KR20110005518A - System, server and method for transmitting of variable bit rate(vbr) video data - Google Patents

Abstract

PURPOSE: A system, a server and a method for transmitting VBR(Variable Bit Rate) video data are provided to calculate a compensation transfer rate and the size of the buffer in order to include the minimum bit amount of the accumulated frame of the VBR video data which are supposed to be transferred. CONSTITUTION: In order to make the total bit amount of received variable bit rate video data include the bit amount of the accumulated frame of video data which are supposed to be transferred, a video transfer server(130) calculates the size of a buffer based on the minimum transfer rate. The VBR video transfer server transfers the calculated buffer size to a terminal(110). Within the available transfer rate range of a connected network, the terminal transfers the VBR video data over the minimum transfer rate.

Description

JR video transmission system, server and method {SYSTEM, SERVER AND METHOD FOR TRANSMITTING OF VARIABLE BIT RATE (VBR) VIDEO DATA}

The present invention relates to a VBR video transmission system, a server, and a method. More specifically, the present invention relates to a VBR video transmission system, a server, and a method for transmitting reliable VBR video data.

Variable Bit Rate (VBR) is a concept opposite to the Constant Bit Rate (CBR) method, which maintains a constant bit rate during video compression. Since CBR has a constant bit rate of video, when a video is transmitted through a network, the CBR video can be reproduced in real time when the video is transmitted at a constant rate. Streaming video uses CBR video a lot.

In order to maintain a constant bitrate, CBR has a problem of mixing a good image with a bad image. In the case of VBR, the video quality can be kept uniform, but in some video, the bitrate is high, and in some video, the bitrate is low, so that the data is transmitted at a constant bit rate, the buffer underflow or overflow at the terminal. ), There is a problem that buffering occurs to perform retransmission or the terminal stops playing and fills the buffer. Current VBR video transmission methods include a method of transmitting at a peak bit rate and a method in which a buffer is made very large and the initial buffering is made long and then played back in the terminal. However, the method of transmitting at the peak rate requires a very high transmission rate in the network and a large buffer size of the required terminal. The method of lengthening the buffering time also requires a very large buffer size of the terminal, and causes a problem that the user must wait a long time initially. Therefore, in the case of VBR video, a transmission method capable of real-time streaming with an appropriate buffering time and buffer size is required.

The present invention is to provide a VBR video transmission system, server and method capable of transmitting reliable VBR video data.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

In order to achieve the above object, the VBR video transmission system according to the present invention uses a buffer to receive and reproduce VBR (Variable BitRate) video data in real time, and transmits the total bit amount of the VBR video data transmitted to the terminal. After calculating the size of the buffer based on the minimum data rate to include the minimum amount of the frame frame of the VBR video data to be transmitted to the terminal, the size is greater than the minimum data rate within the available data rate range of the network to which the terminal is connected. It may include a VBR video transmission server for transmitting VBR video data.

VBR video transmission server according to the present invention is a minimum bit rate calculation unit for calculating a minimum bit rate for transmitting VBR (Variable BitRate) video data in real time, the VBR to transmit the total bit amount of the VBR video data transmitted to the terminal A buffer size calculating unit for calculating a size of a buffer based on the minimum data rate so as to include a minimum amount of accumulated frame bits of video data, and an available data rate range of a network to which the terminal is connected after transmitting the calculated size of the buffer to the terminal. And a data transmitter for transmitting the VBR video data at or above the minimum data rate.

In this case, the terminal further includes a transmission rate measuring unit for measuring an available transmission rate of the network, the buffer size calculation unit, if the calculated minimum transmission rate is larger than the available transmission rate, the total of the VBR video data transmitted to the terminal The size of the buffer is calculated based on the available data rate so that the amount of bits contains the minimum amount of accumulated frame bits of the VBR video data to be transmitted, and the data transmission unit transmits the calculated size of the buffer to the terminal, and then the available size. The VBR video data may be transmitted at a data rate.

Further, when the buffer size receiving unit receiving the recommended buffer size from the terminal and the calculated buffer size are larger than the recommended buffer size, the total amount of bits of the VBR video data transmitted to the terminal is determined. And a correction rate calculation unit for calculating a correction rate based on the recommended buffer size so as to include a minimum amount of accumulated frame bits, wherein the data transmission unit transmits the recommended buffer size as the calculated buffer size to the terminal. The VBR video data may be transmitted at or above the corrected data rate within the available data rate range of the connected network. Here, the terminal further includes a rate measuring unit for measuring the available data rate of the network connected, the buffer size calculating unit, if the calculated correction data rate is greater than the available data rate, the total of the VBR video data transmitted to the terminal The size of the buffer is calculated based on the available data rate so that the amount of bits contains the minimum amount of the frame bit of the VBR video data to be transmitted, and the data transmission unit transmits the calculated size of the buffer to the terminal and then the available data rate. The VBR video data can be transmitted through

The total bit amount of the VBR video data transmitted to the terminal may be determined by the following equation.

P (t) = a '' x t + b ''

However, P (t): total amount of bits transmitted during the t'th frame

a '': baud rate

b '': buffer size

t: frame number transmitted

The cumulative frame bit amount of the VBR video data may be determined by the following equation.

C (T): Cumulative frame bit amount of VBR video data

t: frame number

T: final frame number

f (t): bit rate of tth frame

The minimum data rate may be determined by the following equation.

A: minimum transfer rate

C (T): Total accumulated frame bit amount of VBR video data

t: frame number

T: final frame number

f (t): bit rate of tth frame

The size of the buffer based on the minimum data rate may be determined by the following equation.

Where b is the buffer size

C (t): Total accumulated frame bit amount of VBR video data

a: minimum transfer rate

t: frame number

m: margin taking into account the actual rate change of the network

The size of the buffer based on the available data rate can be determined by the following equation.

Where b is the buffer size

C (t): Total accumulated frame bit amount of VBR video data

A: Available bit rate

t: frame number

m: margin taking into account the actual rate change of the network

The corrected transmission rate may be determined by the following equation.

A ': calibrated baud rate

C (t): Total accumulated frame bit amount of VBR video data

B: Recommended buffer size

t: frame number

Meanwhile, in the VBR video transmission method according to the present invention, the VBR video transmission server calculates a minimum bit rate for transmitting VBR (Variable BitRate) video data in real time, measuring an available bit rate of a network to which the terminal is connected. Comparing a minimum bit rate with the available bit rate, and when the comparison indicates that the minimum bit rate is less than the available bit rate, the total amount of bits of the VBR video data to be transmitted to the terminal is a minimum amount of the accumulated frame bits of the VBR video data to be transmitted; Calculating a size of a buffer based on the minimum data rate to include the data; transmitting the calculated size of the buffer to the terminal, and then transmitting the VBR video data at or above the minimum data rate within a range of available data rates of a network to which the terminal is connected. It may include the step of transmitting.

In this case, after the comparing step, when the calculated minimum data rate is greater than the available data rate, the total bit amount of the VBR video data transmitted to the terminal includes a minimum amount of accumulated frame bits of the VBR video data to be transmitted. The method may further include calculating a size of a buffer based on the available data rate, transmitting the calculated size of the buffer to the terminal, and then transmitting the VBR video data at the available data rate.

Also, after the buffer size calculating step, receiving a recommended buffer size from the terminal, comparing the calculated buffer size with the recommended buffer size, and the result of the comparison, the calculated buffer size is greater than the recommended buffer size. Calculating a corrected transmission rate based on the recommended buffer size so that the total amount of bits of the VBR video data transmitted to the terminal includes at least the cumulative frame bits of the VBR video data to be transmitted; The method may further include transmitting the VBR video data above the corrected transmission rate within the available transmission rate range of a network to which the terminal is connected after transmitting the recommended buffer size to the terminal. Here, after the corrected data rate calculating step, comparing the corrected data rate with the available data rate, and if the corrected data rate is greater than the available data rate, the total bit amount of the VBR video data transmitted to the terminal is to be transmitted. Calculating a size of a buffer based on the available data rate so as to include a minimum amount of accumulated frame bits of VBR video data; transmitting the calculated buffer size to the terminal and transmitting the VBR video data at the available data rate It may further include.

The total bit amount of the VBR video data transmitted to the terminal may be determined by the following equation.

P (t) = a '' x t + b ''

However, P (t): total amount of bits transmitted during the t'th frame

a '': baud rate

b '': buffer size

t: frame number

The cumulative frame bit amount of the VBR video data may be determined by the following equation.

C (T): Cumulative frame bit amount of VBR video data

t: frame number

T: final frame number

f (t): bit rate of tth frame

The minimum data rate may be determined by the following equation.

A: minimum transfer rate

C (T): Total accumulated frame bit amount of VBR video data

t: frame number

T: final frame number

f (t): bit rate of tth frame

The size of the buffer based on the minimum data rate may be determined by the following equation.

Where b is the buffer size

C (t): Total accumulated frame bit amount of VBR video data

a: minimum transfer rate

t: frame number

m: margin taking into account the actual rate change of the network

The size of the buffer based on the available data rate can be determined by the following equation.

Where b is the buffer size

C (t): Total accumulated frame bit amount of VBR video data

A: Available bit rate

t: frame number

m: margin taking into account the actual rate change of the network

The corrected transmission rate may be determined by the following equation.

A`: calibrated baud rate

C (t): Total accumulated frame bit amount of VBR video data

B: Recommended buffer size

t: frame number

On the other hand, the above VBR video transmission method may be recorded as a program on a computer-readable recording medium.

As described above, the VBR video transmission system, the server, and the method according to the present embodiment are configured to buffer the total frame amount of the VBR video data to be transmitted to the terminal to minimize the accumulated frame bit amount of the VBR video data. By calculating the size and the corrected transmission rate, reliable VBR video data can be transmitted.

The buffer size described herein refers to the size of a buffer that matches the initial buffering time (initial buffering amount) required for receiving real-time playback of VBR video data from a terminal.

Hereinafter, a VBR video transmission system, a server, and a method according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a VBR video transmission system according to the present invention.

In the VBR video transmission system illustrated in FIG. 1, a terminal 110 for receiving and playing VBR (Variable BitRate) video data in real time using a buffer and the total bit amount of the VBR video data transmitted to the terminal are transmitted. Calculate the size of the buffer based on the minimum data rate to minimize the cumulative frame bit amount of the VBR video data and transmit it to the terminal, and then transfer the VBR video data above the minimum data rate and below the available data rate of the network to which the terminal is connected. And a VBR video transmission server 130 for transmitting. The transmission rate for transmitting the VBR video data can be informed to the terminal as necessary, and this also applies to the following embodiments.

The terminal 110 is a component that receives and plays VBR video data in real time through a network, and performs buffering for real time playback. Buffering is performed by storing extra media data in advance before playing various media data. The size of the buffer refers to the actual size / capacity of the buffer provided by the predetermined terminal. However, in the present invention, as described above, a buffer having a size necessary for an initial buffering time (buffering amount) performed for real-time reproduction of predetermined video data. Refers to. Therefore, the size of the buffer mentioned in the present invention may be larger or smaller than the actual size of the buffer provided by a given terminal. However, the present invention will propose a way to minimize the size of the buffer as possible.

Variable Bit Rate (VBR) is either an audio or video encoding format. The amount of data output per unit time continuously changes compared to the fixed bit rate (CBR). In addition, bitrate allocation can be efficiently allocated. So it is more complicated than fixed bitrate (CBR). It can optionally encode to variable bitrates on MP3, WMA, Vorbis, and AAC audio, and video is available in MPEG-2 format. An advantage of the variable bit rate is that the capacity allocated per unit bit can be efficiently adjusted. It has a mechanism for allocating more bits where more data is needed and less when there is less data. Thus, the result encoded in the variable bitrate is of better quality than the result encoded in the fixed bitrate. Such VBR-encoded VBR video data can provide a closer picture quality than the original CBR encoded data, but there is a difficulty in real-time transmission because the data bit amount of each frame changes.

The VBR video transmission server 130 is an element for transmitting VBR video data to the terminal in real time through a network. Conventionally, VBR video data is transmitted at a peak bit rate. According to this, the available data rate supported in the network to which the terminal is connected should be large enough to satisfy the peak bit rate. However, in the reality that the available transmission rate of the network is limited, it is not a satisfactory alternative.

Alternatively, VBR video data can be transmitted in real time by setting a long initial buffering time of the terminal. However, in this case, the waiting time of the user may be too long, which is also not a satisfactory alternative. In addition, neither has been able to provide a reliable method for setting the size of the buffer.

Accordingly, when VBR video data is transmitted and played in real time, video playback is interrupted or buffering occurs during playback.

In the present embodiment, the VBR video transmission server 130 includes a buffer based on a minimum data rate so that the total amount of bits of the VBR video data transmitted to the terminal includes at least the accumulated frame bits of the VBR video data to be transmitted. After the size is calculated and transmitted to the terminal, the VBR video data is transmitted at or above the minimum transmission rate and below the available transmission rate of the network to which the terminal is connected.

The meaning of including the minimum amount of the accumulated frame bits of the VBR video data to be transmitted to the terminal, the minimum bit rate, and the size of the buffer based on the minimum bit rate will be described later.

2 is a block diagram showing a VBR video transmission server according to the present invention.

Referring to FIG. 2, the VBR video transmission server according to the present embodiment includes a minimum bit rate calculator 210 for calculating a minimum bit rate for transmitting VBR (Variable Bit Rate) video data in real time, and the VBR video data transmitted to a terminal. A buffer size calculator 230 that calculates a size of a buffer based on the minimum data rate so that the total amount of bits of the VBR video data to be transmitted is minimized, and the size of the buffer is transmitted to the terminal. Thereafter, the data transmission unit 250 transmits the VBR video data above the minimum transmission rate and below the available transmission rate of the network to which the terminal is connected.

The minimum data rate calculator 210 calculates a minimum data rate for transmitting video data in real time. The minimum data rate is calculated by the following equation (1).

A: minimum transfer rate

C (T): Total accumulated frame bit amount of VBR video data

t: frame number

T: final frame number

f (t): bit rate of tth frame

As shown, the minimum rate a is obtained by dividing the total cumulative frame bit amount C (T) of the VBR video data by the final frame number. Therefore, in order to calculate the minimum bit rate a, first, the VBR video data to be transmitted must be analyzed to measure the total cumulative frame bit amount of the VBR video data. The measurement of the total accumulated frame bit amount may be performed by the minimum rate calculator.

The terminal should play back in real time using the transmitted VBR video data. For this purpose, the following equation should be satisfied in the frame t of the video.

P (t) ≥C (t)

Where t is the frame number

If the equation 2 is not satisfied, playback may be interrupted or buffering may occur.

P (t) is the total bit amount of the VBR video data transmitted to the terminal, and is determined by the following equation (3).

P (t) = a '' x t + b ''

However, P (t): total amount of bits transmitted during the t'th frame

a '': baud rate

b '': buffer size

t: frame number transmitted

C (t) is a cumulative frame bit amount of the VBR video data, and is determined by Equation 4 below.

C (T): Cumulative frame bit amount of VBR video data

t: frame number

T: final frame number

f (t): bit rate of tth frame

In FIG. 9 for describing Equation 2, when VBR video data is transmitted using only the minimum bit rate a calculated by the minimum bit rate calculator (P (t) = a × t graph of FIG. 9), Equation 2 is expressed as FIG. Not satisfied That is, an interval equal to ⓐ occurs in which the total amount of transmitted bits is smaller than the amount of accumulated frame bits. In this section, playback is interrupted or buffered because the accumulated amount of bits for reproducing the original image quality does not satisfy the total amount of transmitted bits. The same phenomenon occurs as performance. Accordingly, in order to satisfy Equation 2, a method of increasing the buffer size corresponding to the Y-intercept of FIG. 9 may be used. However, if the buffer size at this time is too large, such as b ', Equation 2 is satisfied, but since the initial buffering time may be long, P (t) straight line (P (T) = a indicating the total amount of bits transmitted). (Xt + b graph) is preferably set to the buffer size in contact with the C (t) curve representing the accumulated frame bit amount.

This process is performed by the buffer size calculator 230. The buffer size calculating unit 230 calculates the size of the buffer based on the minimum data rate so that the total amount of bits of the VBR video data transmitted to the terminal includes at least the cumulative frame bits of the VBR video data to be transmitted. .

At least the total bit rate of the transmitted VBR video data including the accumulated frame bit amount of the VBR video data to be transmitted satisfies Equation 2 above, and at the same time, the total amount of VBR video data transmitted in the accumulated bit rate-time graph. This means that the bit amount P (t) straight line should be in contact with the cumulative frame bit amount C (t) curve of the VBR video data. Since the value of C (t) is known in Equation 4 and the data rate is the minimum data rate in Equation 3, the buffer size calculator can calculate the buffer size b based on the minimum data rate. The buffer size is determined and calculated by 5.

Where b is the buffer size

C (t): Total accumulated frame bit amount of VBR video data

a: minimum transfer rate

t: frame number

m: margin taking into account the actual rate change of the network

The margin m is an extra value considering that the transmission rate provided by the network is not constant, and may be appropriately set in consideration of the network environment, the VBR video transmission server, and the terminal. For example, the video data will be transmitted at a rate higher than or equal to the minimum transmission rate calculated in the present embodiment, but this is a value considering the case where the transmission rate is lower than the minimum transmission rate due to network problems.

As described above, since the buffer size calculated by the buffer size calculator is a value to be used by the terminal, it is necessary to transmit it to the terminal.

The data transmitter 250 transmits the size of the buffer calculated by the buffer size calculator to the terminal, thereby allowing the terminal to set an appropriate buffer size. In addition, the VBR video data is transmitted over the minimum data rate within the available data rate range of the network to which the terminal is connected.

Accordingly, when the VBR video data is transmitted, the terminal sets the buffer to the buffer size calculated by the buffer size calculator. Accordingly, even when the transmission is performed at the minimum transmission rate, the Equation 2 is satisfied, so that the playback is not interrupted or the buffering occurs during the playback, and smooth real-time video playback is performed.

In the embodiment of FIG. 2, there may be a case where the minimum data rate is higher than the available data rate supported by the network. Available data rates are invisible to the VBR video transmission server and terminal. A solution for this is shown in FIG. 3.

3 is a block diagram showing a VBR video transmission server according to another embodiment related to the present invention.

The VBR video transmission server shown in FIG. 3 includes a minimum data rate calculator 210, a buffer size calculator 230, a data transmitter 250, and a data rate measurer 270.

The rate measuring unit 270 measures the available rate of the network to which the terminal is connected.

When the minimum data rate calculated in the embodiment of FIG. 2 is greater than the available data rate, the buffer size calculator may be configured to reduce the amount of accumulated frame bits of the VBR video data to be transmitted by the terminal. To calculate the size of the buffer based on the available data rate.

Since the available data rate is not a target of the VBR video transmission server as mentioned above, the data rate should be set to the available data rate and the buffer size should be calculated based on the available data rate. In this case, the slope of the P (t) graph is smaller than a (not shown) in the cumulative bit amount-time graph of FIG. 9 (not shown). In this state, the buffer size should generally be large to satisfy Equation 2 in this state. .

Specifically, the size of the buffer based on the available data rate is determined and calculated by the following equation (6).

Where b is the buffer size

C (t): Total accumulated frame bit amount of VBR video data

A: Available bit rate

t: frame number

m: margin taking into account the actual rate change of the network

Since the available bit rate A is less than the minimum bit rate a in this embodiment, the buffer size b will be larger than in Equation 5. The buffer size may be larger than the buffer size recommended by the terminal. However, since the transmission rate cannot be higher than the available transmission rate A supported by the network, the buffer size of the terminal is set to the buffer size based on the available transmission rate. If the buffer fails to satisfy the buffer size based on the available data rate due to lack of resources of the terminal, real time playback without interruption and without performing buffering during playback will be impossible.

The data transmitter transmits the calculated size of the buffer to the terminal and then transmits the VBR video data at the available data rate.

For reference, the margin m may be larger than the margin m of Equation 5 in consideration of the fact that the transmission is performed at the available data rate, which is the maximum data rate supported by the network.

Since the minimum data rate calculator is the same as described above, a description thereof will be omitted.

In FIG. 3, the minimum data rate calculated by the minimum data rate calculator is greater than the available data rate. When the minimum data rate is less than or equal to the available data rate, a buffer size based on the available data rate is calculated as shown in Equation 5. FIG. The calculated buffer size may be larger than the recommended buffer size of the terminal, which will be described with reference to FIG. 4.

4 is a block diagram showing a VBR video transmission server according to another embodiment related to the present invention.

The VBR video transmission server according to the present embodiment includes a minimum data rate calculator 210, a buffer size calculator 230, a data transmitter 250, a corrected data rate calculator 240, and a buffer size receiver 290. have.

The buffer size receiver 290 is an element that receives the recommended buffer size from the terminal. The terminal has its buffer resource, that is, the size of the buffer that can be supported in hardware. Therefore, it is not possible to set an infinite buffer size, and even if possible, it is not preferable. The larger buffer size means that the initial buffering time is increased, so that the larger the buffer size, the longer the user waits initially, thereby lowering the reliability of real-time playback. Therefore, it is necessary to ensure that the initial buffering takes place within the time range that the user can expect or expect. Therefore, the terminal may set the recommended buffer size within the buffering time range expected by the user when playing the VBR video. The recommended buffer size is generally smaller than the hardware buffer size, but when the hardware buffer size is small, it may mean the hardware buffer size.

In order to use the recommended buffer size in the VBR video transmission server, the recommended buffer size must be received from the terminal, which is performed through the buffer size receiver. Of course, for this purpose, the terminal also needs to generate the recommended buffer size and transmit it.

When the size of the buffer calculated by the buffer size calculator is greater than the recommended buffer size, the correction rate calculator 240 accumulates the total amount of VBR video data to be transmitted to the terminal. The correction transfer rate is calculated based on the recommended buffer size so that the frame bit amount is minimal. That is, the calibrated data rate calculator is a factor for calibrating a data rate to satisfy a recommended buffer size, and the calibrated data rate calculated by the calibrated data rate calculator is determined and calculated according to Equation 7 below.

A ': calibrated baud rate

C (t): Total accumulated frame bit amount of VBR video data

B: Recommended buffer size

t: frame number

An example in which the correction transmission rate calculated in this way is applied is a graph of P (t) = a '× t + B in FIG. 9.

The data transmission unit transmits the recommended buffer size as the calculated buffer size to the terminal, and then transmits the VBR video data below the correct transmission rate and below the available transmission rate of the network to which the terminal is connected. The above range is determined because a transmission rate higher than the available transmission rate is possible, but a transmission rate higher than the available transmission rate is impossible. This also applies to transmissions above the minimum rates discussed above.

According to this, it is possible to satisfy the recommended buffer size of the terminal. As the data rate is changed, it is necessary to examine again whether the available data rate allows the corrected data rate. As mentioned above, there is no way to use the available data rate in the VBR video transmission server. Therefore, if the corrected data rate is larger than the available data rate, the buffer size based on the available data rate is calculated and transmitted to the terminal. Should. Such a process is shown in FIG.

Referring to FIG. 5, the VBR video transmission server measures the minimum data rate calculator 210, the buffer size calculator 230, the corrected data rate calculator 240, the data transmitter 250, the buffer size receiver 290, and the data rate measurement. A portion 270 is included.

The rate measuring unit measures an available data rate of a network to which the terminal is connected, and performs the same function as the rate measuring unit of FIG. 3.

The buffer size calculator may include a minimum amount of accumulated frame bits of the VBR video data to be transmitted when the calculated corrected transmission rate is greater than the available transmission rate, such that the total amount of bits of the VBR video data transmitted to the terminal is to be transmitted. Calculate the size of the buffer based on the available data rates. In this case, the size of the buffer based on the available data rate is determined and calculated according to Equation 6 described above. According to this, the buffer size calculator calculates the buffer size twice. The first is the buffer size based on the minimum rate, and the second is the buffer size based on the available rate. Calculation of the buffer size based on the available data rate is performed according to a comparison result between the corrected data rate calculated by the corrected data rate calculator and the available data rate measured by the data rate measurer. However, when the buffer size based on the available data rate is calculated, it is recalled that the buffer size does not affect the corrected data rate calculator but is simply bypassed and transmitted to the data transmitter.

The data transmitter transmits the calculated size of the buffer to the terminal and then transmits the VBR video data at the available data rate.

In summary, the method of calculating the buffer size based on the minimum data rate, the method of calculating the buffer size based on the available data rate when the minimum data rate is larger than the available data rate, and the buffer size based on the minimum data rate is larger than the recommended buffer size In this case, there is a method of calculating a corrected transmission rate, and a method of calculating a buffer size based on an available transmission rate when the corrected transmission rate is larger than the available transmission rate. The above description may be made individually or may be made by merging.

Accordingly, since the total bit rate of the VBR video data transmitted to the terminal includes the minimum frame bit amount of the VBR video data to be transmitted, the VBR video data can be reproduced without interruption or buffering during playback. The picture quality provided by the data can be reproduced as it is.

Of course, to this end, a terminal for setting at least a buffer size transmitted from the VBR video transmission server to its own buffer size and transmitting a recommended buffer size to the VBR video transmission server is required.

6 is a block diagram showing a terminal related to the present invention.

The illustrated terminal transmits a recommended buffer size to the VBR video transmission server, and sets a buffer size according to the buffer size transceiver 310 and the buffer size received from the buffer size calculated by the VBR video transmission server. A buffer size setting unit 330 is included. In addition, elements such as a video player which receives VBR video data from a VBR video transmission server and reproduces the data in real time should be provided.

7 is a block diagram illustrating a VBR video transmission server and a terminal according to the present invention.

The VBR video transmission server includes a buffer size receiving unit 410, a cumulative frame bit rate measuring unit 420, a rate measuring unit 430, a transmission adjusting unit 440, and a data transmitting unit 450. A receiver 460, a video player 470, and a buffer size transceiver 480 are included.

The buffer size receiver 410 receives a recommended buffer size from the buffer size transceiver of the terminal, and the recommended buffer size is a comparison element with a buffer size based on the minimum data rate calculated by the VBR video transmission server.

The cumulative frame bit rate measuring unit 420 is an element for measuring the cumulative frame bit amount of the VBR video data to be transmitted in order to calculate the minimum data rate. As described above, it may be included in the minimum rate calculator.

The data rate measuring unit measures an available data rate of a network to which the terminal is connected, and the available data rate is a comparison target with a minimum data rate and a corrected data rate.

The transmission control unit 440 may include a minimum amount of accumulated frame bits of the VBR video data to be transmitted, such as the buffer size calculator and the correction rate calculator, as described above. It is an element that calculates a buffer size or a corrected transfer rate, and also includes a minimum transfer rate calculation unit.

The data transmission unit 450 transmits the buffer size calculated by the transmission control unit to the terminal, specifically, the buffer size transmission / reception unit 480, thereby allowing the terminal to prepare a buffer size and substantially transmitting VBR video data. Do this.

The data receiver 460 receives the VBR video data transmitted from the data transmitter and transmits the VBR video data to the video player.

The buffer size transceiver 480 transmits a recommended buffer size to the buffer size receiver of the VBR video transmission server, and receives the buffer size from the data transmitter. The buffer size is transmitted to the video player to set the buffer size.

8 is a flowchart illustrating a VBR video transmission method according to the present invention.

It is mentioned that the VBR video transmission method may correspond to a process performed by the VBR video transmission server.

First, a minimum bit rate for transmitting VBR (Variable BitRate) video data in real time is calculated (S510). The calculation of the minimum data rate may be performed by the minimum data rate calculator described above, and is specifically determined through Equation 1.

Next, the available transmission rate of the network to which the terminal is connected is measured (S 510). The calculation of the minimum transmission rate and the measurement of the available transmission rate do not need to be considered in a post-mortem relationship. In addition, the recommended buffer size receiving step, which will be described below, may be performed at the same stages as the available data rate measurement and the minimum data rate calculation.

Comparing the calculated minimum data rate with the measured available data rate, if the minimum data rate is less than the available data rate (S520), the total amount of bits of the VBR video data transmitted to the terminal is accumulated. The size of the buffer based on the minimum data rate is calculated to include the minimum amount of frame bits (S540). The size of the buffer based on the minimum data rate may be performed by the buffer size calculator, and is specifically determined through Equation 5.

After the calculated size of the buffer is transmitted to the terminal, the VBR video data is transmitted at least the minimum data rate and below the available data rate of the network to which the terminal is connected (S590).

If the minimum data rate is compared with the available data rate and the minimum data rate is greater than the available data rate (S520), the cumulative frame of the VBR video data to be transmitted is the total amount of bits of the VBR video data transmitted to the terminal. The size of the buffer based on the available data rate is calculated to include the minimum amount of bits (S530). Since the available data rate is not a resource provided by the VBR video transmission server or the terminal, it is difficult to obtain a data rate higher than the available data rate. Therefore, when the minimum data rate is larger than the available data rate, the data rate is set to the available data rate, and the buffer size based on the available data rate can be calculated. Specifically, the buffer size based on the available data rate is calculated by Equation 6.

In this case, after transmitting the calculated size of the buffer to the terminal, the VBR video data should be transmitted at the available data rate (S590).

On the other hand, if the minimum data rate is less than the available data rate and there is a recommended buffer size, the recommended buffer size should also be considered.

If the minimum data rate is less than or equal to the available data rate, a buffer size is calculated based on the minimum data rate. To compare this with the recommended buffer size, the recommended buffer size must first be received from the terminal (S550). As mentioned above, the reception of the recommended buffer size may be at a stage such as calculating the minimum data rate or measuring the available data rate. At least immediately after the buffer size based on the minimum transfer rate has been calculated.

The calculated buffer size is compared with the recommended buffer size transmitted from the terminal. If the calculated buffer size is less than or equal to the recommended buffer size, the calculated buffer size is transmitted to the terminal, and then the VBR video is transmitted. Data is transmitted below the minimum transmission rate and below an available transmission rate of the network to which the terminal is connected (S590).

If the calculated buffer size is larger than the recommended buffer size as a result of the comparison, the recommended buffer so that the total amount of bits of the VBR video data transmitted to the terminal includes a minimum amount of accumulated frame bits of the VBR video data to be transmitted. A corrected transmission rate is calculated based on the size (S570). The correction transmission rate is calculated by the correction transmission rate calculation unit. Specifically, the correction transmission rate is calculated and determined by Equation (7).

After transmitting the recommended buffer size as the calculated buffer size to the terminal, the VBR video data is transmitted above the corrected transmission rate and below the available transmission rate of the network to which the terminal is connected (S590). The buffer size sent to the terminal eventually becomes the recommended buffer size. Although the recommended buffer size is a value also known to the terminal, the terminal can be notified of this to prepare the buffer size.

The corrected transfer rate is calculated when the minimum transfer rate is less than or equal to the available transfer rate and the buffer size based on the minimum transfer rate is larger than the recommended buffer size. However, it is different from the minimum data rate having a size less than the available data rate, and may be larger than the available data rate. Since a data rate larger than the available data rate is not possible, countermeasures are required.

Therefore, when the corrected data rate is larger than the available data rate by comparing the corrected data rate with the available data rate (S580), the accumulated frame bits of the VBR video data to be transmitted are transmitted in the total amount of bits of the VBR video data transmitted to the terminal. The size of the buffer based on the available data rate is calculated to include the minimum amount (S530).

After transmitting the calculated buffer size (buffer size based on the available data rate) to the terminal, the VBR video data is transmitted at the available data rate (S590). Even if the transmitted buffer size is larger than the recommended buffer size, the terminal should set the buffer to the buffer size transmitted from the VBR video transmission server.

On the other hand, the total bit amount of the VBR video data transmitted to the aforementioned terminal can be obtained by Equation 3, and the cumulative frame bit amount of the VBR video data can be obtained by Equation 4.

On the other hand, the VBR video transmission method according to the present invention can be recorded as a program on a computer readable recording medium which can be read by a program.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive. The scope of the present invention is shown by the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Applicable to the transmission and playback system of VBR video data.

1 is a block diagram showing a VBR video transmission system according to the present invention.

2 is a block diagram illustrating a VBR video transmission server according to the present invention.

3 is a block diagram illustrating a VBR video transmission server according to another embodiment related to the present invention.

4 and 5 are block diagrams illustrating a VBR video transmission server according to another embodiment related to the present invention.

6 is a block diagram showing a terminal related to the present invention.

7 is a block diagram showing a VBR video transmission server and a terminal according to the present invention.

8 is a flowchart illustrating a VBR video transmission method according to the present invention.

9 is a accumulated bit rate-time graph for explaining a VBR video transmission method according to the present invention.

Description of the Related Art

210 ... Minimum transfer rate calculator 230 ... Buffer size calculator

250.Data transmission unit

Claims (22)

A terminal for receiving and playing VBR (Variable BitRate) video data in real time using a buffer; And The terminal accesses the terminal after calculating the size of the buffer based on the minimum data rate so that the total bit quantity of the VBR video data transmitted to the terminal includes the accumulated frame bit amount of the VBR video data to be transmitted to the terminal. A VBR video transmission server for transmitting the VBR video data at or above the minimum transmission rate within an available transmission rate range of a network; VBR video transmission system comprising a. A minimum bit rate calculator for calculating a minimum bit rate for transmitting VBR (Variable BitRate) video data in real time; A buffer size calculator configured to calculate a size of a buffer based on the minimum data rate such that the total amount of bits of the VBR video data transmitted to the terminal includes a minimum amount of accumulated frame bits of the VBR video data to be transmitted; A data transmission unit for transmitting the VBR video data at a transmission rate greater than or equal to the minimum transmission rate within the available transmission rate range of a network to which the terminal is connected after transmitting the calculated buffer size to the terminal; VBR video transmission server comprising a. The method of claim 2, Further comprising a data rate measuring unit for measuring the available data rate of the network to which the terminal is connected, The buffer size calculating unit is configured to include the accumulated frame bit amount of the VBR video data to be transmitted to the terminal when the calculated minimum bit rate is larger than the available bit rate, so that the total bit amount of the VBR video data to be transmitted is minimized. Calculate the size of the buffer based on the transfer rate, And the data transmitter transmits the calculated size of the buffer to the terminal and transmits the VBR video data at the available data rate. The method of claim 2, A buffer size receiving unit receiving a recommended buffer size from the terminal; And When the size of the calculated buffer is larger than the recommended buffer size, the total amount of bits of the VBR video data transmitted to the terminal is based on the recommended buffer size so as to include a minimum amount of the accumulated frame bits of the VBR video data to be transmitted. Further comprising a correction rate calculation unit for calculating a correction rate; And the data transmission unit transmits the recommended buffer size as the calculated buffer size to the terminal and then transmits the VBR video data above the corrected transmission rate within the available transmission rate range of the network to which the terminal is connected. The method of claim 4, wherein Further comprising a data rate measuring unit for measuring the available data rate of the network to which the terminal is connected, The buffer size calculating unit is configured to include the accumulated frame bit amount of the VBR video data to be transmitted to the terminal when the calculated corrected transmission rate is greater than the available data rate, so that the total bit quantity of the VBR video data to be transmitted is minimized. Calculate the size of the buffer based on the transfer rate, And the data transmitter transmits the size of the buffer based on the available data rate to the terminal and transmits the VBR video data at the available data rate. The method according to any one of claims 2 to 5, The total bit amount of the VBR video data transmitted to the terminal is determined by the following equation. P (t) = a '' x t + b '' However, P (t): total amount of bits transmitted during the t'th frame a '': baud rate b '': buffer size t: frame number transmitted The method according to any one of claims 2 to 5, The cumulative frame bit amount of the VBR video data is determined by the following equation.

C (T): Cumulative frame bit amount of VBR video data t: frame number T: final frame number f (t): bit rate of tth frame The method of claim 2, The minimum transmission rate is determined by the following equation VBR video transmission server.

A: minimum transfer rate C (T): Total accumulated frame bit amount of VBR video data

t: frame number T: final frame number f (t): bit rate of tth frame The method of claim 2, The size of the buffer based on the minimum data rate is determined by the following equation.

Where b is the buffer size C (t): Total accumulated frame bit amount of VBR video data a: minimum transfer rate t: frame number m: margin taking into account the actual rate change of the network The method according to claim 3 or 5, The size of the buffer based on the available data rate is determined by the following equation.

Where b is the buffer size C (t): Total accumulated frame bit amount of VBR video data A: Available bit rate t: frame number m: margin taking into account the actual rate change of the network The method of claim 4, wherein The corrected transmission rate is determined by the following equation.

A ': calibrated baud rate C (t): Total accumulated frame bit amount of VBR video data B: Recommended buffer size t: frame number In a terminal receiving VBR video data from a VBR video transmission server and playing back in real time, A buffer size transmission / reception unit for transmitting a recommended buffer size to the VBR video transmission server and receiving a buffer size calculated by the VBR video transmission server; And A buffer size setting unit for setting a size of a buffer according to the received buffer size; Terminal comprising a. Calculating, by the VBR video transmission server, a minimum bit rate for transmitting Variable Bit Rate (VBR) video data in real time; Measuring an available data rate of a network to which the terminal is connected; Comparing the minimum rate with the available rate; If the minimum transmission rate is less than or equal to the available transmission rate, the buffer based on the minimum transmission rate is set so that the total amount of bits of the VBR video data transmitted to the terminal includes at least the accumulated frame bits of the VBR video data to be transmitted. Calculating a size; Transmitting the VBR video data above the minimum data rate within the available data rate range of the network to which the terminal is connected after transmitting the calculated buffer size to the terminal; VBR video transmission method comprising a. The method of claim 13, After the comparison step, If the calculated minimum data rate is greater than the available data rate, the buffer based on the available data rate may include a minimum amount of frame bits of the VBR video data to be transmitted, the total amount of bits of the VBR video data transmitted to the terminal. Calculating a size; Transmitting the VBR video data at the available data rate after transmitting the calculated size of the buffer to the terminal. The method of claim 13, After the buffer size calculating step, Receiving a recommended buffer size from the terminal; Comparing the calculated buffer size with the recommended buffer size; If the calculated buffer size is larger than the recommended buffer size as a result of the comparison, the recommended buffer size includes a minimum amount of the accumulated frame bits of the VBR video data to be transmitted to the terminal. Calculating a correction transmission rate based on; And transmitting the recommended buffer size as the calculated buffer size to the terminal and transmitting the VBR video data above the corrected transmission rate within the available transmission rate range of the network to which the terminal is connected. The method of claim 15, After the correction rate calculation step, Comparing the corrected transmission rate with the available transmission rate; If the corrected data rate is greater than the available data rate, the size of the buffer based on the available data rate is set so that the total amount of bits of the VBR video data transmitted to the terminal includes a minimum amount of accumulated frame bits of the VBR video data to be transmitted. Calculating; Transmitting the VBR video data at the available data rate after transmitting the buffer size based on the available data rate to the terminal. The method according to any one of claims 13 to 16, The total bit amount of the VBR video data transmitted to the terminal is determined by the following equation. P (t) = a '' x t + b '' However, P (t): total amount of bits transmitted during the t'th frame a '': baud rate b '': buffer size t: frame number The method according to any one of claims 13 to 16, The cumulative frame bit amount of the VBR video data is determined by the following equation.

C (T): Cumulative frame bit amount of VBR video data t: frame number T: final frame number f (t): bit rate of tth frame The method of claim 13, The minimum transmission rate is determined by the following equation.

A: minimum transfer rate C (T): Total accumulated frame bit amount of VBR video data

t: frame number T: final frame number f (t): bit rate of tth frame The method of claim 13, The size of the buffer based on the minimum data rate is determined by the following equation.

Where b is the buffer size C (t): Total accumulated frame bit amount of VBR video data a: minimum transfer rate t: frame number m: margin taking into account the actual rate change of the network The method according to claim 14 or 16, The size of the buffer based on the available data rate is determined by the following equation.

Where b is the buffer size C (t): Total accumulated frame bit amount of VBR video data A: Available bit rate t: frame number m: margin taking into account the actual rate change of the network The method of claim 15, The corrected transmission rate is determined by the following equation.

A`: calibrated baud rate C (t): Total accumulated frame bit amount of VBR video data B: Recommended buffer size t: frame number

Images