JP2012253822A - Transmission/reception method of mpeg data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate thinning processing of a server side and reception processing of a client side on MPEG data and to reduce influence to a reproduction image even in data lack.SOLUTION: When an I picture of thinned MPEG data is received from a server (S11), a client stores the I picture in a reception data buffer (S13). When a B picture and a P picture, which continue to the I picture, are received (S15), they are stored in the reception data buffer (S13). When the data lacks in a group, reception data buffering is interrupted and a system returns to a next I picture reception (S15), and the picture stored in the reception data buffer is reproduced (S16).

Description

  The present invention relates to a network system in which a server receives MPEG data from a terminal and distributes it to a client, and more particularly to a transmission / reception method corresponding to thinning out of MPEG data or transmission data loss.

  An example of this type of network system is shown in FIG. In a network composed of a plurality of terminals T1 to T4, a server S, and a plurality of clients C1 to C4, MPEG data from the terminals is packetized and placed on a transmission line, and the server S sequentially receives this packet group. And distributed to at least one client.

  Here, there are various network bandwidths between the terminal and the server, and between the server and the client. For example, a high bandwidth (1 Gbps to 100 Mbps) can be obtained due to a restriction due to the transmission speed of an intervening line or a relay device and a data bandwidth restriction of the terminal or the client. ) To low bandwidth (32 kbps to 128 kbps) are mixed.

  For example, as shown in FIG. 6, data is transmitted on the high bandwidth line (100 Mbps) in the route from the terminal T to the server S, and data is transmitted on the low bandwidth line (64 Kbps) in the route from the server S to the client C1. In the route of S → client C2, data is transmitted through a high bandwidth line.

  In such a network system, since the bandwidth is the same between the terminal T and the server S and between the server S and the client C2, the MPEG data from the terminal T can be transmitted to the client C2 without excess or deficiency. On the other hand, since the bandwidth between the server S and the client C1 is low, if the MPEG data received by the server S is transmitted as it is to the client C1, an overflow occurs in the transmission buffer of the server S. Therefore, the server S needs a mechanism for thinning and transmitting the received MPEG data.

  The MPEG image data string buffered in the transmission buffer in the server S is “I, B, B, P, B, B, I, B, B, P, B, B, I, B, B, P, …"become that way. Here, the I picture is compressed with only intra-frame data (corresponding to JPEG data), the P picture is the temporal change from the previous I or P (difference data), and the B picture is from both the previous and next playback images. Predicted (difference data).

  If the MPEG data is randomly thinned out, the I picture (corresponding to JPEG) disappears, and there is a possibility that a data string composed of differential data of only the P picture and the B picture is transmitted, and the client that has received this data string Then, it becomes a disordered image display.

  As a method for thinning out MPEG images, by controlling the thinning rate of a code sequence (B-picture code sequence) of an image that does not become a reference image for inter-picture prediction, it is possible to minimize the loss of smoothness of a reproduced image. Some of them suppress the code transfer rate (see, for example, Patent Document 1).

JP 2001-268574 A

  As in Patent Document 1, in the method of controlling the thinning rate of the B picture, the higher the thinning rate, the greater the influence on the motion of the MPEG image. Further, complicated image processing such as separation of motion activity information of moving images is required.

  In addition, when data loss occurs in network transmission, the image is disturbed in the same way as when thinning out at random.

  An object of the present invention is to provide an MPEG data transmission / reception method capable of simplifying the thinning process on the server side and the receiving process on the client side, and reducing the influence on the reproduced image even if data is lost.

  The present invention is characterized by the following method in order to solve the above problems.

  (1) A MPEG data transmission / reception method in which high-band MPEG data received by a server is thinned out and reproduced by a client that receives the MPEG data in a low band. When an I picture of data is received, the I picture is stored in the received data buffer, and when a B picture and a P picture following the I picture are received, they are stored in the received data buffer, and the received data It has the procedure which reproduces | regenerates the picture stored in the buffer.

  (2) An MPEG data transmission / reception method in which MPEG data received by a server is transmitted to a client, and the MPEG data is received and reproduced by the client. The client transmits an I picture of the MPEG data received from the server. When received, the I picture is stored in the received data buffer, and when the B picture and P picture following the I picture are received, they are stored in the received data buffer and stored in the received data buffer. It has a procedure for reproducing a picture.

  According to the present invention, the client side stores the I picture in the reception data buffer, and when the B picture and the P picture following the I picture are received, the client side sequentially stores them in the reception data buffer and reproduces them. As long as no I picture is lost, the minimum I picture (equivalent to JPEG) can be reproduced. Further, the reception process on the client side automatically deletes from the missing picture to the picture immediately before the next I picture, and since there is no missing I picture corresponding to JPEG, the influence on the reproduced image can be reduced.

The transmission processing flowchart of the server which shows Embodiment 1 of this invention. Example of thinning out by group. The client reception process flowchart which shows Embodiment 2 of this invention. Example of buffering received data. An example of a network system. An example of sending and receiving high and low bandwidth data.

(Embodiment 1)
FIG. 1 is a transmission processing flowchart by the server, and the thinning-out processing in this transmission is realized by computer resources constituting the server and a software configuration using the same.

  When the server receives the MPEG data packet from the terminal, the server performs reception buffering processing for decoding the packet and sequentially storing it in the reception buffer for each client (S1).

  Next, the MPEG data stored in the reception buffer is grouped asynchronously with the reception buffering process (S2). In this grouping process, data from the I picture to the data immediately before the next I picture is grouped as one group.

  Next, thinning out is performed on a group basis (S3). In this thinning process, a group unit is targeted for thinning, the number of groups to be thinned is determined according to the bandwidth of the transmission line, and the number of thinning groups increases as the transmission band decreases.

  Transmission buffering processing is performed in which MPEG data thinned out in groups is sequentially stored in the transmission buffer (S4). The MPEG data stored in the transmission buffer is encoded and transmitted to the destination client (S5).

  A specific process example of the processes S2 and S3 is shown in FIG. In the grouping process (S2), since the data from the I picture to the data immediately before the next I picture are grouped as one group, the first data is grouped as groups 1 to 11 where the I picture becomes the I picture. The group thinning process (S3) indicates a case where two groups are thinned out from three groups, and the thinning result is a transmission data string such as group 1, group 4, group 7, group 10,.

  As described above, according to the present embodiment, MPEG data thinning-out processing includes simple grouping processing for grouping data from an I picture to data immediately before the next I-picture as one group, and thinning-out processing for each group. Since the processing is sufficient and there is no missing I picture equivalent to JPEG, the influence on the reproduced image at the client can be reduced.

(Embodiment 2)
FIG. 3 is a flowchart of MPEG data reception processing by the client, and this reception processing is realized by a computer resource constituting the client and a software configuration using the computer resource.

  The client receives the MPEG data packet transmitted from the server, decodes it, and sequentially captures it (S11). This reception is performed in units of pictures (I, P, B).

  Next, it is checked whether the received picture is an I picture (S12). If it is not an I picture, the process returns to the reception process for the next picture (S11).

  When the received picture is an I picture, this picture is stored in the received data buffer (S13), the next picture following this picture is fetched (S14), and it is checked whether this picture is a continuation of the previous picture (S15). ). If the check is not a continuation of the previous picture, the process returns to the reception process for the next picture (S11). In the case of a continuation picture, the picture is stored in the reception data buffer (S13).

  The check in step S15 is performed based on the sequence number included in the header information of the MPEG data, and the lack of group pictures can be determined based on whether the sequence numbers are continuous.

  Therefore, as shown in the example of buffering in FIG. 4, the received data buffer sequentially stores from the I picture to the picture immediately before the next I picture, and there is data loss in the group (thinning on the server side). If the data loss occurs in the transmission path), the reception data buffering is interrupted and the process returns to the reception of the next I picture, and the deleted reception data is obtained from the data loss picture to the picture immediately before the next I picture. be able to.

  The MPEG data stored in the reception data buffer is reproduced and processed as an image in which they are continuous (S16).

  As described above, according to the present embodiment, when the received MPEG data has been thinned out in units of groups by the server, or has been thinned out at random, or data is lost on the transmission path, I picture As long as there is no omission, a minimum I picture (equivalent to JPEG) can be reproduced. Also, in this reception process, the deletion from the missing picture to the picture immediately before the next I picture is automatically performed, and since there is no missing I picture equivalent to JPEG, the influence on the reproduced image can be reduced.

S server T, T1-T4 terminal C1-C4 client

Claims (2)

An MPEG data transmission / reception method in which high-band MPEG data received by a server is thinned out and reproduced by a client that receives the MPEG data in a low band,
The client stores the I picture in the received data buffer when receiving the I picture of the thinned MPEG data from the server, and when the B picture and the P picture following the I picture are received, Storing in the reception data buffer, and when there is data loss in the group, the reception data buffering is interrupted to return to reception of the next I picture, and a procedure for reproducing the picture stored in the reception data buffer is included. A featured MPEG data transmission / reception method. An MPEG data transmission / reception method in which MPEG data received by a server is transmitted to a client, and the MPEG data is received and reproduced by the client.
The client stores the I picture in the received data buffer when receiving the I picture of the MPEG data received from the server, and when the B picture and the P picture following the I picture are received, It is stored in the reception data buffer, and when there is data loss in the group, the reception data buffering is interrupted to return to reception of the next I picture, and a procedure for reproducing the picture stored in the reception data buffer is provided. MPEG data transmission / reception method.

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