JP3671098B2 - Data transmission device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data transmission device that supplies compressed data to a data reproduction device, such as a video server, for example. In particular, the failure of reproduced data on the data reproduction device by adjusting the supply speed of compressed data, etc. The present invention relates to a technique for preventing inconvenience.
[0002]
[Prior art]
With the recent development of digital signal processing technology, even in image compression processing, after the image signal is digitized, the amount of data can be significantly compressed by the digital signal processing technology. As a standard of such an image compression technique, there is, for example, a moving picture compression standard MPEG (Moving Picture Image Coding Experts Group) standard.
[0003]
As the image signal is digitized as described above, a data transmission device for reproducing an image is required. This image data sending device is generally called a video server, and a function for continuously sending image data at a speed corresponding to the image data encoding process is required. This is because the image signal generally takes several hours, and this amount of data is enormous even when compressed, so the playback side receives the data and performs data expansion and playback at the same time. This is so that only the minimum necessary buffer is required.
[0004]
In the conventional MPEG system, the bit rate of image data is fixed. Therefore, the video server has a function for transmitting image data at a fixed bit rate. A schematic configuration of this conventional video server is shown in FIG. The video server includes a storage device 101 that stores image data, a clock circuit 102 that outputs a reference signal STA at regular intervals, a data suppression circuit 103 that limits data output from the storage device 101, A data amount counting circuit 104 for counting the amount of data output from the storage device 101, a fixed value register 105 in which a fixed value is stored, and a comparison circuit 106 are provided.
[0005]
In this configuration, when the data suppression circuit 103 receives the reference signal STA from the timer circuit 102, the data suppression circuit 103 outputs a data output permission signal ENB to the storage device 101. When the STOP signal is received from the comparison circuit 106, the data output enable signal ENB is interrupted, and the data output from the storage device 101 is stopped.
[0006]
The STOP signal from the comparison circuit 106 is output as follows. As a premise, the fixed value register 105 stores a data amount LIM per unit time as a reference for the bit rate in advance, and the comparison circuit 106 calculates the LIM from the fixed value register 105 and the data amount from the data amount counting circuit 104. When the numerical values are equal, a STOP signal is output to the data suppression circuit 103.
[0007]
In this way, it is possible to realize a data transmission device that transmits a data amount equal to the LIM in the unit time indicated by the reference signal STA. In this apparatus, the bit rate can be changed by changing the value stored in the fixed value register 105.
[0008]
[Problems to be solved by the invention]
By the way, a technique called VBR (Variable Bit Rate) is used in recent demands for improving compression efficiency. This in accordance with the image characteristics is obtained by changing the compression ratio for each portion of the data, for example, relatively less portions motion set low bit rate, conversely, a high bit rate only vigorous parts of motion Thus, it is possible to change the bit rate as necessary, for example, to reduce the average bit rate of the entire data.
[0009]
However, there is a problem that image data created by using the VBR technology cannot be transmitted correctly in a conventional video server. This is because the data transmission speed is always constant in the above-described conventional example, and the bit rate of the image data cannot be changed in the middle of the data. In other words, in the case of image data in which the bit rate increases from the middle, transmission of necessary data is delayed with time, and as a result, necessary data comes at the timing of reproduction on the reproduction apparatus side. Inconvenience that it cannot be reproduced. On the other hand, in the case of image data in which the bit rate is lowered in the middle, if the amount of data supplied from the video server is larger than the amount of data to be played back by the playback device, For example, there may be a problem that the reproduction fails without catching up, and, for example, in the case of image data, frames are dropped and the image cannot be viewed.
[0010]
The image data is typically related to movies, but is not limited to movie information, but is not limited to movie information, is accompanied by background information such as music information with video or so-called video karaoke, or game information. Can be considered. And with the development of multimedia technology in recent years, the scope of application seems to expand more and more.
[0011]
The present invention has been made to solve the above-described problems, and is a data transmission apparatus expected to be used in a system that assumes data transmission in one direction, such as a broadcast media system or a communication media system. Another object of the present invention is to appropriately realize a VBR that makes the encoding bit rate variable.
[0012]
[Means for Solving the Problems and Effects of the Invention]
The compressed data supply device according to claim 1, which has been made to achieve the above object, is used in a system premised on data transmission in one direction to a reproducing device side, and is based on a predetermined information compression coding standard. In the data sending device for sending the compressed data read from the storage means storing the compressed data to the playback device side, the compressed data is VBR ( Variable Bit Rate ) MPEG image data, and the storage means Identifying first screen information set for each screen data included in the compressed data read out from the first data, detecting the number of screens, and detecting the total data amount of the compressed data read out from the storage means. The total amount of data detected by the second detection means and the second detection means is divided by the number of screens detected by the first detection means to calculate the reference data amount And a reference data amount calculating means for permitting reading of the compressed data from the storage means at regular time intervals, and a total data amount detected by the second detecting means after permitting reading of the compressed data Data read control means for prohibiting reading of the compressed data from the storage means when the reference data amount is equal to the reference data amount calculated by the reference data amount calculation means. .
[0013]
This compressed data transmission device is a retention device used in a system that is premised on data transmission in one direction to the reproduction production device, and stores data compressed based on a predetermined information compression coding standard. The compressed data read from the storage means is sent to the playback device side.
The compressed data stored in the storage means is VBR ( Variable Bit Rate ) MPEG image data, and the first detection means sets the screen head set for each screen data included in the compressed data read from the storage means. Identify information . The second detection unit detects the total data amount of the compressed data read from the storage unit. Then, the reference data amount calculation unit calculates the reference data amount by dividing the total data amount detected by the second detection unit by the number of screens detected by the first detection unit. Then, the data read control means permits reading of the compressed data from the storage means at regular intervals, and the total data amount detected by the second detection means after allowing the compressed data to be read is a reference. When it becomes equal to the reference data amount calculated by the data amount calculation means, reading of the compressed data from the storage means is prohibited.
[0014]
In this way, even when data with a high bit rate is transmitted from the middle, data transmission at a data transmission speed corresponding to the bit rate can be realized. Therefore, in the case of data that the transmission of necessary data is delayed with time, the necessary data does not come at the playback timing on the playback device side and cannot be played back, or conversely the data whose bit rate is lowered in the middle In addition, it is possible to prevent the inconvenience that the supplied data amount is larger than the data amount to be reproduced by the reproducing apparatus and the reproduction fails to catch up. Therefore, even in a data transmission apparatus that is expected to be used in a system that assumes data transmission in one direction, such as a broadcast media system or a communication media system, a VBR that makes the encoding bit rate variable can be appropriately realized.
[0015]
Note that compressed data present compressed data delivery device handled because an MPEG image data, the detection subject to the first sensing means is a screen leading information. For example, in a compression standard such as MPEG, there are three types of pictures defined as I (Intra coded) picture, P (Predictive coded) picture, and B (Bidirectionally Predictive coded) picture. Since it has a picture start code (PSC), if it is found, the number of screens can be detected . In general, since a high effectiveness in the many data amount also VBR in the case of MPEG picture image data, as the data handled by the system is one of those whose effect can be expected greatly.
[0016]
Further, as shown in claim 2 , the total data amount detected by the second detection unit corresponding to each screen detected by the first detection unit is sequentially updated by the number of the latest predetermined screens. The reference data amount calculation means further detects the sum total of the total data amount for the latest predetermined number of screens stored in the storage means by the first detection means. The reference data amount may be calculated by dividing by the number of screens .
[0017]
For example, "Latest predetermined picture number" to the case of the 10 screen, and stores data of the latest 10 screens, data delivery rate of the average from the sum of the data amount, i.e. so as to obtain an average bit rate To do. If the data amount is accumulated by updating one screen at a time, the average bit rate from the first screen to the tenth screen is obtained first, and the next is the average bit rate from the second screen to the eleventh screen. Is obtained. In this case, it is possible to cope with finer changes in the bit rate, and an improvement in followability can be expected.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail.
As shown in FIG. 1, a data supply apparatus according to an embodiment of the present invention stores image data compressed based on a predetermined information compression coding standard (for example, MPEG), and the image data according to a request. , A timing circuit 2 that outputs a reference signal STA at regular intervals, a data suppression circuit 3 for limiting data output from the storage device 1, and data output from the storage device 1 A data amount counting circuit 4 for counting the amount, a reference value register 10 in which a reference value is stored, a comparison circuit 6, a head data counting circuit 7, a data amount counting circuit 8, and a reference data amount calculating circuit 9 and.
[0019]
In this configuration, when the data suppression circuit 3 receives the reference signal STA from the timing circuit 2, the data suppression circuit 3 outputs a data output permission signal ENB to the storage device 1. By outputting the data output permission signal ENB, the storage device 1 can output data. When the STOP signal is received from the comparison circuit 6, the data output enable signal ENB is interrupted and the data output from the storage device 1 is stopped.
[0020]
The STOP signal from the comparison circuit 6 is output as follows. First, as a premise, the reference value register 10 stores a data amount LIM per unit time as a reference of the bit rate in advance, and the comparison circuit 6 receives the reference value from the reference value register 10 and the data amount counting circuit 4. The STOP signal is output to the data suppression circuit 3 when the count values of the two become equal.
[0021]
Further, this reference value is determined as follows. That is, the head data counting circuit 7 detects the screen head data of the image data output from the storage device 1, counts this, and outputs the instruction signal TMG to the data amount counting circuit 8 when it reaches a predetermined number. A supplementary explanation will be given for the top data of the screen. For example, in a compression standard such as MPEG, three types of pictures, i.e., I picture, P picture, and B picture, are defined, but any picture has a picture start code (PSC). Therefore, it only has to be detected.
[0022]
The data amount counting circuit 8 counts the data amount of the image data output from the storage device 1. When the TMG signal is received from the head data counting circuit 7, the data amount at that time is calculated as a reference data amount. Output to the circuit 9. The reference data amount calculation circuit 9 receives the data amount output from the data amount counting circuit 8 and divides it by the number of head data counted by the head data counting circuit 7, that is, the number corresponding to the number of screens. This is the reference value, that is, the amount of transmission data per unit time, and is stored in the reference value register 10. As described above, since the comparison circuit 6 outputs the STOP signal to the data suppression circuit 3 when the reference value from the reference value register 10 and the count value from the data amount counting circuit 4 become equal, the reference value is If changed, the timing for outputting the STOP signal will also change accordingly.
[0023]
In this way, even when data whose bit rate is increased from the middle is transmitted from the storage device 1, data transmission at a data transmission speed corresponding to the bit rate can be realized. Therefore, in the case of data that the transmission of necessary data is delayed with time, the necessary data does not come at the playback timing on the playback device side and cannot be played back, or conversely the data whose bit rate is lowered in the middle In addition, it is possible to prevent the inconvenience that the supplied data amount is larger than the data amount to be reproduced by the reproducing apparatus and the reproduction fails to catch up. Therefore, even when applied to a data transmission apparatus that is expected to be used in a system that assumes data transmission in one direction, such as a broadcast media system or a communication media system, a VBR that makes the encoding bit rate variable is appropriate. Can be realized.
[0024]
As mentioned above, although one Embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to such Embodiment, and can implement variously in the range which does not deviate from the main point of this invention.
For example, in the above embodiment, the data to be handled has been described as image data. However, the present invention is not limited to this, and other data may be used. In that case, the head information set for each predetermined unit data according to the data type is used. Find it. However, in the case of image data, since the amount of data is generally large and the effectiveness of VBR is high, it is one of the data that can be expected to be highly effective as data handled by the data transmission apparatus.
[0025]
Further, as another embodiment, a configuration as shown in FIG. 2 is also conceivable. In the case of the above embodiment shown in FIG. 1, the data amount counted by the data amount counting circuit 8 is output to the reference data amount calculating circuit 9, but in this other embodiment, the data amount counting circuit 8 and the reference amount are output. A data amount memory 11 is added between the data amount calculation circuits 9. Since other configurations are the same, description thereof is omitted.
[0026]
In the case of this embodiment, when the data amount counting circuit 8 that counts the data amount of the image data output from the storage device 1 receives the TMG signal from the head data counting circuit 7, the data amount at that time is calculated. Output to the data amount memory 11. The data amount memory 11 accumulates the data amount output from the data amount counting circuit 8 while sequentially updating the data amount by the latest predetermined number of screens. The reference data amount calculating circuit 9 stores the data amount memory 11. The total amount of data output from is received and divided by a number corresponding to the predetermined number of screens.
[0027]
For example, the data amount for the latest 10 screens is accumulated, and the average data transmission speed, that is, the average bit rate is obtained from the sum of the data amounts. When updating the data one screen at a time and accumulating the data amount, first, the reference data amount is calculated from the sum of the data amounts from the first screen to the tenth screen, and then the second screen to the eleventh screen. The reference data amount is calculated from the total amount of data up to.
[0028]
In this way, it is possible to cope with more minute changes in the bit rate, and an improvement in followability can be expected.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a data supply apparatus according to an embodiment.
FIG. 2 is a block diagram illustrating a schematic configuration of a data supply apparatus according to another embodiment.
FIG. 3 is a block diagram showing a schematic configuration of a conventional video server.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Memory | storage device 2 ... Time measuring circuit 3 ... Data suppression circuit 4 ... Data amount counting circuit 6 ... Comparison circuit 7 ... Leading data counting circuit 8 ... Data amount counting circuit 9 ... Reference data amount calculation circuit 10 ... Reference value register 11 ... Data Quantity memory 101 ... Storage device 102 ... Timekeeping circuit 103 ... Data suppression circuit 104 ... Data quantity counting circuit 105 ... Fixed value register 106 ... Comparison circuit

Claims (2)

Compressed data read from storage means used for a system that presupposes one-way data transmission to the playback device side and stores data compressed based on a predetermined information compression coding standard. In the data sending device to send to
The compressed data is VBR ( Variable Bit Rate ) MPEG image data,
First detection means for identifying screen head information set for each screen data included in the compressed data read from the storage means and detecting the number of screens ;
Second detection means for detecting the total data amount of the compressed data read from the storage means;
A reference data amount calculation means for calculating a reference data amount by dividing the total data amount detected by the second detection means by the number of screens detected by the first detection means;
The reading of the compressed data from the storage means is permitted at regular intervals, and the total data amount detected by the second detecting means after allowing the reading of the compressed data is determined by the reference data amount calculating means. A data read control means for prohibiting reading of the compressed data from the storage means when equal to the calculated reference data amount ;
A data transmission device comprising: The apparatus further comprises an accumulating unit for accumulating the total data amount detected by the second detecting unit corresponding to each screen detected by the first detecting unit while sequentially updating the total data amount by the number of the latest predetermined screens. With
The reference data amount calculation means divides the sum of the total data amount for the latest predetermined number of screens stored in the storage means by the number of screens detected by the first detection means, and calculates the reference data amount. The data transmission device according to claim 1, wherein the data transmission device is calculated .

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