KR19990016892A - How to control fast mode of VAudio system - Google Patents

Abstract

The present invention relates to a fast mode control method of a VOD system for performing an effective fast mode by transmitting only I frame data in which a rewind and fast forward mode are performed by a user's request in a VOD system. In the first step of checking the input of the high speed mode signal during the operation, when the high speed mode signal is input, a high speed request message for executing the high speed mode is generated, transmitted to the server, and the VOD system is switched to the high speed mode. A second step, in response to the transmitted fast request message, extracting only I frames included in each frame sequence based on frame header information, and transmitting the extracted I frames to the VOD system; A fourth sequence of sequentially decoding the I frames and displaying them on the monitor System and at the same time as the normal playback key signal is transmitted by generating a normal request message corresponding to the server when the input includes a fifth step of switching from the VOD system, the high-speed mode to the normal playback mode.

Description

How to control fast mode of VAudio system

The present invention relates to a video on demand (VOD) system, and more particularly, to a method of controlling fast forward mode and rewind mode performance of a VOD system. .

As is well known, on-demand video is Movies On Demand (NOD), News On Demand (NOD), which provides instant access to information by title or area of news, and provides services such as news summaries or headlines. Remote shopping, X-ray image transmission, and storage or analysis processing of data transmitted by end users to provide video services in the form of video catalogs or user showcases to purchase desired products. Telemedicine, games, home banking, video conferencing, and other services that provide general banking services, providing information to users and providing information to other end users. Agreement services that provide services that allow you to trade with information, Internet access for access to the Internet Provide services.

In such a general VOD system, the MPEG bit stream format (MPEG-I (Moving Picture Experts Group-I) bit stream format) is used to transmit data. In general, the bit stream is an I-frame. It consists of three frames: P frame (Predicted-frame) and B frame (Bidirectionally-predicted-frame).

Herein, the P frame is encoded by referring to an I frame or a previous frame, and the B frame is encoded by referring to a previous and subsequent I frame or a P frame in both directions.

In other words, the server transmits data in the order of I1, B1, B2, P1, B3, B4, P2, B5, B6, B7, P3, B8, B9, I2, ... The decoded data in the order of I1, P1, B1, B2, P2, B3, B4, P3, B5, B6, B7, I2, B8, B9, ... and back to the original order, that is, I1, B1 , B2, P1, B3, B4, P2, B5, B6, B7, P3, B8, B9, I2, ... will be displayed on the screen.

In the VOD system, when the user performs a rewind mode to search for a specific part previously viewed and watch again while viewing the displayed screen, the server side displays the data based on the time when the rewind signal is generated. Will be sent in reverse order.

For example, while data is transmitted in the order of I1, B1, B2, P1, B3, B4, P2, B5, B6, B7, P3, B8, B9, I2, ... as described above, When a rewind signal is generated from the receiving side and transmitted to the server, the server transmits data in the order of B9, B8, P3, B7, B6, B5, P2, B4, B3, P1, B2, B1, and I1. .

In this case, in order to decode each frame data into the original signal before encoding, the receiving side must decode the first I frame of each transmitted P and B frame data before decoding the frame data. The B frame can be decoded and displayed.

In other words, even if data is transmitted in the order of B9, B8, P3, B7, B6, B5, P2, B4, B3, P1, B2, B1, I1 from the server based on the rewind signal, I1, P1, P2. Since the I1 frame data must be decoded first, such as in the order of P3, B9, B8, B7 B6, ..., delay occurs according to the data, which is transmitted before the I1 frame data, that is, B9, B8 There is a problem that the size of the memory for temporarily storing the P3, B7, B6, B5, P2, B4, B3, P1, B2, B1 increases.

In addition, since the decoded data must be displayed again in the order in which they were transmitted as described above, after the B9 frame data is decoded, a corresponding screen is displayed on the monitor in response to the user's rewind signal, so that other delays are similarly produced. There is a problem that a memory area for temporarily storing each frame data, i.e., I1, P1, P2, and P3, which is generated prior to B9 frame data, must be secured.

In addition, when the user performs the fast forward mode to search for a specific part while watching the screen displayed by the user in the above-described VOD system, the server side refers to the point at which the fast forward signal is generated. This increases the data transfer rate.

Therefore, the amount of data transmitted through the network is also increased, thereby increasing the burden on the network, and the decoder at the receiving side also needs to process more data in a unit time, thereby causing an overload of the system.

Accordingly, the present invention is to solve the above-described problems of the prior art, it is possible to perform a stable high-speed mode using only the I frame that can be independently decoded regardless of the front and rear frame when performing the fast forward or fast backward mode of the VOD system The purpose is to provide a fast mode execution method of the VOD system.

In accordance with an aspect of the present invention, there is provided a video signal having a frame sequence including a plurality of predetermined I, B, and P frames at a predetermined frame rate from a server, and reconstructs the original signal before encoding. A method of controlling a high speed mode in a VOD system for displaying on a monitor, comprising: a first step of checking input of the high speed mode signal during execution of a regeneration mode of the VOD system; A second step of generating a fast request message for execution and transmitting it to the server and simultaneously switching the VOD system to a fast mode; and in response to the transmitted fast request message, each frame string is included in each frame sequence based on frame header information. A third step of extracting only I frames and transmitting to the VOD system, the number according to the switched fast mode A fourth step of successively decoding new I frames and displaying them on the monitor; and generating a normal request message corresponding to the normal playback key signal and transmitting the same to the server. The present invention provides a fast mode control method of a VOD system comprising a fifth step of switching to a normal play mode.

1 is a block diagram illustrating a configuration of a VOD system suitable for applying a fast mode execution method of a VOD system according to an exemplary embodiment of the present invention;

2 is a flowchart illustrating a fast mode control process of a VOD system according to an exemplary embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

100: control unit 210: NIU

220: MPEG decoder 230: graphics control unit

240: key input unit 250: CPU

The above and other objects and various advantages of the present invention will become more apparent from the preferred embodiments of the present invention described below with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a configuration of a VOD system suitable for applying a fast mode execution method of a VOD system according to an exemplary embodiment of the present invention. The server 100, the NIU 210, and the MPEG decoder ( And a VOD set-top 200 configured as a graphic controller 230, a key input unit 240, and a CPU 250.

The server 100 manages a plurality of VOD service subscribers connected through a network and provides various data corresponding to the needs of each subscriber to the VOD set-top 200, and the VOD set-top 200 is provided to each subscriber. The various data provided from the server 100 through the network are displayed on the screen through a predetermined signal processing process.

In detail, the NIU 210 provided on the VOD set-top 200 side provides a transmission / reception interface for various types of information from the server 100 connected through a network under the control of the CPU 250, and the CPU 250. The various request signals provided by the server are provided to the server through the network.

The MPEG decoder 220 decodes the image information provided from the server 100 through the NIU 210, that is, the MPEG data into a predetermined form under the control of the CPU 250, and provides the decoded image to the graphic controller 230. The controller 230 displays the decoded video signal on a monitor not shown.

The CPU 250 controls the overall operation of the VOD set-top 200 by generating a control signal corresponding to the various key signals provided from the key input unit 240, in particular, a high speed mode (REW or FF) key signal. When is input, a control signal for switching the decoding process is generated and provided to the MPEG decoder 220.

And, the key input unit 240 is composed of key metrics on the remote control or its own panel to generate a corresponding key signal by the user's operation.

Referring to the drawings in detail, when the I, P, B frame data for the information requested by the user from the server 100 is transmitted to the NIU 210 of the VOD set-top through a network, the NIU 210 is inputted. The video data is provided to the MPEG decoder 220 under the control of the CPU 250. The MPEG decoder 220 decodes each I, P, and B frame data through a decoding process in a predetermined order, and then controls the graphic controller. To 230.

The graphic controller 230 displays the decoded frame data on the screen in a predetermined order again under the control of the CPU 250.

When the image information is displayed on the screen as described above, if the user inputs a rewind (REW) signal through the key input unit 240 in order to view the screen already viewed by the user, the CPU 250 inputs the key signal. The corresponding request signal is generated and transmitted to the server 100 through the NIU 210.

In response to the rewind request signal transmitted from the VOD set-top 200, the server 100 transmits each frame data in reverse order at the current data position. In this case, the server 100 ignores the P frame and the B frame and I frame. Only data is transmitted.

That is, during the data transfer in the order of I1, B1, B2, P1, B3, B4, P2, B5, B6, B7, P3, B8, B9, I2, ..., the rewind request signal is When generated and transmitted from the VOD set-top 200, the server 200 ignores the P frame data and the B frame data in response to the rewind request signal and transmits only the I frame data in the order of I2, I1, ....

In addition, the VOD set-top 200 decodes I2, I1 .. frame data transmitted from the server 200 in the order of transmission through the MPEG decoder 220 and then displays it on the screen through the graphic control unit 230. A screen corresponding to the rewind request signal of is displayed on a monitor not shown.

That is, when a rewind signal is input from a user and a rewind operation of the VOD system is performed, the server 100 transmits only I frame data that can be independently decoded from each of the I, P, and B frame data, and the VOD set-top 200 By decoding only the transmitted I frame data, it is possible to prevent the delay caused by the decoding order of each frame data.

In addition, since the I frame data to be transmitted can be directly decoded, the storage area for temporarily storing the transmitted data can be reduced and minimized, and the memory area for temporarily storing the decoded data is also displayed by directly displaying the decoded I frame data. It can also be minimized.

While the rewinding screen is displayed through the above-described process, when the user searches for a desired screen and inputs a playback signal through the key input unit 240 at the corresponding position, the CPU 250 sends the playback request signal to the NIU. The server 210 transmits the data to the server 100 through 210.

In addition, the server 100 normally transmits the I, P, and B frame data again from the current data position in response to the reproduction request signal transmitted from the VOD set-top 200, and the VOD set-top 200 includes NIU ( Normal data transmitted through 210, that is, I, P, and B frame data are displayed on the screen after a predetermined signal processing process.

If the user inputs a fast forward (FF) key signal through the key input unit 240 to search for a specific part during the playback mode in which the image data is normally transmitted and displayed in the VOD system, the CPU 250 may enter a key. A fast forward request signal corresponding to the signal is generated and transmitted to the server 100 through the NIU 210.

When the fast forward request signal transmitted from the VOD set-top 200 is received, the control unit 110 of the server 100 extracts only I frame data of the next frame data to be transmitted from the current data position to the VOD set-top 200 side. Will be sent.

Therefore, the VOD set-top 200 decodes only I frame data transmitted from the server 200 through the MPEG decoder 220 and then displays it on the screen through the graphic controller 230, thereby corresponding to the fast forward request signal of the user. The screen is displayed on a monitor not shown.

When the high-speed forward screen is displayed through the above-described process, when the user searches for a desired screen and inputs a playback signal through the key input unit 240 at the corresponding position, the CPU 250 requests a playback. The signal is transmitted to the server 100 through the NIU 210, and the server 100 transmits the I, P, and B frame data normally from the current data position again in response to the reproduction request signal. The normal playback operation is executed.

Therefore, when the fast forward signal is input from the user and the fast forward operation of the VOD system is performed, the server 100 transmits only the I frame data that can be independently decoded from each of the I, P, and B frame data, thereby transmitting the network and the VOD. The overall overload of the system can be reduced.

On the other hand, when performing the rewind (REW) mode or the fast forward mode as described above, the degradation of the displayed screen may occur somewhat by transmitting and decoding only the I frame data of each frame image data, but the fast forward or rewind operation The main screen navigation does not have much influence, which can be ignored.

2 is a flowchart illustrating a high speed mode control process of a VOD system according to an exemplary embodiment of the present invention, which will be described in detail with reference to the accompanying drawings.

During normal playback in which the VOD set-top 200 connected to the server 100 through the network displays image data transmitted from the server 100 through a predetermined signal processing (step 201), the user searches for a specific section. When a rewind (REW) signal or a fast forward (FF) mode key signal is input (step 203), the server 100 stops the transmission of each frame data based on the transmitted request signal. The operation of 100 is switched to the rewind (REW) or fast forward (FF) mode (step 205).

Then, the header information of the previous frame data or the next frame data is read from the current data transmission position (step 207). That is, when the rewind (REW) signal is transmitted from the VOD set-top 200 side at the server 100 side, the header for the data at the previous position is read from the current data position, and the high-speed from the VOD set-top 200 side is read. When the forward (FF) signal is transmitted, it will read the header of the data at the next position from the current data position.

As a result of the reading in step 207 described above, if the read frame data is I frame data (step 209), the corresponding I frame data is transmitted, and the server 100 repeats step 207 as described above. Only when frame data is detected is transmitted to the VOD set-top 200 side (step 211).

Meanwhile, when each I frame data is transmitted to the VOD set-top 200 in response to the user's rewind (REW) or fast forward (FF) signal through the above-described step 209, the VOD set-top 200 is input to each input I. The frame data is decoded through a predetermined process (step 213), and then displayed on the screen through a predetermined signal processing process (step 215).

Through the above process, only I frame data of the corresponding position is displayed on the screen based on the user's rewind (REW) or fast forward (FF) signal, so that the overall operation of the VOD system is performed in the rewind (REW) or fast forward (FF) mode. If the normal playback key signal is input again by the user during the process (step 217), the VOD set-top 200 transmits the normal playback request signal to the server 100.

Then, the server 100 transmits all frame data including I, P, and B frames from the current data position in response to the settlement reproduction request signal, thereby switching the overall operation of the VOD system to the normal reproduction mode (step 219). .

Therefore, as described above, only the I frame data among the I, P, and B frame data is transmitted during the rewind (REW) or the fast forward (FF) mode, so that the memory capacity according to the data reception and the memory according to the decoding of the received data are reduced. Minimize capacity and avoid overloading the network.

On the other hand, when performing the rewind (REW) or fast forward (FF) mode as described above, by adjusting the ratio of the transmitted I frame, it is possible to adjust the performance of the rewind (REW) or fast forward (FF) mode .

That is, if the I frame data detected through the above-described steps 207 and 209 is counted and transmitted only once, the predetermined number n is set, a faster rewind (REW) or a fast forward (FF) is performed. Mode).

On the other hand, in the fast mode control method as described above, since only I frame data having a much larger amount of data than P and B frame data is transmitted, the amount of data transmitted during a unit time (for example, 1 second) is transmitted during normal reproduction. A much larger amount of data is transmitted than the amount of data that is made.

That is, I frame data and frame data composed of P frame data and B frame data having a small amount of data are transmitted to data transmitted from the server during normal playback for one second, but fast forward (FF) or rewind ( When performing REW), the same number of frame data consisting only of I frame data having a large amount of data is transmitted.

Therefore, when the high speed mode of the VOD system as described above may occur, the system may be overloaded due to an increase in the data rate. In view of this, when the frame rate is adjusted during the high speed mode of the VOD system, It is possible to perform the high speed mode of a more stable VOD system.

That is, in response to the fast mode key signal input to the VOD set-top 200, the frame data of the corresponding position is read, and only the I frame data are detected and transmitted, respectively, at a frame rate lower than that of the normal playback. The frame data is transmitted.

For example, if 30 frames of data are transmitted per second in the normal playback mode of the VOD system, each I frame data is set-top at a frame rate that transmits 15 frames of data per second in the high speed mode described above. It will be transmitted to (200).

In addition, the MPEG decoder 220 which receives and decodes I frame data according to performing the high speed mode converts the decoding rate of the I frame data into a rate corresponding to the frame rate of the server based on the control signal of the CPU 250. do.

As a result, when the high speed mode is performed in the VOD system, only the I frame data is transmitted and the frame rate of the transmitted I frame data is adjusted, so that the stable rewinding and the fast forward mode can be performed.

As described above, according to the present invention, when performing the fast forward or rewind mode for searching a specific section in the VOD system, only the I frame data of each I, P, and B frame data is transmitted and decoded, thereby providing a different delay and There is an effect to prevent the overload of the system including the network, and to minimize the memory area for temporarily storing the transmitted data and the memory area for temporarily storing the decoded data.

In addition, by adjusting the ratio of I frames transmitted when the fast forward or rewind mode is performed, a more stable fast forward or rewind mode can be performed.

Claims (3)

In the VOD system, a video signal having a frame sequence including a plurality of preset I, B, and P frames is provided from a server at a predetermined frame rate, restored to an original signal before encoding, and displayed on a monitor. In the method, A first step of checking input of the high speed mode signal while the play mode of the VOD system is executed; A second step of, when the high speed mode signal is input, generates a high speed request message for executing the high speed mode, transmits the high speed request message to the server, and switches the VOD system to the high speed mode; In response to the transmitted fast request message, extracting only I frames included in each frame sequence based on frame header information and transmitting the extracted I frames to the VOD system; A fourth step of sequentially decoding the received I frames according to the switched fast mode and displaying them on the monitor; And A high speed mode control of a VOD system comprising a fifth step of generating a normal request message corresponding to a normal play key signal and transmitting the same to the server and switching the VOD system from the fast mode to a normal play mode. Way. The method of claim 1, wherein when the fast mode is the fast reverse mode, the server reads and transmits I frame data existing at the closest previous position at the time when the fast request message occurs. When the fast mode is a fast forward mode, the high-speed mode control method of the audio system, characterized in that I read from the I frame data in the position after the closest point when the high-speed request message occurs. The method of claim 1, wherein the server transmits the I frame data at an updated frame rate that is at least lower than a frame rate during normal playback when the fast mode is performed.