Method for synchronizing images displayed in multiple electronic devices and the system for the method

Abstract

The present invention provides a method for video synchronization for a plurality of electronic devices, comprising the steps of: a server determining a unique delay time for each electronic device connected to the server; the server transmitting a first video playback message for displaying a first video to the plurality of electronic devices; the plurality of electronic devices determining a playback start time for the first video based on the unique delay time and a maximum delay time; and the plurality of electronic devices displaying the first video from the playback start time of the first video.

Description

Technology Field

[0001] The present invention relates to a method for synchronizing images displayed through a plurality of electronic devices and a system for the same. Background Technology

[0002] Various electronic devices such as smartphones, TVs, tablet PCs, PMPs (portable multimedia players), PDAs (personal digital assistants), laptop PCs (laptop personal computers), and wearable devices are becoming widespread. In particular, as the use of electronic devices increases, the need for content sharing between electronic devices is growing. For example, one electronic device can share content with another electronic device.

[0003] Meanwhile, when multiple electronic devices share content, a playback time discrepancy may occur between the output videos produced by each electronic device. For example, if the time information transmitted by a server to perform synchronization between electronic devices takes time to reach each playback device—that is, the network latency or delay time—varies depending on the wireless network environment of each electronic device, a playback time discrepancy may occur between the electronic device contents.

[0004] Furthermore, there are cases where it is necessary to synchronize screen displays while playing video on multimedia devices. For example, when splitting a single high-resolution video into multiple videos for multi-screen playback, the display timing of these split videos must be precisely synchronized.

[0005] Many multimedia signage devices installed in theaters or performance venues are configured with multiple screens, and it is crucial that the display of these screens is accurately synchronized. Accordingly, technologies for synchronizing video playback on multimedia devices have been proposed in the past, including playback speed maintenance methods using timestamps (PTS) or system clocks (STC), and reference time synchronization methods using time servers or access points (APs).

[0006] However, since these conventional technologies did not take into account the hardware specifications of multimedia devices, precise synchronization was difficult. Due to differences in the performance of the processor chip (SoC) installed in the multimedia device, the type of operating system (OS), and the performance of the decoder, video playback speeds vary slightly from device to device.

[0007] In other words, even if video data is input into the decoder module at exactly the same time, the timing at which the video is displayed on the screen varies slightly depending on the device. Due to these differences in playback speeds across devices, precisely synchronizing the screen display when playing video on multimedia devices becomes an extremely difficult task. The problem to be solved

[0008] The present invention provides a video synchronization method and a system for the same that can prevent video from being displayed smoothly due to video synchronization issues caused by the performance of each device or the influence of a communication network when video is displayed simultaneously through a plurality of display screens. means of solving the problem

[0009] The present invention provides a method for video synchronization for a plurality of electronic devices, comprising the steps of: a server determining a unique delay time for each electronic device connected to the server; the server transmitting a first video playback message for displaying a first video to the plurality of electronic devices; the plurality of electronic devices determining a playback start time for the first video based on the unique delay time and a maximum delay time; and the plurality of electronic devices displaying the first video from the playback start time of the first video.

[0010] According to one embodiment, the step of determining the unique delay time may include the step of transmitting a test message from each electronic device to the server, the step of transmitting a test response message from the server to each electronic device in response to the test message, and the step of determining a unique delay time for each electronic device based on the time at which the server transmitted the test message from each electronic device and the time at which the server transmitted the test response message.

[0011] According to one embodiment, the image synchronization method for the plurality of electronic devices may further include the step of determining the largest value among the unique delay times for each electronic device at the server as the maximum delay time, and the step of transmitting a delay time information message containing information about the maximum delay time from the server to each electronic device.

[0012] According to one embodiment, the video synchronization method for the plurality of electronic devices may further include the steps of: transmitting information regarding the maximum delay time and information regarding the playback time of a first video corresponding to the time at which the newly connected electronic device connected to the server when a new electronic device connects to the server while the video is being played; and determining the playback start time of the first video at the newly connected electronic device based on the maximum delay time, the playback time of the first video corresponding to the time at which the newly connected electronic device connected, a preset waiting time, and the unique delay time of the newly connected electronic device.

[0013] According to one embodiment, a video synchronization method for a plurality of electronic devices may further include: a step of transmitting a first video end message from each electronic device to a server to notify the server of the end of playback of the first video when the playback of the first video ends for each electronic device; a step of checking whether the server has received the first video end message from all electronic devices connected to the server; a step of determining a unique delay time for each electronic device for a plurality of electronic devices connected to the server when the server has received the first video end message from all electronic devices connected to the server; a step of the server transmitting a first video playback message to the plurality of electronic devices for displaying the first video; a step of the plurality of electronic devices determining the start time of playback of the first video based on the unique delay time and the maximum delay time; and a step of the plurality of electronic devices displaying the first video from the start time of playback of the first video.

[0014] According to one embodiment, a video synchronization method for a plurality of electronic devices may include the steps of: the server transmitting a second video playback preparation message for second video playback to each of the electronic devices; when the preparation for the second video playback is completed at each of the electronic devices, transmitting a second video playback preparation completion message from each of the electronic devices to the server; checking whether the server has received the second video playback preparation completion message from all electronic devices connected to the server; when the server has received the second video playback preparation completion message from all electronic devices connected to the server, the server determining a unique delay time for each of the plurality of electronic devices connected to the server; the server transmitting a second video playback message for displaying the second video to the plurality of electronic devices; the plurality of electronic devices determining a playback start time for the second video based on the unique delay time and the maximum delay time; and the plurality of electronic devices displaying the second video by setting the display preference for the second video higher than the display preference for the first video from the playback start time of the second video.

[0015] The present invention provides a method for video synchronization for a plurality of electronic devices, comprising the steps of: receiving information for determining the unique delay time of each electronic device through a vision sensor and information regarding the image quality of an image displayed through each electronic device; determining a corrected delay time for each electronic device based on the information for determining the unique delay time at a server; analyzing the color temperature and MPCD (minimum perceptible color difference) of each image displayed by each electronic device at a server to determine information regarding the image quality and brightness of each image; determining a corrected image quality value for each electronic device based on the information regarding the image quality and brightness at a server; and transmitting the corrected delay time and the corrected image quality value from the server to each electronic device.

[0016] According to one embodiment, information for verifying the inherent delay time may include information regarding the time code of an image displayed on each electronic device or information regarding the frame-by-frame screen configuration of an image displayed on each electronic device.

[0017] The present invention provides a video playback system comprising a server that determines a unique delay time for each electronic device connected to a plurality of electronic devices and transmits a first video playback message for displaying a first video to the plurality of electronic devices, and a plurality of electronic devices that determine a playback start time of the first video based on the unique delay time and a maximum delay time and display the first video from the playback start time of the first video.

[0018] According to one embodiment, the server receives information for verifying the inherent delay time of each electronic device and information regarding the image quality through a vision sensor, determines a corrected delay time for each electronic device based on the information for verifying the inherent delay time, analyzes the color temperature and MPCD (minimum perceptible color difference) of each image displayed on each electronic device to verify information regarding the image quality and brightness of each image, determines a corrected image quality value for each electronic device based on the information regarding the image quality and brightness of each image, and can transmit the corrected delay time and the corrected image quality value to each electronic device. Effects of the invention

[0019] According to one embodiment disclosed in the present invention, the precision of video synchronization can be increased by determining the video playback time by considering the intrinsic delay time of an electronic device connected to a server.

[0020] In addition, according to one embodiment disclosed in the present invention, the playback of a second image can be prepared in advance while simultaneously displaying a first image through an electronic device, and the delay caused by the image conversion displayed through the electronic device can be minimized by rapidly switching from the first image to the second image through adjusting the display preference for the second image.

[0021] In addition, in addition to video synchronization, by correcting the image quality displayed on each electronic device through the color temperature of the image detected by the vision sensor and MPCD analysis, it is possible to control each electronic device to display an image of the same or similar level. Brief explanation of the drawing

[0022] FIG. 1 is a flowchart illustrating an image synchronization method according to a first embodiment disclosed in the present invention. FIG. 2 is a flowchart illustrating a method for determining an intrinsic delay time according to one embodiment disclosed in the present invention. FIG. 3 is a flowchart illustrating a video synchronization method when a new electronic device connects to a server according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating the process of sending and receiving messages between a server and each electronic device when a new electronic device connects to a server according to an embodiment of the present invention. FIG. 5 is a flowchart illustrating a method for displaying the first image again after the first image has ended, according to an embodiment of the present invention. FIG. 6 is a flowchart illustrating a method for displaying a second image during the display of a first image according to an embodiment of the present invention. FIG. 7 is a flowchart illustrating an image synchronization method according to a second embodiment disclosed in the present invention. FIG. 8 is a configuration diagram of a video playback system according to one embodiment of the present invention. Specific details for implementing the invention

[0023] The present invention is susceptible to various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each drawing.

[0024] Terms such as first, second, A, B, etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0025] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0026] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" are intended to specify the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0027] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0029] FIG. 1 is a flowchart illustrating a video synchronization method according to a first embodiment disclosed in the present invention. According to one embodiment, the flowchart illustrated in FIG. 1 can be performed through a video playback system illustrated in FIG. 8.

[0030] According to one embodiment, the video playback system may be composed of a server and at least one electronic device. According to various embodiments, the server may communicate with a plurality of electronic devices wirelessly or via a wired connection, and the server may display content through the plurality of electronic devices.

[0031] According to one embodiment, through step S110, the server can determine a unique delay time for each electronic device for a plurality of electronic devices connected to the server. According to various embodiments, the unique delay time may be determined differently for each electronic device based on the processor performance of each electronic device or the state of the communication network between each electronic device and the server. A specific method for determining the unique time for each electronic device will be described later through the explanation of FIG. 2.

[0032] According to one embodiment, through step S120, the server may transmit a first video playback message for displaying a first video to a plurality of electronic devices. According to various embodiments, prior to step S120, if each electronic device is ready for displaying the first video, it may transmit a first video playback preparation message to the server to indicate that the first video playback preparation is complete, and if the server receives a first video playback preparation message from all electronic devices connected to the server, it may transmit a first video playback message to each electronic device through step S120.

[0033] According to one embodiment, through step S130, each electronic device can determine the playback start time of the first image based on the intrinsic delay time and the maximum delay time. According to various embodiments, the server can determine the maximum delay time by the largest value among the intrinsic delay times for each electronic device. For example, if electronic device 1 and electronic device 2 are connected to the server, and the intrinsic delay time for electronic device 1 is 1 second and the intrinsic delay time for electronic device 2 is 0.5 seconds, the maximum delay time can be determined to be 1 second.

[0034] According to one embodiment, the server may determine a maximum delay time based on the unique delay time of each electronic device received through step S110, and the server may transmit a delay time information message containing information about the determined maximum delay time to each electronic device. According to various embodiments, between steps S110 and S130, the server may determine a maximum delay time and periodically transmit information about the determined maximum delay time to each electronic device. For example, the server may determine a unique delay time for each electronic device connected to the server at 5-second intervals, determine the largest value among the determined unique delay times of each electronic device as the maximum delay time, and transmit it to each electronic device.

[0035] According to one embodiment, the playback start time of the first video may be determined by subtracting the intrinsic delay time of the electronic device from the maximum delay time. For example, if the maximum delay time is 1 second and the intrinsic delay time of the electronic device displaying the first video is 0.5 seconds, the playback start time of the first video may be t1 + 0.5 seconds, which is calculated by adding 0.5 seconds (maximum delay time - intrinsic delay time) to t1, the reference time at which the server commands video playback. According to various embodiments, through step S140, a plurality of electronic devices may display the first video starting from the playback start time of the first video determined through step S130.

[0037] FIG. 2 is a flowchart illustrating a method for determining an intrinsic delay time according to one embodiment disclosed in the present invention. The flowchart illustrated in FIG. 2 is a detailed implementation of step S110 of FIG. 1, and the flowchart illustrated in FIG. 2 can be performed through the video playback system illustrated in FIG. 8.

[0038] According to one embodiment, a test message can be transmitted from each electronic device to a server via step S210. According to various embodiments, a server that has verified the test message transmitted via step S210 can immediately transmit a test response message to the electronic device that transmitted the test message via step S220.

[0039] According to one embodiment, through step S230, the server can determine a unique delay time for each electronic device based on the time at which each electronic device sends a test message and the time at which the server sends a test response message. According to various embodiments, a unique delay time for each electronic device can be determined using the following Equation 1.

[0040] [Formula 1]

[0041]

[0042] In the above Equation 1, t latencyis the intrinsic delay time, t2 is the time the server sent the test response message, and t1 is the time the electronic device sent the test message.

[0043] For example, if the time the server sent the test response message is 3:51:07 and the time the electronic device sent the test message is 3:51:06, the intrinsic latency of the electronic device may be 0.5 seconds.

[0044] According to one embodiment, the intrinsic delay time of an electronic device may be determined whenever a new electronic device is connected to a server. For example, if electronic device 1 is connected to a server at time t1 and electronic device 2 is connected at time t2, the process for determining the intrinsic delay time for electronic device 1 may be performed at time t1, and the process for determining the intrinsic delay time for electronic device 2 may be performed at time t2. According to various embodiments, the process for determining the intrinsic delay time for each electronic device may be performed when the communication environment between the new server and the electronic device changes or at preset time intervals.

[0046] FIG. 3 is a flowchart illustrating a video synchronization method when a new electronic device connects to a server according to an embodiment of the present invention. According to an embodiment, the flowchart illustrated in FIG. 3 can be performed through the video playback system illustrated in FIG. 8.

[0047] According to one embodiment, step S310 can be used to determine whether a new electronic device has been connected to the server. According to various embodiments, if a new electronic device has been connected to the server, step S320 can be used to transmit information regarding the maximum delay time and information regarding the playback time of the first video corresponding to the time the new electronic device connected.

[0048] More specifically, when a new electronic device connects to the server, the server may transmit to the newly connected electronic device information regarding the maximum delay time determined through communication with the previously connected electronic device and time information regarding the first video at the moment the new electronic device connects. For example, if the maximum delay time managed by the server is 1 second, and the time information of the first video displayed by another electronic device at the moment the electronic device connects corresponds to 10 seconds, the server may transmit to the newly connected electronic device information indicating that the maximum delay time is 1 second and the playback time of the first video corresponding to the time the electronic device connects is 10 seconds.

[0049] According to one embodiment, through step S330, the newly connected electronic device can determine the playback start time of the first video based on the maximum delay time, the playback time of the first video corresponding to the time when the newly connected electronic device connected, a preset waiting time, and the inherent delay time of the newly connected electronic device. More specifically, the video playback time of the newly connected electronic device can be determined through the following Equation 2.

[0050] [Equation 2]

[0051]

[0052] In the above Equation 2, t display t is the playback start time of the first video of the newly connected electronic device, t3 is the playback time of the first video corresponding to the time when the newly connected electronic device connected, t4 is a preset waiting time, t5 is the maximum delay time, and t6 is the natural delay time of the newly connected electronic device.

[0053] According to one embodiment, if the playback time of the first video corresponding to the time when the newly connected electronic device connects is 5 seconds, the preset waiting time is 3 seconds, the maximum delay time is 1 second, and the inherent delay time of the newly connected electronic device is 0.1 seconds, the playback start time of the first video may be 7.9 seconds (6 seconds + 3 seconds - 1 second - 0.1 seconds). According to various embodiments, the playback start time of the first video may be a server-based time.

[0055] FIG. 4 is a flowchart illustrating the process of transmitting and receiving messages between a server and each electronic device when a new electronic device connects to a server according to an embodiment of the present invention. More specifically, FIG. 4 is a flowchart illustrating the process of transmitting and receiving messages for image display when electronic device 1 is connected to a server and electronic device 2, a new electronic device, newly connects to the server at 4 seconds.

[0056] According to one embodiment, the server may transmit a video playback message through step S410 at 0 seconds as the server reference time. According to various embodiments, after receiving the video playback message, the electronic device 1 may determine the video playback start time based on the maximum delay time and the inherent delay time. For example, if the maximum delay time is 1 second and the inherent delay time of the electronic device 1 is 1 second, the electronic device 1 internally performs an operation for video display starting from 0 seconds, and the video actually displayed through the electronic device 1 may be displayed starting from 1 second as the server reference time through step S420.

[0057] According to one embodiment, electronic device 2 may be newly connected to the server through step S430. According to various embodiments, through step S440, the server may transmit information regarding the video playback time to the newly connected electronic device 2. More specifically, through step S440, the server may transmit information regarding the maximum delay time and information regarding the video playback time corresponding to the time when electronic device 2 connected.

[0058] According to one embodiment, electronic device 2 can determine the video playback start time through step S450. The method for determining the video playback start time according to step S450 is the same as step S330 of FIG. 3, so it is omitted in this description. According to various embodiments, electronic device 2 can display the video starting from the video playback start time determined through step S460. Using the example of FIG. 3 above, 7.9 seconds as the server reference time can be determined as the video playback start time of electronic device 2 through step S450, and in this case, electronic device 2 can display the video starting from 7.9 seconds.

[0060] FIG. 5 is a flowchart illustrating a method for displaying the first image again after the first image has ended, according to an embodiment of the present invention. According to an embodiment, the flowchart illustrated in FIG. 5 can be performed through the image playback system illustrated in FIG. 8.

[0061] According to one embodiment, when the playback of the first video ends, each electronic device may transmit a first video end message to the server via step S510 to notify the server of the end of the playback of the first video. According to various embodiments, the server may check whether it has received the first video end message from all electronic devices connected to the server via step S520.

[0062] According to one embodiment, when the server receives a first video end message from all electronic devices, the server can improve the accuracy of video playback synchronization by checking the unique delay time of each electronic device once again and determining the video playback start time based thereon before transmitting a video playback message for the playback of the first video to each electronic device. According to various embodiments, since the unique delay time or maximum delay time of each electronic device may vary depending on various factors such as the intrusion of a new electronic device during the playback of the first video, the disconnection of an existing connected electronic device, or changes in the communication environment, the server may additionally perform a process to synchronize video playback between each electronic device connected to the server before requesting the playback of a new video after one video display has ended.

[0063] Meanwhile, since the description of steps S530 to S560 is identical or similar to the description of steps S110 to S140 illustrated in FIG. 1, the description of steps S530 to S560 is replaced by the description of steps S110 to S140.

[0065] FIG. 6 is a flowchart illustrating a method for displaying a second image while displaying a first image according to an embodiment of the present invention. More specifically, FIG. 6 is a process that can be performed when the first image is to be switched to and displayed as a second image while the first image is being displayed through each electronic device. The flowchart illustrated in FIG. 6 can be performed through the image playback system illustrated in FIG. 8.

[0066] According to one embodiment, through step S610, the server may send a message indicating preparation for playing the second video to an electronic device displaying the first video. According to various embodiments, through step S620, each electronic device may send a message indicating preparation for playing the second video to the server when preparation for playing the second video is complete.

[0067] More specifically, each electronic device can complete preparations for the playback of the second video by displaying the first video while simultaneously playing the second video internally. For example, each electronic device can display multiple videos simultaneously, and by differentiating the display preference for each video, only one video can be effectively displayed on the screen. That is, the electronic device can display the first video and the second video simultaneously, but can set the display preference for the first video to be high and the display preference for the second video to be low so that only the first video is displayed through the electronic device's display. Therefore, each electronic device that receives the message preparing for the playback of the second video can display the first video while simultaneously playing the second video, which has a low display preference so that it is not displayed on the screen, and then send a message to the server indicating that preparation for the playback of the second video is complete.

[0068] According to one embodiment, through step S630, the server can check whether it has received a second video playback readiness message from all electronic devices. According to various embodiments, if the server has received a second video playback readiness message from all electronic devices through step S630, it can determine a unique delay time for each electronic device through step S640. Meanwhile, since the description of steps S640 to S660 is identical or similar to the description of steps S110 to S130 illustrated in FIG. 1, the description of steps S640 to S660 is replaced by the description of steps S110 to S130.

[0069] According to one embodiment, through step S670, a plurality of electronic devices can display the second video by setting the display preference for the second video higher than the display preference for the first video from the start time of playback of the second video. More specifically, as described above, each electronic device plays the second video through a separate frame internally while simultaneously playing the first video after receiving the message preparing for playback of the second video or before. In step S670, by setting the display preference for the second video being played through the separate frame higher than the display preference for the first video, the second video can be immediately displayed on the screen externally displayed by each electronic device.

[0071] FIG. 7 is a flowchart illustrating a video synchronization method according to a second embodiment disclosed in the present invention. According to one embodiment, the flowchart illustrated in FIG. 7 can be performed through a video playback system illustrated in FIG. 8.

[0072] According to one embodiment, in step S710, information for determining the inherent delay time of each electronic device and information regarding the image quality of the image displayed through each electronic device can be received through a vision sensor. According to various embodiments, the information for determining the inherent delay time may include information regarding the timecode of the image displayed on each electronic device or information regarding the frame-by-frame screen composition of the image displayed on each electronic device.

[0073] According to one embodiment, each electronic device may display a time code related to the playback time of an image in milliseconds on a specific part of the screen, and a vision sensor may recognize the time code for each frame of the detected image. According to various embodiments, each electronic device may receive information for verifying the unique delay time of each electronic device by inserting an image having a specific color into a specific frame constituting the displayed image.

[0074] According to one embodiment, through step S720, the server can determine a corrected delay time for each electronic device based on information for verifying the unique delay time. If the server has verified the unique delay time information through the time code of each electronic device using the preceding example, it can determine the corrected delay time based on the difference in time recorded in the time code of each electronic device. For example, if the time code of electronic device 1 is 2.541 seconds and the time code of electronic device 2 is 2.555 seconds, 0.014 seconds can be determined as the corrected delay time.

[0075] On the other hand, if the server receives information about the frame-by-frame screen composition of the video displayed on each electronic device, it can determine a correction delay time based on the time information of when a frame composed of a specific video was received. For example, if each electronic device has 60 frames and a white screen is composed in the 20th frame, and a frame composed of a white screen is received at electronic device 2 0.009 seconds after the time when a frame composed of a white screen is received at electronic device 1, then 0.009 seconds can be determined as the correction delay time.

[0076] According to one embodiment, through step S730, the server can analyze the color temperature and MPCD of each image displayed on each electronic device to verify information regarding the image quality and brightness of each image. According to various embodiments, through step S740, the server can determine a corrected image quality value for each electronic device based on the information regarding the image quality and brightness of each image.

[0077] According to one embodiment, correction delay time and correction quality values ​​can be transmitted from the server to each electronic device through step S750. According to various embodiments, each electronic device can receive the correction delay time and correction quality values ​​and perform a process for video time or quality synchronization.

[0078] For example, if electronic device 1 receives information about a correction delay time of +0.014 seconds, electronic device 1 can delay the video playback time by 0.014 seconds to match the video playback synchronization time with other electronic devices. Meanwhile, if electronic device 2 receives a correction quality value from a server, it can overlay a transparent RGBA frame based on the correction quality value onto the video to match the video quality synchronization with other electronic devices.

[0080] FIG. 8 is a configuration diagram of a video playback system according to one embodiment of the present invention.

[0081] According to one embodiment, the video playback system may include a server (810) that determines a unique delay time for each electronic device for a plurality of connected electronic devices (820) and transmits a first video playback message for displaying a first video to the plurality of electronic devices (820), and a plurality of electronic devices (820) that determine a playback start time for the first video based on the unique delay time and a maximum delay time and display the first video from the playback start time of the first video.

[0082] According to one embodiment, the plurality of electronic devices (820) transmit a test message to the server (810), and the server (810) transmits a test response message to the plurality of electronic devices (820) in response to the test message. A unique delay time can be determined for each electronic device based on the time at which the plurality of electronic devices (820) transmit the test message and the time at which the server (810) transmits the test response message. According to various embodiments, the server (810) determines the largest value among the unique delay times for each electronic device as the maximum delay time and transmits a delay time information message containing information about the maximum delay time to the plurality of electronic devices (820).

[0083] According to one embodiment, when a new electronic device connects to the server while the video is being played, the server (810) may transmit information regarding the maximum delay time and information regarding the playback time of the first video corresponding to the time when the newly connected electronic device connected to the server to the newly connected electronic device. According to various embodiments, the newly connected electronic device may determine the playback start time of the first video based on the maximum delay time, the playback time of the first video corresponding to the time when the newly connected electronic device connected to the server, a preset waiting time, and the inherent delay time of the newly connected electronic device.

[0084] According to one embodiment, the server (810) receives information for verifying the unique delay time of each electronic device and information regarding the image quality through a vision sensor, determines a correction delay time for each electronic device based on the information for verifying the unique delay time, analyzes the color temperature and MPCD (minimum perceptible color difference) of each image displayed on each electronic device to verify information regarding the image quality and brightness of each image, determines a correction image quality value for each electronic device based on the information regarding the image quality and brightness of each image, and transmits the correction delay time and the correction image quality value for each electronic device.

[0086] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and a person skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

Claim 1 A method for synchronizing images displayed through multiple electronic devices, comprising: a step in which a server determines a unique delay time for each electronic device for multiple electronic devices connected to the server; a step in which the server transmits a first image playback message for displaying a first image to the multiple electronic devices; a step in which the multiple electronic devices determine a playback start time for the first image based on the unique delay time and a maximum delay time; a step in which the multiple electronic devices display the first image from the playback start time of the first image; a step in which the server transmits a second image playback preparation message for playing a second image to each electronic device; a step in which, when preparation for playing the second image is completed at each electronic device, each electronic device transmits a second image playback preparation completion message to the server; a step in which the server checks whether it has received the second image playback preparation completion message from all electronic devices connected to the server; a step in which, when the server has received the second image playback preparation completion message from all electronic devices connected to the server, the server determines a unique delay time for each electronic device for multiple electronic devices connected to the server; and a step in which the server displays the second image to the multiple electronic devices. A method for video synchronization for a plurality of electronic devices, comprising: a step of transmitting a second video playback message; a step in which the plurality of electronic devices determine a playback start time of the second video based on the inherent delay time and the maximum delay time; and a step in which the plurality of electronic devices display the second video by setting the display preference for the second video higher than the display preference for the first video from the playback start time of the second video. Claim 2 A method for video synchronization of multiple electronic devices according to claim 1, wherein the step of determining the unique delay time comprises: transmitting a test message from each electronic device to the server; transmitting a test response message from the server to each electronic device in response to the test message; and determining a unique delay time for each electronic device based on the time at which the server transmitted the test message from each electronic device and the time at which the server transmitted the test response message. Claim 3 A method for video synchronization of a plurality of electronic devices, wherein, in claim 1, the server determines the largest value among the unique delay times for each electronic device as the maximum delay time; and the server transmits a delay time information message containing information about the maximum delay time to each electronic device. Claim 4 A method for video synchronization for a plurality of electronic devices, wherein, in the first instance, when a new electronic device connects to the server while the first video is being played, the server transmits information regarding the maximum delay time and information regarding the playback time of the first video corresponding to the time the new electronic device connected to the server to the newly connected electronic device; and further comprises the step of determining the playback start time of the first video based on the maximum delay time, the playback time of the first video corresponding to the time the new electronic device connected to the server, a preset waiting time, and the inherent delay time of the newly connected electronic device at the newly connected electronic device. Claim 5 A method for video synchronization for a plurality of electronic devices according to claim 1, further comprising: a step of transmitting a first video end message from each electronic device to the server to notify the server of the end of playback of the first video when playback of the first video ends for each electronic device; a step of checking whether the server has received the first video end message from all electronic devices connected to the server; a step of determining a unique delay time for each electronic device for a plurality of electronic devices connected to the server when the server has received the first video end message from all electronic devices connected to the server; a step of the server transmitting a first video playback message to the plurality of electronic devices for displaying the first video; a step of the plurality of electronic devices determining the start time of playback of the first video based on the unique delay time and the maximum delay time; and a step of the plurality of electronic devices displaying the first video from the start time of playback of the first video. 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