KR100701032B1 - Video data transmission control system for network and method therefore - Google Patents

Abstract

The present invention provides a system and method for controlling video data transmission on a network for minimizing deterioration of video quality due to loss of delta frames of video data transmitted through a network. To this end, the present invention transmits a key frame and a delta frame of a compressed video stream through a multimedia communication network in a packet form, and stops transmission of only the next delta frames and the key frame according to whether a specific delta frame is lost by a packet response. And a client for receiving the packet of the key frame and the delta frame according to the compressed video stream from the server, and transmitting a response signal for the reception result of each packet to the server.

Video, stream, key frame, delta frame, packet, transmission deadline

Description

VIDEO DATA TRANSMISSION CONTROL SYSTEM FOR NETWORK AND METHOD THEREFORE}             

1 is a view showing a packet transmission form of a video data frame through a conventional network;

FIG. 2 is a diagram illustrating an unusable state of a delta frame following a delta frame loss of a video data packet transmitted through a conventional network; FIG.

3 is a diagram illustrating a state in which each video frame is individually packetized according to a video data adjusting method on a network according to the present invention;

4 is a diagram showing the configuration of a video data transmission control system on a network according to the present invention;

FIG. 5 is a diagram illustrating a state in which a next delta frame is not transmitted due to the loss of a delta frame during transmission of each packetized video data frame according to a preferred embodiment of the present invention; FIG.

6 is a flowchart illustrating the operation of a video data adjusting method on a network according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: video receiving unit, 15: video encoding unit,

20: frame alignment, 25, 65: stream buffer,

30: packet generation unit, 35: packet transmission control unit,

40: packet transmitter, 45: response receiver,

50: packet receiving control unit, 55: packet receiving unit,

60: response transmitter, 70: frame recovery unit,

75: video decoding unit, 80: video playback unit,

85: network transmission unit, 100: server,

200: Client.

The present invention relates to a system for controlling video data transmission over a network and a method thereof, and more particularly, to a network for minimizing the occurrence of video quality deterioration due to a frame loss of video data transmitted through a multimedia communication network such as the Internet. Video data transmission control system and method thereof.

As is well known, in the case of a multimedia communication network such as the Internet, as a network is established through a digital subscriber line (xDSL) or a dedicated line capable of transmitting a large amount of data and improving data transmission speed, such as a video broadcasting, etc. There is an increasing demand for large data transfer services.

In order to meet the demand for large data transmission services such as video broadcasting, MPEG 1MPEG (Moving Picture Expert) is a standard for efficiently compressing and efficiently transmitting digital video data as a result of the acceleration of technology development for multimedia technology. Group 1), MPEG 2, MPEG 4, MPEG 7 multimedia data compression technology has been proposed and put to practical use.

The MPEG technology compresses video data and audio data of a video separately and streams them in a packet form through a network. In the case of video data, a key frame including picture information of actual video data is included. As a delta frame that contains motion information such as I frame and correlation between each key frame, it is divided into P and B frames, and each frame is compressed in both directions so that data can be aligned. have.

Meanwhile, in the case of MPEG 1, one key frame is generated every second, and in the case of MPEG 4, one key frame is generated every 4 to 5 seconds. As shown in FIG. Video data can be generated and transmitted in packet units. Typically, 20 to 30 frames of I, P, and B frame data per packet can be included as payload data, and one pay The load is automatically sized via the TCP protocol, but when one packet size exceeds the standard of the packet size specified by the protocol, it is divided into several payloads and transmitted.

MPEG video data transmitted in the form of a packet through a network can be transmitted by preserving the data sorting order in the order of I, P, and B frames, which are reference criteria for video compression. If the frame is not normally received by the client on the data receiving side, the P and B frames as delta frames associated with the I frame also cause significant data loss, resulting in deterioration in image quality of the overall video reproduction.

Also, in the state of transmitting a frame of video data in the form of a packet through a network, as shown in FIG. 2, if a frame loss occurs for a specific telta frame in the packet, a telta frame and a key frame subsequently transmitted thereafter. As a result of the loss of correlation, the use of subsequent telta frames becomes impossible, and since the normal reproduction of key frames becomes difficult, there is a problem that image quality deteriorates in video playback.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a video data transmission control system on a network for minimizing deterioration of video quality due to loss of delta frames of video data transmitted through a network, and To provide a way.

It is another object of the present invention to provide video quality by not transmitting delta frames between the following key frames unless transmission due to the loss of a delta frame is made within a valid time based on a key frame of video data transmitted through a network. The present invention provides a video data transmission control system and a method for minimizing degradation.

It is still another object of the present invention to provide a video data transmission control system and a method for generating and transmitting individual frames of a video in a separate packet form for measuring effective transmission time of video frames and for selective transmission.

In order to achieve the above object, according to the system of the present invention, a key frame and a delta frame of a compressed video stream are transmitted through a multimedia communication network in the form of a packet, and according to whether a specific delta frame is lost due to a packet response. Receiving a server that controls the transmission of the key frame only after stopping the transmission of the delta frame, and receives the packet of the key frame and delta frame according to the compressed video stream from the server, and transmits a response signal for the result of receiving each packet It provides a video data transmission control system on a network, characterized in that configured as a client.

In order to achieve the above object, according to the method of the present invention, transmitting a key frame and a delta frame of the compressed video stream to the client in the form of a packet in the server, and transmitting a response signal according to the reception of the video packet in the client Determining whether the delta frame is validly transmitted based on a response signal received from the client at the server, and when a specific delta frame is not effectively transmitted, stopping transmission of a next delta frame and transmitting state of only a key frame. It provides a video data adjusting method on the network, characterized in that consisting of the step of determining.

Hereinafter, the present invention configured as described above will be described in detail with reference to the accompanying drawings.

That is, FIG. 3 is a diagram illustrating a state in which each video frame is individually packetized according to a video data adjusting method on a network according to the present invention.

As shown in FIG. 3, in the embodiment of the present invention, key frames (I frames) and telta frames (P, B frames) of MPEG data are generated as separate packets, respectively, and are used to transmit I, P, and B frames as moving image data. Frames can be transmitted over the network in sequence.

That is, one frame of MPEG video data consists of one packet, and each packet includes header information, payload parsing information, and payload data. The payload stream number of each packet includes an audio number, a key frame, or a telta. Frame classification information and presentation time are included.

The presentation time included in the header information of the key frame packet is used as a criterion for calculating a transmission valid time of a subsequently transmitted telta frame packet, and a subsequent telta frame according to whether or not a telta frame is transmitted within this transmission valid time. The normal transmission of the key frame or the subsequent stop of transmission of the telta frame and the transmission state of only the key frame are determined.

On the other hand, the server for transmitting the MPEG video data to the client side determines the transmission end time as the transmission effective time of the frame to determine whether the effective transmission of each frame, the calculation formula for the transmission dead time is As shown in 1.

Transmission end time = (presentation time-buffering time) + transmission start time

Next, Figure 4 is a diagram showing the configuration of the video data transmission control system on the network according to the present invention.

As shown in FIG. 4, the video data transmission control system according to the present invention includes a server 100 and a client 200, and the server 100 includes a video receiver 10 and a video encoder 15. And a frame alignment unit 20, a stream buffer 25, a packet generator 30, and a packet transfer control unit 35.

In addition, the client 200 includes a packet reception control unit 50, a stream buffer 65, a frame recovery unit 70, a video decoding unit 75, a video playback unit 80, and a network transmission unit 85. It is configured to include.

In the server 100, the video receiving unit 10 receives a video data stream of MPEG format generated from a separate multimedia server (preferably Window Media Server).

The video encoding unit 15 encodes the MPEG video stream received through the video receiving unit 10 and divides the MPEG video stream into I frames as key frames and P and B frames as telta frames. ) Is to arrange the video frame encoded by the video encoding unit 15 divided by the frame for each transmission time, which is to be aligned according to the transmission end time of each frame calculated by Equation (1).

The stream buffer 25 buffers the encoded video frame by arranging queues according to the order arranged by transmission time by the frame aligning unit 20, and the packet generator 30 stores the stream buffer ( Video frame of key frame and telta frame through 25) is packetized into separate packets.

The packet transmission control unit 35 transmits the packet data of a video frame individually packetized through the packet generation unit 30 to the client through a multimedia communication network such as the Internet, and for each packet, the client 200. Depending on whether or not the packet of the delta frame is normally transmitted within the transmission deadline for the key frame by the acknowledgment (ACK) signal received from the), the transmission continuation of the delta frame or stop transmission.

Here, the packet transmission control unit 35 transmits each frame packet to the client 200 through a multimedia communication network in a TCP / IP or UDP environment according to the arrangement order of the frames determined by the frame alignment unit 20. And a response receiver 45 for receiving a response signal transmitted for each packet from the client 200 as a result of the transmission of the frame packet.

The packet transmission control unit 35 is based on the transmission end time calculated in consideration of the transmission start time at which the packet is transmitted from the packet transmitter 40, the presentation time included in the key frame packet, and the buffering time at the receiving side. It is determined whether or not the Telta frame packet is normally received by the response signal received by the response receiving unit 45. If the delta frame is normally transmitted within the transmission deadline after the previous key frame packet is transmitted, the subsequent Telta frame Normally send packets and key frame packets sequentially.

On the other hand, if the telta frame after the key frame is not effectively transmitted within the transmission deadline, the packet transmission controller 35 determines that the telta frame is lost and stops transmission of the telta frame afterwards. Then, the next keyframe and delta frames are transmitted.

In the client 200, the packet reception control unit 50 may include a packet reception unit 55 that receives a frame packet from the packet transmission control unit 35 of the server 100 through a multimedia communication network; The packet receiver 55 includes a response transmitter 60 for transmitting a response signal to the server 100 each time a packet is received by the packet receiver 55.

The stream buffer 65 sequentially buffers the key frame packet and the telta frame packet received through the packet receiver 55 of the packet reception controller 50, and the frame recovery unit 70 stores the stream buffer ( Each frame packet through 65) is used to recover the frame data into a key frame and a telta frame.

The video decoding unit 75 decodes the frame-restored key frame and telta frame in the form of video stream data capable of network transmission and playback, and the video playback unit 80 decodes the decoded video stream data. The video signal is processed to be reproduced through a monitor screen provided in the corresponding client 200.

The network transmission unit 85 transmits the video stream data decoded through the video decoding unit 75 to a specific local client through the network so that the client 200 can be applied as a relay client.

On the other hand, the server 100 and the client 200, as shown in Figure 5, after the key frame packet is transmitted, the specific Telta frame packet is lost in the state of transmitting the Telta frame packet, the transmission deadline time has elapsed If the response signal for the packet is not received, the next key frame packet to be transmitted before the next key frame packet is stopped, and the next key frame packet can be transmitted to the client 200.

Next, the operation of the present invention made as described above will be described in detail with reference to the flowchart of FIG. 6.

First, the video receiving unit 10 of the server 100 receives MPEG video stream data from a separate media server (step S10), and the video encoding unit 15 encodes the received video stream data to a key frame. The division is made in the form of a delta frame (step S11).

In this state, the frame arranging unit 20 of the server 100 performs a process of sequentially arranging the moving picture frames for each transmission time (step S12), and the packet generating unit 30 performs the stream buffer 25. Packet is separately packetized for each frame (step S13).

The packet transmission controller 35 of the server 100 transmits the video packet packetized for each frame to the client 200 through the multimedia communication network through the packet transmitter 40 (step S14). The packet reception control unit 50 of 200 receives the frame packet from the server 100 through the packet reception unit 55 (step S15).

Here, the packet reception control unit 50 of the client 200 transmits a response signal through the response transmitter 60 whenever a key frame packet or a delta frame packet is received through the packet receiver 55 (step) In operation S16, the response receiving unit 45 of the server 35 may receive the response signal transmitted from the client 200 to determine whether the frame packet transmitted is normally received within the transmission deadline (step S17). ).

On the other hand, the packet transmission control unit 35 of the server 100 determines whether or not a subsequent delta frame packet has been transmitted within the transmission deadline time after the key frame packet has been transmitted (step S18).

As a result of the determination, if it is determined that each delta frame packet is effectively transmitted within the transmission deadline time, the packet transmission control unit 35 repeatedly executes the process of step S17 from step S13 to the next delta frame packet and the next key frame. Packet transmission will be executed normally.

However, if it is determined that the transmission deadline for the specific delta frame packet is exceeded according to the determination result of step S18, the transmission of the next delta frame packet is stopped and only the next key frame packet is transmitted (step s19).

In this state, the client 200 receives the video packet received through the packet receiving unit 55 and passes through the stream buffer 65 through the frame restoring unit 70 to restore the frame in the form of a frame (step S20). The video decoding unit 75 decodes each video frame reconstructed by the frame reconstructing unit 70 and converts the video frames to the original video stream form (step S21).

At this time, the client 200 processes the video stream in the video playback unit 80 so that the video stream can be played through the monitor, or transmits the video stream to the desired local side through the network transmission unit 85. (Step S22).

Next, the server 100 determines whether the transmission of the video stream is terminated (step S23), and when it is determined that the transmission of the video stream is ended, the packet transmission control unit 35 The transmission of the video packet through the network is terminated (step S24).

On the other hand, the present invention is not limited to the above-described typical preferred embodiments, but can be carried out in various ways without departing from the gist of the present invention, various modifications, alterations, substitutions or additions are common in the art Those who have knowledge will easily understand. If the implementation by such improvement, change, replacement or addition falls within the scope of the appended claims, the technical idea should also be regarded as belonging to the present invention.

As described above, when the server transmits the MPEG video stream to the client through the network, the server generates and transmits the video frames of the key frame and the delta frame as separate packets, respectively, By determining whether the delta frame is transmitted within the transmission deadline based on the duration and presentation time, if the delta frame cannot be transmitted normally even after exceeding the transmission deadline, transmission for the delta frame between the next key frame is performed. By making it possible to stop, it is possible to minimize the deterioration of video quality due to the loss of delta frames generated during network transmission of the MPEG video stream.

Claims (14)

The key frame and the delta frame of the compressed video stream are generated in the form of individual packets and transmitted through the multimedia communication network, and the key frame only after the transmission of the next delta frame is stopped depending on whether the specific delta frame is lost by the packet response. The server that controls the transfer, And a client configured to receive a packet of a key frame and a delta frame according to the compressed video stream from the server, and transmit a response signal to the server in response to the reception result of each packet. The method of claim 1, And the compressed video stream is a video stream to which a compression algorithm of a moving picture expert group (MPEG) format is applied. delete The method of claim 1, The packet includes a packet number, header information including key frame or telta frame identification information, transmission time, duration, and presentation time, and a page including a key frame or delta frame of one frame. Video data transmission control system on the network, characterized in that configured to include the load information. The method of claim 1, The server, the video receiving unit for receiving a compressed video stream from a separate media server, A video encoding unit encoding the compressed video stream and dividing the compressed video stream into video frames of a key frame and a delta frame; A frame aligning unit for sorting the key frame and the delta frame by transmission time; A buffer that buffers the video frames arranged by the transmission time by alignment of a queue; A packet generator for generating the key frame and the delta frame as individual packets, The key frame packet and the delta frame packet are sequentially transmitted to the client in a sorted order according to the transmission time, and whether a specific delta frame packet is valid even after passing a preset transmission deadline through a response signal received from the client. And a packet transmission control unit which determines to stop transmission of the next delta frame and to transmit only a key frame when the specific delta frame packet is not valid. delete The method of claim 5, The transmission deadline is Transmission end time = (presentation time-buffering time) + transmission start time Video data transmission control system on a network, characterized in that determined by the relationship of. The method of claim 5, The client receives a key frame packet and a delta frame packet from the server, the packet reception control unit for transmitting a response signal according to the reception of each packet to the server; A buffer for buffering the received video frame packet; A frame restoring unit for restoring the key frame packet and the delta frame packet to a video frame; A video decoding unit for decoding the video frame and converting the video frame into a video stream; And a video output unit configured to output the compressed video stream for playback or to transmit it locally for transmission over a network. A first step of generating, by the server, a key frame and a delta frame of the compressed video stream in the form of individual packets and transmitting them to the client; A second step of transmitting, by the client, a response signal according to the reception of a video packet; A third step of determining whether a specific delta frame is validly transmitted within a preset transmission deadline based on a response signal received from a client at the server; And a fourth step of determining whether to stop transmission of the next delta frame and to transmit only a key frame when the specific delta frame is not effectively transmitted. The method of claim 9, The first step is to apply a compression algorithm in the MPEG format to the compressed video stream, characterized in that the video data on the network. delete The method of claim 9, The first step includes receiving a compressed video stream from a separate media server; Encoding and compressing the compressed video stream into video frames of key frames and delta frames; Buffering the key frame and the delta frame by sorting the transmission time; Generating the key frame and the delta frame into separate packets, And sequentially transmitting the key frame packet and the delta frame packet to the client in the order arranged according to the transmission time. delete The method of claim 12, The transmission deadline is [0027] Method of controlling moving picture data on a network, characterized in that it is determined by a relation of transmission end time = (presentation time of key frame-buffering time) + transmission start time.]

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