AU2003248319B2 - Motion picture transmission system, transmission system for emergency medical service and motion picture transmitting device - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): MITSUBISHI DENKI KABUSHIKI KAISHA Invention Title: MOTION PICTURE TRANSMISSION SYSTEM, TRANSMISSION SYSTEM FOR EMERGENCY MEDICAL SERVICE AND MOTION PICTURE TRANSMITTING DEVICE The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 MOTION PICTURE TRANSMISSION SYSTEM, TRANSMISSION SYSTEM FOR EMERGENCY MEDICAL SERVICE AND MOTION PICTURE TRANSMITTING DEVICE BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to a motion picture transmission system, a transmission system for an emergency medical service and a motion picture transmitting device, and more particularly to an improvement of a motion picture transmission system for transmitting high-quality frame pictures by using a transmission path having a narrow band.

2. Description of the Related Art A system for transmitting information concerning the condition of a patient from an ambulance carrying the patient to a doctor at a remote place through mobile communications via an artificial satellite has been considered in the field of remote medical service (as disclosed in "EMERGENCY MEDICAL SERVICE APPLICATION <NUMBER OF LINES AND BAND NEEDED FOR MOTION PICTURE TRANSMISSION FROM AMBULANCE> ADDRESSED TO OBLONG/FIGURE- OF-EIGHT SATELLITE" written by Hisashi Nakajima, other four persons, February of 2001, pp17-24 of Technical Research Report SANE2000-178 SAT2000-127 of The Institute of Electronics, Information and Communication Engineers (hereinafter referred to as "non-patent document If a doctor in a hospital can grasp the condition of a patient through a data communication line when an ambulance attendant makes a medical procedure or medical cure in an ambulance, the doctor can give a proper instruction to the ambulance attendant. A high-speed data communication line through which a high-quality motion H,\akhoo\Kee\Temp\P50789 AU.doc 24/09/03 3 picture can be transmitted is needed to implement such a remote medical service.

Communication satellites used in the conventional mobile communication are geosynchronous satellites on the equator or low-orbit go-around satellites, and each satellite has a small antenna elevation angle. Therefore, shadowing caused by obstruction of buildings or a clump of trees to communications is liable to occur, and thus these satellites are unsuitable as communication means at the emergency carrying time. Therefore, motion picture transmission using an artificial satellite passing through quasi-zenith (quasi-zenith satellite) has been proposed.

The quasi-zenith satellite is a satellite (so-called figure-of-eight satellite or the like) going around an oblong orbit higher in altitude than a geosynchronous satellite, and it has a feature that a large antenna elevation angle can be secured and shadowing occurs hardly.

According to the non-patent document i, it is reported that a band width of 6Mbps per ambulance is needed and at least 50 ambulances are needed to operate at the same time all over the country. Accordingly, in the case of the quasi-zenith satellite (figure-of-eight satellite), it is estimated that a line capacity of (6Mbps per satellite) x 50 satellites 300Mbps is needed.

However, the line capacity of 300Mbps imposes an excessively large load on the line design of the quasizenith satellite, and it is necessary to reduce the required line capacity at maximum.

A method of reducing the information amount of a motion picture by reducing the quality of each frame picture constituting the motion picture in MPEG 2 is known as a conventional technique for reducing the transmission HR\akhoo\Keep\Temp\PS0789 AU.doc 24/09/03 4 band width of a motion picture. In general, the motion picture is constructed by a series of image frames sampled at a frame period, and the data amount of the motion picture can be reduced by reducing the data amount of each frame.

Furthermore, a method disclosed in JP-A-7-15609 (hereinafter referred to as "patent document is known as another conventional technique. The technique described in this publication uses wavelet transform as a coding method of a motion picture. According to this technique, by carrying out the wavelet transform at a transmission terminal, a motion picture can be decoded at a reception terminal without receiving all the signals needed to decode the motion picture at the stage that a predetermined signal is received when wavelet decoding is carried out at the reception terminal. Therefore, the transmission band width of the motion picture can be reduced.

If these techniques are applied, the motion picture data can be transmitted in accordance with the band width of the transmission path between a motion picture transmission terminal and a motion picture reception terminal. That is, the band width transmitted from the motion picture transmission terminal can be reduced, and the line capacity needed for the transmission of the motion picture can be reduced.

However, according to MPEG2 or the conventional method disclosed in the patent document i, there is a problem that the quality of each frame picture constituting a motion picture is deteriorated in any case.

Therefore, these conventional techniques are not.applied to a field in which high quality is required to frame pictures. Particularly when a doctor observes the H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 5 condition of a patient through transmitted motion pictures under an application to the medical field, the doctor is neededto observe the facial expression of the patient minutely, however, under such an application, it is impossible to reduce the bandwidth by using the conventional techniques.

Here, when a motion picture is transmitted in the form of a series of image frames, it may be considered that the quality of each frame image is not deteriorated, but the frame rate is reduced to reduce the data amount of the motion picture. That is, the data amount of each frame is not reduced, but the number of frames is reduced.

Particularly under the application to the medical field, a motion picture representing the facial expression of a patient has a smaller movement as compared with general motion pictures. Therefore, it is desirable to reduce the required transmission band width by reducing the frame transmission rate without lowering the quality of each frame image.

However, according to the MPEG2 standard which has been already popular as an encoder for motion pictures in the general market, it is necessary to set the frame rate to about 30 frames per second at all times, and thus transmission control for reducing the rate is not permitted. It is possible in principle to adopt an encoder which can control the frame rate. However, it is not preferable from the viewpoint of the cost performance that a peculiar encoder which goes against the MPEG2 standard is introduced into a motion picture transmission terminal.

Besides, as another proposal may be considered that activities of introducing a change of the standard will be broadened to newly introduce the control of reducing the H \akhoo\Keep\Temp\P50789 AU.doc 24/09/03 6 frame rate into the standard specification of MPEG 2.

However, it is estimated that it is difficult to achieve agreements on the standard change of the broadly-popular MPEG2 standard in the standardization organization.

SUMMARY OF THE INVENTION SAccording to one aspect of the present invention 00 there is provided a motion picture transmission system Scomprising: a motion picture transmission terminal for transmitting motion picture frame data which comprises a series of picture frames generated at a predetermined frame rate in the form of one data packet or two or more data packets; a motion picture transmission device for discarding data packets received from the motion picture transmission terminal on the basis of attribute data in data packets to reduce the number of packets; and a motion picture reception terminal for receiving data packets from the motion picture transmission device which were not discarded, wherein the motion picture reception terminal transmits a packet reducing instruction to the motion picture transmission device, and the motion picture transmission device discards the data packets from the motion picture transmission terminal on the basis of the packet reducing instruction from the motion picture reception terminal.

According to another aspect of the present invention there is provided a transmission system for emergency medical service for transmitting motion picture data from a motion picture transmission terminal mounted in a vehicle through a communication satellite to a motion picture reception terminal mounted in a medical H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 7 institution, wherein the motion picture transmission terminal transmits each frame data of motion picture data comprising a series of picture frames generated at a predetermined frame rate in the form of one data packet or two or more data packets, and the vehicle is equipped with O_ a motion picture transmission device for discarding data Spackets on the basis of attribute data in data packets 00 received from the motion picture transmission terminal to Sreduce the number of packets based on a packet reducing instruction received from a motion picture reception terminal, and a satellite line controller for transmitting the data packets from the motion picture transmission device to the communication satellite in a wireless style.

According to another aspect of the present invention there is provided a motion picture transmission device for receiving motion picture data generated at a predetermined frame rate from a motion picture transmission terminal and transmitting the motion picture data to a motion picture reception device, comprising: a first communication line interface for receiving each frame data in the form of one data packet or in the form of two or more data packets from the motion picture transmission terminal; a packet reducing controller for discarding data packets on the basis of attribute data in data packets received from the motion picture transmission terminal to reduce the number of packets based on a packet reducing instruction received from a motion picture reception terminal; and a second communication line interface for transmitting to the motion picture reception terminal data packets after the number of packets is reduced.

H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 -8 THIS PAGE HAS BEEN LEFT INTENTIONALLY BLANK 00 H:\deboram\keep\specifications\P50789 speci amended 20050719 AUdoc 19/07/05 9 BRIEF DESCRIPTION OF THE DRAWINGS

(N

Fig. 1 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a first embodiment of the present invention; Fig. 2 is a block diagram showing an example of the rn construction of each device of Fig. 1; 00 SFig. 3 is a conceptual diagram showing an example of MPEG data in which many MPEG pictures are arranged in the image-pickup order on the time axis (horizontal direction); Fig. 4 is a diagram showing an example of the construction of a data packet transmitted from an MPEG transmission terminal 1 to an MPEG reception terminal 3; Fig. 5 shows an example when packets are discarded every picture group GOP; Fig. 6 shows an example when only pictures on which motion compensation has been carried out are discarded; H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 10 Fig. 7 shows an example when only pictures on which bi-directional motion compensation has been carried out are discarded; Fig. 8 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a second embodiment of the present invention; Fig. 9 is a block diagram showing an example of the main part of a motion picture transmission device 2A; io Fig. 10 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a third embodiment of the present invention; Fig. 11 is a diagram showing an example under another operation state of the motion picture transmission system of Fig. Fig. 12 is a block diagram showing an example of the main part of a motion picture transmission device 2B of Figs. 10 and 11; Fig. 13 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a fourth embodiment of the present invention; Fig. 14 is a block diagram showing an example of the construction of the main part of the motion picture transmission device 2C of Fig. 13; Fig. 15 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a fifth embodiment of the present invention; Fig. 16 is a block diagram showing an example of the construction of the main part of a motion picture transmission device 2D of Fig. Ht\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 11 Fig 17 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a sixth embodiment of the present invention; Fig. 18 is a diagram showing the schematic construction of a motion picture transmission system for emergency medical service; Fig. 19 is a diagram showing an example of the construction of the main part of an ambulance 61 of Fig.

18; and Fig. 20 is a diagram showing another example of the construction of the main part of the ambulance 61 of Fig.

18.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described hereunder with reference to the accompanying drawings.

[First Embodiment] Fig. 1 is a schematic diagram showing an example of the construction and operation of a motion picture transmission system according to a first embodiment of the present invention. An MPEG transmission terminal 1 and an MPEG reception terminal 3 are connected to each other through a communication network NW, and packeted motion picture data are transmitted from the MPEG transmission terminal 1 to the MPEG reception terminal 3.

The communication network NW comprises a first transmission path 41, a second transmission path 42 and a motion picture transmission device 2. The motion picture transmission device 2 is connected to the MPEG transmission terminal 1 through the first transmission path 41, and also it is connected to the MPEG reception H.\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 12 terminal 3 through the second transmission path 42, thereby relaying the data transmission from the MPEG transmission terminal 1 to the MPEG reception terminal 3.

The transmission band width of the MPEG motion picture through the second transmission path 42 is narrower than the transmission band width of the MPEG motion picture through the first transmission path 41, and thin-out of motion picture data packets is carried out in the motion picture transmission device 2. That is, the motion picture transmission device 2 discards some of packets received from the second transmission path 42, and transmits the remaining packets to the second transmission path 42.

The thin-out of packets is carried out every picture frame (containing every assembly of picture frames) on the basis of the attribute data of the received packets, so that the frame transmission rate is reduced in the motion picture transmission device 2. That is, an MPEG motion picture is transmitted from the MPEG transmission terminal 1 at a high frame transmission rate, but the MPEG motion picture thus transmitted is received at a lower frame transmission rate at the MPEG reception terminal 3.

Fig. 2 is a block diagram showing an example of the construction of each device in Fig. 1.

The MPEG transmission terminal 1 comprises an MPEG encoder 10 and a packet transmitter 11. Motion picture data input from an image pickup device or the like are coded by the MPEG encoder 10 and converted to MPEG-TS (Transport Stream). The packet transmitter 11 encapsulates MPEG-TS to IP packets, and then transmits the IP packets to the first transmission path 41.

The MPEG reception terminal 3 comprises a packet receiver 30 and an MPEG decoder 31, and an IP packet H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 13 received from the second transmission path 42 is developed into MPEG-TS by the packet receiver 30. The MPEG decoder 31 decodes the MPEG-TS thus developed, and outputs the motion picture data to video display equipment or the like.

Fig. 3 is a conceptual diagram showing an example of the MPEG data, and many MPEG pictures are arranged in the image-pickup order on the time axis (in the horizontal direction). In general, a motion picture is divided into picture frames comprising still pictures sampled at a predetermined frame rate (30 frames per second), and the motion picture data comprises a series of picture frames.

The frame picture of MPEG is called a picture, and the pictures are classified into three kinds of picture types, I pictures (Intra-coded pictures), P pictures (Predictivecoded pictures) and B pictures (Bidirectionally predictive-coded pictures) The I picture is a picture from which the data amount is reduced through in-frame coding processing, and the coding is carried out on the basis of only a picture frame to be coded. Normally, it is generated by quantizing a coefficient achieved through two-dimensional DCT (Discrete Cosine Translation) and then subjecting the quantized coefficient to entropy coding.

The P picture and the B picture are pictures from which the data amount is reduced through the coding processing between picture frames, and the coding is carried out by motion compensation using other picture frames. In the case of the P picture, the coding is carried out by performing forward prediction using a picture frame in one direction on the time axis (past picture frame). In the case of the B picture, the coding is carried out by performing forward and backward Hi\akhoo\Keep\Temp\P5O1R9 AU~doc 24/09/03 i4 prediction using picture .frames in bidirection on the time axis (past and future picture frames) A series of pictures are sectioned into picture groups (GOP: Group Of Pictures) which provide access points at the random access time. Each picture group comprises plural pictures which are different in type and arranged according to a predetermined rule, and these picture groups are accessed every picture group at the random access time.

Fig. 4 is a diagram showing an example of the construction of the data packet transmitted from the MPEG transmission terminal 1 to the MPEG reception terminal 3.

The data packet 5 shown in Fig. 4 comprises an IP header an UDP header 51, an RTP header 52 and an RTP payload 53. The RTP payload 53 comprises an MPEG header 54 and an MPEG content With respect to the data packet, IP (Internet Protocol), UDP (User Datagram Protocol) and RTP (Real-time Transport Protocol) are adopted as communication protocols of a network layer, a transport layer and an application layer. Furthermore, the MPEG content 55 is added with an MPEG header 54 on the basis of IETF (Internet Engineering Task Force) Standard RFC2250 (RTP Payload Format for MPEG1/MPEG2 Video), and encapsulated as an MPEG payload 53.

UDP/IP is a simple communication protocol in which no attention is paid to missing of transmission packet and fluctuation of delay on the transmission path. Retransmission processing is not carried out even when a packet is missing, so that high-speed data transmission can be performed and thus it is broadly used for motion picture data for which real-time is required. IP addresses, etc. for a transmission source and a H.\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 15 transmission destination are stored in the IP header Furthermore, port numbers, etc. for a transmission source and a transmission destination are stored in the UDP header 51.

A timestamp and a sequence number are stored in the RTP header 52, and the MPEG reception terminal 3 can detect the delay time and the packet missing on the transmission path on the basis of the RTP header. Such a reception status is periodically transmitted and fed back from the MPEG reception terminal 3 to the MPEG transmission terminal 1 by using RTCP (RTP Control Protocol) In the RTP header 52 is stored a 1-bit marker representing the end of a picture group (GOP). Therefore, by analyzing the RTP header 52, the MPEG reception terminal 3 can identify the last packet of each GOP on the basis of the marker.

The MPEG content 55 is constructed by one MPEG-TS (Transport Stream) packet or by two or more MPEG-TS (Transport Stream) packets. MPEG-TS is packet data of 188 bytes generated from the MPEG picture. In the MPEG header 54 is stored a picture type of MPEG picture contained in the MPEG content 55. Therefore, the MPEG reception terminal 3 can identify the picture type by analyzing the MPEG header 54.

Next, the operation in the motion picture transmission device 2 will be described.

When receiving an IP packet from the MPEG transmission terminal 1, the motion picture transmission device 2 analyzes the attribute information of the MPEG motion picture data contained in the IP packet to judge whether the IP packet concerned should be discarded or not. Decision of discard is performed every picture group H \akhoo\Keep\Temp\P50789 AU.doc 24/09/03 -16 (GOP) or every picture, and IP packets are discarded every IP packet. As a result, IP packets which are not discarded and thus remain are transmitted to the MPEG reception terminal 3.

Figs. 5 to 7 are conceptual diagrams showing an example of a method of reducing the band width by the motion picture transmission device 2. Particularly, Fig.

shows a case where packets are discarded every picture group GOP. The motion picture transmission device 2 identifies the last packet of the picture group on the basis of the RTP header 52 in the IP packet received. On the basis of the identification result, the IP packets are discarded or relayed every picture group. If picture groups of M are discarded every picture groups of N in such a manner as described above, the transmission band width can be reduced to For example, if discard and relay are alternately carried out every picture group, the transmission band width can be reduced to 1/2.

Fig. 6 shows a case where only pictures on which motion compensation has been conducted are discarded.

The motion picture transmission device 2 identifies the picture type of the MPEG content 55 on the basis of the MPEG header 54 in the IP packet received. On the basis of the identification result, the IP packets are discarded or relayed every picture. Pictures to be discarded are pictures which have been subjected to motion compensation, that is, P pictures and B pictures, and I pictures are relayed.

Fig. 7 shows a case where only pictures on which bidirectional motion compensation has been conducted are discarded. As in the case of Fig. 6, the motion picture transmission device 2 discards or relays IP packets every picture on the basis of the identification result of the H-\akhoo\Keep\Temp\PS0789 AU.doc 24/09/03 17 picture type. At this time, only B pictures on which forward prediction and backward prediction have been carried out are discarded, and I pictures and P pictures are relayed.

It is desirable that the transmission band width reducing method can be freely selected from plural reducing methods in accordance with the content type, the band width or the condition of the transmission path.

These band width reducing methods may be used in suitable combination. For example, only P packets and B packets in a predetermined picture group may be discarded.

Furthermore, these band width reducing methods are examples, and another method for thinning out packets on the basis of attribute data in received packets may be adopted.

In the motion picture transmission system according to this embodiment, a series of pictures constituting an MPEG motion picture are transmitted in the form of packets from the MPEG transmission terminal 1 through the transmission path 41 to the motion picture transmission device 2, and some of the packets received by the motion picture transmission device 2 are discarded. At this .time, on the basis of the attribute data contained in the received packets, the picture group or picture type is identified, and the received packets are discarded every picture group or picture. Only the packets which are not discarded, but remain are transmitted through the second transmission path 42 to the MPEG reception terminal 3.

That is, the motion picture transmission device 2 transmits motion picture data to the MPEG reception terminal 3 while giving preference to the image quality of each picture frame over smoothness of motion. Therefore, even when the second transmission path 42 has no H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 18 sufficient band width, a motion picture which is high in image quality every frame can be transmitted.

Particularly, when the band width of the second transmission path 41 is narrower than the band width of the first transmission path, the motion picture data are transmitted from the MPEG transmission terminal 1 at a high transmission rate, and the transmission rate is reduced in the motion picture transmission device 2, so that the picture data of high image quality can be received at the MPEG reception terminal 3.

In addition, the motion picture transmission system does not need any special MPEG transmission terminal 1, and thus the price can be reduced. That is, the system can be constructed at a low price, not by reducing the frame transmission rate at the MPEG transmission terminal 1 to enhance the quality of each frame picture, but by reducing the frame transmission rate at the motion picture transmission device 2 connected to the MPEG transmission terminal 1 through the broad-band first transmission path 41.

[Second Embodiment] Fig. 8 is a schematic diagram showing an example of the construction and operation of the'motion picture transmission system according to a second embodiment of the present invention.

A motion picture transmission device 2A is a device which can freely select any band reducing method from plural band reducing methods, and reduce the transmission band width of the MPEG motion picture data by the selected reducing method. The MPEG reception terminal 3 indicates a reducing method to the motion picture transmission device 2A, and the motion picture transmission device 2A H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 19 selects the reducing method concerned on the basis of this indication.

Fig. 9 is a block diagram showing an example of the main part of the motion picture transmission device 2A of Fig. 8.

The motion picture transmission device 2A comprises communication line interfaces 20 and 21, and an MPEG band reducing controller 22. The communication line interfaces 21 control the connection to the communication network NW. That is, the communication line interface 20 carries out the connection control to the MPEG transmission terminal 1 through the first transmission path 41, and the communication line interface 21 carries out the connection control to the MPEG reception terminal 3 through the second transmission path 42.

The MPEG band reducing controller 22 comprises a packet reducing controller 23 and a reception terminal request processor 24. When receiving a reduction method indicating packet from the MPEG reception terminal 3 through the communication line interface 21, the reception terminal request processor 24 extracts the information on the reducing method contained in the packet concerned, and outputs it to the packet reducing controller 52.

Thereafter, the packet reducing processing of the packet reducing controller 23 is carried out by the reducing method indicated by the MPEG reception terminal 3. The reducing method indicated by the reducing method indicating packet may be each reducing method shown in the first embodiment (Figs. 5 to a reduction rate of the transmission band width or a combination thereof.

The motion picture transmission system according to this embodiment transmits a reducing method indicating packet from the MPEG reception terminal 3 to the motion H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 20 picture transmission device 2, and the motion picture transmission device 2 selects the transmission band reducing method of MPEG motion picture on the basis of the packet concerned. Therefore, the quality of the frame picture from the MPEG reception terminal 3 serving as a transmission destination can be controlled. That is, the reducing processing of the motion picture transmission device 2 can be controlled in accordance with the frame picture quality required.

[Third Embodiment] Fig. 10 is a schematic diagram showing an example of the construction and operation of the motion picture transmission system according to a third embodiment of the present invention. In the motion picture transmission system, two MPEG transmission terminals 1A and lB are connected to one MPEG reception terminal 3 through the communication network NW, and packeted motion picture data are transmitted from each of the MPEG transmission terminals 1A, 1B to the MPEG reception terminal 3.

That is, an OLE LINK1MPEG transmission terminal OLE LINK1 1A and an MPEG transmission terminal lB are connected to the motion picture transmission device 2B through a broad-band first transmission path 41, and also connected to an MPEG reception terminal 3 through a narrow-band second transmission path 42. The motion picture transmission device 2B relays data packets to be transmitted from the MPEG transmission terminal 1A and the MPEG transmission terminal lB to the MPEG reception terminal 3.

The motion picture transmission device 2B is a device which can select the band reducing method every MPEG transmission terminal 1A, 1B. The MPEG reception terminal 3 indicates the reducing method (containing the H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 21 reduction rate) of each MPEG transmission terminal to the motion picture transmission device 2A, and the motion picture transmission device 2A selects the reducing method on the basis of this indication.

A display device 6 is connected to the MPEG reception terminal 3 to display both the motion pictures transmitted from the MPEG transmission terminals 1A and lB. Since the band reducing method can be indicated with respect to each motion picture from the MPEG reception terminal 3, the image quality can be controlled for each motion picture in accordance with the requirement at the reception side. Fig. 10 shows a case where a motion picture from the MPEG transmission terminal 1A is transmitted without being reduced in band width and then displayed, however, a motion picture from the MPEG transmission terminal lB is transmitted with reducing the band width thereof to a quarter and then displayed in low image quality.

Fig. 11 is a diagram showing another operation state of the motion picture transmission system of Contrarily to the case of Fig. 10, the motion picture from the MPEG transmission terminal lB is displayed in high quality. If the MPEG reception terminal 3 instructs the motion picture transmission device 2B so that the motion picture from the MPEG transmission terminal 1A is transmitted with reducing the band width to a quarter, and the motion picture from the MPEG transmission terminal 1B is transmitted without reducing the band width, the motion picture from the MPEG transmission terminal 1A can be displayed in low image quality, and the motion picture from the MPEG transmission terminal 1B can be displayed in high image quality.

H, \akhoo\Keep\Temp\P50789 AU.doc 24/09/03 22 Fig. 12 is a block diagram showing an example of the main part of the motion picture transmission device 2B shown in Figs. 10 and 11. In Fig. 12, an MPEG band reducing controller 22 comprises a packet reducing controller 23, a reception terminal request processor 24 and a reducing control table 25. The motion picture transmission device 2B is different from the motion picture transmission device 2A (the second embodiment 2) in that it is equipped with a reducing control table The reducing control table 25 stores and holds the band reducing method every MPEG transmission terminal 1A, 1B, and is renewed by the reception terminal request processor 24. The packet reducing controller 23 selects the band reducing method every MPEG transmission terminal 1A, lB corresponding to a packet transmission source on the basis of the reducing control table 25, and discards MPEG packets.

When receiving a reducing method indicating packet from the MPEG reception terminal 3 through the communication line interface 21, the reception terminal request processor 24 extracts the information about the transmission source as a reduction processing target (MPEG transmission terminal 1A or IB) and the reducing method which are contained in the packet concerned, and writes the information into the reducing control table 25 while associating the transmission source with the reducing method.

In the motion picture transmission system according to this embodiment, the reducing method indicating packet containing the information on the transmission source and the reducing method is transmitted from the MPEG reception terminal 3, and the motion picture transmission device 2B selects the method of reducing the transmission band of H \akhoo\Keep\Temp\P50789 AU.doc 24/09/03 23 the MPEG motion picture every transmission terminal 1A, lB. Therefore, the quality of the frame picture from the MPEG reception terminal 3 corresponding to the transmission source can be controlled, and in accordance with the frame picture quality needed at the reception side, the reduction processing in the motion picture transmission device 2B can be controlled, and the transmission band width can be adjusted.

For example, in the case where two or more motion pictures are received at the MPEG reception terminal 3, if high-quality frame pictures are needed for a specific motion picture, the transmission band of the specific motion picture can be enlarged with the total transmission band being fixed by reducing the transmission band of the other motion picture.

[Fourth Embodiment] Fig. 13 is a schematic diagram showing an example of the construction and operation of the motion picture transmission system according to a fourth embodiment of the present invention. The motion picture transmission system of this embodiment is constructed to have a load status monitoring device 7, and a motion picture transmission device 2C selects the transmission band reducing method in accordance with the load status of the communication network NW.

The load status detecting device 7 detects the load status of the communication network NW, particularly the second transmission path 42 serving as a narrow-band transmission path, and notifies the load status thus detected to the motion picture transmission device 2C.

The load statuscan be detected by monitoring the traffic of the communication network NW. Furthermore, as another method, the load status may be identified on the basis of H,\akhoo\Keep\Temp\P50789 AU.doc 24/09/03 24 the number of MPEG transmission terminals 1 connected to the communication network NW.

Fig. 14 is a block diagram showing an example of the construction of the main part of the motion picture transmission device 2C of Fig. 13. In Fig. 14, the MPEG band reducing controller 22 comprises a packet reducing controller 23, a reception terminal request processor 24, a reducing control table 25 and a load status reaction processor 26. The motion picture transmission device 2C of this embodiment is different from the motion picture transmission device 2B (third embodiment) of Fig. 12 in that the load status reaction processor 26 is equipped.

When receiving a load status notification from the load status detecting device 7, the load status reaction processor 26 renews the reducing control table 25 in accordance with the load status. That is, when the load of the communication network NW is increased, the reduction control table 25 is renewed so that the MPEGpacket reduction processing is carried out for a larger number of transmission terminals 1 or the reduction processing in which the reduction rate of the transmission band is higher is carried out. When the load is reduced, the reverse renewal processing is carried out.

In the motion picture transmission system of this embodiment, the load status detecting device 7 detects the load of the communication network NW, and the motion picture transmission device 2C selects the method of reducing the transmission band of the MPEG motion picture on the basis of the load status notification from the load status detecting device 7. Therefore, the quality of the frame picture can be controlled in accordance with the load status of the communication network NW.

Hs\akhoo\Keep\Temp\PsOB9 AU.doc 24/09/03 25 The load status detecting device 7 may be any device which can notify a load status to the load status reaction processor 26 of the motion picture transmission device 2C, and it may be a'device out of the communication network NW or a device in the communication network NW. Furthermore, it may be equipped in the motion picture transmission device 2C.

[Fifth Embodiment] Fig. 15 is a schematic diagram showing an example of the construction and operation of the motion picture transmission system according to a fifth embodiment of the present invention. When relating a reception status report packet transmitted from the MPEG reception terminal 3 to the MPEG transmission terminal i, a motion picture transmission device 2D changes the reception status report packet, and suppresses reduction in quality of the frame picture transmitted from the MPEG transmission terminal i.

Furthermore, the motion picture transmission device 2D detects occurrence of congestion in the communication network NW, and outputs it to a network managing center 8.

As described above, the MPEG reception terminal 3 determines the number of packets which have not been normally received the number of missing packets) on the basis of the RTP headers in the received packets, and transmits a reception status report packet (RTCP packet) containing the number of missing packets to the MPEG transmission terminal 1 periodically.

When the number of missing packets is large, it is ordinarily estimated that congestion occurs in the communication network NW. Therefore, when the number of missing packets which is contained in the reception status report packet is large or when no reception status report packet can be received for a predetermined period, the H, \akhoo\Keep\Temp\PS5O789 AU.doc 24/09/03 26 MPEG transmission terminal 1 reduces the subsequent transmission band width.

Here, the frame transmission rate of the MPEG transmission terminal 1 is fixed. Therefore, in order to reduce the transmission band width, it is required to change coding parameters in the MPEG encoder 10 and reduce the quality of the frame pictures. That is, if the transmission band width in the MPEG transmission terminal 1 is reduced, the quality of the frame pictures is lowered.

For this purpose, the motion picture transmission device 2D changes the packet missing number in the reception status report packet from the MPEG reception terminal 3 and transmits it to the MPEG transmission terminal 1. As described above, the discard of packets in the motion picture transmission device 2D is hidden to the MPEG transmission terminal 1 to disguise the reception status of the MPEG packet as being more excellent than the actual reception status, thereby preventing the transmission image quality of the MPEG transmission terminal 1 from being reduced due to the discard of the packet.

Fig. 16 is a block diagram showing an example of the construction of the main part of the motion picture transmission device 2D of Fig. 15. The MPEG band reducing controller 22 of Fig. 16 comprises a packet reducing controller 23, a reception terminal request processor 24, a reducing control table 25, a load status reaction processor 26 and a reception status report packet controller 27. The motion picture transmission device 2D is different from the motion picture transmission device 2C (fourth embodiment) in that the reception status report packet controller 27 is equipped.

H;\akhoo\Keep\Temp\P0789 AU.doc 24/09/03 27 The reception status report packet controller 27 receives a reception status report packet from the MPEG reception terminal 3 through the communication line interface 21. The packet missing number in the reception status report packet thus received is read out, and the packet missing number is changed to be reduced by the packet number discarded in the packet reducing controller 23. That is, only the packet number discarded in the motion picture transmission device 2D is excluded. The number of packets discarded in the motion picture transmission device 2D can be calculated by reading out the reducing method from the reduction control table Alternatively, when the packet number discarded by the packet reducing controller 23 is held, the packet number concerned may be used.

When the packet missing number exceeds the packet discard number, it is estimated that congestion may occur in the communication network NW. Therefore, when the packet missing number after the change exceeds a predetermined value (for example, may be zero), the reception status report packet controller 27 notifies occurrence of congestion to the network managing center 8.

The network managing center 8 receiving this notification increases the band width of the communication network NW, or reduces the transmission band width every MPEG transmission terminal 1.

In the motion picture transmission system according to this embodiment, the motion picture transmission device 2D changes the packet missing number of the reception status report packet transmitted from the MPEG reception terminal 3 to the MPEG transmission terminal i.

Therefore, the quality of the picture frame transmitted from the MPEG transmission terminal 1 can be prevented H, \akhoo\Keep\Temp\PS0789 AU.doc 24/09/03 28 from being lowered due to the packet discard at the motion picture transmission device 2D.

[Sixth Embodiment] Fig. 17 is a schematic diagram showing an example of the construction and operation of the motion picture transmission system according to a sixth embodiment of the present invention. A motion picture transmission device 2E generates a reception status report packet which is originally generated by the MPEG reception terminal 3, and transmits the reception status report packet thus generated to the MPEG transmission terminal 1, thereby suppressing reduction in quality of the frame picture transmitted from the MPEG transmission terminal 1.

The detailed construction of the motion picture transmission device 2E is the same as the motion picture transmission device 2D shown in Fig. 16. The MPEG reception terminal 3 periodically transmits the reception status report packet (RTCP packet), however, there is a case where no reception status report packet has arrived at the motion picture transmission device 2E due to congestion, transmission error or the like in the communication network NW even when a predetermined fixed time elapses. In this case, the MPEG transmission terminal 1 lowers the quality of the frame picture.

Therefore, when no reception status report packet has arrived even after a predetermined elapses, the reception status report packet controller 27 generates a reception status report packet by itself, and transmits it through the communication line interface 20 to the MPEG transmission terminal i. The motion picture transmission device 2E stores and holds the information needed to generate the reception status report packet, for example, the information in the RTP header when the MPEG packet is Ht\akhoo\Keep\Temp\P50789 AU~doc 24/09/03 29 relayed, and the reception status report packet is generated on the basis of the information concerned.

In the motion picture transmission system according to this embodiment, the motion picture transmission device 2E generates the reception status report packet, and transmits it to the MPEG transmission terminal i.

Therefore, even when the reception status report packet is not normally transmitted from the MPEG reception terminal 3 to the MPEG transmission terminal 1, the reception status of the MPEG packet can be disguised as being more excellent than the actual status, so that the transmission image quality from the MPEG transmission terminal 1 can be prevented from being lowered.

[Seventh Embodiment] In this embodiment, the motion picture transmission system of each of the first to sixth embodiments is applied to a motion picture transmission system for emergency medical service.

Fig. 18 shows the schematic construction of the motion picture transmission system for emergency medical service. Plural ambulances 61 and plural hospitals 65 are connected to one another through a satellite communication line and an earth network 64. An MPEG transmission terminal (not shown) is mounted in an ambulance 61, and an MPEG reception terminal (not shown) is mounted in a hospital 65. When a patient is urgently carried, the condition of the patient and the diagnosis result achieved by diagnosing equipment are transmitted as motion picture data from the ambulance 61 to the hospital The relay between the satellite communication line and the earth network 64 is carried out by a feeder station 63 set up on the earth. That is, the ambulance 61 as a mobile makes communications with the feeder station H \akhoo\Keep\Temp\PSO789 AU.doc 24/09/03 30 63 through the communication satellite 62. The communication satellite 62 is a quasi-zenith satellite which can secure a large antenna elevation angle in the ambulance 61, and it covers most of all the country of Japan.

Fig. 19 is a diagram showing an example of the construction of the main part of the ambulance 61. In the ambulance 61 are mounted an antenna 71, a satellite line controller 72, a motion picture transmission device 73, an MPEG transmission terminal 74 and a camera The MPEG transmission terminal 74 is connected to the motion picture transmission device 73 through an LAN cable such as 100Base-TX or the like, and transmits/receives IP packets to/from the motion picture transmission device 73. The motion picture transmission device 73 is connected to the satellite line controller 72, and the satellite line controller 72 transmits/receives RF signals to/from the communication satellite through the antenna 71.

The camera 75 is connected to the MPEG transmission terminal 74, and the condition of the patient which is picked up by the camera 75 is output as motion picture data to the MPEG transmission terminal 74. The MPEG transmission terminal 74 codes the motion picture data according to the MPEG standard (for example, MPEG2), and outputs the motion picture data thus coded to the motion picture transmission device 73.

The motion picture transmission device 73 corresponds to the motion picture transmission devices 2 to 2E in the first to sixth embodiments. It carries out the thin-out processing on a data packet received from the MPEG transmission terminal 74, and then outputs the data packet to the satellite line controller 72. That is, the H,\akhoo\Keep\Temp\PS0789 AU.doc 24/09/03 31 motion picture data after the band is reduced is transmitted from the antenna 71 to the communication satellite 62.

The communication satellite 62 can cover a broad area. However, if the number of ambulances 61 actuating at the same time is increased, the band width which can be allocated to each ambulance 61 is narrowed. Therefore, the motion picture transmission device 73 is interposed between the MPEG transmission terminal 74 and the satellite line controller 72.

That is, the motion picture transmission device 73 is connected to the MPEG transmission terminal 74 through a broader transmission path than the transmission band width of the satellite communication line allocated to each ambulance 61 to reduce the frame transmission rate at the motion picture transmission device 73. Therefore, even when the band width of the satellite communication line thus allocated is narrow, the motion picture data can be transmitted without reducing the quality of the frame picture.

In general, when the patient being emergently carried is subjected to a remote diagnosis, information on the color or the shape becomes important in many cases.

When a motion picture is transmitted, the motion picture is required to be transmitted while giving preference to the image quality over the smoothness of the motion.

Therefore, if the frame transmission rate is reduced by the motion picture transmission device 73 in accordance with the band width of an available satellite communication line, a doctor could make a remote diagnosis.

Fig. 20 is a diagram showing another construction of the main part of the ambulance 61 of Fig. 18. The motion Hs\akhoo\Keep\Temp\P5O789 AU.doc 24/09/03 32 picture transmission device 73 is connected to plural MPEG transmission terminals 74 through an LAN cable, and motion picture data are output from each MPEG transmission terminal 74 to the motion picture transmission device 73, and transmitted through the satellite communication line to the MPEG reception terminal of the hospital In this case, three MPEG transmission terminals 74 are connected. One of these MPEG transmission terminals 74 is connected to a diagnosis device 76 such as an ultrasonic diagnosis device or the like, and the other two MPEG transmission terminals 74 are connected to cameras A color motion picture is output from the camera and ultrasonic echo images (monochromatic motion picture) is output from the diagnosis device 76. A doctor makes a diagnosis while viewing the motion picture.

When the band width of an available satellite communication line is narrow, there may occur such a requirement that the frame transmission rate is needed to be reduced for some motion pictures. In such a case, the doctor judges which packet reducing method should be adopted for which motion picture, and transmits the judgment result as a reducing control indicating packet from the MPEG reception terminal, whereby the band width as a whole can be suppressed. That is, the presence or absence of the packet reduction or the reduction rate is varied in accordance with the importance level of each motion picture, whereby the band width allocated can be effectively used and the judgment thereof is made by a doctor at the reception side.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as H.\akhoo\Keep\Temp\PSO789 AU~doc 24/09/03 I 33 "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

H,\akhoo\Keep\Temp\PS0789 AU.doc 24/09/03

Claims (21)

1. A motion picture transmission system comprising: a motion picture transmission terminal for transmitting motion picture frame data which comprises a series of picture frames generated at a predetermined frame rate in the form of one data packet or two or more 00 data packets; a motion picture transmission device for discarding data packets received from the motion picture transmission terminal on the basis of attribute data in data packets to reduce the number of packets; and a motion picture reception terminal for receiving data packets from the motion picture transmission device which were not discarded, wherein the motion picture reception terminal transmits a packet reducing instruction to the motion picture transmission device, and the motion picture transmission device discards the data packets from the motion picture transmission terminal on the basis of the packet reducing instruction from the motion picture reception terminal.

2. The motion picture transmission system according to claim i, wherein the motion picture transmission device receives motion picture data transmitted from two or more motion picture transmission terminals, and the motion picture reception terminal transmits to the motion picture transmission device a packet reducing instruction containing an indication of motion picture data which is targeted to be subjected to data-packet reduction.

3. The motion picture transmission system according to claim i, wherein the motion picture transmission terminal is connected to the motion picture transmission device through a first transmission path, and the motion H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 picture reception terminal is connected to the motion picture transmission device through a second transmission path having a narrower band width than the first transmission path.

4. The motion picture transmission system according to claim i, further comprising a load status detecting Sdevice for detecting a load status of the second 00 transmission path through which the motion picture M reception terminal and the motion picture transmission device are connected to each other, and transmitting a load status notification packet to the motion picture transmission device, and the motion picture transmission device discards data packets from the motion picture transmission terminal on the basis of the load status notification packet.

The motion picture transmission system according to claim i, wherein the motion picture reception terminal generates a reception status report packet containing a packet missing number, and transmitting the reception status report packet to the motion picture transmission device, and the motion picture transmission device changes the packet missing number in the reception status report packet on the basis of the number of discarded data packets, and transmitting the reception status report packet thus changed to the motion picture transmission terminal.

6. The motion picture transmission system according to claim i, wherein the motion picture reception terminal generates a reception status report packet containing a packet missing number and transmitting the reception status report packet to the motion picture transmission device every predetermined period, and the motion picture transmission device generates a reception status report H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 I packet and transmits the reception status report packet thus generated to the motion picture transmission terminal when no reception status report packet has arrived from the motion picture reception terminal for a predetermined period.

7. A transmission system for emergency medical service for transmitting motion picture data from a motion 00 picture transmission terminal mounted in a vehicle through a communication satellite to a motion picture reception terminal mounted in a medical institution, wherein the motion picture transmission terminal transmits each frame data of motion picture data comprising a series of picture frames generated at a predetermined frame rate in the form of one data packet or two or more data packets, and the vehicle is equipped with a motion picture transmission device for discarding data packets on the basis of attribute data in data packets received from the motion picture transmission terminal to reduce the number of packets based on a packet reducing instruction received from a motion picture reception terminal, and a satellite line controller for transmitting the data packets from the motion picture transmission device to the communication satellite in a wireless style.

8. The transmission system for emergency medical service according to claim 7, wherein the communication satellite is a communication satellite going around an elliptical orbit.

9. A motion picture transmission device for receiving motion picture data generated at a predetermined frame rate from a motion picture transmission terminal and transmitting the motion picture data to a motion picture reception device, comprising: H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 a first communication line interface for receiving each frame data in the form of one data packet or in the form of two or more data packets from the motion picture transmission terminal; a packet reducing controller for discarding data packets on the basis of attribute data in data packets Sreceived from the motion picture transmission terminal to 00 Sreduce the number of packets based on a packet reducing Minstruction received from a motion picture reception terminal; and a second communication line interface for transmitting to the motion picture reception terminal data packets after the number of packets is reduced.

The motion picture transmission device according to claim 9, wherein the packet reducing controller discards the data packets every picture frame on the basis of the attribute data in the reception packets to thereby reduce a frame transmission rate.

11. The motion picture transmission device according to claim 10, wherein the first communication line interface receives from the motion picture transmission terminal independently-decodable first frame data, and second frame data which is decoded together with another frame data, and the packet reducing controller discards data packets every second frame data on the basis of attribute data in received packets.

12. The motion picture transmission device according to claim 10, wherein the first communication line interface receives from the motion picture transmission terminal independently-decodable first frame data, second frame data which is decoded together with another frame data existing in one direction on the time axis, and third frame data which are decoded together with H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 two or more other frame data existing bidirectionally on the time axis, and the packet reducing controller discards data packets every third frame data on the basis of attribute data in received packets.

13. The motion picture transmission device according to claim 9, wherein the first communication line interface receives from the motion picture transmission 00 terminal grouped frame data which provide access points at a random access time, and the packet reducing controller discards data packets every grouped frame data on the basis of attribute data in received packets.

14. The motion picture transmission device according to claim 9, further comprising a reducing control table for storing a packet reducing method in association with the motion picture transmission terminal, wherein the first communication line interface receives data packets from two or more motion picture transmission terminals, and the packet reducing controller discards data packets according to a packet reducing method indicated every motion picture transmission terminal on the basis of the reducing control table.

The motion picture transmission device according to claim 14, further comprising a reception terminal request processor for renewing the reducing control table on the basis of a packet reducing instruction received from the motion picture reception terminal.

16. The motion picture transmission device according to claim 14, further comprising a load status reaction processor for renewing the reducing control table on the basis of a load status of a transmission path through which the motion picture transmission device and H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 r the motion picture reception terminal are connected to each other.

17. The motion picture transmission device according to claim 9, further comprising a reception status report packet for renewing the packet missing number in the reception status report packet received from Sthe motion picture reception terminal on the basis of the 00 number of discarded data packets, wherein the second communication line interface transmits the reception status report packet thus renewed to the motion picture transmission terminal.

18. The motion picture transmission device according to claim 9, further comprising a reception status report packet controller for generating a reception status report packet when no reception status report packet has arrived from the motion picture reception terminal for a predetermined period, wherein the second communication line interface transmits the reception status report packet thus renewed to the motion picture transmission terminal.

19. A motion picture transmission system as claimed in any one of claims 1 to 6, and substantially as herein described with reference to the drawings. A transmission system for an emergency medical service as claimed in claim 7 or claim 8, and substantially as herein described with reference to the drawings.

H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05 1

21. A motion picture transmission device as claimed (N in any one of claims 9 to 18, and substantially as herein described with reference to the drawings. Dated this 19th day of July 2005 0 MITSUBISHI DENKI KABUSHIKI KAISHA SBy their Patent Attorneys 00 GRIFFITH HACK SFellows Institute of Patent and 10 Trade Mark Attorneys of Australia (Ni H:\deboram\keep\specifications\P50789 speci amended 20050719 AU.doc 19/07/05