KR20050084698A - Multi video compressing method and video stream server system - Google Patents

Abstract

The present invention relates to a multiple video compression method and a video stream server system for accessors with different network bandwidths, and more particularly, to a multiple video compression method and a transmission method for clients having different resolutions or limited network bandwidths. .

According to the present invention, the video recording means; Video acquisition means for reading the captured video data; Video compression means for compressing the read video data to have different multiple resolutions using a video compression encoding scheme; Moving picture compression control means for controlling a compression command of the moving picture compression means; And a stream server means for simultaneously transmitting the compressed video data having the multi-resolution to a client to which at least two are connected through a network interface.

Therefore, the present invention can transmit high-definition / high-definition video data for clients without limitations in network bandwidth or playback resolution while compressing and transmitting it in a format for accessors with limited network conditions or playback resolution.

Description

Multi video compressing method and video stream server system for users with different network bandwidths

The present invention relates to a multiple video compression method and a video stream server system for users with different network bandwidths. More specifically, the present invention relates to a multiple video compression scheme and a transmission scheme for clients having different resolutions or limited network bandwidths.

With the development of the Internet, video stream servers have been installed on the Internet, and remote conditions, traffic conditions, and children's conditions in kindergartens / nursery centers can be checked through the Internet. This is possible because a video server is installed on the Internet and users can connect to the server and receive images there. Such a video compression type video server has a higher compression rate than a general still image compression type video server.

This reduces the load on the network and increases its efficiency. Stream servers using this video compression method can be used by any client that can connect to the Internet-either using a personal computer or including the H.323 protocol or Session Initiation Protocol (SIP). If there is a stream server, a video phone or an application program capable of calling or a mobile terminal capable of receiving video and accessing the Internet (patent registration: 10-0394834), etc.-has become an environment in which video can be played back.

1 is a block diagram of a conventional H.263 video encoder.

As shown, the motion estimation and compensation unit 1 performs motion estimation and motion compensation using the input image and the previous image. The frame memory unit 2 of the motion predictor and compensator 1 stores a previous image, and the motion predictor 4 compares the stored previous image with a currently input input image to predict motion between frames. The compensator 3 compensates for the motion of the previous image stored in the frame memory 2 with the motion vector predicted by the motion predictor 4.

After the motion compensation process is completed, the signal is sent to the subtractor 5 to obtain a difference from the currently input image, and the DCT unit 6 performs the DCT transformation, and then the quantization unit 7 performs the quantization process. do. The inverse quantization unit 9 inverse quantizes the error signal output from the quantization unit 7, and the inverse DCT unit 10 inverses DCT the inverse quantized signal.

The adder 11 adds the output signal of the inverse DCT unit 10 and the motion compensation predicted signal to store the current frame information in the frame memory unit 2 for the next frame encoding. The bit rate controller 12 controls the operation of the quantizer 7 according to the length of the bit string output from the variable length encoder 8, and the variable length encoder 8 receives the quantized signal from the quantizer 7. The variable-length encoding is performed on a bit string to output the encoding of one frame.

2 to 4 is a method of compressing the image data input through the camera by the video compression coding method described above and transmitting to the client connected to the video stream server 100 via a network wherever the Internet is available. It is an embodiment of a system that can be connected to such a system (computer 200, video phone 300, mobile terminal 400) to watch a video. In this case, the video stream server 100 includes a moving picture compressor 101, a network interface (I / F) 102, and a network 103.

3 is a system including a H.323 or SIP protocol 103 capable of video communication and accessing a server by protocol definition using an H.323 / SIP compatible video telephone 300 or an application program to view a video. For example, FIG. 4 is a structure of a remote monitoring system using a mobile terminal 400 (eg, IMT-2000) capable of internet access and video reception and playback. The mobile terminal 400 capable of accessing the Internet connects to the video stream server 100 remotely installed by using the wireless internet relay server 500 that allows access to the Internet based on the wireless Internet protocol.

5 simply illustrates a relationship between a general video stream server 100 and a client. As shown in the drawing, the stream server 100 generally receives a plurality of clients connected to and receives video data from the stream server 100. Each client and server can be connected to different paths due to the parallelism characteristic of Ethernet network. Each transmission rate is different due to the differences in the individually used bandwidths.

As described above, the existing video compressor 101 used in the video stream server 100 has a structure of compressing at one resolution set as shown in FIG. 1 and transmitting the same to the client. In the example of FIGS. The video stream server 100 transmits the data encoded at a fixed resolution to all the clients connected according to which client is connected.

For example, a client (eg, mobile terminal 400) whose maximum playback resolution is smaller than the resolution currently encoded may not be connected to a system currently encoded with a large resolution and transmitted to a client (eg, PC 200). . In this case, this problem can be solved by transmitting the encoding to the client having the lowest reproducible resolution. However, in this case, the problem that the available resolution is limited to the resolution available in the client having the smallest playback resolution occurs.

Eventually, there is only one type of client that can connect to a video stream server to monitor a surveillance site-the second embodiment (see Fig. 3) is a client computer, the third embodiment is an H.323 / SIP compatible videophone, Embodiment 4 (see FIG. 5) has the disadvantage that the mobile terminal is limited.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a multiple video compression method and a video stream server system for accessors of clients having different resolutions or limited network bandwidths.

As the technical idea for achieving the above object of the present invention

Video recording means;

Video acquisition means for reading the captured video data;

Video compression means for compressing the read video data to have different multiple resolutions using a video compression encoding scheme;

Moving picture compression control means for controlling a compression command of the moving picture compression means; And

And stream server means for simultaneously transmitting the compressed video data having the multi-resolution to a client to which at least two are connected through a network interface.

In addition, the present invention provides a video compression and transmission method for accessors of clients having different network bandwidths based on the video stream server system,

A first step of connecting a client having a different network bandwidth to a video stream server through a network interface;

Requesting transmission of compressed video data at a resolution executable at a network bandwidth used by the client;

A third step of checking whether the requested compressed image data is in the form of a PPF or SPF frame;

A fourth step of checking whether the SPF frame data exists in the frame buffer when the SPF frame data is requested as a result of the third step;

A fifth step of finding SPF frame data to be transmitted if there is frame data of the SPF as a result of the fourth step;

And a sixth step of returning the next SPF frame data of the previously transmitted SPF frame data when the SPF frame data to be transmitted is previously transmitted and the next SPF frame data is transmitted as a result of the fifth step. It provides a video compression method.

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the embodiment of the present invention will be described in detail.

6 is a block diagram of a video stream server according to the present invention. The video stream server 100 includes a camera 201, an image obtainer 202, a multiple video compressor 203, a stream server 204, and a network interface. 205, the video compression control unit 206.

The present invention provides a method of generating data compressed at two resolutions with one encoder and a video stream server that can simultaneously transmit to two clients having different resolutions.

In order to implement this, FIG. 7 shows a block configuration of the multi video compressor, FIG. 8 shows an output example of the multi video compressor, and FIG. 9 shows a detailed configuration of a stream server transmitting the data to the client using the data. It was.

For example, when the image is transmitted to clients having different resolutions, the output of the multi-video compressor 203 is shown in FIG. 8. Such video data is stored in order in the frame buffer 204b of the stream server 204. The frame buffer controller 204c is configured with a primary picture format (hereinafter referred to as PPF) currently set in the system as shown in FIG. The frame buffer is managed as divided by the resolution and the resolution to be transmitted to another accessor (Secondary Picture Format, hereinafter referred to as SPF). When a request of the data transmission / reception unit 205a of the network interface 205 is requested, It will transmit data.

At this time, in order to simultaneously transmit video data to different accessors with different playback resolutions, the video at the time of compression by one video compressor should be compressed to another resolution.

The method is shown in FIG. 7 and its features can be seen in the structure of the motion prediction and compensation unit 1.

The motion prediction and compensator 1 includes first and second frame memory units 2 (2a) storing previous image data used when compressing an image with a PPF and previous image data used when compressing an image with an SPF, respectively. )Wow; First and second motion predictors (4) (4a) for predicting motion between frames by comparing the stored previous image data with current input image data; And first and second motion compensators 3 and 3a for compensating for the motion of previous image data stored in the first and second frame memory units 2 and 2a, respectively, using the predicted motion vectors. .

At this time, if the multi-stream video compression command is not transmitted from the stream server 204 through the video compression control unit 206, the video compression is performed by the PPF using the data of the first frame memory unit 2.

If a multi-video compression command is delivered, when the video compression of the current frame is completed, the compression related variables (MB (Macro Block), GOB number, MV (Motion Vector), etc.) are backed up. In step 202, the size of the input image is adjusted, and the multi-video compressor 203 is changed to a variable related to the SPF compression. The output bit stream is generated by performing motion prediction and compensation using the second frame memory unit 2a. The second frame memory unit 2a is updated, the related variables are backed up, and the original PPF compression is returned to compress the original PPF.

Looking at the operation of the video stream server according to the present invention.

If a client having a playback resolution different from that set in the current system or a client whose network bandwidth is limited is connected, the frame buffer of the stream server 204 in the data transceiver 205a of the network interface 205 shown in FIG. 9 is connected. The controller 204c makes a request for the image data compressed to the resolution available in the network bandwidth used by the client or the resolution used by the client. The operation of the frame buffer controller 204c for the transmission data request from the data transceiver 205a is shown in FIG.

The frame buffer controller 204c checks whether the requested data is PPF or SPF, and when the PPF is PPF, finds the data to be transmitted in the frame buffer and returns the corresponding frame data.

However, if the SPF is requested by the data transmission / reception unit 205a, it is checked whether the frame data of the SPF exists in the frame buffer. When the frame data of the SPF exists, the frame data to be transmitted is found among the data of the SPF frame buffer. In case of transmitting to the next frame data, the next frame data of the previously transmitted frame data may be returned.

At this time, if the first data is to be transmitted from the INTRA frame, and if there is INTRA frame data to check if there is transmitted from the frame data, if not, request to compress the INTRA frame using the video compression control unit 206 When the frame data enters the buffer, the data is returned.

If there is no frame data of the SPF in the frame buffer, the moving image compression control unit 206 transmits a command to generate the compressed data of the SPF to the image acquirer 202 and the multiple moving image compressor 203. The multi-video compressor 203 receiving the command generates the SPF compressed data in the manner described above and delivers the compressed data to the compressed data controller 204a. The compressed data controller 204a stores the compressed data of the SPF of one frame in the frame buffer. The frame buffer control unit 204c returns this data.

Therefore, the video stream server operates as a general video stream server before requesting SPF data from the data transmitting / receiving unit 205a, and a client having a playback resolution different from that set in the client or system having a limited network bandwidth. In the special situation of access, it operates as a stream server using multiple video compression methods according to the client's situation.

As described above, in the related art, a client (eg, using a dial-up network) having a limitation of a playback resolution or a network bandwidth (eg, using a dial-up network) is connected to a stream server to receive and play an image. There was a problem that the video format for this client had to be fixed or the amount of data to be transmitted had to be limited.

However, when using the multiple video compressor and the stream server structure using the compressor as in the present invention, it is possible to transmit the high resolution / high definition image data (PPF) to the client without limitations in the network bandwidth or playback resolution, while simultaneously It can be compressed and transmitted in a format for accessors with limited resolution, so it is not restricted by the connected device.

1 is a block diagram of a conventional H.263 video encoder.

2 to 4 are configuration diagrams of a video stream server system connected to a client through a network according to a conventional embodiment.

5 is a configuration diagram of a video stream server system connected to a plurality of clients through a network according to a conventional embodiment.

6 is a configuration diagram of a video stream server system according to the present invention.

7 is a block diagram of an H.263 video encoder according to the present invention.

8 is a diagram illustrating an output example of a multiple video compressor according to the present invention.

9 is a detailed configuration diagram of a stream server according to the present invention.

10 is a flowchart illustrating a process of compressing and transmitting multiple videos in a stream server according to the present invention.

Claims (8)

Video recording means; Video acquisition means for reading the captured video data; Video compression means for compressing the read video data to have different multiple resolutions using a video compression encoding scheme; Moving picture compression control means for controlling a compression command of the moving picture compression means; And And stream server means for simultaneously transmitting the compressed video data having the multi-resolution to a client to which at least two are connected via a network interface. The video stream server system according to claim 1, wherein the client includes a computer (PC), a video telephone, and a mobile communication terminal having limited playback resolution or limited network bandwidth. The method of claim 1, wherein the video compression means First and second frame storage units which store previous image data used when compressing an image with PPF and previous image data used when compressing with SPF; First and second motion predictors for comparing the stored previous image data with current input image data to predict movement between frames; And The video stream server further comprises a motion prediction and compensation unit having first and second motion compensators for compensating for motion of previous image data stored in the first and second frame storage units using the predicted motion vectors, respectively. system. The method according to claim 1 or 2, wherein in the stream server means The apparatus further includes a frame buffer unit configured to divide and manage the resolution (PPF) currently set in the system and the resolution (SPF) to be transmitted to another client, depending on the type of client in case of a request for data transmission and reception through a network interface. The video stream server system, characterized in that for transmitting the data of the frame buffer. In the video compression method for the clients of different network bandwidth on the video stream server system, A first step of connecting a client having a different network bandwidth to a video stream server through a network interface; Requesting transmission of compressed video data at a resolution executable at a network bandwidth used by the client; A third step of checking whether the requested compressed image data is in the form of a PPF or SPF frame; A fourth step of checking whether the SPF frame data exists in the frame buffer when the SPF frame data is requested as a result of the third step; A fifth step of finding SPF frame data to be transmitted if there is frame data of the SPF as a result of the fourth step; And a sixth step of returning the next SPF frame data of the previously transmitted SPF frame data when the SPF frame data to be transmitted is previously transmitted and the next SPF frame data is transmitted as a result of the fifth step. How to compress video. The video compression method according to claim 5, wherein when the compressed video data requested in the third step is PPF frame data, the frame buffer finds data to be currently transmitted and returns the corresponding frame data. The video compression method of claim 5, wherein when the frame data of the SPF does not exist in the frame buffer in the fourth step, the SPF compression data is generated, stored in the frame buffer, and returned. The method of claim 5, further comprising: checking whether the INTRA frame data exists when the first SPF frame data to be transmitted in the fifth step is transmitted; And if the INTRA frame data does not exist, compressing the data into an INTRA frame, and returning the INTRA frame data when the compressed INTRA frame data enters the frame buffer.