JP2004040526A - System for distributing image and system for distributing and reproducing image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent image reproduction from being interrupted because the amount of data of unreproduced image stored in a buffer of a client side becomes zero. <P>SOLUTION: A syntax analyzing means 12 analyzes the syntax of encoded string data with the encoded string data obtained by dividing moving image data into one or a plurality of tiles, applying discrete wavelet transformation to a pixel value for each tile and hierarchically compressing and encoding the pixel value as an object. An encoded string preparing means 13 simultaneously and parallelly performs a plurality of operations that prepare different encoded string data from the encoded string data on the basis of this analysis result. A load measuring means 16 measures the load of the encoded string preparing means 13. A parameter preparing means 17 prepares a parameter in preparing encoded string data on the basis of the measured load. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image distribution system and an image distribution and reproduction system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a moving image distribution technology in which moving image data is supplied from a server, a transfer request of moving image data is issued from a client to a server, and a moving image is reproduced by a client based on the received data. . In this technique, download reproduction and stream reproduction are generally known as methods in which a reproduction device on the client side receives and reproduces moving image data from a server.
[0003]
Download reproduction is to reproduce the data downloaded from the server to the buffer of the client. This type is to reproduce the data once it is loaded into the buffer. There is a disadvantage that the playback time is short, but if all the data is received and then played back, there is an advantage that the moving image can be played regardless of the processing load on the server side, the speed of the transmission path, and the congestion situation. .
[0004]
On the other hand, streaming playback is a process in which a playback device on a client side continuously requests data from a server and performs a playback process of a moving image in parallel with an operation of acquiring the data on a buffer. In this type, since the client continuously receives moving image data, the data in its own buffer is reproduced and discarded, while new data is overwritten. Therefore, there is an advantage that a long-time moving image can be reproduced without being limited by the storage capacity of the buffer.
[0005]
However, there are disadvantages in that the server load increases due to an increase in the number of clients accessing the server at the same time, and the transmission line is easily affected by the speed. Therefore, there is a possibility that a serious problem that reproduction of a moving image is stopped due to an increase in a load on a server or a decrease in speed of a transmission line. In general, as a method for avoiding such a serious influence, a method called scalability for changing the capacity of moving image data is known.
[0006]
Conventionally, MPEG1 / MPEG2 / MPEG4 dedicated to moving images and Motion JPEG which treats still images as continuous frames have been used as image compression / decompression algorithms. Recently, however, the encoding of the latter Motion still images has been used. As for, a new method called Motion JPEG2000 is being standardized as an international standard.
[0007]
[Problems to be solved by the invention]
However, in the conventional moving image distribution technology, distribution contents are generally stored on a server in advance with a plurality of scalabilities, and a user selects the most suitable scalability according to a transmission capability of a communication path and a reproduction capability of a client. It is common to perform streaming playback.
[0008]
In this case, since the user who operates the client selects appropriate scalability in consideration of the restriction of the communication path, the load on the server side that distributes image data to a plurality of clients simultaneously and in parallel is determined, and the most suitable is determined. Scalability could not be selected. If the load on the server becomes excessive, the transmission of the code string data to each client tends to be delayed, and the unreproduced moving image data buffered by the client performing the streaming reproduction becomes 0, and the image reproduction is performed. Is broken.
[0009]
An object of the present invention is to prevent the data amount of an unreproduced image stored in a buffer on the client side from becoming zero and the reproduction of an image to be interrupted even when streaming reproduction is performed at a distribution destination of moving image data. It is to prevent.
[0010]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided code string data obtained by dividing moving image data into one or a plurality of rectangular regions for each frame, performing discrete wavelet transform on pixel values for each rectangular region, and hierarchically compressing and encoding. Syntax analysis means for analyzing the syntax of the code string data, and code string creation means capable of simultaneously performing a plurality of tasks of creating another code string data from the code string data based on the analysis result. A transmitting unit that can simultaneously transmit each of the code string data created by the code string creating unit to a plurality of destinations via a network; a load measuring unit that measures a load of the code string creating unit; Parameter creating means for creating a code string parameter when creating code string data by the code string creating means from the measured load; and As parameters of the code string data for creating a code string data by forming means, and a parameter instructing means for adjusting the data amount per unit time to be transmitted by said transmission means, an image distribution system comprising a.
[0011]
Therefore, even if there are many transmission destinations transmitting the code string data in parallel and the load on the code string creation means becomes excessive and transmission is delayed, the load is detected and the appropriate load is detected. By using such a parameter, the moving image data is divided into one or a plurality of rectangular regions for each frame, and the pixel value is discrete wavelet-transformed for each rectangular region. Therefore, it is possible to create code string data that can display a moving image with a small amount of data and distribute it to each distribution destination. It can be prevented that the data amount of the unreproduced image held in the buffer becomes 0 and the reproduction of the image is interrupted.
[0012]
According to a second aspect of the present invention, in the image distribution system according to the first aspect, the parameter created by the parameter creating unit is a parameter related to an image resolution or a frame rate obtained when decoding the code string data, or , Parameters relating to the quantization level of the image.
[0013]
Therefore, it is possible to use a parameter having relatively little effect on the quality of the image, so that the data amount of the code string data can be reduced while maintaining the quality of the image to some extent.
[0014]
According to a third aspect of the present invention, in the image distribution system according to the first or second aspect, the load measured by the load measuring unit is the number of code string data being concurrently created by the code string creating unit. It is.
[0015]
Therefore, it is possible to easily determine the load on the code string creating means from the number of code string data being created simultaneously and in parallel.
[0016]
According to a fourth aspect of the present invention, there is provided an image distribution system that distributes moving image data via a network, and a plurality of image reproduction systems that receive the distributed moving image data and display the image on an image display device. The moving image distribution system includes: dividing moving image data into one or a plurality of rectangular regions for each frame; and performing discrete wavelet transform on pixel values for each of the rectangular regions to code-sequentially compressively code data. As an object, a syntax analysis means for analyzing the syntax of the code string data, and a code string creation means capable of simultaneously performing a plurality of operations for creating another code string data from the code string data based on the analysis result, Transmitting means for simultaneously transmitting each of the code string data created by the code string creating means to a plurality of destinations via a network; A load measuring means for measuring the load, a parameter creating means for creating a code string parameter when the code string data is created by the code string creating means from the measured load, and the created parameter by the code string creating means. Parameter instructing means for adjusting a data amount per unit time transmitted by the transmitting means as a parameter of the code string data when creating the code string data, wherein each of the image reproducing systems comprises: Receiving means for receiving the code string data transmitted from the CPU, decoding means for decoding the received code string data, a buffer for buffering the decoded moving image data, and displaying the decoded image data. And a display device.
[0017]
Therefore, even if there are many transmission destinations transmitting the code string data in parallel and the load on the code string creation means becomes excessive, and the transmission is delayed, the load is detected, and the reception side detects the load. By using the fact that the moving image data is divided into one or a plurality of rectangular regions for each frame, and the pixel values are discretely wavelet-transformed for each rectangular region and compression-coded hierarchically, Code stream data that can display moving images with the amount of data can be created and distributed to each destination, so even if streaming playback is performed at the destination of moving image data, it is retained in the buffer on the client side It is possible to prevent the data amount of the unreproduced image from becoming 0 and the reproduction of the image from being interrupted.
[0018]
According to a fifth aspect of the present invention, in the image distribution / reproduction system according to the fourth aspect, the parameter created by the parameter creating unit is a parameter relating to an image resolution or a frame rate obtained when decoding the code string data; Alternatively, it is a parameter related to the quantization level of the image.
[0019]
Therefore, it is possible to use a parameter having relatively little effect on the quality of the image, so that the data amount of the code string data can be reduced while maintaining the quality of the image to some extent.
[0020]
According to a sixth aspect of the present invention, in the image distribution / reproduction system according to the fourth or fifth aspect, the load measured by the load measuring means is a code string data being concurrently created by the code string creating means. Is a number.
[0021]
Therefore, it is possible to easily determine the load on the code string creating means from the number of code string data being created simultaneously and in parallel.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described.
[0023]
FIG. 1 is a block diagram showing the overall system configuration of the first embodiment. 1, in this system, a server 1 that implements an image distribution system of the present invention and a client 2 that implements an image reproduction system of the present invention are connected via a communication path 3 via a network.
[0024]
The server 1 includes a magnetic storage device 11 that stores moving image data. The magnetic storage device 11 stores code string data obtained by compressing and encoding original moving image data using the JPEG2000 algorithm. Therefore, the code string data is obtained by dividing the moving image data into one or a plurality of rectangular areas (tiles) for each frame, and performing a discrete wavelet transform (DWT) on each of the tiles to obtain a hierarchical structure. It is created by compression encoding.
[0025]
When distributing the code string data to the client 2, the syntax analysis means 12 analyzes the syntax of the code string data, that is, the information described in the data of the header, and the code string creation means 13 performs the analysis based on the analysis result. Then, another code string data is created from the code string data. Then, the generated code string data is transmitted to the client 2 via the communication path 3 via the communication interface 14 which realizes a transmission unit. The code string creation means 13 can create a plurality of code string data simultaneously and in parallel for a plurality of clients 2. The code string creating means 13 includes code string creating means 131 to 13n (n = 1, 2, 3,... N) for creating one piece of code string data, respectively. Create data.
[0026]
The parameter instructing means 15 instructs a parameter used when the code string creating means 13 creates code string data, and adjusts the data amount per unit time when transmitting the code string data by changing the parameter. .
[0027]
The load measuring unit 16 measures the load of the code string creating unit 13. The measurement of the load is determined by, for example, the number of code string data being simultaneously and concurrently created by the code string creating means 13, that is, the number of active code string data among the code string creating means 131 to 13n. Can be.
[0028]
The parameter creating unit 17 creates a code string parameter when the code string creating unit 13 creates code string data from the load measured by the load measuring unit 16.
[0029]
Specifically, for example, a parameter relating to an image resolution or a frame rate obtained when decoding code string data, or a parameter relating to a quantization level of an image can be used. More specifically, the parameters are created, for example, as follows. That is, a threshold value is provided for the load measurement value by the load measurement means 16, and when the load is lower than the threshold value, a large data amount per unit time when transmitting the code string data is maintained. That is, parameters are created so as to increase the image resolution, increase the frame rate, or reduce the quantization level of the image.
[0030]
Then, when the load exceeds the threshold value, the load on the code string creating means 13 is large, so that the data amount per unit time when transmitting the code string data is reduced. That is, parameters are created so as to increase the image resolution, increase the frame rate, or reduce the quantization level of the image.
[0031]
When adjusting the frame rate, all frames are transmitted when the load is small, but the frame rate is reduced as shown in FIG. 2 as the load increases. That is, FIG. 2A shows the original code string data. This code string data includes n frames (bit streams). As shown in FIG. 2B, even-numbered (2, 4,...) Frames are deleted, and By transmitting only one frame, the frame rate can be reduced by half, and the data amount can be reduced by half. When deleting even-numbered (2, 4,...) Frames, only odd-numbered (1, 3,...) Frames from which even-numbered (2, 4,. The header (Herder) is rewritten to obtain new code string data.
[0032]
When adjusting the image resolution, all the sub-band data is transmitted in order to transmit high-resolution image data when the load is small. However, as the load increases, transmission from lower sub-bands is stopped. , Low-resolution image data is transmitted.
[0033]
That is, FIG. 3A shows the contents of a code data file including all the original sub-band data. Here, code data is arranged in order of each subband. Delimiters are included in the breaks between the subbands, so that the boundaries can be easily determined. When the load is small, transmission is performed up to the last sub-band (0), but as the load increases, transmission is performed up to sub-band 1 or 2, 3 and lower sub-bands are not transmitted so as to not transmit the subsequent sub-bands. The band data is deleted, and a new code string as shown in FIG. 3B is created.
[0034]
FIG. 4 shows one subband in the code string of FIG. The sub-band contains coded data in order from the MSB of the bit plane. In the example of FIG. 4, the 2-bit plane data is discarded from the LSB of the original data in FIG. 4A, and a new code string shown in FIG. 4B is created to reduce the data amount. .
[0035]
As shown in FIG. 1, the client 2 implements the image reproduction system of the present invention, and reproduces an image by streaming reproduction. That is, each client 2 (clients 201, 202, 203,..., 20n) receives the code string data created by any of the code string creating units 131 to 13n through the communication interface 21 that implements the receiving unit. The received code string data is decoded by the decoding unit 23, and the decoded moving image data is buffered in the buffer 22 and displayed on the display device 24.
[0036]
The code string data stored in the magnetic storage device 11 is divided into one or a plurality of tiles for each frame by the JPEG2000 algorithm, and the pixel values are discretely wavelet transformed for each tile and hierarchically compressed. Since the encoding has been performed, the syntax analysis means 12 analyzes the syntax of the code string data, and the code string creation means 13 extracts the image resolution and frame rate indicated by the parameters from the code string data based on the analyzed syntax. Alternatively, new code string data is created by selecting necessary data so as to be at the image quantization level.
[0037]
The parameter is created a plurality of times periodically, for example, every one minute or every five minutes while one piece of moving image data is reproduced by the client 2. During the reproduction of the moving image data, the image resolution, the frame rate, or the quantization level of the image may fluctuate.
[0038]
Therefore, the load on the code string creating means 13 becomes excessive, and the transmission of the code string data to each client 2 tends to be delayed, and the data buffered in the buffer 22 in the client 2 becomes low, and the image is reproduced. Is likely to be interrupted, the image resolution is reduced, the frame rate is reduced, or the quantization level of the image is reduced, and the amount of code string data transmitted from the server 1 to the client 2 per unit time is reduced. It is possible to prevent the reproduction of the image from being interrupted even if the number is reduced.
[0039]
In this case, the parameters are related to the image resolution, the frame rate, or the quantization level of the image, so that the image resolution is reduced, the frame rate is reduced, or the quantization level of the image is reduced. Even if the amount of code string data per unit time is reduced, the effect on image quality can be made relatively small.
[0040]
【The invention's effect】
According to the first and fourth aspects of the present invention, even when streaming reproduction is performed at the destination of moving image data, the data amount of the unreproduced image held in the buffer on the client side becomes 0 and the reproduction of the image is stopped. It is possible to prevent disconnection.
[0041]
According to the second and fifth aspects of the present invention, it is possible to reduce the data amount of the code string data while maintaining the image quality to some extent.
[0042]
According to the third and sixth aspects of the present invention, in the first, second, fourth and fifth aspects, the load on the code string creating means is easily determined from the number of code string data being created simultaneously and in parallel. be able to.
[Brief description of the drawings]
FIG. 1 is a block diagram of a system configuration according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram in a case where a frame rate of code string data is adjusted in the system of FIG. 1;
FIG. 3 is an explanatory diagram when adjusting the image resolution of code string data in the system of FIG. 1;
FIG. 4 is an explanatory diagram when adjusting the image resolution of code string data in the system of FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image distribution system 2 Image reproduction system 12 Syntax analysis means 13 Code string creation means 14 Transmission means 15 Parameter instruction means 16 Load measurement means 17 Parameter creation means 21 Receiving means 22 Buffer 23 Decoding means 24 Display device

Claims (6)

The moving image data is divided into one or a plurality of rectangular regions for each frame, and pixel values of each of the rectangular regions are subjected to discrete wavelet transform. Parsing means for parsing the syntax,
Code string creating means capable of simultaneously performing a plurality of tasks of creating another code string data from the code string data based on the analysis result,
Transmitting means for simultaneously transmitting each code string data created by the code string creating means to a plurality of destinations via a network;
Load measuring means for measuring the load of the code string creating means,
Parameter creation means for creating a code string parameter when creating code string data by the code string creation means from the measured load,
Parameter indicating means for adjusting the amount of data per unit time transmitted by the transmitting means as a parameter of the code string data when the generated parameters are used to generate code string data by the code string generating means,
An image distribution system comprising: The parameter created by the parameter creation unit is a parameter related to an image resolution or a frame rate obtained when decoding the code string data, or a parameter related to a quantization level of an image.
The image distribution system according to claim 1. The load measured by the load measuring unit is the number of code string data being concurrently created by the code string creating unit.
The image distribution system according to claim 1. An image distribution system that distributes moving image data via a network,
A plurality of image reproduction systems that receive the distributed moving image data and display the images on an image display device;
With
The video distribution system,
The moving image data is divided into one or a plurality of rectangular regions for each frame, and pixel values of each of the rectangular regions are subjected to discrete wavelet transform. Parsing means for parsing the syntax,
Code string creating means capable of simultaneously performing a plurality of tasks of creating another code string data from the code string data based on the analysis result,
Transmitting means for simultaneously transmitting each code string data created by the code string creating means to a plurality of destinations via a network;
Load measuring means for measuring the load of the code string creating means,
Parameter creation means for creating a code string parameter when creating code string data by the code string creation means from the measured load,
Parameter indicating means for adjusting the amount of data per unit time transmitted by the transmitting means as a parameter of the code string data when the generated parameters are used to generate code string data by the code string generating means,
With
Each of the image reproduction systems,
Receiving means for receiving the code string data transmitted from the transmitting means,
Decoding means for decoding the received code string data;
A buffer for buffering the decoded moving image data;
A display device for displaying the decoded image data,
Has,
Image distribution and playback system. The parameter created by the parameter creation unit is a parameter related to an image resolution or a frame rate obtained when decoding the code string data, or a parameter related to a quantization level of an image.
The image distribution / reproduction system according to claim 4. The load measured by the load measuring unit is the number of code string data being concurrently created by the code string creating unit.
The image distribution / reproduction system according to claim 4.

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