WO2021120124A1

WO2021120124A1 - Method and apparatus for video display, and computer storage medium

Info

Publication number: WO2021120124A1
Application number: PCT/CN2019/126722
Authority: WO
Inventors: 王晓东
Original assignee: 上海飞来信息科技有限公司
Priority date: 2019-12-19
Filing date: 2019-12-19
Publication date: 2021-06-24
Also published as: CN113424487B; CN113424487A

Abstract

A method and apparatus for video display, and a computer storage medium. The method is a subframe-level display method, and comprises: a receiving terminal receives a data packet from a transmitting terminal, the data packet comprising subframe-level video data and time information of a frame timing signal (S110); determines a local time corresponding to the time information according to the time information and a timing relationship between the transmitting terminal and the receiving terminal (S120); determines the timing signal for screen refresh according to the local time and a preset delay time, the delay time being preset at the receiving terminal according to delays of processing at different subframe levels (S130); and start current-frame screen refresh according to the timing signal (S140). After the time of the frame timing signal of the transmitting terminal, delay is made by a fixed delay time to generate frame timing for screen refresh display. Such subframe-level control to display screen refresh can avoid a long wait caused by asynchronization and achieve minimum display delay.

Description

Method, device and computer storage medium for video display

Technical field

The embodiments of the present invention relate to the field of multimedia, and more specifically, to a method, device, and computer storage medium for video display.

Background technique

In the wireless image transmission system, the sequence of each step of video streaming is arranged in a streamlined manner. Among them, the steps of video streaming include: the generating end of the video stream (such as a camera), the image processing part, the video compression part, and the wireless transmission part. , Video decompression part, video display part (such as LCD screen), etc. Moreover, in the process of video streaming, the timing of each step needs to be matched with each other.

However, in the current common system, the timing between some steps may not be matched. For example, at the receiving end, the received video frame may be asynchronous with the frame timing displayed on the screen. At the next screen refresh moment , The arrival of the new video frame is uncertain, so the previous frame may be displayed, the next frame may be displayed normally, or the next frame may be skipped to display the next frame, and so on. This may cause end-to-end delay jitter, as well as increased delay caused by buffering to overcome the delay jitter.

Summary of the invention

The embodiments of the present invention provide a method, a device and a computer storage medium for video display, which can ensure low end-to-end delay in video transmission.

In a first aspect, a method for video display is provided, the method is a sub-frame level display method, and the method includes:

The receiving end receives a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal;

The receiving end determines the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

The receiving end determines a timing signal for refreshing the screen according to the local time and a preset delay time, where the delay time is preset at the receiving end according to the delay of each level of processing at the subframe level. Fixed

Start the current frame refresh according to the timing signal.

In a second aspect, a device for video display is provided, the device is a receiving end of sub-frame level display, and the device includes:

The receiving unit is configured to receive a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal;

A first determining unit, configured to determine the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

The second determining unit is configured to determine a timing signal for refreshing the screen according to the local time and a preset delay time, wherein the delay time is based on the delay of each level of processing at the sub-frame level. Pre-set at the end;

The processing unit is configured to start the current frame refresh according to the timing signal.

In a third aspect, a device for video display is provided, including: a memory and a processor, wherein the memory is used to store computer instructions; the processor is used to call the computer instructions, when the When computer instructions are executed, they are used to perform sub-frame level display methods, including:

Start the current frame refresh according to the timing signal.

In a fourth aspect, a computer-readable storage medium is provided, and a computer program is stored thereon, and when the computer program is executed by a processor, the steps of the method described in the first aspect are realized.

It can be seen that, in the embodiment of the present invention, the display refreshing of the receiving end is controlled at the sub-frame level. After the time of the frame timing signal of the sending end, the fixed delay time is delayed to generate the frame timing of the refreshing display, which can avoid Due to the asynchronous time, a long wait is caused to achieve the minimum display delay.

Description of the drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, without creative labor, other drawings can be obtained based on these drawings.

Figure 1 is a schematic diagram of image transmission in the prior art;

FIG. 2 is a schematic flowchart of a method for video display according to an embodiment of the present invention;

Figure 3 is a schematic diagram of image transmission and display according to an embodiment of the present invention;

4 is another schematic diagram of image transmission and display according to the embodiment of the present invention;

FIG. 5 is a schematic block diagram of an apparatus for video display according to an embodiment of the present invention;

Fig. 6 is another schematic block diagram of an apparatus for video display according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

In a wireless video transmission system, in order to reduce the delay of image transmission, sub-frame level processing is adopted, that is, video data is compressed and packaged in a time unit less than one frame, and then transmitted through the wireless physical layer. Video frame, data compression and packaging, physical layer transmission, data reception, decompression, and display are performed in parallel in a pipeline manner in a time unit less than one video frame to obtain a lower image transmission delay.

In most systems, since the time of data reception is completely asynchronous with the timing of the video display part, in order to ensure the correctness of the display, the display generally adopts the method of frame buffering, and it will only proceed when the entire frame of data is received. Display, as shown in Figure 1, after the video is decompressed, make sure to get a whole frame of data, and then display it. This introduces a frame-level delay. Furthermore, in order to prevent timing jitter, a multi-frame buffer is required; long-term timing drift will also cause repeated display or dropped frame display.

The display screen mentioned in this application may be a liquid crystal display (LCD), and those skilled in the art will understand that the display screen may also be of other types, which is not limited by the present invention.

In order to overcome the influence of timing drift, an embodiment of the present invention provides a method for video display. As shown in FIG. 2, the method is a sub-frame level display method and includes:

S110: The receiving end receives a data packet from the sending end, where the data packet includes sub-frame level video data and time information of the frame timing signal;

S120: The receiving end determines the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

S130: The receiving end determines a timing signal for refreshing the screen according to the local time and a preset delay time, where the delay time is preset at the receiving end according to the delay of each level of processing at the subframe level;

S140: Start refreshing the current frame according to the timing signal.

In the embodiment of the present invention, a fixed delay time is preset at the receiving end, denoted as T. Exemplarily, the preset fixed delay time T may include delays of various stages of pipeline processing at the sub-frame level, including delays of image processing, video compression, physical layer transmission, and video decoding.

Among them, since the embodiment of the present invention adopts a sub-frame level video transmission mode, the delays of all levels of pipeline processing are also at the sub-frame level. Exemplarily, the delay time T may be the sum of the delays of various levels of processing at the sub-frame level. Specifically, the delay time T is equal to the sum of the following delays: sub-frame level delay of image processing, sub-frame level delay of video compression, sub-frame level delay of physical layer transmission, and sub-frame level delay of video decoding . The delay of each level of processing can be determined in advance, and a fixed delay time T can be obtained by summation, and set at the receiving end. For example, the delay time T can be stored in advance in the form of a parameter at the receiving end. It can be seen that, in the embodiment of the present invention, all levels of processing in the entire image transmission system adopt sub-frame level control, so that the delay time T is fixed, thereby avoiding excessive jitter of the frame rate of the screen refresh.

Exemplarily, before the method shown in FIG. 2, the receiving end and the sending end perform time synchronization, so as to determine the timing relationship between the sending end and the receiving end. Specifically, the wireless communication physical layer of the receiving end maintains synchronization with the wireless communication physical layer of the transmitting end according to the physical layer timing adjustment mechanism. In other words, the timing relationship is used to indicate the synchronization between the wireless communication physical layer of the receiving end and the wireless communication physical layer of the transmitting end.

Exemplarily, before S110, when the sensor at the sending end generates the frame timing signal for video data output, the frame timing signal is sent to the wireless communication physical layer, and the value of the timing counter of the physical layer is latched, and the value represents the frame timing The time information of the signal. And, the sending end sends the time information together with the video data to the receiving end.

In other words, the time information is the value of the timing counter of the physical layer at the transmitting end when the transmitting end generates the frame timing signal for video data output. Therefore, in S110, the receiving end can receive the video data and the time information of the frame timing signal. Assume that the time information of the frame timing signal is represented as t0.

Exemplarily, in S120, the wireless communication physical layer of the receiving end obtains the local time t corresponding to the time information of the frame timing signal of the transmitting end according to the timing relationship between the receiving end and the transmitting end.

As an example, if the timing relationship between the receiving end and the sending end indicates that the clock difference between the receiving end and the sending end is Δt, the local time t=t0+Δt corresponding to the time information of the frame timing signal can be determined. Wherein, Δt can be any value, for example, less than zero, greater than zero, or equal to zero.

Exemplarily, in S130, it may be determined that the time of refreshing the screen is t+T, and a timer of the physical layer may be set to determine the timing of refreshing the current frame at time t+T.

Exemplarily, in S140, a liquid crystal display controller (LCDC) may initiate a screen refresh according to the timing signal determined in S130.

It can be seen that, in the embodiment of the present invention, sub-frame level control is adopted for the display refreshing of the receiving end. After the time of the frame timing signal of the sending end, a fixed delay time is delayed to generate the frame timing of the refreshing display, which can avoid the time delay. Asynchrony causes a long wait to achieve the minimum display delay. Moreover, since the entire image transmission system adopts sub-frame level control from the video stream generation, image processing, video compression, wireless transmission, and video decompression processes, image jitter can be avoided and the impact of timing drift can be overcome.

Exemplarily, the method of the embodiment of the present invention may be as shown in FIG. 3, in which, at the transmitting end, the time information of the transmitted frame timing signal is recorded by a latch counter, and the value of the counter will be sent to the receiver together with the video data. end. Then the sending end sends the video data together with the value representing the time information of the frame timing signal through compression, packing, coding and modulation, etc.

At the receiving end, the video data and the values sent together are obtained through demodulation, decoding, video decompression, etc. Subsequently, the receiving end can determine the local time t based on the value, and then display the sub-frame level on the display screen after a fixed delay T.

The embodiment of the present invention includes the time information of the frame timing signal while sending the video data at the transmitting end, so that the receiving end can determine the display timing based on the preset delay time. The embodiment of the present invention not only uses the sub-frame level transmission mode, but also uses the sub-frame level display mode to ensure the minimum delay time and also overcome the influence of timing drift.

In order to understand the transmission of video data in the embodiment of the present invention more intuitively, as shown in Figure 4, the black bold arrow represents the transmission process of video data, and the black thin dashed arrow represents the transmission and determination process of corresponding time information. . It can be understood that the "parameter T" shown at the receiving end in FIG. 4 is a fixed delay time preset before the video data transmission.

In this way, through the method of the embodiment of the present invention, the frame timing of the sending end is recorded and sent to the receiving end, and the receiving end restores the frame timing of the sending end and adjusts the LCD screen refreshing at the sub-frame level according to the preset fixed delay time. The frame timing makes it possible to start the refreshing display when the received data of the frame is at the right moment, which reduces the delay of the video display on the screen, thereby reducing the delay of the entire image transmission system. And the start time of refreshing the screen is adjusted according to the frame timing of the sending end, avoiding the jitter and drift of the frame timing of the sending end and the frame timing displayed on the LCD of the receiving end caused by clock asynchronous, avoiding the display frame dropping and frame skipping, and get In order to achieve low latency of transmission.

It should be noted that the embodiment of the present invention does not limit the specific devices of the sending end and the receiving end. For example, the sending end and the receiving end may be two independent devices, and the two may be located in the same physical space or in different physical spaces, and they can communicate in a wired or wireless manner. For example, the sending end and the receiving end can be integrated in one physical device and belong to two different modules. In addition, in the embodiment of the present invention, data transmission can be directly or indirectly performed between the sending end and the receiving end.

In addition, an embodiment of the present invention also provides a device for video display. As shown in FIG. 5, the device may be a receiving end of sub-frame level display, and the device 20 shown in FIG. 5 includes a receiving unit 210, The first determining unit 220, the second determining unit 230, and the processing unit 240.

The receiving unit 210 is configured to receive a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal;

The first determining unit 220 is configured to determine the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

The second determining unit 230 is configured to determine the timing signal for refreshing the screen according to the local time and the preset delay time, where the delay time is preset at the receiving end according to the delay of each level of processing at the subframe level ；

The processing unit 240 is configured to start the current frame refresh according to the timing signal.

Exemplarily, the preset delay time is the sum of the delays of various levels of processing at the sub-frame level. Among them, all levels of processing can include: image processing, video compression, physical layer transmission, and video decoding.

Exemplarily, the time information is the value of the timing counter of the physical layer of the sending end when the sending end generates the frame timing signal of the video data output.

Exemplarily, the timing relationship represents synchronization between the wireless communication physical layer of the receiving end and the wireless communication physical layer of the transmitting end.

Exemplarily, the second determining unit 230 may be specifically configured to: generate a timing signal for refreshing the screen at time t+T, where t represents the local time, and T represents the delay time. Among them, the delay time T is the delay at the sub-frame level.

The device shown in FIG. 5 can be used to implement each step of the method for video display shown in FIG. 2. To avoid repetition, details are not described herein again.

A person of ordinary skill in the art may realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered as going beyond the scope of the present invention.

In addition, the embodiment of the present invention also provides another device for video display, including a memory, a processor, and a computer program stored on the memory and running on the processor. When the processor executes the program, The steps of the method for video display shown in FIG. 2 are implemented.

As shown in FIG. 6, the device 30 may include a memory 310 and a processor 320. The memory 310 stores computer program codes for implementing corresponding steps in the method for video display according to an embodiment of the present invention. The processor 320 is configured to run the computer program code stored in the memory 310 to execute the corresponding steps of the method for video display according to the embodiment of the present invention.

Exemplarily, the following steps are performed when the computer program code is run by the processor 320: receiving a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal; according to the time information and The timing relationship between the sending end and the receiving end determines the local time corresponding to the time information; according to the local time and the preset delay time, the timing signal for refreshing the screen is determined, where the delay time is based on each level of the subframe level The processing delay is preset at the receiving end; according to the timing signal, the current frame refresh is started.

Exemplarily, the processor 320 may be specifically configured to: generate a timing signal for refreshing the screen at time t+T, where t represents the local time, and T represents the delay time. Among them, the delay time T is the delay at the sub-frame level.

The device 30 shown in FIG. 6 may be a receiving end of sub-frame level display, which can be used to implement each step of the method for video display shown in FIG. 2. In order to avoid repetition, it will not be repeated here.

In addition, the embodiment of the present invention also provides a computer storage medium on which a computer program is stored. When the computer program is executed by the processor, the steps of the method for video display shown in FIG. 2 can be realized. For example, the computer storage medium is a computer-readable storage medium.

In one embodiment, the computer program instructions, when run by the computer or processor, cause the computer or processor to perform the following steps: receive a data packet from the sending end, and the data packet includes sub-frame level video data and frame timing signals. Time information; according to the time information and the timing relationship between the sending end and the receiving end, determine the local time corresponding to the time information; according to the local time and the preset delay time, determine the timing signal for refreshing the screen, where the delay time It is preset at the receiving end according to the delay of each level of processing at the sub-frame level; according to the timing signal, the current frame refresh is started.

The computer storage medium may include, for example, a memory card of a smart phone, a storage component of a tablet computer, a hard disk of a personal computer, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disk read-only memory ( CD-ROM), USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media.

In addition, an embodiment of the present invention also provides a computer program product, which contains instructions, which when executed by a computer, cause the computer to execute the steps of the method for video display shown in FIG. 2.

In one embodiment, when the instruction is executed by the computer, the computer executes: receiving a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal; according to the time information and sending The timing relationship between the terminal and the receiving terminal determines the local time corresponding to the time information; according to the local time and the preset delay time, the timing signal for refreshing the screen is determined, where the delay time is processed according to each level of the subframe level The delay is preset at the receiving end; according to the timing signal, the current frame refresh is started.

It can be seen that, in the embodiment of the present invention, sub-frame level control is adopted for the display refreshing of the receiving end. After the time of the frame timing signal of the sending end, a fixed delay time is delayed to generate the frame timing of the refreshing display, which can avoid the time delay. Asynchrony causes a long wait to achieve the minimum display delay. Moreover, because the entire image transmission system adopts sub-frame level control from the video stream generation, image processing, video compression, wireless transmission, and video decompression processes, and the start time of refreshing the screen is adjusted according to the frame timing of the sender, avoiding The jitter and drift of the frame timing of the transmitting end and the frame timing displayed on the LCD of the receiving end caused by the clock asynchronous avoids the displayed frame loss and frame skipping, and obtains low transmission delay.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, it can be implemented in the form of a computer program product in whole or in part. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the processes or functions described in the embodiments of the present invention are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center. Transmission to another website, computer, server, or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media. The usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a digital video disc (DVD)), or a semiconductor medium (for example, a solid state disk (SSD)), etc. .

A person of ordinary skill in the art may realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.

In the several embodiments provided in this application, it should be understood that the disclosed system, device, and method can be implemented in other ways. For example, the device embodiments described above are merely illustrative, for example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, the functional units in the various embodiments of the present application may be integrated into one processor, or each unit may exist alone physically, or two or more units may be integrated into one unit.

The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application. Should be covered within the scope of protection of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

A method for video display, characterized in that the method is a sub-frame level display method, and the method includes:

The receiving end receives a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal;

The receiving end determines the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

The receiving end determines a timing signal for refreshing the screen according to the local time and a preset delay time, where the delay time is preset at the receiving end according to the delay of each level of processing at the subframe level. Fixed

Start the current frame refresh according to the timing signal.
The method according to claim 1, wherein the delay time is the sum of the delays of various levels of processing at the sub-frame level.
The method according to claim 1 or 2, wherein the various levels of processing include: image processing, video compression, physical layer transmission, and video decoding.
The method according to any one of claims 1 to 3, wherein the time information is the timing counter of the physical layer of the sending end when the sending end generates the frame timing signal output by the video data. The numerical value.
The method according to any one of claims 1 to 4, wherein the timing relationship represents the synchronization of the wireless communication physical layer of the receiving end and the wireless communication physical layer of the transmitting end.
The method according to any one of claims 1 to 5, wherein the determining the timing signal for refreshing the screen comprises:

The timing signal for refreshing the screen is generated at time t+T, where t represents the local time, and T represents the delay time.
The method according to any one of claims 1 to 6, wherein the delay time is a sub-frame level delay.
A device for video display, characterized in that, the device is a receiving end of sub-frame level display, and the device includes:

The receiving unit is configured to receive a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal;

A first determining unit, configured to determine the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

The second determining unit is configured to determine a timing signal for refreshing the screen according to the local time and a preset delay time, wherein the delay time is based on the delay of each level of processing at the sub-frame level. Pre-set at the end;

The processing unit is configured to start the current frame refresh according to the timing signal.
8. The apparatus according to claim 8, wherein the delay time is the sum of the delays of the processing of each stage at the sub-frame level.
The device according to claim 8 or 9, wherein the processing at all levels includes: image processing, video compression, physical layer transmission, and video decoding.
The apparatus according to any one of claims 8 to 10, wherein the time information is a timing counter of the physical layer of the sending end when the sending end generates the frame timing signal output by the video data. The numerical value.
The apparatus according to any one of claims 8 to 11, wherein the timing relationship represents synchronization of the wireless communication physical layer of the receiving end and the wireless communication physical layer of the transmitting end.
The device according to any one of claims 8 to 12, wherein the second determining unit is specifically configured to: generate the timing signal of the refreshing screen at time t+T, where t represents the Local time, T represents the delay time.
The device according to any one of claims 8 to 13, wherein the delay time is a sub-frame level delay.
A device for video display, characterized in that the device is a receiving end of sub-frame level display, and the device includes: a memory, a processor, and a memory stored in the memory and running on the processor When the processor executes the computer program, the processor performs the following actions:

Receiving a data packet from the sending end, the data packet including sub-frame level video data and time information of the frame timing signal;

Determine the local time corresponding to the time information according to the time information and the timing relationship between the sending end and the receiving end;

Determining a timing signal for refreshing the screen according to the local time and a preset delay time, wherein the delay time is preset at the receiving end according to the delay of each level of processing at the subframe level;

Start the current frame refresh according to the timing signal.
The apparatus according to claim 15, wherein the delay time is the sum of the delays of the processing of each stage at the sub-frame level.
The device according to claim 15 or 16, wherein the various levels of processing include: image processing, video compression, physical layer transmission, and video decoding.
The apparatus according to any one of claims 15 to 17, wherein the time information is a timing counter of the physical layer of the sending end when the sending end generates the frame timing signal output by the video data. The numerical value.
The apparatus according to any one of claims 15 to 18, wherein the timing relationship represents the synchronization of the wireless communication physical layer of the receiving end and the wireless communication physical layer of the transmitting end.
The device according to any one of claims 15 to 19, wherein the processor is specifically configured to: generate the timing signal for refreshing the screen at time t+T, where t represents the local time , T represents the delay time.
The apparatus according to any one of claims 15 to 20, wherein the delay time is a sub-frame level delay.
A computer storage medium having a computer program stored thereon, wherein the computer program implements the steps of any one of claims 1 to 7 when the computer program is executed by a processor.