JP2003111048A - Server and program for content reproduction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contents reproduction technology capable of efficiently attaining fast forward reproduction and rewinding reproduction of contents without the need for downloading of entire contents to a terminal. SOLUTION: A server transmits a table including a data position random accessible in the contents and a data quantity in the unit of contents independently coded, to a terminal. The terminal repeats processing of referring to the table to transmit the data position and the prescribe data quantity to the server and receiving data of the contents corresponding to the data position and the data quantity to reproduce the contents.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for reproducing content such as video and audio via a network. In particular, the present invention relates to a technology that enables fast-forward reproduction and rewind reproduction of contents.

[0002]

2. Description of the Related Art In the prior art, in order to perform fast-forward playback and rewind playback of content such as MPEG-2, the entire content is downloaded (buffered) from a server to a terminal, and the buffered content is played back. It was processing.

[0003]

However, in MPEG-2 contents (for example, DVD) such as movies, the size of the whole contents may be several GB, and in such a case, it is assumed that a high-speed line can be prepared. However, it is difficult to store the entire contents in the terminal. Further, in the case of such a large data size, it is necessary to temporarily store it as a file, which may cause a copyright management problem.

Further, when downloading the entire contents as described above, there is a problem that the data of the frame which is not necessary for the fast-forward reproduction is also received, and the network is not effectively used.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a technique capable of efficiently performing fast-forward playback and rewind playback of content without downloading the entire content to a terminal. And

[0006]

In order to achieve the above object, the present invention can be configured as follows.

The present invention is a server for transmitting content to a terminal for content reproduction via a network, wherein a randomly accessible data position in the content and independently encoded content corresponding to the data position. Means for transmitting a table including a unit data amount to a terminal, means for randomly accessible data position in the content, and means for receiving a predetermined data amount from the terminal, and corresponding to the data position and the predetermined data amount Means for transmitting the data of the content to be transmitted to the terminal.

According to the present invention, a randomly accessible data position (for example, a GOP head position in MPEG) in a content and a content unit (for example, an I picture in MPEG) that is independently encoded and corresponds to the data position. Since the table including the data amount is transmitted to the terminal, the terminal refers to the table to enable random access to the content without downloading the entire content, and, for example, only the I picture is downloaded. By making continuous requests, fast-forward playback and rewind playback are possible.

That is, the predetermined data amount is set as the data amount of the content unit independently encoded corresponding to the data position, the terminal continuously changes the data position, and the data position and the predetermined data are changed. The amount of data and the amount of data are received from the terminal and the data of the data position and the content data corresponding to the predetermined amount of data are repeatedly transmitted to the terminal.

Further, if the terminal requests the server for the data amount between the randomly accessible data position and the next data position, normal reproduction is possible.

Further, the terminal according to the present invention acquires a table including a randomly accessible data position in the content and the data amount of the content unit independently encoded corresponding to the data position, and uses the table. With reference to the content, a randomly accessible data position in the content and a predetermined data amount from the data position are transmitted to the server, and content data corresponding to the data position and the predetermined data amount is received from the server. ,Reproduce.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description, MPEG-2Vi
Although the GOP configuration of deo will be described as an example, the present invention can be applied to various encoding methods other than MPEG-2 as long as the content is randomly accessible (video and audio can be multiplexed).

First, the outline of the present invention will be described with reference to FIGS.

As shown in FIG. 1, MPEG-2 contents (hereinafter, contents are also referred to as streams).
Is composed of a plurality of GOPs (Group Of Pictures). The number of frames included in a GOP is normally about 15 frames (0.5 seconds), the head of the GOP is an intra-frame predicted I picture that is independently coded without using a reference screen, and the subsequent frames are It is a combination of inter-predicted P pictures or B pictures. In interframe prediction,
Decoding is possible only when there is a frame used for prediction, while intra-frame prediction does not require information of other frames.

Therefore, as shown in FIG. 1, fast-forward reproduction can be realized by searching the head of the GOP in the stream and decoding and displaying only the I picture. Also, by searching, decoding and displaying in the reverse direction,
It is possible to realize rewind reproduction. Moreover, random access is possible by designating an arbitrary GOP head position.

FIG. 2 is a sequence diagram of content reproduction according to the present invention.

On the server side, the GOP head position of each content is searched in advance and a table (GOP head position information, I picture stream size, GOP stream size) is stored together with the content. The terminal downloads the table before receiving the content (steps 1 to 4).
As a result, the terminal can instantly grasp the data position of the frame to be displayed.

That is, the terminal uses the information in this table to obtain the G required according to the reproduction method requested by the user.
The OP start position and the stream size are selected, and the stream is requested to the server (steps 5 and 6). The terminal receives a stream in response to the request from the server and sequentially reproduces the stream, thereby realizing a reproduction method such as fast-forward reproduction and rewind reproduction within the content (step 7-).

The terminal can request the data from the GOP head position shown in the downloaded table for each GOP required for decoding, and the server delivers the data from the requested position. As a result, the terminal does not need to buffer the data required for fast-forward reproduction and rewind reproduction.

Further, as described above, by making a table of the data size of the I picture and the data size of the GOP in advance, it is possible to request only the I picture at the time of fast forward reproduction or rewinding reproduction, and request the entire GOP at the time of normal reproduction. It is possible. Therefore, the terminal requests / acquires only the necessary data size according to the situation, and it is not necessary to send unnecessary data to the network.

Next, the system configuration and operation of the present invention will be described in detail.

FIG. 3 is a block diagram of a content reproduction system according to the embodiment of the present invention. As shown in the figure, the content reproduction system of the present invention has a configuration in which a server 1 and a terminal 2 are connected to a network 3.

The server 1 has content data 11 consisting of stream data and a table linked to the stream data, and a stream delivery section 12 for delivering the stream data. The terminal 2 has a stream request unit 21 that requests stream data from the server 1, and a decoder unit 22 that decodes content (stream data). The network 3 is, for example, the Internet or an intranet.

The terminal 2 acquires the table 23 from the server 1 and stores it. The stream request unit 21 has a table 23.
The content is requested by transmitting the position and size to the stream distribution unit 12, the stream distribution unit 12 transmits the stream data corresponding to the request to the terminal 2, and the decoder unit 22 performs decoding. As a result, an image or the like is displayed.

The details of each unit in the above system will be described below.

First, a method of generating a table in the server 1 will be described.

FIG. 4 shows an example of the stream structure of MPEG-2. As shown in this example, the MPEG-2 stream is composed of a sequence header 5 and a plurality of GOPs 6. One GOP is composed of a GOP header 7 and a plurality of picture data 8, and a picture header 9 exists at the beginning of the picture data. Each picture data becomes image data for one frame.

At the beginning of each header, from the byte boundary, as shown in FIG.
Since the synchronization marker shown in 1 exists, the head of each header is detected by searching this synchronization marker. Also,
The I picture data size can be obtained as the size from the GOP head position to the end of the head picture data, and the GOP data size can be obtained as the size from the GOP head position to the end of the GOP in one GOP.

A table is created based on the values thus obtained. An example of the table is shown in FIG. In this example, No. The 74-byte data indicated by 0 is a sequence header.

FIG. 7 shows a flowchart of processing in the stream request unit 21 of the terminal 2. As shown in the figure, the stream request unit 21 determines the playback type requested by the user (step 21), and performs various types of playback (normal playback, fast-forward playback, rewind playback) according to the determination result. Perform stream request processing. The stream request process is performed in GOP units. The stream request processing for each reproduction will be described below.

In the case of normal reproduction (step 22), as shown in FIG. 8, first, the GOP at the time when the normal reproduction is desired to start.
The head position and the GOP data size for this GOP head position are requested to the server 1 (step 221). After receiving the requested stream, the GOP head position immediately after the received stream and the GOP for the GOP head position
Request the stream size (step 222). Normal reproduction is realized by repeating this.

In the case of fast forward reproduction (step 23), FIG.
As shown in, first, G at the time you want to start fast forward playback.
The OP start position and the I picture data size for this GOP start position are requested (step 231). After receiving the requested stream, G immediately after the received stream
The OP start position and the I picture data size for the GOP start position are requested (step 232). By repeating this, fast-forward reproduction is realized.

In the case of rewinding reproduction (step 24), FIG.
As shown in 0, first, the GOP start position at the time when the rewind reproduction is to be started and the I picture data size for this GOP start position are requested (step 241). After receiving the requested stream, the GOP head position immediately before the received stream and the I picture data size for the GOP head position are requested (step 242). Rewinding reproduction is realized by repeating this.

Further, just before the reproduction type is determined, the desired GOP can be arbitrarily selected to enable random access within the content. That is, as shown in FIG. 11, when a position at which random access is desired is selected in the terminal 2 (for example, the 134545th byte of No. 3 in FIG. 6 is selected), the terminal 2 selects a GOP byte (7 bytes) from that position.
(1904 bytes) of stream data is requested to the server 1. The server 1 transmits the data to the terminal 2, and the terminal 2 decodes and displays the data. In this way
Content can be played by random access. Of course, random access can also be performed for fast forward playback and rewind playback.

FIG. 12 shows the stream distribution unit 1 of the server 1.
2 shows a flowchart of stream distribution processing in 2. As shown in the figure, the stream distribution unit 1 of the server 1
2 receives the GOP head position and the data size from the stream request unit 21 of the terminal 2 (step 31), and the GO
Based on the P head position, data of the requested size is acquired from the stream data (step 32), and the acquired data is transmitted to the terminal 2 (step 33). Since the stream request process by the stream request unit 21 is performed in GOP units, the stream distribution process is also performed in GOP units.

The decoder unit 22 of the terminal 2 sequentially decodes the data distributed from the server 1 and displays the decoded video.
Operations such as fast-forward reproduction and rewind reproduction are realized by the method of acquiring stream data, and therefore the decoding process itself may be the same as that of the conventional technique.

The processing on the terminal side and the server side in the present invention can be realized as a program, respectively, and the programs corresponding to the terminal side and the server side are installed in the computer as the terminal and the computer as the server, respectively, to reproduce the content of the present invention. Processing can be performed.

The present invention is not limited to the above embodiments, and various modifications and applications are possible within the scope of the claims.

[0039]

According to the present invention, it is possible to efficiently perform fast-forward reproduction, rewind reproduction and random access of content without buffering the entire content in the terminal.

Further, since the terminal requests / acquires only the required data size from the server according to the situation, there is no need to send useless data to the network, and the network can be used effectively.

[0041]

[Brief description of drawings]

FIG. 1 is a diagram for explaining the outline of the present invention.

FIG. 2 is a sequence diagram of content reproduction according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a content reproduction system according to the embodiment of the present invention.

FIG. 4 is a diagram showing an example of a stream structure of MPEG-2.

FIG. 5 is a diagram showing a synchronization marker.

FIG. 6 is a diagram showing an example of a table.

FIG. 7 is a flowchart of processing in the stream request unit 21 of the terminal 2.

FIG. 8 is a diagram showing stream request processing in normal reproduction.

FIG. 9 is a diagram showing stream request processing in fast-forward reproduction.

FIG. 10 is a diagram showing stream request processing in rewind reproduction.

FIG. 11 is a diagram for explaining a random access method.

FIG. 12 is a diagram showing a flowchart of stream distribution processing in the stream distribution unit 12 of the server 1.

[Explanation of symbols]

1 server 2 terminals 3 network 5 Sequence header 6 GOP 7 GOP header 8 picture data 9 Picture header 11 Content data 12 Stream distribution section 21 Stream Request Section 22 Decoder section

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C053 FA28 GA11 GB05 GB21 GB38                       HA21 JA01 LA15                 5C059 MA00 PP05 PP06 PP07 RC02                       RC04 SS08 SS17 SS18 UA01                       UA36 UA38 UA39                 5C064 BA01 BB10 BC18 BC23 BD02                       BD08 BD14                 5D044 AB07 BC03 CC06 CC08 DE28                       DE40 DE55 FG10 FG18 FG24                       GK04 GK08 GK12 HH07

Claims (9)

[Claims] 1. A server for transmitting content to a terminal for content reproduction via a network, wherein a randomly accessible data position in the content and an independently encoded content unit corresponding to the data position. Means for transmitting to the terminal a table including the data amount of, a means for receiving a randomly accessible data position in the content and a predetermined data amount from the terminal, and corresponding to the data position and the predetermined data amount. And a means for transmitting data of the content to be transmitted to the terminal. 2. The predetermined data amount is a data amount of a content unit that is independently encoded and corresponds to the data position, and the terminal continuously changes the data position to determine the data position and the predetermined data amount. 3. The server according to claim 2, further comprising: repeatedly receiving the data amount and the data amount of the content from the terminal and transmitting the data of the content corresponding to the data position and the predetermined data amount to the terminal. 3. The server according to claim 1, wherein the randomly accessible data position is a head position of a GOP in MPEG, and the independently encoded content unit is an I picture. 4. A program for causing a computer to execute a process of transmitting content to a terminal for content reproduction via a network, the data position being randomly accessible in the content, and independently corresponding to the data position. A procedure of transmitting to the terminal a table including the data amount of each content unit to be encoded, a procedure of receiving a randomly accessible data position in the content and a predetermined data amount from the terminal, the data position and the A program for causing a computer to execute a procedure of transmitting content data corresponding to a predetermined data amount to a terminal. 5. The predetermined data amount is a data amount of a content unit that is independently encoded and corresponds to the data position, and the terminal continuously changes the data position to determine the data position and the predetermined data amount. 5. The program according to claim 4, wherein the computer is made to repeatedly execute the step of receiving the data amount and the amount of data from the terminal and transmitting the data of the content corresponding to the data position and the predetermined data amount to the terminal. 6. The program according to claim 4, wherein the randomly accessible data position is a head position of a GOP in MPEG, and the independently encoded content unit is an I picture. 7. A program for causing a computer to execute a process of playing back content stored in a server via a network, wherein a randomly accessible data position in the content and independent coding corresponding to the data position. A procedure for acquiring a table containing the data amount of each content unit, and referring to the table, transmitting a randomly accessible data position in the content and a predetermined data amount from the data position to the server A program that causes a computer to execute a procedure and a procedure of receiving content data corresponding to the data position and the predetermined data amount from a server and reproducing the content data. 8. The predetermined data amount is a data amount of content units independently encoded corresponding to the data position, and the data position and the predetermined data amount are transmitted to a server,
The program according to claim 7, which causes a computer to execute a procedure of continuously receiving data of a content corresponding to the data position and the predetermined data amount from a server by continuously changing the data position. 9. The program according to claim 7, wherein the randomly accessible data position is a head position of a GOP in MPEG, and the independently encoded content unit is an I picture.