHz wide channel.

[0064] Very High Throughput (VHT) STAs may support 20MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. The 40 MHz, and / or 80 MHz, channels may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining 8 contiguous 20 MHz channels, or by combining two noncontiguous 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, the data, after channel encoding, may be passed through a segment parser that may divide the data into two streams. Inverse Fast Fourier Transform (IFFT) processing, and time domain processing, may be done on each stream separately. The streams may be mapped on to the two 80 MHz channels, andthe data may be transmitted by a transmitting STA. At the receiver of the receiving STA, the above described operation for the 80+80 configuration may be reversed, and the combined data may be sent to the Medium Access Control (MAC).

[0065] Sub 1 GHz modes of operation are supported by 802.11 af and 802.11 ah. The channel operating bandwidths, and carriers, are reduced in 802.11 af and 802.11ah relative to those used in 802.11n, and 802.11ac. 802.11af supports 5 MHz, 10 MHz and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11 ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11 ah may support Meter Type Control / Machine- Type Communications, such as MTC devices in a macro coverage area. MTC devices may have certain capabilities, for example, limited capabilities including support for (e.g., only support for) certain and / or limited bandwidths. The MTC devices may include a battery with a battery life above a threshold (e.g., to maintain a very long battery life).

[0066] WLAN systems, which may support multiple channels, and channel bandwidths, such as 802.11 n, 802.11 ac, 802.11 af, and 802.11 ah, include a channel which may be designated as the primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by a STA, from among all STAs in operating in a BSS, which supports the smallest bandwidth operating mode. In the example of 802.11 ah, the primary channel may be 1 MHz wide for STAs (e.g., MTC type devices) that support (e.g., only support) a 1 MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) settings may depend on the status of the primary channel. If the primary channel is busy, for example, due to a STA (which supports only a 1 MHz operating mode), transmitting to the AP, the entire available frequency bands may be considered busy even though a majority of the frequency bands remains idle and may be available.

[0067] In the United States, the available frequency bands, which may be used by 802.11 ah, are from 902 MHz to 928 MHz. In Korea, the available frequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the available frequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidth available for 802.11 ah is 6 MHz to 26 MHz depending on the country code.

[0068] FIG. 1 D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As noted above, the RAN 113 may employ an NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0069] The RAN 113 may include gNBs 180a, 180b, 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c overthe air interface 116. In one embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a, for example, may use multiple antennas to transmit wireless signals to, and / or receive wireless signals from, the WTRU 102a. In an embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum while the remaining component carriers may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and / or gNB 180c).

[0070] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using transmissions associated with a scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and / or lasting varying lengths of absolute time).

[0071] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c without also accessing other RANs (e.g., such as eNode-Bs 160a, 160b, 160c). In the standalone configuration, WTRUs 102a, 102b, 102c may utilize one or more of gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone configuration, WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using signals in an unlicensed band. In a non-standalone configuration WTRUs 102a, 102b, 102c may communicate with / connect to gNBs 180a, 180b, 180c while also communicating with / connecting to another RAN such as eNode-Bs 160a, 160b, 160c. For example, WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In the non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for servicing WTRUs 102a, 102b, 102c.

[0072] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184b, routing of control planeinformation towards Access and Mobility Management Function (AMF) 182a, 182b and the like. As shown in FIG. 1 D, the gNBs 180a, 180b, 180c may communicate with one another over an Xn interface.

[0073] The CN 115 shown in FIG. 1 D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the foregoing elements are depicted as part of the CN 115, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0074] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of NAS signaling, mobility management, and the like. Network slicing may be used by the AMF 182a, 182b in order to customize CN support for WTRUs 102a, 102b, 102c based on the types of services being utilized WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0075] The SMF 183a, 183b may be connected to an AMF 182a, 182b in the CN 115 via an N11 interface. The SMF 183a, 183b may also be connected to a UPF 184a, 184b in the CN 115 via an N4 interface. The SMF 183a, 183b may select and control the UPF 184a, 184b and configure the routing of traffic through the UPF 184a, 184b. The SMF 183a, 183b may perform other functions, such as managing and allocating UE IP address, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, and the like. A PDU session type may be IP-based, non-IP based, Ethernet-based, and the like.

[0076] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

[0077] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs102a, 102b, 102c with access to the other networks 112, which may include other wired and / or wireless networks that are owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local Data Network (DN) 185a, 185b through the UPF 184a, 184b via the N3 interface to the UPF 184a, 184b and an N6 interface between the UPF 184a, 184b and the DN 185a, 185b.

[0078] In view of Figures 1A-1 D, and the corresponding description of Figures 1A-1 D, one or more, or all, of the functions described herein with regard to one or more of: WTRU 102a-d, Base Station 114a-b, eNode- B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-b, UPF 184a-b, SMF 183a-b, DN 185a- b, and / or any other device(s) described herein, may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more, or all, of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0079] The emulation devices may be designed to implement one or more tests of other devices in a lab environment and / or in an operator network environment. For example, the one or more emulation devices may perform the one or more, or all, functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. The one or more emulation devices may perform the one or more, or all, functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for purposes of testing and / or performing testing using over-the-air wireless communications.

[0080] The one or more emulation devices may perform the one or more, including all, functions while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in a testing scenario in a testing laboratory and / or a non-deployed (e.g., testing) wired and / or wireless communication network in order to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communications via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0081] This application describes a variety of aspects, including tools, features, examples, models, approaches, etc. Many of these aspects are described with specificity and, at least to show the individual characteristics, are often described in a manner that may sound limiting. However, this is for purposes of clarity in description, and does not limit the application or scope of those aspects. Indeed, all of the different aspects may be combined and interchanged to provide further aspects. Moreover, the aspects may be combined and interchanged with aspects described in earlier filings as well.

[0082] The aspects described and contemplated in this application may be implemented in many different forms. FIGs. 5-11 described herein may provide some examples, but other examples are contemplated. The discussion of FIGs. 5-11 does not limit the breadth of the implementations. At least one of the aspects generally relates to video encoding and decoding, and at least one other aspect generally relates to transmitting a bitstream generated or encoded. These and other aspects may be implemented as a method, an apparatus, a computer readable storage medium having stored thereon instructions for encoding or decoding video data according to any of the methods described, and / or a computer readable storage medium having stored thereon a bitstream generated according to any of the methods described.

[0083] In the present application, the terms "reconstructed” and "decoded” may be used interchangeably, the terms "pixel” and "sample” may be used interchangeably, the terms "image,” "picture” and "frame” may be used interchangeably.

[0084] Various methods are described herein, and each of the methods comprises one or more steps or actions for achieving the described method. Unless a specific order of steps or actions is required for proper operation of the method, the order and / or use of specific steps and / or actions may be modified or combined. Additionally, terms such as "first,” "second,” etc., may be used in various examples to modify an element, component, step, operation, etc., such as, for example, a "first decoding” and a "second decoding.” Use of such terms does not imply an ordering to the modified operations unless specifically required. So, in this example, the first decoding need not be performed before the second decoding, and may occur, for example, before, during, or in an overlapping time period with the second decoding.

[0085] Various methods and other aspects described in this application may be used to modify modules, for example, decoding modules, of a video encoder 200 and decoder 300 as shown in FIG. 2 and FIG. 3. Moreover, the subject matter disclosed herein may be applied, for example, to any type, format or version of video coding, whether described in a standard or a recommendation, whether pre-existing or future- developed, and extensions of any such standards and recommendations. Unless indicated otherwise, or technically precluded, the aspects described in this application may be used individually or in combination.

[0086] Various numeric values are used in examples described the present application, such as 1 , 2, 4, 7, 8, 16, 32, 64, etc. These and other specific values are for purposes of describing examples and the aspects described are not limited to these specific values.

[0087] FIG. 2 is a diagram showing an example video encoder 200. Variations of example encoder 200 are contemplated, but the encoder 200 is described below for purposes of clarity without describing all expected variations.

[0088] Before being encoded, the video sequence may go through pre-encoding processing (201), for example, applying a color transform to the input color picture (e.g., conversion from RGB 4:4:4 to YCbCr 4:2:0), or performing a remapping of the input picture components in order to get a signal distribution moreresilient to compression (for instance using a histogram equalization of one of the color components). Metadata (e.g., which may include film grain parameters determined by pre-processing as described herein) may be associated with the pre-processing and attached to the bitstream.

[0089] In the encoder 200, a picture is encoded by the encoder elements as described below. The picture to be encoded is partitioned (202) and processed in units of, for example, coding units (Cus). Each unit is encoded using, for example, either an intra or inter mode. When a unit is encoded in an intra mode, it performs intra prediction (260). In an inter mode, motion estimation (275) and compensation (270) are performed. The encoder decides (205) which one of the intra mode or inter mode to use for encoding the unit, and indicates the intra / inter decision by, for example, a prediction mode flag. Prediction residuals are calculated, for example, by subtracting (210) the predicted block from the original image block.

[0090] The prediction residuals are then transformed (225) and quantized (230). The quantized transform coefficients, as well as motion vectors and other syntax elements, are entropy coded (245) to output a bitstream. The encoder can skip the transform and apply quantization directly to the non-transformed residual signal. The encoder can bypass both transform and quantization, i.e., the residual is coded directly without the application of the transform or quantization processes.

[0091] The encoder decodes an encoded block to provide a reference for further predictions. The quantized transform coefficients are de-quantized (240) and inverse transformed (250) to decode prediction residuals. Combining (255) the decoded prediction residuals and the predicted block, an image block is reconstructed. In-loop filters (265) are applied to the reconstructed picture to perform, for example, deblocking / SAO (Sample Adaptive Offset) filtering to reduce encoding artifacts. The filtered image is stored at a reference picture buffer (280).

[0092] FIG. 3 is a diagram showing an example of a video decoder. In example decoder 300, a bitstream is decoded by the decoder elements as described below. Video decoder 300 generally performs a decoding pass reciprocal to the encoding pass as described in FIG. 2. The encoder 200 also generally performs video decoding as part of encoding video data.

[0093] In particular, the input of the decoder includes a video bitstream, which may be generated by video encoder 200. The bitstream is first entropy decoded (330) to obtain transform coefficients, motion vectors, and other coded information. The picture partition information indicates how the picture is partitioned. The decoder may therefore divide (335) the picture according to the decoded picture partitioning information. The transform coefficients are de-quantized (340) and inverse transformed (350) to decode the prediction residuals. Combining (355) the decoded prediction residuals and the predicted block, an image block is reconstructed. The predicted block may be obtained (370) from intra prediction (360) or motion-compensated prediction (i.e., inter prediction) (375). In-loop filters (365) are applied to the reconstructed image. The filtered image is stored at a reference picture buffer (380).

[0094] The decoded picture can further go through post-decoding processing (385), for example, an inverse color transform (e.g., conversion from YcbCr 4:2:0 to RGB 4:4:4) or an inverse remapping performing the inverse of the remapping process performed in the pre-encoding processing (201). The post-decoding processing can use metadata derived in the pre-encoding processing and signaled in the bitstream. In an example, the decoded images (e.g., after application of the in-loop filters (365) and / or after post-decoding processing (385), if post-decoding processing is used) may be sent to a display device for rendering to a user.

[0095] FIG. 4 is a diagram showing an example of a system in which various aspects and examples described herein may be implemented. System 400 may be embodied as a device including the various components described below and is configured to perform one or more of the aspects described in this document. Examples of such devices, include, but are not limited to, various electronic devices such as personal computers, laptop computers, smartphones, tablet computers, digital multimedia set top boxes, digital television receivers, personal video recording systems, connected home appliances, and servers. Elements of system 400, singly or in combination, may be embodied in a single integrated circuit (IC), multiple les, and / or discrete components. For example, in at least one example, the processing and encoder / decoder elements of system 400 are distributed across multiple les and / or discrete components. In various examples, the system 400 is communicatively coupled to one or more other systems, or other electronic devices, via, for example, a communications bus or through dedicated input and / or output ports. In various examples, the system 400 is configured to implement one or more of the aspects described in this document.

[0096] The system 400 includes at least one processor 410 configured to execute instructions loaded therein for implementing, for example, the various aspects described in this document. Processor 410 can include embedded memory, input output interface, and various other circuitries as known in the art. The system 400 includes at least one memory 420 (e.g., a volatile memory device, and / or a non-volatile memory device). System 400 includes a storage device 440, which can include non-volatile memory and / or volatile memory, including, but not limited to, Electrically Erasable Programmable Read-Only Memory (EEPROM), Read-Only Memory (ROM), Programmable Read-Only Memory (PROM), Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), flash, magnetic disk drive, and / or optical disk drive. The storage device 440 can include an internal storage device, an attached storage device (including detachable and non-detachable storage devices), and / or a network accessible storage device, as non-limiting examples.

[0097] System 400 includes an encoder / decoder module 430 configured, for example, to process data to provide an encoded video or decoded video, and the encoder / decoder module 430 can include its own processor and memory. The encoder / decoder module 430 represents module(s) that may be included in a device to perform the encoding and / or decoding functions. As is known, a device can include one or both ofthe encoding and decoding modules. Additionally, encoder / decoder module 430 may be implemented as a separate element of system 400 or may be incorporated within processor 410 as a combination of hardware and software as known to those skilled in the art.

[0098] Program code to be loaded onto processor 410 or encoder / decoder 430 to perform the various aspects described in this document may be stored in storage device 440 and subsequently loaded onto memory 420 for execution by processor 410. In accordance with various examples, one or more of processor 410, memory 420, storage device 440, and encoder / decoder module 430 can store one or more of various items during the performance of the processes described in this document. Such stored items can include, but are not limited to, the input video, the decoded video or portions of the decoded video, the bitstream, matrices, variables, and intermediate or final results from the processing of equations, formulas, operations, and operational logic.

[0099] In some examples, memory inside of the processor 410 and / or the encoder / decoder module 430 is used to store instructions and to provide working memory for processing that is needed during encoding or decoding. In other examples, however, a memory external to the processing device (for example, the processing device may be either the processor 410 or the encoder / decoder module 430) is used for one or more of these functions. The external memory may be the memory 420 and / or the storage device 440, for example, a dynamic volatile memory and / or a non-volatile flash memory. In several examples, an external non-volatile flash memory is used to store the operating system of, for example, a television. In at least one example, a fast external dynamic volatile memory such as a RAM is used as working memory for video encoding and decoding operations.

[0100] The input to the elements of system 400 may be provided through various input devices as indicated in block 445. Such input devices include, but are not limited to, (i) a radio frequency (RF) portion that receives an RF signal transmitted, for example, over the air by a broadcaster, (ii) a Component (COMP) input terminal (or a set of COMP input terminals), (ill) a Universal Serial Bus (USB) input terminal, and / or (iv) a High Definition Multimedia Interface (HDMI) input terminal. Other examples, not shown in FIG. 4, include composite video.

[0101] In various examples, the input devices of block 445 have associated respective input processing elements as known in the art. For example, the RF portion may be associated with elements suitable for (I) selecting a desired frequency (also referred to as selecting a signal, or band-limiting a signal to a band of frequencies), (ii) down-converting the selected signal, (ill) band-limiting again to a narrower band of frequencies to select (for example) a signal frequency band which may be referred to as a channel in certain examples, (iv) demodulating the down-converted and band-limited signal, (v) performing error correction, and / or (vi) demultiplexing to select the desired stream of data packets. The RF portion of various examples includes one or more elements to perform these functions, for example, frequency selectors, signal selectors,band-limiters, channel selectors, filters, downconverters, demodulators, error correctors, and demultiplexers. The RF portion can include a tuner that performs various of these functions, including, for example, downconverting the received signal to a lower frequency (for example, an intermediate frequency or a nearbaseband frequency) or to baseband. In one set-top box example, the RF portion and its associated input processing element receives an RF signal transmitted over a wired (for example, cable) medium, and performs frequency selection by filtering, down-converting, and filtering again to a desired frequency band. Various examples rearrange the order of the above-described (and other) elements, remove some of these elements, and / or add other elements performing similar or different functions. Adding elements can include inserting elements in between existing elements, such as, for example, inserting amplifiers and an analog- to-digital converter. In various examples, the RF portion includes an antenna.

[0102] The USB and / or HDMI terminals can include respective interface processors for connecting system 400 to other electronic devices across USB and / or HDMI connections. It is to be understood that various aspects of input processing, for example, Reed-Solomon error correction, may be implemented, for example, within a separate input processing IC or within processor 410 as necessary. Similarly, aspects of USB or HDMI interface processing may be implemented within separate interface les or within processor 410 as necessary. The demodulated, error corrected, and demultiplexed stream is provided to various processing elements, including, for example, processor 410, and encoder / decoder 430 operating in combination with the memory and storage elements to process the data stream as necessary for presentation on an output device.

[0103] Various elements of system 400 may be provided within an integrated housing, Within the integrated housing, the various elements may be interconnected and transmit data therebetween using suitable connection arrangement 425, for example, an internal bus as known in the art, including the Inter- IC (I2C) bus, wiring, and printed circuit boards.

[0104] The system 400 includes communication interface 450 that enables communication with other devices via communication channel 460. The communication interface 450 can include, but is not limited to, a transceiver configured to transmit and to receive data over communication channel 460. The communication interface 450 can include, but is not limited to, a modem or network card and the communication channel 460 may be implemented, for example, within a wired and / or a wireless medium.

[0105] Data is streamed, or otherwise provided, to the system 400, in various examples, using a wireless network such as a Wi-Fi network, for example IEEE 802.11 (IEEE refers to the Institute of Electrical and Electronics Engineers). The Wi-Fi signal of these examples is received over the communications channel 460 and the communications interface 450 which are adapted for Wi-Fi communications. The communications channel 460 of these examples is typically connected to an access point or router that provides access to external networks including the Internet for allowing streaming applications and otherover-the-top communications. Other examples provide streamed data to the system 400 using a set-top box that delivers the data over the HDMI connection of the input block 445. Still other examples provide streamed data to the system 400 using the RF connection of the input block 445. As indicated above, various examples provide data in a non-streaming manner. Additionally, various examples use wireless networks other than Wi-Fi, for example a cellular network or a Bluetooth® network.

[0106] The system 400 can provide an output signal to various output devices, including a display 475, speakers 485, and other peripheral devices 495. The display 475 of various examples includes one or more of, for example, a touchscreen display, an organic light-emitting diode (OLED) display, a curved display, and / or a foldable display. The display 475 may be for a television, a tablet, a laptop, a cell phone (mobile phone), or another device. The display 475 can also be integrated with other components (for example, as in a smart phone), or separate (for example, an external monitor for a laptop). The other peripheral devices 495 include, in various examples, one or more of a stand-alone digital video disc (or digital versatile disc) (DVD, for both terms), a disk player, a stereo system, and / or a lighting system. Various examples use one or more peripheral devices 495 that provide a function based on the output of the system 400. For example, a disk player performs the function of playing the output of the system 400.

[0107] In various examples, control signals are communicated between the system 400 and the display 475, speakers 485, or other peripheral devices 495 using signaling such as AV. Link, Consumer Electronics Control (CEC), or other communications protocols that enable device-to-device control with or without user intervention. The output devices may be communicatively coupled to system 400 via dedicated connections through respective interfaces 470, 480, and 490. Alternatively, the output devices may be connected to system 400 using the communications channel 460 via the communications interface 450. The display 475 and speakers 485 may be integrated in a single unit with the other components of system 400 in an electronic device such as, for example, a television. In various examples, the display interface 470 includes a display driver, such as, for example, a timing controller (T Con) chip.

[0108] The display 475 and speakers 485 can alternatively be separate from one or more of the other components, for example, if the RF portion of input 445 is part of a separate set-top box. In various examples in which the display 475 and speakers 485 are external components, the output signal may be provided via dedicated output connections, including, for example, HDMI ports, USB ports, or COMP outputs.

[0109] The examples may be carried out by computer software implemented by the processor 410 or by hardware, or by a combination of hardware and software. As a non-limiting example, the examples may be implemented by one or more integrated circuits. The memory 420 may be of any type appropriate to the technical environment and may be implemented using any appropriate data storage technology, such as optical memory devices, magnetic memory devices, semiconductor-based memory devices, fixed memory, and removable memory, as non-limiting examples. The processor 410 may be of any type appropriate to thetechnical environment, and can encompass one or more of microprocessors, general purpose computers, special purpose computers, and processors based on a multi-core architecture, as non-limiting examples.

[0110] Various implementations involve decoding. "Decoding,” as used in this application, can encompass all or part of the processes performed, for example, on a received encoded sequence in order to produce a final output suitable for display. In various examples, such processes include one or more of the processes typically performed by a decoder, for example, entropy decoding, inverse quantization, inverse transformation, and differential decoding. In various examples, such processes also, or alternatively, include processes performed by a decoder of various implementations described in this application, for example, receiving a video picture; receiving an indication of a ratio value corresponding to the video picture; based on the ratio value, adjusting a number of code words of a mapping function that is associated with the video picture; and decoding the video picture based on the mapping function.

[0111] As further examples, in one example "decoding” refers only to entropy decoding, in another example "decoding” refers only to differential decoding, and in another example "decoding” refers to a combination of entropy decoding and differential decoding. Whether the phrase "decoding process” is intended to refer specifically to a subset of operations or generally to the broader decoding process will be clear based on the context of the specific descriptions and is believed to be well understood by those skilled in the art.

[0112] Various implementations involve encoding. In an analogous way to the above discussion about "decoding,” "encoding” as used in this application can encompass all or part of the processes performed, for example, on an input video sequence in order to produce an encoded bitstream. In various examples, such processes include one or more of the processes typically performed by an encoder, for example, receiving a video picture; receiving an indication of a ratio value corresponding to the video picture; based on the ratio value, adjusting a number of code words of a mapping function that is associated with the video picture; and decoding the video picture based on the mapping function.

[0113] As further examples, in one example "encoding” refers only to entropy encoding, in another example "encoding” refers only to differential encoding, and in another example "encoding” refers to a combination of differential encoding and entropy encoding. Whether the phrase "encoding process” is intended to refer specifically to a subset of operations or generally to the broader encoding process will be clear based on the context of the specific descriptions and is believed to be well understood by those skilled in the art.

[0114] Note that syntax elements as used herein, for example, coding syntax on intensity interval, grain parameters, block offset, scaling factor, etc., are descriptive terms. As such, they do not preclude the use of other syntax element names.

[0115] When a figure is presented as a flow diagram, it should be understood that it also provides a block diagram of a corresponding apparatus. Similarly, when a figure is presented as a block diagram, it should be understood that it also provides a flow diagram of a corresponding method / process.

[0116] The implementations and aspects described herein may be implemented in, for example, a method or a process, an apparatus, a software program, a data stream, or a signal. Even if only discussed in the context of a single form of implementation (for example, discussed only as a method), the implementation of features discussed can also be implemented in other forms (for example, an apparatus or program). An apparatus may be implemented in, for example, appropriate hardware, software, and firmware. The methods may be implemented in, for example, a processor, which refers to processing devices in general, including, for example, a computer, a microprocessor, an integrated circuit, or a programmable logic device. Processors also include communication devices, such as, for example, computers, cell phones, portable / personal digital assistants ("PDAs”), and other devices that facilitate communication of information between end-users.

[0117] Reference to "one example” or "an example” or "one implementation” or "an implementation,” as well as other variations thereof, means that a particular feature, structure, characteristic, and so forth described in connection with the example is included in at least one example. Thus, the appearances of the phrase "in one example” or "in an example” or "in one implementation” or "in an implementation,” as well any other variations, appearing in various places throughout this application are not necessarily all referring to the same example.

[0118] Additionally, this application may refer to "determining” various pieces of information. Determining the information can include one or more of, for example, estimating the information, calculating the information, predicting the information, or retrieving the information from memory. Obtaining may include receiving, retrieving, constructing, generating, and / or determining.

[0119] Further, this application may refer to "accessing” various pieces of information. Accessing the information can include one or more of, for example, receiving the information, retrieving the information (for example, from memory), storing the information, moving the information, copying the information, calculating the information, determining the information, predicting the information, or estimating the information.

[0120] Additionally, this application may refer to "receiving” various pieces of information. Receiving is, as with "accessing,” intended to be a broad term. Receiving the information can include one or more of, for example, accessing the information, or retrieving the information (for example, from memory). Further, "receiving” is typically involved, in one way or another, during operations such as, for example, storing the information, processing the information, transmitting the information, moving the information, copying the information, erasing the information, calculating the information, determining the information, predicting the information, or estimating the information.

[0121] It is to be appreciated that the use of any of the following"and / or,” and "at least one of,” for example, in the cases of “A / B,” "A and / or B,” and "at least one of A and B” is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of both options (A and B). As a further example, in the cases of "A, B, and / or C” and "at least one of A, B, and C,” such phrasing is intended to encompass the selection of the first listed option (A) only, or the selection of the second listed option (B) only, or the selection of the third listed option (C) only, or the selection of the first and the second listed options (A and B) only, or the selection of the first and third listed options (A and C) only, or the selection of the second and third listed options (B and C) only, or the selection of all three options (A and B and C). This may be extended, as is clear to one of ordinary skill in this and related arts, for as many items as are listed.

[0122] Also, as used herein, the word "signal” refers to, among other things, indicating something to a corresponding decoder. Encoder signals may include, for example, number of intensity intervals, number of model values, grain parameters, grain identification, scaling factor, etc. In this way, in an example the same parameter is used at both the encoder side and the decoder side. Thus, for example, an encoder can transmit (explicit signaling) a particular parameter to the decoder so that the decoder can use the same particular parameter. Conversely, if the decoder already has the particular parameter as well as others, then signaling may be used without transmitting (implicit signaling) to simply allow the decoder to know and select the particular parameter. By avoiding transmission of any actual functions, a bit savings is realized in various examples. It is to be appreciated that signaling may be accomplished in a variety of ways. For example, one or more syntax elements, flags, and so forth are used to signal information to a corresponding decoder in various examples. While the preceding relates to the verb form of the word "signal,” the word "signal” can also be used herein as a noun.

[0123] As will be evident to one of ordinary skill in the art, implementations may produce a variety of signals formatted to carry information that may be, for example, stored or transmitted. The information can include, for example, instructions for performing a method, or data produced by one of the described implementations. For example, a signal may be formatted to carry the bitstream of a described example. Such a signal may be formatted, for example, as an electromagnetic wave (for example, using a radio frequency portion of spectrum) or as a baseband signal. The formatting may include, for example, encoding a data stream and modulating a carrier with the encoded data stream. The information that the signal carries may be, for example, analog or digital information. The signal may be transmitted over a variety of different wired or wireless links, as is known. The signal may be stored on, or accessed or received from, a processor- readable medium.

[0124] Many examples are described herein. Features of examples may be provided alone or in any combination, across various claim categories and types. Further, examples may include one or more of the features, devices, or aspects described herein, alone or in any combination, across various claim categories and types. For example, features described herein may be implemented in a bitstream or signal that includes information generated as described herein. The information may allow a decoder to decode a bitstream, the encoder, bitstream, and / or decoder according to any of the embodiments described. For example, features described herein may be implemented by creating and / or transmitting and / or receiving and / or decoding a bitstream or signal. For example, features described herein may be implemented a method, process, apparatus, medium storing instructions, medium storing data, or signal. For example, features described herein may be implemented by a TV, set-top box, cell phone, tablet, or other electronic device that performs decoding. The TV, set-top box, cell phone, tablet, or other electronic device may display (e.g., using a monitor, screen, or other type of display) a resulting image (e.g., an image from residual reconstruction of the video bitstream). The TV, set-top box, cell phone, tablet, or other electronic device may receive a signal including an encoded image and perform decoding. A coding loop may be updated with a luma mapping function, at encoder and decoder side, based on the reconstruction samples (e.g., already) generated in the current slice or picture. Compression efficiency may be affected. The bitrate may be reduced while maintaining the quality, and / or the quality may be improved while maintaining the bitrate. Features associated with block partitioning are described herein.

[0125] Features described herein may be associated with luma mapping with chroma scaling (LMCS) for SDR contents. In some sequences (e.g., for captured content), a data range of the luma samples may or may not correspond to 1024 levels for a 10-bit signal. The data range of the luma samples may correspond to a range of 64-940 (e.g., a standard range). The LMCS function may modify the luma of the content to exploit (e.g., 10-bit) capabilities. A mapping function may be applied to luma based on a pre-calculated LUT, computed at the encoder side. Values of the LUT may be defined by the encoder based on characteristic of the content. The 10-bit representation (e.g., 1024 levels) may be split into 16 pieces (e.g., intervals) of 64 levels. The LMCS mapping function derivation in an encoder may include the following steps in the Random- Access mode.

[0126] Video parameters may be calculated. For a video or video chunk, parameters may be extracted on l-frames, such as the histogram and the local variance of the frame luma samples, per pieces. The result of the histogram may be given with 16 values (corresponding to the 16 pieces). A piece may correspond to 1 / 16 of the range of values between 0 and 1023 for a 10 bits signal. Hist[0] may corresponds to the occurrence of samples having a luma between 0 and 63 on the (e.g., whole) picture, Hist[1] for the occurrence of samplehaving a luma between 64 and 127, etc.. Hist[i] for i=0 to 15 may be normalized so that Hist[0] + ... + Hist

[0015] = 1.0.

[0127] The variance of the sample P having the value of luma P(x,y) may be calculated as the sum of square value of pixel on a 5*5 window divided by the size of the window minus the square of the average value on the window. The variance may be summed with variances of the same piece, and the piece may be determined by the luma value of the current sample.

[0128] Whether to apply LMCS may be determined. If HistfO] and Hist

[0015] are both below a threshold (e.g., 0.001), the LCMS function may be activated (e.g., the Code Words (CW) from 0-63 and 960-1023 may or may not be used for coding the sequence).

[0129] A global number of code words may be calculated . 896 codes may be used to code values between 64 and 959. The global number of code words (NbCW) may be a multiple of 14. NbCW may be determined based on thresholds calculated from a histogram and variance values.

[0130] CWs may be refined per piece. The number of CWs per piece may be the same (e.g., NbCW may be a multiple of 14). The refinement process may use the histogram and the variance value of a piece to modify the number of CWs per piece (e.g., noted below m_binCW[i] for the piece of index I) around the initial value that is calculated. The refinement process may include the following: for (int i = 0; I < 16; I++) { if (Hist[i] > 0.001) { if Hist[i] > 0.4 { hist = 0.4}; else {hist = Histfi]}; deltal = (uint16_t)(10.0 * hist + 0.5); delta2 = (uint16_t)(20.0 * hist + 0.5); if (normVarfi] < 0.8) { m_binCW[i] = m_binCW[i] + delta2;} else if (normVarfi] < 0.9){ m_binCW[i] = m_binCW[i] + deltal ;} if (normVarfi] > 1 ,2){ m_binCW[i] = m_binCW[i] - delta2;} else if (normVarfi] > 1.1) { m_binCW[i] = m_binCW[i] - deltal ;}}A correction may be applied such that the sum of number of CWs per piece is not above 1023.

[0131] An example may include a QP<= 22. A processing may be applied for QP<=22 with a threshold to determine whether the NbCW is modified or not. If NbCW is modified, the value may be set to 924.

[0132] LUT may be generated. In examples, the LUT corresponding to the number of CWs per piece may be generated. The LUT corresponding to the number of CWs per piece may be the Forward_Mapping LUT and may be used when there is a conversion from the non-mapped to the mapped domain. In parallel, the lnverse_Mapping LUT may be generated based on the same number of CWs per piece. The lnverse_Mapping LUT may be used when there is a conversion from the mapped to the non-mapped domain.The Forward_Mapping and lnverse_Mapping may be applied to the video for frames (e.g., frames other than l-frames).

[0133] LMCS parameters may be signaled. The LMCS parameters may be signaled by the encoder in the APS. Table 1 : LMCS syntax table.

[0134] YThe decoder may decode the information, rebuild the forward and inverse mapping functions, and use the functions during the decoding process (e.g., forward mapping may be applied to inter prediction luma samples, and inverse mapping may be applied after the reconstruction process and before the in-loop filtering).

[0135] Features described herein may be associated with luma mapping with chroma scaling (LMCS) for HDR contents. In some SDR sequences (e.g., for captured content SDR sequences), a data range of the luma signal may or may not correspond to 1024 levels (e.g., such as for a 10-bit signal) and may correspond to the range of 64-940. For an HDR signal, when the HDR signal is in PQ format, the code range may be reduced because the maximum value of 1023 may correspond to a peak luminance of 10000 cd / m2, which may or may not be used. Grading may use a peak luminance up to 1000, 4000 or 5000 cd / m2, which may lead to a luma codeword around 720, 850 and 875, respectively. The LMCS function may modify the luma signal of the content to exploit the 10-bit capabilities. A mapping function may be applied to a luma signal due to a pre-calculated function or LUT computed at the encoder side. Values of the function or LUT may be defined by the encoder based on characteristic of the content. The 10-bit representation (1024 levels) may be split into a given number of N pieces (e.g., 16 intervals) of 1024 / N levels (e.g., 64 when 16 intervals are used). The luma mapping function may be defined as a piece-wise linear function, defined in N segments. As in an SDR case, the Forward_Mapping function may be modeled by a piece-wise linear model, for example, of 16 pieces.

[0136] For an input value x (e.g., in [0,1023] for a 10-bit signal), a Forward_Mapping LUT may be built from the piece-wise linear function. In parallel, an lnverse_Mapping LUT may be generated based on the same piece-wise linear function. An lnverse_Mapping LUT may be used when a conversion from the mapped to the non-mapped domain is required. The Forward_Mapping and lnverse_Mapping may be applied to a picture of the video.

[0137] A mapping function may correspond to, or may be defined as, a set of numbers of CWs per piece, where for a piece of the function, a (e.g., one) number of CWs may be assigned.

[0138] An encoder may derive the LMCS function by extracting video parameters (e.g., histogram, variance) from the I frame and calculating the number of code words per piece based on histogram and local variance. Since the number of CWs per piece depends on the content, the values may be calculated at the encoder side, and the number of CWs per piece may be transmitted for a piece into the bitstream every I frame. There may be a (e.g., extra) cost to transmit the data. The amount of data to be transmitted may be limited by selecting a limited number of predefined sets of a number of CWs per piece (e.g., 4, 8 or 16) to be transmitted. The encoder may determine the best set of number of CWs per piece for the current chunk (e.g.,segment) of video. As described herein, the best set of CWs per piece for the current chunk may be referred to as CODE.

[0139] The CODE may be selected by making an exhaustive rate-distortion optimization (RDO), which may include encoding the picture for the possible CODEs, and choosing the CODE leading to the best ratedistortion value. For a given CODE, a complete encoding of the picture may be performed. The complete encoding may choose for a CTU of the picture partitioning trees and coding modes among the possible partitioning trees and the available coding modes leading to the best rate-distortion criterion. The ratedistortion criterion may include a metric mixing the bitrate R(CODE) obtained when encoding the picture (or video) and a distortion D(CODE) corresponding to a distance between the samples of the decoded picture and the samples of the original picture, as depicted in Equation (1).RD(CODE) = D(CODE) + R(CODE) (1)

[0140] Parameter X is a parameter (e.g., a lagrangian parameter) than may depends on the quantization parameter (QP) used for encoding the picture. D may correspond to the mean square error or the mean absolute error.

[0141] The coding cost of signaling the CODE may be reduced, as described herein. The best set of "CW per piece for the current chunk” (e.g., the CODE) may be selected and the selection information may be indicated in video data (e.g., transmitted into the bitstream). Processes to estimate the CODE may be performed based on an analysis of an input picture to be coded. Signaling mechanism may lead to a reduced signaling cost of the CODE.

[0142] A CODE may be identified based on input features computed from the input picture (or pictures) samples used in a gradient boosting decision tree to select the best CODE among a set of possible CODEs.

[0143] The features computed from the input picture samples may be based on Min and Max values of the video, on a histogram of the picture (or pictures) samples, on a variance of the picture samples, on temporal information, or parameters extracted from the picture (or pictures) samples.

[0144] The set of possible CODEs may be obtained from an initial CODE by applying a fixed ratio to the value of the initial CODE. The set of possible CODEs may be obtained from an initial CODE by changing at least a (e.g., one) value of the initial CODE. The features may be computed from the mapped input picture samples using at least a (e.g., one) CODE from the set of possible CODEs. An example process may include signaling the information related to the CODE into the bitstream to reduce the CODE signaling cost.

[0145] Features described herein may be associated with a gradient boosting decision tree, the best CODE may be selected using a regression algorithm named a LightGBM algorithm. LightGBM may be a gradient boosting framework that uses tree-based learning algorithms.

[0146] Once the training of the LightGBM is achieved, the inference process may aim at predicting the gain when using a given CODE given the input features computed on the picture. The set of input features used for the training and for the inference process may be defined.

[0147] Examples described herein may apply for types of machine learning algorithms, such as a random forest and a neural-network with deep learning algorithms.

[0148] To train the LightGBM model, a dataset may be obtained by encoding a set of test sequences at (e.g., different) QPs (e.g., QP 22, 27, 32, 37) using different CODEs. The set of CODEs in which the best CODE will be selected may be defined by applying (e.g., different) ratios to the number of Codewords of an initial CODE that may, for example, correspond to an identity mapping function or to a pre-defined mapping function. The process to calculate a CODE with a ratio R may include the following: define for the current frame the MIN and MAX values; define the total number of pieces N between the piece in which the MIN value belongs and the piece in which the MAX value belongs; and apply a ratio R to the number of Codewords for a piece (e.g., the ratio R may satisfy the condition N*64*R<2n), where n may be the bit-depth of the video samples.

[0149] In examples, the initial CODE may correspond to 64 CWs per piece for the 16 pieces for a 10-bit signal. If the min of the video samples is 64 and the max is 960, then N=14. Applying a ratio R of 1.1 means that the number of CWs per piece may be equal to ROUND (64 * 1 .1) = 70. In examples, the ratio R=1 .1 may be acceptable since 14*70=980 <1024.

[0150] In an example process, the initial CODE may be represented as a LUT, and an element of the LUT may be scaled as follows, in Equation (2): scaledLUT[ x ] = M in ( 2An - 1 , round(R*LUT[ x ]) ), for x=0 to 2An (2) where round (.) may return the closest integer value.

[0151] For a piece i, nbCWs(i) may be computed as (scaledLUT[ (i+1 )*K ] - scaledLUT[ i*K ] ), where K = 2An / maxNbPieces, and maxNbPieces is the maximum number of pieces (for instance, for a 10-bit signal, maxNbPieces = 16, K = 64).

[0152] For a sequence and a CODE, the coding gain and the input features values may be derived. The coding gain may be a BD-rate coding gain, a PSNR coding gain, or a probability of a coding gain. The BD- rate coding gain may provide an average bitrate variation indication between the anchor (e.g., sequence encoded with the initial CODE) and the test (e.g., sequence encoded with a CODE) over the 4 QPs. A negative value may indicate a bitrate decrease, which may be associated with a coding gain. A PSNR coding gain may provide an average PSNR variation indication between the anchor (e.g., sequence encoded with the initial CODE) and the test (e.g., sequence encoded with a CODE) over the 4 QPs. The probability of acoding gain may provide an average probability of coding gain between the anchor (e.g., sequence encoded with the initial CODE) and the test (e.g., sequence encoded with a CODE) over the 4 QPs. The gain may be the BD-rate coding gain, the PSNR coding gain, or the probability of a coding gain. The cost function for the training process may be the L1 or L2 distance between the predicted Gain and the real Gain.

[0153] Example features may be used for training and inference. The input features of the LightGBM model may include the following: MIN and MAX values of the picture samples; and / or a histogram of the picture samples per piece. For a piece, the number of pixels belonging to the piece may be calculated as follows:For a pieceNB _pixel[piece] =0For a pixel (between 0 and Nb_pixel _picture)For a piece (between 0 and 15)If piece*64<pixel_value <(piece+1) * 64NB_pixel[piece] +=1

[0154] The mean variance of the picture samples per piece may be calculated. For a piece, the mean value of the variance of pixels belonging to the piece may be calculated as follows:For a pieceSum_variance[piece] =0NB _pixel[piece] =0For a pixel (between 0 and Nb_pixel _picture)Calculate the variance of the pixelFor a piece (between 0 and 15)If piece*64<pixel_value <(piece+1) * 64Sum_variance [piece] +=variance of the pixelNB_pixel[piece] +=1For a piece (between 0 and 15)Mean_variance[piece] = Sum_variance [piece] / NB _pixel[piece]

[0155] Temporal variances may be computed between the current picture Icur and distant pictures that have been motion compensated Imc. In examples, the temporal variance between the current picture Icur and a distant picture with a temporal distance d may be computed as follows, in Equation (3):where the picture may be divided into blocks, Nbik being the number of blocks.

[0156] Parameter(s)(e.g., the sum of square errors, and / or the number of non-zero errors) when applying the forward mapping function (fwdMap) and the inverse mapping function (invMap) to the picture samples may be shown in Equations (4) and (5) :>

[0157] Because of rounding, the piece-wise linear inverse mapping function may or may not be the exact inverse of the piece-wise linear forward mapping function.

[0158] Characteristics (e.g., any other characteristics) of the picture or of the video may be used as feature for the decision algorithm.

[0159] FIG. 5 illustrates an example flowchart of inference for a ratio selection. FIG. 5 provides an example flowchart of the inference process in examples of a CODE defined by a fix ratio. The input of the process may be a picture, for example, the first picture of the clip to be coded or of the chunk to be coded when the video is coded per chunk (e.g., when random access coding is performed with intra pictures coded in the bitstream). At 501 , a parameter maxGain may be set to 0. The parameter may store the value of the maximum gain among the possible ratio values to be tested. At 502, a loop may be performed on the possible values of a ratio. At 503, the considered features may be computed. At 504, the inference using the machine-learning model may be performed, with the features from 503 as input. An estimation of the gain may be performed when using the tested ratio value. The estimated gain at 504 may be compared to the maxGain at 505. At 506, if the estimated gain is higher than the maxGain, maxGain value may be updated with a gain, and the current ratio may be stored as best_ratio. If the estimated gain is not higher than the maxGain, the next step (e.g., 507) may be performed. At 507, whether the end of the loop over possible ratio values is reached or not may be checked. If the end of loop is not reached, a next ratio value may be tested (e.g., at 502). If the end of loop is reached, the output of the inference process may be the estimated value of the best ratio, corresponding to the value best_ratio.

[0160] A number of CWs per piece may be defined individually per piece. In examples, the set of CODEs in which the best CODE will be selected may be defined by modifying at least a (e.g., one) number of Codewords for a piece of the initial CODE. The initial CODE may have an equal number of CWs per piece. The process to calculate a CODE belonging to the set of CODEs may include the following: define for the current frame the MIN and MAX values; define the total number of pieces N between the piece in which the MIN value belongs and the piece in which the MAX value belongs; and / or modify at least a (e.g., one) number of Codewords for a piece of the initial CODE (e.g., the set of codes may satisfy the condition Apiece nbCW piece) < 2n, where n is the bit-depth of the video samples). In examples, the initial CODE may correspond to 64 CWs per piece for the 16 pieces for a 10-bit signal. If the min of the video is 64 and the max is 960, then N=14 and 896 levels out of 1023 may be used. It may be possible to consider CODEs where the number of CWs for at least a piece is higher than 64. A set of CODEs may be defined this way and the best one for a sequence may be determined.

[0161] For a sequence and a CODE, the coding Gains and the input features values may be derived.

[0162] The cost function for the training process may be defined as the L1 or L2 distance between the predicted gain and the real gain. FIG. 6 illustrates an example flowchart of inference for a set of CODES. FIG. 6 shows an example inference process in examples of a CODE chosen among a set of CODEs. The input of the process may be a picture, for example, the first picture of the clip to be coded, or of the chunk to be coded when the video is coded per chunk (e.g., when random access coding is performed with regular intra pictures coded in the bitstream). At 601 , a parameter maxGain may be set to 0. maxGain may store the value of the maximum gain among the possible CODEs to be tested. At 602, a loop may be performed on the possible CODEs. At 603, the considered features may be computed. At 604, the inference using the machine-learning model may be performed, with the features from 603 as input. At 603, an estimation of the gain may be performed when using the tested CODE. The estimated gain from 604 may be compared to the maxGain at 605. At 606, if the estimated gain is higher than the maxGain, a maxGain value may be updated with the gain, and the current CODE may be stored as best_code. If the estimated gain is not higher than the maxGain, the next step (e.g., at 607) may be performed. At 607, whether the end of the loop over possible ratio values is reached or not may be checked. If the end of loop is not reached, a next CODE may be tested (e.g., at 602). If the end of loop is reached, the output of the inference process may be the estimated best CODE, corresponding to the value best_code.

[0163] The features may be computed from the mapped input picture samples using at least a (e.g., one) CODE of the set of possible CODEs. In examples, a feature may be extracted from the video where a forward mapping function has (e.g., already) been applied. In examples, when the feature extracted from the contentis based on histograms, for a piece, the number of samples belonging to the piece may be calculated as follows:For a pieceNB _pixel[piece] =0For a pixel (between 0 and Nb_pixel _picture)For a piece (between 0 and 15)If piece*64<Forward_mapping(pixel_value) <(piece+1) * 64NB_pixel[piece] +=1

[0164] FIG. 7 illustrates an example flowchart of inference with a feature computed based on a mapped video. FIG. 7 illustrates an example flowchart of the inference process when a CODE is defined by a fix ratio. The input of the process may be a picture, for example, the first picture of the clip to be coded, or of the chunk to be coded when the video is coded per chunk (e.g., when random access coding is performed, with regular intra pictures coded in the bitstream). At 701 , a parameter maxGain may be set to 0. maxGain may store the value of the maximum gain among the possible ratio values to be tested. At 702, a loop may be performed on the possible values of the ratio. At 703, considered features may be computed on a mapped video corresponding to the (e.g., all) ratios. At 704, the inference using the machine-learning model may be performed, with the features from 703 as input. An estimation of the gain may be performed when using the tested ratio value. The estimated gain from 704 may be compared to the maxGain at 705. At 706, if the estimated gain is higher than the maxGain, maxGain value may be updated with the gain, and the best ratio may be stored as best_ratio. If the estimated gain is not higher than the maxGain, the next step (e.g., at 707) may be performed. At 707, whether the end of the loop over possible ratio values is reached or not may be checked. If the end of loop is not reached, a next ratio value may be tested (e.g., at 702). If the end of loop is reached, the output of the inference process may be the estimated value of the best ratio, corresponding to the value best_ratio.

[0165] The information related to the optimal CODE may be indicated in video data (e.g., signaled into the bitstream). When the LMCS is applied, lmcs_data set may be signaled (e.g., encoder-side) or parsed (e.g., decoder side), and an indication (e.g., a flag) may be added in the LMCS data. For example, indication lmcs_cw_code_selection_flag may indicate whether the LMCS codewords are individually transmitted or the codewords are belonging to a pre-defined code. When lmcs_cw_code_selection_flag is false, the codewords may be transmitted. When lmcs_cw_code_selection_flag is true, the lmcs_cw_ratio_code_flag may be tested. When indication lmcs_cw_ratio_code_flag is true, a ratio lmcs_cw_ratio may be transmitted. WhenImcs_cw_ratio_code_flag is false, the index of pre-defined CODE lmcs_cw_nb_codes (e.g., among the predefined set of CODEs) may be transmitted.Table 2: LMCS Syntax Table

[0166] In examples, the process may include the following:If LMCS is enabled for the picture (ph_lmcs_enabled_flag is true) Execute ImcsjdataIf lmcs_cw_code_selection_flag is falseRecompute LMCS codewords from lmcs_delta_abs_cw[ i ] and lmcs_delta_sign_cw_flag[ i ]Else if lmcs_cw_code_selection_flag is trueIf lmcs_cw_ratio_code_flag is trueRecompute LMCS codewords from the lmcs_cw_ratio and the initial value of codewords (64).Else If lmcs_cw_ratio_code _flag is falseGet associated LMCS codewords to the corresponding code number lmcs_cw_code_idx (up to 16 codes with 4 bits, or 4 codes if 2 bits)

[0167] In examples, one of lmcs_cw_ratio and lmcs_cw_code_idx may be signaled. In examples, lmcs_cw_ratio may correspond to an index used to fetch the ratio value in a table of pre-defined ratios.

[0168] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMS1 . A video encoding device comprising: a processor configured to: determine a plurality of candidate ratio values associated with a video picture; determine a plurality of respective coding gains associated with the plurality of candidate ratio values; select a ratio value from the plurality of candidate ratio values based on their respective associated coding gains; based on the selected ratio value, adjust a number of code words of a mapping function that is associated with the video picture; and encode the video picture based on the mapping function.

2. The device of claim 1 , wherein the processor is further configured to: partition a range of luma sample values of the video picture into a plurality of luma sample value pieces, wherein the plurality of luma sample value pieces correspond to a respective plurality of subranges of luma values; based on the selected ratio value, determine the number of code words for the plurality of luma sample value pieces; map the plurality of luma sample value pieces to updated luma sample values based on the determined number of code words for the plurality of luma sample value pieces; and generate the mapping function based on the mapped plurality of luma sample value pieces.

3. The device of any of claims 1 or 2, wherein the processor is further configured to: include an indication of the selected ratio value in video data, wherein the video picture is encoded based further on the indication.

4. The device of claim 3, wherein the processor is further configured to: determine whether to signal a plurality of code words individually or whether the plurality of code words are associated with pre-defined codes, wherein the indication of the selected ratio value is included in video data based on determining that the plurality of code words are associated with pre-defined codes.

5. The device of any of claims 1 or 2, wherein the processor is further configured to: determine that a code word is associated with a pre-defined code; andinclude an index associated with the code word in video data, wherein the video picture is encoded based further on the code word.

6. The device of any of claims 1 to 5, wherein the processor is further configured to: determine at least one feature from a plurality of mapped video picture samples associated with the video picture using at least one ratio value from the plurality of candidate ratio values, wherein the coding gain is determined based on the determined at least one feature.

7. The device of claim 6, wherein the at least one feature comprises at least one of a minimum value of the plurality of mapped video picture samples, a maximum value of the plurality of mapped video picture samples, a histogram of the plurality of mapped video picture samples per piece, a variance of the plurality of mapped video picture samples per piece, or a temporal variance between the plurality of mapped video picture samples and samples of a second video picture that is distinct from the video picture.

8. The device of any of claims 1 to 7, wherein the processor is further configured to: apply a gradient boosting decision tree algorithm to the plurality of candidate ratio values, wherein the coding gain is determined based on applying the gradient boosting decision tree algorithm to the plurality of candidate ratio values.

9. A video decoding device comprising: a processor configured to: receive a video picture; receive an indication of a ratio value corresponding to the video picture; based on the ratio value, adjust a number of code words of a mapping function that is associated with the video picture; and decode the video picture based on the mapping function.

10. The device of claim 9, wherein the processor is further configured to: partition a range of luma sample values of the video picture into a plurality of luma sample value pieces, wherein the plurality of luma sample value pieces correspond to a respective plurality of subranges of luma values; based on the ratio value, determine the number of code words for the plurality of luma sample value pieces;map the plurality of luma sample value pieces to updated luma sample values based on the determined number of code words for the plurality of luma sample value pieces; and generate the mapping function based on the mapped plurality of luma sample value pieces.11 . The device of any of claims 9 to 10, wherein the processor is further configured to: apply the mapping function to a plurality of inter predicted luma samples; and decode the video picture based further on applying the mapping function to the plurality of inter predicted luma samples.

12. The device of any of claims 8 to 11 , wherein the processor is further configured to: determine that a plurality of codewords belong to predefined code words, wherein the indication of the ratio value is received based on determining that the plurality of codewords belong to predefined code words.

13. The device of any of claims 1 to 12, further comprising a memory operatively connected to the processor.

14. A method for video encoding, the method comprising: determining a plurality of candidate ratio values associated with a video picture; determining a plurality of respective coding gains associated with the plurality of candidate ratio values; selecting a ratio value from the plurality of candidate ratio values based on their respective associated coding gains; based on the selected ratio value, adjusting a number of code words of a mapping function that is associated with the video picture; and encoding the video picture based on the mapping function.

15. The method of claim 14, wherein the method further comprises: partitioning a range of luma sample values of the video picture into a plurality of luma sample value pieces, wherein the plurality of luma sample value pieces correspond to a respective plurality of subranges of luma values; based on the selected ratio value, determining the number of code words for the plurality of luma sample value pieces;mapping the plurality of luma sample value pieces to updated luma sample values based on the determined number of code words for the plurality of luma sample value pieces; and generating the mapping function based on the mapped plurality of luma sample value pieces.

16. The method of any of claims 14 or 15, wherein the method further comprises: including an indication of the selected ratio value in video data, wherein the video picture is encoded based further on the indication.

17. The method of claim 16, wherein the method further comprises: determining whether to signal a plurality of code words individually or whether the plurality of code words are associated with pre-defined codes, wherein the indication of the selected ratio value is included in video data based on determining that the plurality of code words are associated with pre-defined codes.

18. The method of any of claims 14 or 15, wherein the method further comprises: determining that a code word is associated with a pre-defined code; and including an index associated with the code word in video data, wherein the video picture is encoded based further on the code word.

19. The method of any of claims 14 to 18, wherein the method further comprises: determining at least one feature from a plurality of mapped video picture samples associated with the video picture using at least one ratio value from the plurality of candidate ratio values, wherein the coding gain is determined based on the determined at least one feature.

20. The method of claim 19, wherein the at least one feature comprises at least one of a minimum value of the plurality of mapped video picture samples, a maximum value of the plurality of mapped video picture samples, a histogram of the plurality of mapped video picture samples per piece, a variance of the plurality of mapped video picture samples per piece, or a temporal variance between the plurality of mapped video picture samples and samples of a second video picture that is distinct from the video picture.21 . The method of any of claims 14 to 20, wherein the method further comprises: applying a gradient boosting decision tree algorithm to the plurality of candidate ratio values, wherein the coding gain is determined based on applying the gradient boosting decision tree algorithm to the plurality of candidate ratio values.

22. A method for video decoding, the method comprising: receiving a video picture; receiving an indication of a ratio value corresponding to the video picture; based on the ratio value, adjusting a number of code words of a mapping function that is associated with the video picture; and decoding the video picture based on the mapping function.

23. The method of claim 22, wherein the method further comprises: partitioning a range of luma sample values of the video picture into a plurality of luma sample value pieces, wherein the plurality of luma sample value pieces correspond to a respective plurality of subranges of luma values; based on the ratio value, determining the number of code words for the plurality of luma sample value pieces; mapping the plurality of luma sample value pieces to updated luma sample values based on the determined number of code words for the plurality of luma sample value pieces; and generating the mapping function based on the mapped plurality of luma sample value pieces.

24. The method of any of claims 22 to 23, wherein the method further comprises: applying the mapping function to a plurality of inter predicted luma samples; and decoding the video picture based further on applying the mapping function to the plurality of inter predicted luma samples.

25. The method of any of claims 22 to 24, wherein method further comprising: determining that a plurality of codewords belong to predefined code words, wherein the indication of the ratio value is received based on determining that the plurality of codewords belong to predefined code words.

26. A computer-readable medium comprising medium comprising instructions for causing one or more processors to perform the method of any one of claims 14 to 25.

27. A computer program product which is stored on a non-transitory computer readable medium and comprises program code instructions for implementing the steps of a method according to at least one of claims 14 to 25 when executed by a processor.

28. Video data comprising information representative of the video picture encoded according to one of the methods of any of claims 14-21 .

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