Video stream transmission method, device, equipment and medium based on Unity

Abstract

The embodiment of the present invention provides a method, device, equipment and medium for transmitting video streams based on Unity, which relates to the field of computer technology. The method includes building a streaming server; setting at least one camera in a Unity scene, and collecting video data in the screen in real time through the camera; transmitting the video data collected by the camera to an encoder for encoding; transmitting the encoded video data to a background server through the streaming server; decoding the encoded video data in the background server, and displaying the decoded video data. In this application, the video data in the screen is collected in real time by the camera in the Unity scene, which ensures the high quality and real-time performance of the video data and improves the transmission stability; because the Unity engine supports cross-platform development, it can be applied to a variety of operating systems and devices; improves the scalability, and facilitates the addition and upgrading of subsequent functions.

Description

Technical Field

[0001] The present invention relates to the field of computer technology, and in particular to a Unity-based video stream transmission method, device, equipment and medium. Background Art

[0002] With the rapid development of the Internet and communication technology, video streaming technology has been widely used in various fields. However, traditional video streaming transmission methods have certain limitations, such as low transmission efficiency, poor real-time performance, and susceptibility to network fluctuations. Therefore, it is of great practical significance to study an efficient and stable video streaming transmission method. Summary of the invention

[0003] In view of this, an embodiment of the present invention provides a video stream transmission method based on Unity to solve the technical problems of low transmission efficiency, poor real-time performance, and susceptibility to network fluctuations in the video stream transmission method in the prior art. The method includes:

[0004] Build a streaming server;

[0005] At least one camera is set in the Unity scene, and video data on the screen is collected in real time through the camera;

[0006] Transmitting the video data collected by the camera to an encoder for encoding;

[0007] Transmitting the encoded video data to the backend server through the streaming server;

[0008] The encoded video data is decoded in the background server, and the decoded video data is displayed.

[0009] The embodiment of the present invention also provides a video stream transmission device based on Unity to solve the technical problems of low transmission efficiency, poor real-time performance and susceptibility to network fluctuations in the video stream transmission method in the prior art. The device includes:

[0010] Push streaming server building module, used to build a push streaming server;

[0011] A camera setting module, used to set at least one camera in the Unity scene, and to collect video data on the screen in real time through the camera;

[0012] An encoding module, used for transmitting the video data collected by the camera to an encoder for encoding;

[0013] A transmission module, used to transmit the encoded video data to the backend server through the streaming server;

[0014] The decoding and displaying module is used to decode the encoded video data in the background server and display the decoded video data.

[0015] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, any of the above-mentioned Unity-based video stream transmission methods is implemented to solve the technical problems of low transmission efficiency, poor real-time performance, and susceptibility to network fluctuations in the video stream transmission method in the prior art.

[0016] An embodiment of the present invention also provides a computer-readable storage medium, which stores a computer program for executing any of the above-mentioned Unity-based video stream transmission methods, so as to solve the technical problems of low transmission efficiency, poor real-time performance, and susceptibility to network fluctuations in the video stream transmission method in the prior art.

[0017] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification include at least: building a streaming server; setting at least one camera in the Unity scene, and collecting video data in the screen in real time through the camera; transmitting the video data collected by the camera to the encoder for encoding; transmitting the encoded video data to the background server through the streaming server; decoding the encoded video data in the background server, and displaying the decoded video data. In this application, the video data in the screen is collected in real time by the camera in the Unity scene, which ensures the high quality and real-time performance of the video data, and directly transmits the video data to the back-end server through the streaming server, realizing the method of transmitting the video stream to the background based on Unity, and improving the transmission stability. At the same time, because the Unity engine supports cross-platform development, it can run on multiple platforms and be applied to multiple operating systems and devices; it has high scalability, which is convenient for the subsequent addition and upgrading of functions. The method of this application can be widely used in remote monitoring, online education, game live broadcast, intelligent analysis and other fields, and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 is a flowchart of a Unity-based video streaming transmission method provided by an embodiment of the present invention;

[0020] Figure 2 is a structural block diagram of a computer device provided by an embodiment of the present invention;

[0021] Figure 3 It is a structural block diagram of a Unity-based video stream transmission device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0023] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0024] In an embodiment of the present invention, a video stream transmission method based on Unity is provided, such as Figure 1 As shown, the method includes:

[0025] Step S101, building a streaming server;

[0026] Step S102: setting at least one camera in the Unity scene, and collecting video data on the screen in real time through the camera;

[0027] Step S103, transmitting the video data collected by the camera to the encoder for encoding;

[0028] Step S104: transmitting the encoded video data to the backend server through the streaming server;

[0029] Step S105: decoding the encoded video data in the background server, and displaying the decoded video data.

[0030] Build a streaming server; set up at least one camera in the Unity scene, and use the camera to collect video data in the screen in real time; transmit the video data collected by the camera to the encoder for encoding; transmit the encoded video data to the background server through the streaming server; decode the encoded video data in the background server, and display the decoded video data. In this application, the video data in the screen is collected in real time by the camera in the Unity scene, which ensures the high quality and real-time performance of the video data, and directly transmits the video data to the back-end server through the streaming server, realizing the method of transmitting the video stream to the background based on Unity, and improving the transmission stability. At the same time, because the Unity engine supports cross-platform development, it can run on multiple platforms and be applied to multiple operating systems and devices; it has high scalability, which is convenient for the subsequent addition and upgrading of functions. The method of this application can be widely used in remote monitoring, online education, game live broadcast, intelligent analysis and other fields, and has broad market prospects.

[0031] In specific implementation, multiple cameras can be set according to actual application conditions, and cameras can be arranged at multiple locations in the scene at the same time, so that multiple cameras observe different viewport contents to improve the efficiency and flexibility of video acquisition. In addition, in this embodiment, synchronous acquisition and synchronous playback of video data and audio data can also be performed.

[0032] In one embodiment, the building of a streaming server includes:

[0033] Build a streaming server based on the RTMP protocol through the node.js service and node-media-server module.

[0034] Node.js is an open source, cross-platform JavaScript runtime environment that allows developers to execute JavaScript code on the server side. Node.js is built on the Chrome V8 engine, with high performance and high concurrency processing capabilities, and is particularly suitable for building real-time applications. Node.js services have the following features: Non-blocking I / O: Node.js uses an event-driven, non-blocking I / O model, which enables it to handle a large number of concurrent connections without blocking the process due to waiting for I / O operations. This model is very suitable for handling high-concurrency network requests, such as Web servers, real-time communication applications, etc. Single-threaded event loop: Node.js uses a single-threaded model and handles asynchronous operations in the task queue through an event loop mechanism. This design makes Node.js perform well when handling I / O-intensive tasks. Rich ecosystem: Node.js has a large community and a rich third-party module library (NPM, Node Package Manager), and developers can easily find and use a variety of powerful libraries and frameworks. Cross-platform: Node.js supports multiple operating systems such as Windows, Linux, and macOS, making development and deployment more flexible. Based on the above characteristics, this embodiment uses the node.js service to support cross-platform and run on multiple operating systems, which improves the flexibility and portability of the system; it can efficiently handle a large number of concurrent connections, ensuring high performance and low latency of the system; and it makes resource utilization more efficient, suitable for processing real-time applications.

[0035] node-media-server is a lightweight media server module based on Node.js. It is used to build streaming media servers for RTMP, RTSP, HTTP and RTMPT protocols. This module can help developers quickly implement functions such as live video, video on demand, and video recording. The node-media-server module has the following advantages: Easy to use: simple configuration and easy to integrate into existing node.js applications; High performance: based on the asynchronous I / O model of node.js, it can handle a large number of concurrent connections; Strong scalability: functions can be extended through plug-ins and custom events. Building a streaming server through the node-media-server module gives the system a good modular design, which is easy to expand and maintain.

[0036] In one embodiment, the method of building a streaming server based on the RTMP protocol through the node.js service and the node-media-server module includes:

[0037] Deploy the node.js service, use the node package manager to import the node-media-server module, and assign it to the NodeMediaServer class;

[0038] The node-media-server module is used to define a configuration object, including defining an RTMP service part and an HTTP service part, wherein the RTMP service part is used to configure relevant parameters of the RTMP protocol, and the HTTP service part is used to configure relevant parameters of the HTTP protocol, and the streaming of the encoded video data is realized through the HTTP protocol;

[0039] Create a new NodeMediaServer instance and pass the configuration object to the new NodeMediaServer instance, and the NodeMediaServer class initializes and configures the streaming server according to the parameters in the configuration object;

[0040] The streaming server is started by calling the run() method.

[0041] In this embodiment, a flexible streaming server configuration is implemented. The RTMP protocol is used to transmit the video stream. This protocol is dedicated to real-time video streaming and has low latency and high reliability. The HTTP protocol is used to pull the video data, which is convenient for the client to watch through the browser or other HTTP clients. Therefore, the parameters of the RTMP and HTTP services are defined through the configuration object, making the configuration management more flexible and convenient.

[0042] In the specific implementation, the node-media-server module is imported through the require function and assigned to the constant NodeMediaServer. In this way, we can use the NodeMediaServer class to create and configure the media server; define a configuration object config, which contains various configuration parameters for RTMP and HTTP services. These parameters are used to specify the behavior of the server, such as the listening port, data segment size, heartbeat packet sending and timeout period, etc.; create a new NodeMediaServer instance nms, and pass the previously defined configuration object config to it. The NodeMediaServer class will initialize and configure the media server according to the parameters in the configuration object. In this way, the behavior and function of the server can be set flexibly; call the run() method of the nms instance to start the media server. The run() method will start the RTMP and HTTP services according to the parameters in the configuration object config, so that the server starts listening to the specified port and processing client requests. Specifically, calling the run() method will perform the following operations:

[0043] Start RTMP service: According to the configuration of config.rtmp, start RTMP service and listen to the specified port;

[0044] Start HTTP service: According to the configuration of config.http, start HTTP service and listen to the specified port;

[0045] Initialize the event loop: Set up the event loop to handle events such as client connection requests, data transfer, and disconnection.

[0046] In one embodiment, the relevant parameters of the RTMP protocol include the port number listened by the RTMP service, the data segment size, whether to cache GOP data, the time interval for sending heartbeat packets, and the heartbeat timeout; the relevant parameters of the HTTP protocol include the port number listened by the HTTP service and the sources allowed for cross-domain access.

[0047] In this embodiment, by configuring the allow_origin parameter of the HTTP service, the sources that are allowed to be accessed across domains can be controlled, thereby enhancing the security of the system.

[0048] In one embodiment, the method further comprises:

[0049] Creating a video capture software development kit in the Unity scene;

[0050] Setting acquisition parameters of the camera through an application programming interface in the video acquisition software development kit, wherein the acquisition parameters include a video source, an acquisition type, and an address of the streaming server;

[0051] The camera collects video data on the screen in real time based on the collection parameters.

[0052] During specific implementation, the video capture software development kit in this embodiment is set as VideoCaptureSDK, which is a software development kit for video capture and processing. It provides a series of APIs (application programming interfaces) and tools to help developers integrate video capture, encoding, transmission and processing functions in applications. In this embodiment, the API in VideoCaptureSDK is used to set the acquisition parameters of the camera. The camera collects video data in real time according to the set acquisition parameters. APIs and tools are provided to collect video data from the camera. The collected video data will be sent to the encoder for encoding. The encoded video data is sent to the streaming server through the transmission module in VideoCaptureSDK based on the streaming target URL parameter. The transmission module can use RTMP or WebRTC protocol; the streaming server receives the encoded video stream and forwards it to the background server. The background server can be written in C++, Java or Python, and is responsible for decoding, displaying and further processing of the video stream, such as storage, forwarding, analysis, etc.

[0053] Specifically, the video source is set to screen recording, and the acquisition type is set to live broadcast. By directly recording the video on the screen and in live broadcast, the implementation and efficient transmission of the video stream can be realized. This method is not only applicable to real-time application scenarios such as game live broadcast and online education, but can also be extended to other fields that require real-time video transmission. It should be noted that the settings of the video source and acquisition type here are only exemplary and not limiting.

[0054] In one embodiment, the encoder uses H.264 or H.265 encoding standards for encoding. By using H.264 or H.265 encoding standards to encode video data, it has a high compression ratio and good image quality, can effectively compress video data, reduce the demand for transmission bandwidth, and combine the RTM or WebRTC protocol transmission protocol of the transmission module to ensure the stable transmission of the video stream.

[0055] In one embodiment, the backend server is written in C++, Java or Python.

[0056] In one embodiment, the backend server can perform real-time monitoring, video storage, playback and other functions on the video stream.

[0057] In one embodiment, the backend server can perform intelligent analysis such as face recognition and object recognition on the video stream.

[0058] In one embodiment, the Unity engine runs on Windows, macOS, Linux, Android, or iOS platforms.

[0059] The Unity-based video stream transmission method in the embodiment of the present application adopts the Unity engine to realize real-time acquisition, encoding, transmission and background decoding of video streams, thereby improving the real-time performance and quality of video stream transmission; adopts advanced encoding standards and transmission protocols to ensure stable transmission of video streams; the background server is rich in functions to meet the needs of different application scenarios; has good cross-platform performance and can be applied to a variety of operating systems and devices; has high scalability to facilitate the addition and upgrading of subsequent functions; can be widely used in remote monitoring, online education, game live broadcast, intelligent analysis and other fields, and has broad market prospects.

[0060] In this embodiment, a computer device is provided, such as Figure 2 As shown, it includes a memory 201, a processor 202, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, any of the above-mentioned Unity-based video stream transmission methods is implemented.

[0061] Specifically, the computer device may be a computer terminal, a server or a similar computing device.

[0062] In this embodiment, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program for executing any of the above-mentioned Unity-based video stream transmission methods.

[0063] Specifically, computer-readable storage media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. Information can be computer-readable instructions, data structures, program modules or other data. Examples of computer-readable storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable storage media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0064] Based on the same inventive concept, a video stream transmission device based on Unity is also provided in the embodiment of the present invention, as described in the following embodiments. Since the principle of solving the problem by the video stream transmission device based on Unity is similar to the video stream transmission method based on Unity, the implementation of the video stream transmission device based on Unity can refer to the implementation of the video stream transmission method based on Unity, and the repetitions are not repeated. As used below, the term "unit" or "module" can implement a combination of software and / or hardware of a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware is also possible and conceived.

[0065] Figure 3 is a structural block diagram of a video stream transmission device based on Unity according to an embodiment of the present invention, such as Figure 3 As shown, it includes: a streaming server building module 301, a camera setting module 302, an encoding module 303, a transmission module 304 and a decoding and display module 305. The structure is described below.

[0066] A streaming server building module 301 is used to build a streaming server;

[0067] A camera setting module 302 is used to set at least one camera in the Unity scene, and to collect video data on the screen in real time through the camera;

[0068] An encoding module 303 is used to transmit the video data collected by the camera to an encoder for encoding;

[0069] The transmission module 304 is used to transmit the encoded video data to the backend server through the streaming server;

[0070] The decoding and displaying module 305 is used to decode the encoded video data in the background server and display the decoded video data.

[0071] In one embodiment, the streaming server building module 301 is further used to:

[0072] Build a streaming server based on the RTMP protocol through the node.js service and node-media-server module.

[0073] In one embodiment, the streaming server building module 301 is further used to:

[0074] Deploy the node.js service, use the node package manager to import the node-media-server module, and assign it to the NodeMediaServer class;

[0075] The node-media-server module is used to define a configuration object, including defining an RTMP service part and an HTTP service part, wherein the RTMP service part is used to configure relevant parameters of the RTMP protocol, and the HTTP service part is used to configure relevant parameters of the HTTP protocol, and the streaming of the encoded video data is realized through the HTTP protocol;

[0076] Create a new NodeMediaServer instance and pass the configuration object to the new NodeMediaServer instance, and the NodeMediaServer class initializes and configures the streaming server according to the parameters in the configuration object;

[0077] The streaming server is started by calling the run() method.

[0078] In one embodiment, the streaming server building module 301 is further used to:

[0079] The relevant parameters of the RTMP protocol include the port number monitored by the RTMP service, the data segment size, whether to cache GOP data, the time interval for sending heartbeat packets, and the heartbeat timeout period; the relevant parameters of the HTTP protocol include the port number monitored by the HTTP service and the sources allowed for cross-domain access.

[0080] In one embodiment, the Unity-based video stream transmission device further includes:

[0081] A video capture software development kit creation module, used to create a video capture software development kit in the Unity scene;

[0082] An acquisition parameter setting module, used to set acquisition parameters of the camera through an application programming interface in the video acquisition software development kit, wherein the acquisition parameters include a video source, an acquisition type, and an address of the streaming server;

[0083] The acquisition module is used for the camera to acquire video data on the screen in real time based on the acquisition parameters.

[0084] In one embodiment, the acquisition parameter setting module is further used to: set the video source to screen recording, and set the acquisition type to live broadcast.

[0085] In one embodiment, the encoding module 303 is further configured to: the encoder adopts H.264 or H.265 encoding standard for encoding.

[0086] The embodiments of the present invention achieve the following technical effects: building a streaming server; setting up at least one camera in the Unity scene, and collecting video data in the screen in real time through the camera; transmitting the video data collected by the camera to the encoder for encoding; transmitting the encoded video data to the background server through the streaming server; decoding the encoded video data in the background server, and displaying the decoded video data. In this application, the video data in the screen is collected in real time by the camera in the Unity scene, which ensures the high quality and real-time performance of the video data, and directly transmits the video data to the back-end server through the streaming server, realizing the method of transmitting the video stream to the background based on Unity, and improving the transmission stability. At the same time, because the Unity engine supports cross-platform development, it can run on multiple platforms and be applied to multiple operating systems and devices; it has high scalability, which is convenient for the subsequent addition and upgrading of functions. The method of the present application can be widely used in remote monitoring, online education, game live broadcast, intelligent analysis and other fields, and has broad market prospects.

[0087] Obviously, those skilled in the art should understand that the modules or steps of the above-mentioned embodiments of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order from that here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. In this way, the embodiments of the present invention are not limited to any specific combination of hardware and software.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A video streaming transmission method based on Unity, characterized in that: The method comprises: Building a streaming server, the building of the streaming server includes: building a streaming server based on the RTMP protocol through the node.js service and the node-media-server module; the building of the streaming server based on the RTMP protocol through the node.js service and the node-media-server module includes: deploying the node.js service, using the node package manager to import the node-media-server module, and assigning it to the NodeMediaServer class; defining a configuration object through the node-media-server module, including defining an RTMP service part and an HTTP service part, the RTMP service part is used to configure the relevant parameters of the RTMP protocol, the HTTP The TP service part is used to configure the relevant parameters of the HTTP protocol, and realize the streaming of the encoded video data through the HTTP protocol; create a new NodeMediaServer instance, and pass the configuration object to the new NodeMediaServer instance, and the NodeMediaServer class initializes and configures the streaming server according to the parameters in the configuration object; start the streaming server by calling the run() method; wherein the relevant parameters of the RTMP protocol include the port number monitored by the RTMP service, the data segment size, whether to cache GOP data, the time interval for sending heartbeat packets, and the heartbeat timeout; the relevant parameters of the HTTP protocol include the port number monitored by the HTTP service and the source allowed for cross-domain access; At least one camera is set in the Unity scene, and video data on the screen is collected in real time through the camera; Transmitting the video data collected by the camera to an encoder for encoding; Transmitting the encoded video data to the backend server through the streaming server; The encoded video data is decoded in the background server, and the decoded video data is displayed.

2. The video streaming transmission method based on Unity as claimed in claim 1, characterized in that The method further comprises: Creating a video capture software development kit in the Unity scene; Setting acquisition parameters of the camera through an application programming interface in the video acquisition software development kit, wherein the acquisition parameters include a video source, an acquisition type, and an address of the streaming server; The camera collects video data on the screen in real time based on the collection parameters.

3. The video streaming transmission method based on Unity as claimed in claim 2, characterized in that: The video source is set to screen recording, and the acquisition type is set to live broadcast.

4. The Unity-based video streaming transmission method according to claim 1, wherein: The encoder uses the H.264 or H.265 encoding standard for encoding.

5. A Unity-based video stream transmission device, implementing the Unity-based video stream transmission method as described in any one of claims 1 to 4, characterized in that: include: A streaming server building module is used to build a streaming server. The building of the streaming server includes: building a streaming server based on the RTMP protocol through the node.js service and the node-media-server module; building a streaming server based on the RTMP protocol through the node.js service and the node-media-server module includes: deploying the node.js service, using the node package manager to import the node-media-server module, and assigning it to the NodeMediaServer class; defining a configuration object through the node-media-server module, including defining an RTMP service part and an HTTP service part, wherein the RTMP service part is used to configure relevant parameters of the RTMP protocol. The HTTP service part is used to configure the relevant parameters of the HTTP protocol, and realize the streaming of the encoded video data through the HTTP protocol; create a new NodeMediaServer instance, and pass the configuration object to the new NodeMediaServer instance, and the NodeMediaServer class initializes and configures the streaming server according to the parameters in the configuration object; start the streaming server by calling the run() method; wherein the relevant parameters of the RTMP protocol include the port number monitored by the RTMP service, the data segment size, whether to cache GOP data, the time interval for sending heartbeat packets, and the heartbeat timeout; the relevant parameters of the HTTP protocol include the port number monitored by the HTTP service and the source allowed for cross-domain access; A camera setting module, used to set at least one camera in the Unity scene, and to collect video data on the screen in real time through the camera; An encoding module, used for transmitting the video data collected by the camera to an encoder for encoding; A transmission module, used to transmit the encoded video data to the backend server through the streaming server; The decoding and displaying module is used to decode the encoded video data in the background server and display the decoded video data.

6. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the Unity-based video streaming transmission method according to any one of claims 1 to 4 is implemented.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program for executing the Unity-based video streaming transmission method according to any one of claims 1 to 4.

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