KR20040058396A - A device and a method of transmitting video signal with real time controlled - Google Patents

Abstract

PURPOSE: An apparatus and a method for transmitting a video signal by controlling the same in real time are provided to decrease or increase a data transfer rate or the quantity of data by interworking with a bit transfer error generating environment, thereby improving the quality of a video signal. CONSTITUTION: A video encoder(100) encodes an input analog video signal into a digital video signal. A video signal control unit(110) encodes the video signal of the video encoder by a video code control signal and wireless channel information, and outputs the encoded video signal at a set transmission speed. A buffer(120) stores the signal applied from the video signal control unit. A multiplexer channel coding unit(130) multiplexes the signal of the buffer and an audio signal to output the multiplexed signals in coded bit to a transmission channel.

Description

Real-time control transmission device and method of video signal {A DEVICE AND A METHOD OF TRANSMITTING VIDEO SIGNAL WITH REAL TIME CONTROLLED}

The present invention is to control the data transmission amount of the transmitting side in real time according to the environment of the wireless channel in which the video signal is transmitted in a mobile communication system capable of video communication, so that the receiving side receives and maintains a video signal of stable image quality without deterioration.

The mobile communication system communicates with the other party anytime and anywhere while using a mobile terminal registered with a subscription. As a result of the continuous technological development, the line use and the equipment price become low, and the usage is increasing rapidly.

In the case of the communication with the image or the video added using the mobile communication system as described above, it is possible to improve the quality degradation problem in which the image quality received from the mobile terminal is damaged due to the quality problem of the wireless reception channel. Development of the method is necessary.

Hereinafter, a conventional video signal transmission method of a mobile communication system will be described with reference to the accompanying drawings.

Attached for describing the prior art, FIG. 1 is a functional configuration diagram of a transmission video signal processing unit of a mobile communication system according to the prior art.

Referring to FIG. 1, the transmission video signal processor of the conventional mobile communication system includes a video encoder 10 which receives and encodes a video signal captured by a video camera, and encodes the video signal.

An image signal controller 20 for controlling and outputting the signal of the video encoder 10 in a manner such as turbo coding or convolutional coding in consideration of image size and data transmission speed;

A buffer unit 30 temporarily storing and outputting a signal of the image signal controller 20;

The mux channel coding unit 40 is configured to add an audio signal AUDIO SIGNAL to the signal of the buffer unit 30 and output the coded bit.

Hereinafter, according to the prior art of the above configuration, it will be described in detail with reference to Figure 1 attached to the transmission video signal processing unit of the mobile communication system.

Various video signals applied from video cameras or still cameras, which use a general CCD (CHARGE COUPLED DEVICE) device to capture video, are encoded by a video encoder 10 into a predetermined digital video signal. (ENCODE) is output.

The signal output from the video encoder 10 is controlled by the image signal controller 20 to control conditions such as a frame size (PICTURE_SIZE), frame rate data (FRAME / SEC), data rate (DATA RATE), and the like. Signal, buffer status signal (B_OCC), video signal type control signal (VOP_TYPE), signal to control processing (regardless of or related to the previous frame) (INTRA / INTER), signal to control INTRA encoding at regular intervals (MB_REFRESH) The signal is controlled by a signal BUFFER_SIZE indicating the size of the video buffer, a signal CODED_NOTCODED for controlling video signal encoding, and the like, and is encoded and output.

The signal of the video signal controller 20 is temporarily stored in the buffer 30, and the signal of the buffer 30 is applied to the mux channel coding unit 40.

The mux channel coding unit 40 mucks the video signal or the video signal applied from the buffer 30 together with the audio level signal, and outputs the coded bit coded to the channel.

As described above, the conventional technique uses turbo coding or convolutional coding to channel-decode a picture quality degradation problem caused by a high bit error error (BER) of a transmitted video signal. CODING) adds an extra bit (REDUNDANCY BIT) to the bit stream (BIT STREAM) of the video signal.

The video encoder according to the prior art generates a bit stream (BIT STREAM) at a unilaterally determined channel data transmission rate without reflecting information on a quality level of a channel currently being used, and has a high BER or a bit instantaneously. If the BIT LOSS is large, the instantaneous deterioration of the image quality becomes large, and the normal control of the data rate becomes difficult.

That is, in the related art, when the BER is high or the bit loss is large, the bit error is detected and corrected, or when the bit error correction is impossible, the specific portion of the image screen is closed by the CONCEALMENT measure. By suture, there is a problem such as deterioration of image quality or instantaneous screen freeze as a manual follow-up to deal with a condition where data error has already occurred.

In addition, the prior art can control the quality of the radio channel, but less bit loss (BIT LOSS) is generated by the power control between the base station and the mobile terminal, it is assigned to the base station cell by the increase of the output power There is a problem that the channel capacity is instantaneously reduced and the interference occurs in the adjacent mobile terminals.

According to the present invention, a mobile communication system capable of video communication reflects the quality of a channel environment in which the video signal is transmitted, and transmits the transmission speed of the video signal in advance in real time by controlling the transmission, so that normal picture quality without deterioration is continued. It is an object of the present invention to provide an apparatus and method for maintaining the same.

In order to achieve the above object, the present invention provides a video encoder for encoding and outputting an input analog video signal into a digital video signal; A video signal controller which encodes a video signal of the video encoder by a video code control signal and wireless channel information and outputs the video signal at a set transmission rate; A buffer to store a signal applied from the image signal controller; The mux channel coding unit multiplexes the signal of the buffer and the voice level signal and outputs the coded bits to the transmission channel.

In addition, the present invention devised to achieve the above object, it is determined whether the bit error rate of the radio channel to which the video signal is transmitted is greater than the threshold value, and if it is larger than the threshold value to transmit the video signal in the intra mode Intra process; Determining whether the bit error rate of the radio channel is greater than a threshold value, and if the bit error rate is greater than the threshold value, reducing the number of video signal transmission frames; It is determined whether the bit error rate of the radio channel by the above process is larger than the threshold value, and when the bit error rate is larger than the threshold value, there is a downward process of reducing the coding speed by the image signal controller step by step.

1 is a functional configuration diagram of a conventional mobile communication system transmission video signal processor;

2 is a functional configuration diagram of a real-time video signal transmission apparatus according to the present invention;

3 is a flowchart illustrating a method of transmitting a real-time video signal according to the present invention.

** Explanation of symbols on the main parts of the drawing **

10,100: video encoder 20,110: video signal controller

30,120: buffer 40,130: mux channel coding unit

Hereinafter, an apparatus and method for transmitting a real-time video signal in a wireless environment of a video signal transmission mobile communication system according to the present invention will be described with reference to the accompanying drawings.

Attached to explain the present invention, Figure 2 is a functional block diagram of a real-time video signal transmission apparatus according to the present invention, Figure 3 is a flow chart of a real-time video signal transmission method according to the present invention.

Referring to FIG. 2, a real-time video signal transmission apparatus of a mobile communication system for transmitting a video signal in a wireless environment includes a video encoder 100 for encoding and outputting an analog video signal into a digital video signal;

The video signal of the video encoder 100 includes a frame unit size (PICTURE_SIZE) of the video signal, a data rate FRAME / SEC, a data rate DATA RATE, a buffer state signal B_OCC, and a video signal. Type control signal (VOP_TYPE), control signal (INTRA / INTER) for processing the previous frame or not, INTRA encoding control signal (MB_REFRESH) of constant period, signal indicating buffer size (BUFFER_SIZE), video signal encoding control signal ( CODED_NOTCODED) is encoded by bit error rate (BER), frame bit error rate (FER), bit error rate threshold, frame bit error rate threshold, and cycle time inputted through wireless channel information and output at the set transmission rate. The video signal controller 110,

A buffer 120 for storing and outputting a video signal applied from the video signal controller 110 under a corresponding control;

The mux channel coding unit 130 multiplexes the video signal VIDEO SIGNAL and the audio signal AUDIO SIGNAL of the buffer 120 and outputs the CODED coded to the transmission channel. .

Referring to FIG. 3, in the video signal real-time transmission method of a mobile communication system for transmitting a video signal according to a wireless environment, a bit error rate (BER) and a frame bit error rate (FER) of a wireless channel to which the video signal is transmitted are respectively corresponded. If it is greater than the threshold value (S10), and if the determination is larger than the threshold value (S10), the transmission of the video signal in the intra mode (INTRA MODE) that normally transmits the video signal in the frame (FRAME) unit wireless transmission (S20) intra process,

It is determined whether the bit error rate (BER) and the frame bit error rate (FER) of the radio channel by the intra process are larger than the corresponding threshold value (S30). FRAME) the frame process of reducing the number (S40) and transmitting,

It is determined whether the bit error rate and the frame bit error rate (FER) of the radio channel by the frame process are greater than the corresponding threshold value (S50). If the determination is greater than the threshold value (S50), the image signal controller 110 In step S60, if the encoding speed is reduced, the determination is made whether or not to wirelessly transmit the video signal. If the processing continues, the process returns to the intra process (S10).

Hereinafter, the present invention having the above configuration will be described in detail with reference to FIGS. 2 and 3.

The video encoder 100 converts an analog video signal from an image capturing apparatus using a CCD or the like into a digital video signal, and receives the digital video signal. Frame size of the video signal (PICTURE_SIZE), frame rate of data (F_RATE), data rate (D_RATE), buffer status signal (B_OCC), video signal type control signal (VOP_TYPE), previous frame INTRA / INTER to control the related INTER MODE or INTRA MODE to be processed irrespective of previous frame, signal to control INTRA encoding at regular intervals (MB_REFRESH), buffer to store the video signal The control signal according to the signal BUFFER_SIZE indicating the size of the signal, the video signal coding control signal CODED_NOTCODED, or the like is input, and there is no input from the corresponding receiver not shown in FIG. Bit error rate of the radio channel is input as channel information (BER), a frame bit error rate (FER), the threshold value of bit error rate, given the critical value of the frame bit error rate, cumulative to the BER and FER, and enter the cycle time value to determine.

The image signal control unit 110 is a bit error rate (BER) and a frame bit error rate (FER) of a radio channel input as radio channel information applied from a receiver not shown in FIG. 2, in particular by the control signal applied as described above. The video signal of a frame unit to be transmitted wirelessly is determined based on a bit error rate threshold value, a frame bit error rate threshold value, and a period time value, and stored in the buffer 120.

The video signal that is determined and output by the video signal controller 110 is measured according to radio environment information applied from a receiving side, that is, a value measured during a predetermined period (PERIOD) of BER and FER corresponds to a corresponding threshold value (THRESHOLD VALUE). In case of greater than), since the bit error (BIT ERROR) is large in the video signal to be transmitted wirelessly, the intra mode (INTRA MODE) for processing and transmitting the video signal in the frame unit is operated.

When transmitting in the intra mode as described above, when an error occurs in the video signal to be transmitted wirelessly, degradation occurs only in the video signal of the frame in which the error occurs, and does not affect the video signal of another frame.

In addition, when processing as described above and measuring the wireless environment again in real time to detect that the BER and FER values continue to be high, the video signal controller 110 decreases the number of video signals in units of frames transmitted per second.

For example, when a video signal of 15 frames per second is transmitted (15 FRAME / SEC), the number of frames to be damaged is relatively reduced by lowering the number transmitted per second to 10 or 5 frames.

Even in the real-time processing as described above, in a wireless environment in which errors continue to be transmitted to the wireless transmission data, and the BER and FER values are high, the video signal controller 110 again reconstructs a coding rate proportional to the BER and FER values. Lower it.

That is, for example, when the BER and FER values continue to increase, the video signal controller 110 lowers the encoding speed of the video signal in real time, such as 5/10/15/20%. By reducing the load on 120, the encoding pause caused by insufficient capacity of the buffer 120 is reduced, and the video signal transmission rate is relatively low, thereby reducing the error occurrence rate.

The method of using the apparatus of the present invention as described above will be described in detail with reference to the attached FIG. 3, and the image signal controller 110 determines whether the BER and FER values are greater than a corresponding threshold value (S10). In the determination, if the BER and FER values are larger than the threshold value, the BER and FER values are processed in an intra mode for transmitting a video signal in units of frames (S20), and the BER and FER of the wireless environment are checked in real time (S30).

If the BER and FER values confirmed in real time are still larger than a corresponding threshold value, that is, if the wireless environment continues to be bad, the image signal controller 110 reduces the number of image frames transmitted per second, thereby causing an error. Reduce (S40), again check the wireless environment in real time (S50).

If the BER and FER values of the wireless environment continue to be high in the confirmation (S50), the video signal controller 110 reduces the amount of data transmitted per second by reducing the encoding speed of the video signal, thereby wirelessly transmitting the data. The possibility of error occurrence of the bit is reduced (S60). If it is determined that the video signal to be transmitted continues to be transmitted, the process returns to the intra process S10, and if there is no video signal to be transmitted, the process proceeds to the end (S70).

According to the present invention having the above configuration, when transmitting a video signal using a mobile communication system, the image quality and data transmission speed or data amount of an instant video signal in real time in conjunction with BER and FER of a receiving channel wireless environment. Control to increase or decrease.

In addition, in a time division multiplex (TDD) method having the same transmit / receive frequency, it is possible to actively cope with changes in the wireless environment in real time, and similar effects may be obtained in a FDD (FREQUENCY DIVISION DUPLEX) method having a different transmit / receive frequency.

In addition, the embodiment according to the present invention is not limited to the above description, and various alternatives, modifications, and changes can be made within the scope apparent to those skilled in the art.

According to the present invention, the mobile communication system that transmits the video signal actively lowers or raises the data transmission rate or amount of data transmitted in real time in association with the bit transmission error generation environment of the receiving channel. There is an industrial use effect to improve the signal quality.

In addition, since the transmission output power is not controlled, there is an industrial use effect that does not temporarily reduce the channel capacity allocated to the base station cell or affect the adjacent channel.

In addition, since the image signal is transmitted with good image quality without being influenced by the wireless environment, there is a convenient effect in use that improves the reliability of the system.

Claims (4)

A video encoder for encoding and outputting an input analog video signal into a digital video signal; A video signal controller which encodes a video signal of the video encoder by a video code control signal and wireless channel information and outputs the video signal at a set transmission rate; A buffer for storing a signal applied from the image signal controller; And a mux channel coding unit configured to multiplex the signal of the buffer and the audio level signal and output the coded bits to the transmission channel. The video signal controller of claim 1, And a bit error rate, a frame bit error rate, a bit error rate threshold, a frame bit error rate threshold, and a cycle time as radio channel information. An intra process of determining whether a bit error rate of a wireless channel through which a video signal is transmitted is greater than a threshold, and transmitting the video signal in an intra mode when the bit error rate is larger than a threshold; Determining whether the bit error rate of the radio channel is greater than a threshold value, and if the bit error rate is greater than the threshold value, a frame process of reducing the number of video signal transmission frames; It is determined whether the bit error rate of the radio channel by the above process is greater than the threshold value, and if it is greater than the threshold value, the real-time control transmission method of the video signal, characterized in that the downward process to reduce the coding speed by the video signal controller step by step . The method of claim 3, wherein the determination, And determining whether a bit transmission error rate occurring for a predetermined time and a bit transmission error rate occurring in a frame unit are greater than each corresponding threshold value.