KR102738566B1 - Method for video frame transmission to minimize image quality degradation - Google Patents

Abstract

A method for transmitting a video frame for minimizing image quality degradation, performed by a server according to the present invention, comprises: (a) a step of generating a main frame stream and a sub frame stream, each of which consists of at least one of an I-Frame, a P-Frame, and a B-Frame; (b) a step of transmitting the main frame stream to a plurality of user terminals; and (c) a step of transmitting the sub frame stream to the user terminal that has requested it until the next main frame stream transmission timing when a request for the sub frame stream is received from at least one user terminal.

Description

{METHOD FOR VIDEO FRAME TRANSMISSION TO MINIMIZE IMAGE QUALITY DEGRADATION}

The present invention relates to a method for transmitting video frames, and more specifically, in the field of real-time streaming video transmission, to a technology for transmitting video frames with minimal degradation in image quality by allowing a server to immediately transmit a sub-frame stream corresponding to a missing frame when transmitting encoded video frames.

With the development of wireless communication technology, video calls, remote video conferencing, and real-time broadcasting are being provided through networks, and as non-face-to-face work is becoming more active due to external factors, the demand for remote video conferencing, remote video meetings, and real-time streaming services through networks is increasing, and real-time video transmission services are being utilized in various fields.

However, as real-time video transmission services become popular, multiple terminals are connected to a limited server through the network, and many requests are concentrated on the server at once as frame streams are requested from the server for various reasons. This increases the load on the server, and depending on the network conditions, the video may be interrupted, stopped, or the image quality may deteriorate.

According to the existing video frame transmission method, when a problem occurs due to network delay or bottleneck, if the terminal requests frame transmission for the disconnected part from the server, the next main frame is transmitted and the frame for the disconnected part is not transmitted in this way. Accordingly, since the connection with the currently streaming frame is not smooth, a phenomenon may occur where a part of the video appears to be disconnected to the user. In addition, it may affect other terminals that share the same main frame stream, and when multiple terminals request frames at the same time, a load may be generated during the server processing.

Accordingly, there is a need for a video frame transmission method that provides a frame stream without affecting the main frame stream. In real-time video processing, there are three methods for simultaneous transmission of multiple user terminals: the Mesh method, the SFU method, and the MCU method.

The mesh method is a method that transmits video by directly connecting all user terminals without going through a server, which requires less cost and guarantees real-time performance, but it is a method that is difficult to maintain high quality because it places a load on the user terminal.

The SFU method is a method in which the server relays centrally, and the user terminal is connected to the server. The user terminal transmits the video only to the server, but the reception is connected to the number of other user terminals. Since the video is transmitted and received through the server, there is an advantage in that the load on each user terminal is reduced when a small number of user terminals are connected, but there is a disadvantage in that when the total number of user terminals increases, the network usage increases in proportion to the number of users, which increases the load on the user terminal.

The MCU method is a method in which images transmitted from multiple user terminals are mixed or processed by a central server and then received and transmitted to each user terminal. Since multiple media packets transmitted from user terminals are compressed into a single packet, the network utilization rate is maintained constant regardless of the number of user terminals, and since the user terminal is also guaranteed a certain amount of network and CPU utilization, a stable video communication service can be provided.

However, since all media processing is done on the server, the CPU usage of the server increases, and the image quality may deteriorate due to the processing of all packets on the server. In addition, when designing an MCU server, it is difficult to operate sufficient video encoders due to the burden of increased CPU usage of the server. This is because operating a number of encoders corresponding to the number of connected user terminals can provide optimized image quality, but since CPU usage on the MCU server increases significantly, the increase in CPU usage can be minimized by transmitting the same encoded video compressed into one to each user terminal. In addition, since the network environment is different for each user terminal, and if an I-Frame is requested from the MCU server due to packet loss during communication depending on the network environment, the MCU server generates repeated I-Frames at the request of each user terminal.

Repeated occurrence of I-Frames ultimately causes increased network traffic and deterioration of video quality, and since the same encoded video is transmitted to user terminals, even user terminals that did not request I-Frames receive I-Frames, resulting in deterioration of video quality in all user terminals.

The present invention is intended to solve the problems of the prior art described above, and aims to transmit video frames without affecting the main frame stream even when frame transmission requests are made simultaneously from multiple user terminals by allowing a server to respond to frame transmission requests from user terminals by utilizing a sub-frame stream.

As a technical means for achieving the above-described technical task, in a video frame transmission method for minimizing image quality degradation, performed by a server according to one embodiment of the present invention, the method comprises the steps of: (a) generating a main frame stream and a sub frame stream, each of which is composed of at least one of an I-Frame, a P-Frame, and a B-Frame; (b) transmitting the main frame stream to a plurality of user terminals; and (c) when a request for the sub frame stream is received from at least one user terminal, transmitting the sub frame stream to the user terminal that has requested it until the next sequential main frame stream transmission timing.

Additionally, the server is configured with a media stream generation device and a media stream transmission device, and the sub-frame stream is configured with a smaller number of frames than the main frame stream.

In addition, the step (a) generates the main frame stream and the sub-frame stream in parallel through the media stream generating device.

In addition, the media stream transmission device includes a plurality of sub-transmission devices generated in a number equal to the number of the plurality of user terminals, and each sub-transmission device receives a main frame stream or sub-frame stream request of a user terminal corresponding to it.

In addition, in the step (c), when any one of the following occurs: when a network packet transmitted to the user terminal is lost; when a packet bottleneck occurs due to instability in network communication; and when the integrity of the network packet itself is defective and decoding is determined to be impossible at the user terminal; the user terminal requests the sub-frame stream.

In addition, in the step (a), when the main frame stream is composed of a first unit main frame, …, n-th unit main frame (n is a natural number greater than 1) in chronological order, and the sub-frame stream is composed of a first unit sub-frame, …, m-th unit sub-frame (m is a natural number greater than 1) in chronological order, a timestamp regarding the time at which the corresponding video is played is generated by linking each main frame stream and each sub-frame stream.

In addition, the step (c) transmits the sub-frame stream having a timestamp corresponding to the video playback time requested by the user terminal even if the transmission of one unit main frame is not completed, and when the time for transmitting the next unit main frame arrives, the transmission of the sub-frame stream is stopped and the next unit main frame is transmitted.

The above unit main frame and unit sub-frame are configured to start from an I-Frame and are configured to be consecutive with P-Frames, but the number of P-Frames in the unit sub-frame is less than that in the unit main frame.

Additionally, the above server can be configured as an MCU-type server environment.

Also, in a video frame transmission device for minimizing image quality degradation, which is performed by a server, the device comprises: a memory storing a program for transmitting a video frame for minimizing image quality degradation; and a processor for executing the program, wherein the processor performs the method according to execution of the program, the method comprising: (a) generating a main frame stream and a sub-frame stream each composed of at least one of an I-Frame, a P-Frame, and a B-Frame; (b) transmitting the main frame stream to a plurality of user terminals; and (c) when receiving a request for the sub-frame stream from at least one user terminal, transmitting the sub-frame stream to the user terminal that has requested it until the next sequential main frame stream transmission timing.

Conventional technology transmits video and real-time video using a single main frame stream regardless of network conditions, which causes problems such as video interruption, freezing, and deterioration of image quality due to frequent generation of I-Frames requested from user terminals. In addition, there is also the problem of load being placed on the server CPU by generating I-Frames.

Accordingly, the present invention generates a main frame stream and a sub frame stream in parallel, links the timestamps of each unit frame, and transmits a unit sub frame corresponding to the timestamp of the main frame stream as needed. Through this, the server can minimize an increase in CPU usage by activating the sub frame stream when there is an I-Frame request from a user terminal, and other user terminals that have not requested an I-Frame can continue to receive the main frame stream and play back video frames with minimal degradation in image quality.

Therefore, in terms of network utilization, the overall network utilization of the server is reduced because the transmission cycle of the I-Frame is longer.

FIG. 1 is a structural diagram of a video frame transmission system for minimizing image quality degradation according to one embodiment of the present invention.
FIG. 2 is a main server configuration diagram of a video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention.
FIG. 3 is a configuration diagram of a media stream transmission device for a video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention.
FIG. 4 is a flowchart of a video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention.
FIG. 5 is a diagram showing the configuration of a main frame stream of a conventional video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention.
FIG. 6a is an exemplary diagram showing the difference in configuration of a main frame stream and a sub frame stream of a video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention.
FIG. 6b is an exemplary diagram of a method for minimizing image quality degradation in a video frame transmission method according to one embodiment of the present invention.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are assigned similar drawing reference numerals throughout the specification.

Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another element in between. Also, when a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

In this specification, the term 'unit' includes a unit realized by hardware, a unit realized by software, and a unit realized using both. In addition, one unit may be realized by using two or more pieces of hardware, and two or more units may be realized by one piece of hardware. Meanwhile, the '~ unit' is not limited to software or hardware, and the '~ unit' may be configured to be in an addressable storage medium and may be configured to reproduce one or more processors. Accordingly, as an example, the '~ unit' includes components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and '~sub-components' may be combined into a smaller number of components and '~sub-components' or further separated into additional components and '~sub-components'. In addition, the components and '~sub-components' may be implemented to regenerate one or more CPUs within the device or the secure multimedia card.

The "user terminal" mentioned below may be implemented as a computer or a portable terminal including a video capturing device capable of accessing a server or other terminal via a network. Here, the computer may include, for example, a notebook, desktop, laptop equipped with a WEB Browser, VR HMD (e.g., HTC VIVE, Oculus Rift, GearVR, DayDream, PSVR, etc.). Here, the VR HMD includes all of a PC-use (e.g., HTC VIVE, Oculus Rift, FOVE, Deepon, etc.), a mobile-use (e.g., GearVR, DayDream, Storm Magic, Google Cardboard, etc.), a console-use (PSVR), and a Stand Alone model (e.g., Deepon, PICO, etc.) that is implemented independently. Portable terminals are wireless communication devices that ensure portability and mobility, for example, and may include not only smart phones, tablet PCs, and wearable devices, but also various devices equipped with communication modules such as Bluetooth (BLE, Bluetooth Low Energy), NFC, RFID, ultrasonic, infrared, WiFi, and LiFi. In addition, "network" refers to a connection structure that enables information exchange between each node, such as terminals and servers, and includes a local area network (LAN), a wide area network (WAN), the Internet (WWW: World Wide Web), wired and wireless data communication networks, telephone networks, and wired and wireless television communication networks. Examples of wireless data communication networks include, but are not limited to, 3G, 4G, 5G, 3GPP (3rd Generation Partnership Project), LTE (Long Term Evolution), WIMAX (World Interoperability for Microwave Access), Wi-Fi, Bluetooth, infrared, ultrasonic, visible light communication (VLC), and LiFi.

First, the structure of a video frame transmission system for minimizing image quality degradation according to one embodiment of the present invention will be described with reference to FIG. 1.

A video frame transmission system for minimizing image quality degradation consists of a main server (100) and a user terminal (200). A plurality of user terminals (200) can be connected to one main server (100) at the same time.

The main server (100) receives images captured from each user terminal (200) or a specific terminal (not shown), encodes the received images to create a main frame stream (300) and a sub frame stream (310), and then transmits the images to other user terminals (200) to enable a multi-party video call or video conference.

The user terminal (200) transmits the captured image to the server and receives the image of another user terminal (200) from the server. The user terminal (200) may be configured as an integrated unit with the camera, or may be a device to which the camera is separately connected.

The video frame transmission system for minimizing image quality degradation according to an additional embodiment of the present invention can be configured as a system for real-time streaming transmission and VOD video transmission. The user terminal (200) transmits the captured video to the main server (100), and other user terminals (200) can receive the video in real time or at a desired time.

One embodiment of the present invention can be implemented by modifying the method within a designable range for those skilled in the art, not only in the MCU method but also in the SFU method, and can also be applied to a video encoder in other technical fields requiring video transmission.

Hereinafter, with reference to FIG. 2, the configuration of the main server (100) of the video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention will be described.

The main server (100) is composed of a media stream generation device (110) and a media stream transmission device (120).

The media stream generation device (110) encodes the video received from each user terminal (200) into a main frame stream (300) and a sub frame stream (310). A description of the main frame stream (300) and the sub frame stream (310) will be described later with reference to FIG. 6a.

The media stream transmission device (120) transmits the main frame stream (300) and sub frame stream (310) generated by the media stream generation device (110) to each user terminal (200). A description of the transmission of the main frame stream (300) and sub frame stream (310) will be described later with reference to FIG. 6b.

Hereinafter, with reference to FIG. 3, the configuration of a media stream transmission device (120) of a video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention will be described.

The media stream transmission device (120) may be composed of n sub-transmission devices. The n sub-transmission devices, which are composed of sub-transmission device 1 (121), sub-transmission device 2 (122), ??, and sub-transmission device n (123), are configured to have the same number of user terminals (200) and transmit a main frame stream (300) or a sub-frame stream (310) to the user terminal (200) corresponding to each sub-device. At this time, the sub-transmission device is a virtual transmission device configured in software and providing transmission of a frame stream.

Accordingly, when some frames are not transmitted due to a network problem at each user terminal and a signal requesting the corresponding frame is transmitted to the main server (100), since a corresponding sub-transmission device is configured for each user terminal (200), the main server (100) can immediately react and provide feedback to the user terminal (200) that transmitted the corresponding request signal.

Hereinafter, with reference to FIG. 4, the operation sequence of a video frame transmission method for minimizing image quality degradation according to one embodiment of the present invention will be described in detail.

First, the main server (100) encodes images in the media stream generation device (110) to generate a main frame stream (300) and a sub frame stream (310) in parallel (S100). Hereinafter, the configuration of the main frame stream (300) and the sub frame stream (310) according to one embodiment of the present invention will be described.

First, let's define the terms shown in the drawing. GOP is a group of image frames for which encoding is complete, and it consists of I-Frame, P-Frame, and B-Frame. I-Frame is called a key frame and is a core frame that serves as the basis for GOP. The first frame of GOP always starts with I-Frame. Since the entire frame is compressed, the amount of data is large and the capacity is large. In Fig. 5, I-Frame is indicated by the alphabet "I". P-Frame is a frame that predicts and stores only the data for the part that is different from the previously located I-Frame. For example, when a person stands still and only bends and stretches his or her arm, a frame that predicts only the data for the moving arm is a P-Frame. Since only the part that is different is compressed in this way, the capacity is one-third of the size of I-Frame. In Fig. 5, P-Frame is indicated by the alphabet "P". B-Frame is located between I-Frame and P-Frame and is a frame that stores the movement between I-Frame and P-Frame as estimated data. It compresses only the differences and has a capacity of one-third of P-Frame.

FIG. 6A is a diagram showing the difference in configuration between a main frame stream (300) and a sub frame stream (310) according to one embodiment of the present invention. In FIG. 6A, it can be seen that a GOP of a main frame stream (300) is composed of one I-Frame and nine P-Frames, and a GOP of a sub frame stream (310) is composed of one I-Frame and three P-Frames. At this time, the number of P-Frames of the main frame stream GOP and the number of P-Frames of the sub frame stream GOP is one embodiment, and may be configured so that the P-Frames of the sub frame stream GOP are greater than the P-Frames of the main frame stream GOP. In addition, the number of frames of the sub frame stream GOP may be a variable form that is transmitted in direct response to a sub frame stream requested by a user terminal. Accordingly, the number of frames in the sub frame stream GOP may not be fixed, but may change depending on the situation.

In real-time video communication technology, a method to reduce network traffic due to video frame transmission and maintain image quality is to minimize the occurrence of I-Frames and maximize the occurrence of P-Frames and B-Frames. However, B-Frames can be excluded from the configuration if necessary.

The main frame stream (300) and the sub frame stream (310) are formed in a structure in which multiple GOPs are sequentially formed. The GOP of the main frame stream may be called a unit main frame, and the GOP of the sub frame stream may be called a unit sub frame.

The main frame stream GOP is composed of the first main frame stream GOP, ??, and the nth main frame stream GOP, and the sub-frame stream GOP is composed of the first sub-frame stream GOP, ??, and the mth sub-frame stream GOP. Each frame stream GOP is configured to start from an I-Frame and is configured to have P-Frames consecutively. At this time, the number of P-Frames of the sub-frame stream GOP is configured to be less than the number of P-Frames of the main frame stream GOP.

The main server (100) transmits the generated main frame stream (300) to the first user terminal in real time. (S110) The media stream transmission device (120) of the main server (100) transmits the main frame stream (300) to the first user terminal through the sub-transmission device 1 (121).

The main server (100) transmits the generated main frame stream (300) to the second user terminal in real time. (S120) The media stream transmission device (120) of the main server (100) transmits the main frame stream (300) to the second user terminal through the sub-transmission device 2 (122). In the same way, the main frame stream (300) can be transmitted to the nth user terminal through the sub-transmission device n (123).

The first user terminal requests the main server (100) to transmit the I-Frame of the sub-frame stream GOP. (S130) The user terminal (200) requests the main server (100) to transmit the I-Frame of the sub-frame stream GOP in any of the following cases: when a network packet transmitted while receiving the main frame stream (300) is lost; when a packet bottleneck occurs due to instability in network communication; and when the integrity of the network packet itself is defective and decoding is determined to be impossible by the user terminal (200).

For example, the first user terminal can request an I-Frame of a sub-frame stream GOP from the main server (100) when the network speed is lower than a preset value (EX: 3 mbps).

The server transmits an I-Frame of a sub-frame stream GOP having a timestamp corresponding to the time requested from the user terminal. (S140) Then, after one section of the sub-frame stream GOP ends, at the timing when the next main frame stream GOP is to be played, the I-Frame of the next main frame stream GOP is transmitted. (S150)

In the conventional case, when there is a problem such as not receiving some P-Frames of main frame stream GOPs due to packet loss at the terminal side while the main frame stream (300) is being transmitted as shown in FIG. 5, the terminal can request the I-Frame of the next main frame stream GOP to the main server (100). At this time, the main server (100) ignores the set main frame stream GOP and immediately transmits the I-Frame of the next main frame stream GOP. Therefore, as shown in FIG. 5, instead of transmitting the P-Frame of the lost main frame stream GOP, it skips it and transmits the I-frame of the next main frame stream GOP. If requests for the I-frame of the main frame stream GOP occur frequently in this way, it increases network traffic and also deteriorates the image quality of the video transmitted to the user terminal (200). Additionally, frequent requests may increase the load on the server and may also affect the transmission of the main frame stream (300) to other user terminals (200).

On the other hand, one embodiment of the present invention can solve the problem of the prior art by transmitting the I-Frame of the sub-frame stream GOP corresponding to the point where the packet is lost.

That is, the main server simultaneously generates the main frame stream (300) and the sub frame stream (310) in parallel, and when a packet is lost and some P-Frames of the main frame stream GOP are missing at the user terminal, the server can quickly respond by transmitting the I-Frame of the sub frame stream GOP corresponding to the missing frame without skipping to the next main frame stream GOP. Meanwhile, if other user terminals (200) than the user terminal (200) that requested the I-Frame of the sub frame stream GOP did not request the I-Frame of the sub frame stream GOP because packet loss did not occur, the main frame stream (300) continues to be transmitted, and thus the degradation of image quality due to the request for transmission of the I-Frame of the sub frame stream GOP is minimized.

Specifically, referring to FIG. 6B, FIG. 6B is a diagram showing a main frame stream (300) that is activated and being transmitted and a sub frame stream (310) that is deactivated and not being transmitted, and the main frame stream (300) and the sub frame stream (310) have a main frame stream GOP and a sub frame GOP, respectively. Each main frame GOP and sub frame GOP is configured to have a timestamp as metadata, and the timestamp means a time interval identifier regarding the time at which the corresponding frame is played back.

The time (①) at which the first user terminal requests transmission of the I-Frame of the sub-frame stream GOP due to unstable network is the same as the time at which only the fourth P-Frame of the first main frame GOP is transmitted. For example, the sub-frame stream GOP corresponding to this time among the sub-frame streams (310) may be the sub-frame stream GOP in the third section of Fig. 6b. Accordingly, the main server (100) transmits the I-Frame of the sub-frame stream GOP in the third section to the user terminal (②), thereby activating the sub-frame stream (310).

That is, even if the transmission of the first main frame stream GOP is not completed, the I-Frame of the sub frame stream GOP having the timestamp corresponding to the playback time requested by the user terminal (200) is transmitted. Since the sub frame stream (310) is transmitted, the main frame stream (300) is not affected, and the transmission of the main frame stream (300) of other user terminals (200) (EX: the second user terminal, the third user terminal, etc.) is not affected.

This provision of sub-frame stream GOPs is carried out until the time to transmit the second main frame stream GOP is reached. In Fig. 6b, only the third sub-frame stream GOP is transmitted (③), but in some cases, the second main frame stream GOP may be transmitted after the third and fourth sub-frame stream GOPs are transmitted.

Afterwards, if there are no special circumstances such as packet loss, the main server (100) continues to transmit the main frame stream (300) to the first user terminal. (S160) When the transmission of the sub-frame stream GOP is completed, the next main frame stream GOP starts, and when the I-Frame of the main frame stream GOP is transmitted, the main frame stream (300) is activated and transmitted in real time to the first user terminal.

An embodiment of the present invention may also be implemented in the form of a recording medium containing computer-executable instructions, such as program modules, that are executed by a computer. The computer-readable medium may be any available medium that can be accessed by a computer, and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include all computer storage media. The computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer-readable instructions, data structures, program modules, or other data.

Although the methods and systems of the present invention have been described with respect to specific embodiments, some or all of their components or operations may be implemented using a computer system having a general-purpose hardware architecture.

The above description of the present invention is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential characteristics of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive. For example, each component described as a single component may be implemented in a distributed manner, and likewise, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

100: Main server 200: User terminal
110: Media stream generator 120: Media stream transmission device
300: Main Frame Stream 310: Sub Frame Stream

Claims (10)

In a method of transmitting video frames to minimize image quality degradation performed by a server,
(a) a step of generating a main frame stream and a sub frame stream each consisting of at least one of an I-Frame, a P-Frame, and a B-Frame;
(b) a step of transmitting the main frame stream to multiple user terminals; and
(c) when receiving the sub-frame stream request from at least one user terminal, a step of transmitting the sub-frame stream to the requesting user terminal until the next sequential main frame stream transmission timing occurs,
The above step (c)
If a network packet transmitted to the above user terminal is lost;
When packet bottleneck occurs due to instability in network communication; and
When it is determined that the integrity of the network packet itself is defective and decoding is not possible at the user terminal; when any of the following applies, a step of requesting the subframe stream at the user terminal;
If the user terminal is missing at least one frame among the I-Frame, P-Frame and B-Frame of the main frame stream, the user terminal requests the I-Frame through the sub-frame stream,
The step of the server activating the sub-frame stream and transmitting the I-Frame of the sub-frame stream to the user terminal is included.
A method of transmitting video frames to minimize image quality degradation. In paragraph 1,
The above server is composed of a media stream generation device and a media stream transmission device,
The above sub-frame stream is composed of a smaller number of frames than the above main frame stream,
A method of transmitting video frames to minimize image quality degradation. In the second paragraph,
The above step (a)
The main frame stream and the sub frame stream are generated in parallel through the above media stream generating device.
A method of transmitting video frames to minimize image quality degradation. In the second paragraph,
The above media stream transmission device
It includes a plurality of sub-transmitting devices generated in the same number as the number of the above-mentioned multiple user terminals,
Each sub-transmitter receives a main frame stream or sub-frame stream request from its corresponding user terminal.
A method of transmitting video frames to minimize image quality degradation. delete In paragraph 1,
Step (a) above,
The above main frame stream is composed of the first unit main frame, ..., nth unit main frame (n is a natural number greater than 1) in chronological order,
When the above subframe stream is composed of the 1st unit subframe, ..., mth unit subframe (m is a natural number greater than 1) in time order,
Each main frame stream and each sub frame stream are generated by linking them to a timestamp about the time at which the video is played.
A method of transmitting video frames to minimize image quality degradation. In paragraph 1,
The above step (c)
Even if the transmission of one main frame unit is not completed, the sub-frame stream having a timestamp corresponding to the video playback time requested by the user terminal is transmitted,
When the time for transmitting the next main frame of the above sequence arrives, the transmission of the sub-frame stream is stopped and the next main frame of the above sequence is transmitted.
A method of transmitting video frames to minimize image quality degradation. In Article 7,
The above unit main frame and unit sub-frame are configured to start from an I-Frame and are configured to be consecutive with P-Frames, but the number of P-Frames in the unit sub-frame is less than that in the unit main frame.
A method of transmitting video frames to minimize image quality degradation. In paragraph 1,
The above server can be configured as an MCU-type server environment.
A method of transmitting video frames to minimize image quality degradation. In a video frame transmission device for minimizing image quality degradation performed by a server,
A memory storing a program for transmitting video frames to minimize image quality degradation; and
comprising a processor for executing the above program,
The above processor performs the above method according to the execution of the above program,
The above method
(a) a step of generating a main frame stream and a sub frame stream each consisting of at least one of an I-Frame, a P-Frame, and a B-Frame;
(b) a step of transmitting the main frame stream to multiple user terminals; and
(c) a step of transmitting the sub-frame stream to the requesting user terminal until the next main frame stream transmission timing arrives when the sub-frame stream request is received from at least one user terminal;
The above step (c)
If a network packet transmitted to the above user terminal is lost;
When packet bottleneck occurs due to instability in network communication; and
When it is determined that the integrity of the network packet itself is defective and decoding is not possible at the user terminal; when any of the following applies, a step of requesting the subframe stream at the user terminal;
If the user terminal is missing at least one frame among the I-Frame, P-Frame and B-Frame of the main frame stream, the user terminal requests the I-Frame through the sub-frame stream,
The step of the server activating the sub-frame stream and transmitting the I-Frame of the sub-frame stream to the user terminal is included.
A video frame transmission device to minimize image quality degradation.

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