JP5068224B2 - Video transmission / reception system and control method thereof - Google Patents

Description

  The present invention relates to a video transmission / reception system and a video switching method, a video transmission / reception system, a video switching method, a video transmission device, a video reception device, and a control device, and in particular, one of a plurality of video transmission devices in video relay / transmission. Video transmission / reception system and video switching method for preventing video signal interference and temporary omission when switching received video to video from another video transmission device The present invention relates to a video switching method, a video transmission device, a video reception device, and a control device.

  In a conventional video playback system in which there are a plurality of video transmission devices connected to video sources such as cameras and VTRs, and one of them is played back, a video signal is always output from each video transmission device. Thus, a technique such as electrical switching by a video switching device is taken. For example, there is a method of performing analog / digital conversion of a video signal, buffering video data using a memory, and maintaining synchronization during video switching (see, for example, Patent Document 1).

  In addition, there is a technique in which video switching devices are connected in multiple stages and one video is selected from a number of video transmission devices and played back (see, for example, Patent Document 2).

  Further, there is a system in which a video transmission device and a video reproduction device are connected via a network, and each video is transmitted as a plurality of encoded streams (see, for example, Patent Document 3).

Furthermore, there is a method of transmitting video on a plurality of servers existing on the network in order by a VOD (video on demand) method and reproducing the video playback device so that there is no video break (for example, (See Patent Document 4).
JP-A-6-253213 JP 2003-186460 A Japanese Patent Laid-Open No. 11-112964 Japanese Patent Laid-Open No. 11-41585

  However, in the conventional systems as shown in Patent Documents 1 and 2, the video transmission device and the video switching device must be directly electrically connected to each other. When there are a large number of video transmission devices and they are distributed at different positions, it is difficult to electrically connect each video transmission device and video switching device directly. On the other hand, when the multistage connection of the video switching device as in Patent Document 2 is used, if there is a transmission delay between the video playback device and the video switching device, it is difficult to switch the video at the time desired by the user. is there.

  In addition, as shown in Patent Document 3, the video transmission path is a packet-switched network and the video transmission device is used, so that the video transmission device and the video reproduction device can be connected even when the transmission distance is long. Becomes easier. However, in this case, if the total bit rate of the encoded stream exceeds the bandwidth of the transmission path, congestion occurs and video transmission cannot be performed correctly, so the number of connectable video transmissions or video quality is limited. .

  In Patent Document 4, only the encoded stream from one selected server among a plurality of servers serving as video transmission devices is transmitted, but at the moment of video switching, two encoded streams exist on the transmission path at the same time. Therefore, in order to avoid degradation of video quality due to congestion, the total bit rate of the two encoded streams must be smaller than the bandwidth of the transmission path. In packet-switched networks, switching is controlled so that packet arrival congestion does not occur. Transmission delay time between each video transmission device and the congestion occurrence point and packet arrival time fluctuation (jitter) Therefore, it is necessary to control the start / stop of video transmission of each video transmission device.

  The present invention has been made in view of the above points, and in a situation where there are a plurality of video transmission devices, the interference of video signals regardless of the number of video transmission devices, the location of the video transmission devices, and the transmission distance from the video reception / playback device. Video transmission / reception system, video switching method, video transmission / reception system, video switching method, video transmission device, and video reception capable of switching received video accurately at the time requested by the user without causing image quality degradation due to congestion or congestion An object is to provide a device and a control device.

  In order to solve the above problems, in the present invention, only one of a plurality of video transmission devices performs video transmission to one video reception device, stops video transmission of the video switching source, and switches the video switching destination. Video transmission is started and video switching is performed in the video receiver. In addition, each video transmission device transmits the generated time code to the video reception device regardless of whether or not video transmission is performed, and the video reception device uses the time code difference from each measured video transmission device to the video transmission device. On the other hand, the video transmission start time is designated. The time code here is a value representing the time in the video signal, and is typically a SMPTE time code with one frame of the video signal as a minimum unit, but if it is time information synchronized with the input video signal. It can be anything.

According to claim 1 of the present invention, there is provided a video transmission / reception system in which a video reception device switches received video from one video transmission device to another video transmission device among a plurality of video transmission devices,
The video transmission device includes:
Video input means;
Video transmission means for transmitting a video signal to the video receiver;
Time code generation means for generating a time code T;
Time code transmitting means for transmitting the time code T to the video receiver;
Video transmission stop means for receiving video transmission stop time code ET and stopping video transmission when T = ET or video transmission start time code ST is received, and video transmission is performed when T = ST Video transmission start means for starting
With
The video receiver is
Video receiving means for receiving the video signal from the video transmitting device via a transmission path;
Video output means;
In response to the reception of the video signal, the video reception device starts counting the internal time code in units of video lines, receives the time code T, and receives the time code T and the time code T when the time code T is received. A time code measuring means for obtaining a measurement time code based on the internal time code;
The video transmission stop time code generation means for generating and transmitting the video transmission stop time code ET to the video transmission device of the current video reception destination, or the video transmission start time to the video transmission device of the video switching destination Video transmission start time code generating means for generating and transmitting the code ST;
And switching received video from the plurality of video transmission devices.

According to a second aspect of the present invention, there is provided a video transmission / reception system in which a video reception device switches received video from one video transmission device to another video transmission device among a plurality of video transmission devices,
The video receiver is
In response to the reception of the video signal, the video reception device starts counting the internal time code in units of video lines, receives the time code T, and receives the time code T and the time code T when the time code T is received. A time code measuring means for obtaining a measurement time code based on the internal time code,
The controller is
Video transmission stop time code generating means for generating and transmitting a video transmission stop time code ET to the current video receiving destination video transmitting apparatus, or a video transmission starting time code ST for the video switching destination video transmitting apparatus Video transmission start time code generating means for generating and transmitting

According to claim 3 of the present invention, the video transmission start time code generating means of the control device comprises:
By adding the difference between the measurement time code of the video switching destination transmitted from the video reception device and the measurement time code of the current video reception destination transmitted from the video reception device to the video transmission stop time code ET And means for generating the video transmission start time code ST.

According to claim 4 of the present invention, among the plurality of video transmission devices, only two video transmission devices of a video switching source and a switching destination transmit the time code T to the video reception device.
The video transmission / reception system according to claim 1 or 2.

According to claim 5 of the present invention, the video receiving device comprises:
Means for measuring the delay time between the video switching source and the switching destination video transmission device,
The video transmission stop time code generating means includes
A value obtained by adding the time code T from the switching source video transmission apparatus and the longer one of the delay times, measured at the time of receiving the video switching request from the user, is the video transmission stop time code ET. Including means to
The video transmission / reception system according to claim 1 or 2.

According to claim 6 of the present invention, the video receiving device comprises:
Including means for measuring a difference between measurement time codes of a video switching destination and a switching source video transmission device a plurality of times,
The video transmission start time code generating means is
Means for generating a video transmission start time code ST by adding the average value to the video transmission start time code ET;

According to claim 7 of the present invention, the video transmission means, the time code transmission means, the video reception means, the time code measurement means, the video transmission stop time code generation means, the video transmission start time code generation means,
Packet transmission / reception is performed via the packet transmission network.

According to claim 8 of the present invention, the measurement time code transmission means, the video transmission stop time code generation means, the video transmission start time code generation means,
Packet transmission / reception is performed via the packet transmission network.

According to claim 9 of the present invention, there is provided a video switching method in which a video receiving device switches received video from one video transmitting device to another video transmitting device among a plurality of video transmitting devices,
In each video transmission device,
Generating a time code;
A step of transmitting a time code to a video receiver via a video transmission path regardless of whether or not video is transmitted;
In the video receiver,
Receiving the video signal from the video transmission device via a transmission path;
In response to the reception of the video signal, the video reception device starts counting the internal time code in units of video lines, receives the time code T, and receives the time code T and the time code T when the time code T is received. Obtaining a measurement time code based on the internal time code;
A step of generating and transmitting the video transmission stop time code ET to the current video receiving destination video transmitting device, or a step of generating the video transmission start time code ST to the video switching destination video transmitting device. Transmitting.

According to claim 10 of the present invention, there is provided a video switching method in which a video receiving device switches received video from one video transmitting device to another video transmitting device among a plurality of video transmitting devices,
In the video receiver,
In response to the reception of the video signal, the video reception device starts counting the internal time code in units of video lines, receives the time code T, and receives the time code T and the time code T when the time code T is received. Obtaining a measurement time code based on the internal time code,
In the control device,
Video transmission stop time code generating means for generating and transmitting a video transmission stop time code ET to the current video receiving destination video transmitting apparatus, or a video transmission starting time code ST for the video switching destination video transmitting apparatus Generating and transmitting.

  As described above, according to the present invention, even in a situation where there are a plurality of video transmission devices, regardless of the number of video transmission devices, the location of the video transmission devices, and the transmission distance from the video reception / playback device, The received video can be switched accurately at the time requested by the user without causing image degradation.

  First, the operation principle of the present invention will be described.

  FIG. 1 is a principle configuration diagram of the present invention.

The system of FIG. 1 includes a video receiving device and a plurality of video transmitting devices, and selects one of the plurality of video transmitting devices to receive a video. During this time, other video transmitting devices stop video transmission. A video transmission / reception system,
The video transmission device
Video input means;
Video transmission means for transmitting a video signal to a video receiver;
Time code generation means for generating a time code T;
Time code transmitting means for transmitting the time code T to the video receiver;
Video transmission stop means for receiving video transmission stop time code ET and stopping video transmission when T = ET or video transmission start time code ST is received, and video transmission is performed when T = ST Video transmission start means for starting
With
The video receiver
Video receiving means for receiving a video signal from a video transmission device via a transmission path;
Video output means;
Time code measuring means for obtaining a time code generated by the video transmission device;
Video transmission stop time code generating means for generating and transmitting a video transmission stop time code ET to the current video receiving destination video transmitting apparatus, or a video transmission starting time code ST for the video switching destination video transmitting apparatus Video transmission start time code generating means for generating and transmitting the video, and switching received video from a plurality of video transmission devices.

  The video transmission device and the video reception device may be implemented by a personal computer, a workstation, a dedicated computer, or any computer capable of executing the above-described functions.

  FIG. 2 is a diagram for explaining the principle of the present invention.

The method of FIG. 2 transmits a video transmission stop request to the video transmission device from the state in which the video reception device is receiving one of the video transmission devices, and transmits the video to another video transmission device. A video switching method for transmitting a start request and switching a received video,
In each video transmission device,
Generating a time code (step S1);
Performing a step (step S2) of transmitting a time code to the video receiver via the video transmission path regardless of whether or not the video is transmitted;
In the video receiver,
And step (step S3) for generating a video transmission stop time code ET _A,
A step (step S4) of transmitting ETA to the video transmission device A which is a video switching source;
Generating a time code OT _B and timecode OT _A difference DT _B to ET _A addition to video transmission start time code ST _B from the video transmission apparatus A from the video transmitting apparatus B that is measured by the video receiver (Step S5),
A step (step S6) of transmitting ST _B to the video transmission device B as a video switching destination;
In the video transmitting apparatus A, the step (step S7) receiving the ET _A,
Performs the step of the time code T _A which itself produced to stop at the same time video transmission becomes to ET _A (step S8), and the,
In video transmission device B,
Receiving ST _B (step S9);
A step (step S10) that the time code _{T B} which itself produces starts simultaneously video transmission becomes in ST _B,
The received video is switched from the video of the video transmission device A to the video of the video transmission device B.

  FIG. 3 is a diagram for explaining the operation principle of the video transmission start time code generation processing of the present invention.

The transmission paths of the two video transmission devices A and B and the two video reception devices are combined into one by the transmission path coupling device 10 on the way. The transmission path coupling device 10 indicates a packet switching device in a packet transmission network, a device that electrically adds signals of two routes, and the like. When video transmission is performed simultaneously from each of the video transmission devices A and B, This is where congestion or video signal interference occurs. The time codes generated by the video transmission devices A and B are T _A and T _B , respectively, and the time codes from the video transmission devices A and B measured by the video reception device 20 are OT _A and OT _B , respectively. If the transmission delay time from A, B to the transmission path coupling device 10 is D _A , D _B , and the transmission delay time from the transmission path coupling device 10 to the video reception device 20 is DC,
T _A = OT _A + D _C + D _A (1)
T _B = OT _B + D _C + D _B (2)
This relationship holds. When the video transmission apparatus A performs control so that video transmission is stopped when T _A = ET _A, and video transmission apparatus B is controlled to start video transmission when T _B = ST _B , The conditions for preventing congestion or interference in the transmission path coupler 10 are as follows:
_{ET A + D A -T A '} = ST B + D B -T B' (3)
It becomes. Here, T _A ′ and T _B ′ indicate the values of T _A and T _{B at} a certain time. Assuming that the time code measured by the video receiver 20 at this time is OT _A ′ and OT _B ′, according to Equation (1), Equation (2), and Equation (3),
_{ST B = ET A + OT B} '-OT A' (4)
Holds.

In the transmission path coupling device 10,
_{ET A '= ET A + D} A -T A', ST B '= ST B + D B -T B'
When, by the video transmission fadeout portion which will be described later in the video transmitting apparatus A, the bit rate of the video signal A is remained as _'from time ET _A' time ET A in FIG. 4 to + FT, described later in the video transmitting apparatus B the video transmitting fade-section of the bit rate of the video signal B changes as from time ST _B in FIG. 4 to time ST B ₊ FT. This cross-fading process can be performed by consuming the buffer of the video receiving device 20 at the time of video transmission fading out, and the transition of the buffer amount in the video transmitting devices A and B and the video receiving device 20 at this time is as follows. As shown in FIG.

As a result, the transmission delays D _A and D _B shown in FIG. 3 fluctuate due to network jitter and the like, so that when the total bit rate of the video signal A and the video signal B at the instant of video switching varies, The ratio can be suppressed and the occurrence of instantaneous congestion as shown in FIG. 6 can be prevented.

  According to the principle of the present invention described with reference to FIGS. 1 to 6, the temporal granularity of the switching control depends on the granularity of the time code and the granularity of the processing unit in the video transmission / reception apparatus. For example, when the time code granularity is in units of one frame of video and the transmission / measurement of the time code and the start / stop processing of video transmission are performed in units of one frame of video in the video transmission / reception apparatus, the accuracy is less than the time of one frame of video. Switching control cannot be performed. This means that the time at which the stream is switched is at most around one frame time of video, and it is unavoidable that overlap occurs at the time of switching. In order to prevent network congestion due to this overlap, crossfading processing is performed according to the above-described principle.

  The present invention further performs switching control for one frame or less of video, that is, for each video line, in order to prevent stream overlap itself. However, if the granularity of the time code sent from the video transmission apparatus is set on a line basis or the processing granularity of the video transmission / reception apparatus is set on a line basis, the network load and the processing load increase and the cost of the system increases. Therefore, the present invention prevents an increase in the cost of the system and performs switching control in line units.

In order to realize line-by-line switching control, in the present invention, the time code indicating the position of the video in the time axis direction is a frame number in units of one video screen, and a line in units of one scanning line as a finer unit. Contains a number. If the time code is T, the frame number is F, and the line number is L, T = F. L. If the number of video lines constituting one video frame is L _MAX , 0 ≦ L ≦ L _MAX −1. When L = L _MAX −1, when L is increased by 1, F is increased by 1 and L becomes 0. . Ta = Fa. La, Tb = Fb. For Lb, addition and subtraction are performed as follows:
Ta + Tb
= (Fa + Fb). (La + Lb)
... When La + Lb <L _MAX = (Fa + Fb + 1). (La + Lb-L _MAX )
... When La + Lb ≧ L _MAX (5)
Ta-Tb
= (Fa-Fb). (La-Lb)
... When La ≧ Lb = (Fa−Fb−1). (La-Lb + L _MAX )
... When La <Lb (6)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 7 is a configuration diagram of the video transmission / reception system according to the first embodiment of the present invention.

  The video transmission / reception system shown in the figure includes video transmission devices 100A and 100B and a video reception device 300.

  The video transmission device 100A includes a video input unit 110A, a video transmission unit 120A, a time code generation unit 130A, a time code transmission unit 140A, a video transmission stop unit 150A, and a video transmission start unit 160A. The video transmitting apparatus 100B is configured in the same manner, and the subscript of each element is indicated as B.

  The video reception device 300 includes a video reception unit 310, a video output unit 320, a time code measurement unit 330, a video transmission stop time code generation unit 340, and a video transmission start time code generation unit 350.

  Transmission paths between the plurality of video transmission apparatuses 100A and 100B and the video reception apparatus 300 are combined into a single path coupling apparatus 10 as shown in FIG. The transmission path is a line occupation type or packet transmission type path. When the transmission path is a line occupation type path, the path coupling device 10 is a line switching unit or a signal addition unit. When the transmission path is a packet transmission type path, the path coupling unit is a packet switching unit.

  FIG. 8 is a sequence chart of the operation in the first embodiment of the present invention.

In step S101, the video signal is input to the video input units 110A and 110B in the video transmission device 100A that is the video switching source and the video transmission device 100B that is the video switching destination. At the same time, time codes T _A and T _B associated with the input video signal are generated in time code generation units 130A and 130B, respectively. The time code is generated based on the clock of the input video signal, or when the time code is given to the input video signal, the time code may be used as it is as the generation time code. Video apparatus 100A and the video transmission apparatus 100B generates a time code for each fixed line respectively, and transmits the time code transmission unit 140A, the time code _{T A} and _{T B} from 140B to the video receiving apparatus 300. Note that in the generally used SMPTE time code and the like, the minimum unit of time information is one frame of video, but a time code in a finer unit may be generated using a horizontal synchronization signal of video. That is, the time code may include a frame number in units of one video screen and a line number in units of one scanning line as a finer unit.

Next, in step S102, the video transmission device 100A transmits the input video signal from the video signal transmission unit 120A via the transmission path. In order to reduce the bandwidth of the video transmission, the video may be encoded here. At the same time, it transmits the video transmitter 100A and a video transmission device 100B, the time code transmission unit 140A, 140B from the time code _{T A} and _{T B} to the video reception apparatus 300. The transmission path of the time code must be the same as the video transmission path. The transmission interval of the time code must be the same between the video transmission device 100A and the video transmission device 100B.

In step S <b> 103, in the video reception device 300, the video transmission unit 310 receives the video transmitted from the video transmission device 100 </ b> A, and the video output unit 320 outputs the video. If the video is encoded, a decoding process is also performed. At the same time, the time code measuring unit 330 of the video reception device 300 starts counting the internal time code RT _(n) according to the reception status of the video stream. Specifically, the internal line number is incremented by 1 when data reception for one video line is completed, the internal frame number is incremented by 1 when data reception for one video frame is completed, and the internal line number is set to 0. Reset to.

In step S104, the time code measuring unit 330 of the video reception device 300 receives and records the time codes T _A and T _B from both video transmission devices 100A and 100B. At the same time, the time code measuring unit 330 records the internal time codes RT _A and RT _B when the time codes T _A and T _B are received.

In step S105, the time code measurement unit 330 of the video reception device 300 measures the measurement time codes OT _A and OT _B. Specifically, assuming that the internal time code when calculating the measurement time code in the video reception device is RT _(n) and that the calculation is performed for each predetermined time dRT, the following equation is established:
RT _(n) = RT _(n-1) + dRT (7)
Accordingly, the measurement time codes OT _A and OT _{B at} the internal time code RT _(n) are obtained as follows:
_{OT A = T A + (RT} (n) -RT A) (8)
OT _B = T _B + (RT _(n) −RT _B ) (9)
As a result, the time code can be measured with the accuracy of the number of lines regardless of the time code transmission interval from the video transmission devices 100A and 100B and the accuracy of the time code.

If a time code packet is received a plurality of times between RT _(n−1) and RT _(n) , the values T _A and T _B of the last received time code packet and RT _A and RT _B at the time of reception are received. May be used to obtain the measurement time codes OT _A and OT _B. When no time code is received, a value obtained by adding dRT to the previous measurement time code may be used as the measurement time code.

  Thereby, even when the timing for receiving the time code is before and after the boundary of the video frame in the receiving device, the measurement of the time code can be continued.

  Further, the time code measurement may be stopped when the time code packet is not continuously received a certain number of times.

In step S106, the video transmission stop time code generating unit 340 generates video transmission stop time code ET _A, is transmitted via the transmission path to the video transmitter 100A. ET _A may be a value designated in advance by the user, or may be generated based on OT _A when a video switching request is received from the user. However, in this case, when the ET _A video transmission start time code ST _B reaches the video transmitter 100A and a video transmission device 100B, you must already have to generate ET _A so that time is not past . Therefore, to set a sufficiently long time compared to previously transmission delay time, or to generate an ET _A adds that value to OT _A, both from the video receiving device 300 the video transmitting devices 100A, the transmission delay time to the 100B measured, the longer transmission delay time of adding the OT _a, it is desirable to generate ET _a. The transmission delay time is measured using ICMP (Internet Control Message Protocol) Echo Message, Echo Reply Message, and the like.

In step S107, after generating the ET _A In the picture transmission start time code generator 350,
DT _B = OT _B -OT _A
ST _B = ET _A + DT _B
By generating a ST _B, transmitted over the transmission path to the video transmitter 100B. DT _B is a difference between OT _B and OT _A at a certain time, but may be obtained by measuring OT _B and OT _{A a} plurality of times at different times in advance and using an average value of the differences.

The transmission path of the ET _A and ST _B is may not necessarily be the same video transmission path. Also, if the transmission path of the packet transmission type, transmission of the ET _A and ST _B is performing packet transmission using a packet format such as UDP / IP (User Datagram Protocol / Internet Protocol), a packet-switched portion of the path Since there is no address resolution table (not shown) and the first packet may not reach the video transmission device, the address resolution packet is transmitted to both the video transmission devices 100A and 100B in advance. It is desirable that an address resolution table exists on the exchange unit. The address resolution packet is transmitted using ICMP Echo Message or the like.

In step S108, the video transmission stop portion 150A of the video transmission devices 100A, receives the ET _A, the T A = ET _A when stopping the video transmission simultaneously. Further, parallel, in a video transmission start portion 160B of the video transmission apparatus 100B, receives the ST _B, the T B = ST _B when starting the video transmission simultaneously.

In step S109, the video receiving apparatus 300, and at the same time the time code of the video from the video transmission apparatus 100A is ET _A, the received video is switched to the image from the video transmission apparatus 100B.

[Second Embodiment]
FIG. 9 shows a configuration of a video transmission / reception system according to the second embodiment of the present invention.

The video transmission / reception system shown in the figure includes video transmission devices 100A and 100B, a video reception device 400, and a control device 500. The control device 500 may be implemented by a personal computer, a workstation, a dedicated computer, or any computer capable of executing the functions described above.

In the present embodiment, the video transmission stop time code generation unit 340 and the video transmission start time code generation unit 350 of the video reception device 300 in the first embodiment are moved to the control device 500, and a measurement time code is newly added. Is configured to include a measurement time code transmission unit that transmits the information to the control device 500.

  The video reception device 400 includes a video reception unit 410, a video output unit 420, a time code measurement unit 430, and a measurement time code transmission unit 440.

  The control device 500 includes a video transmission stop time code 510 and a video transmission start time code generation unit 520. These configurations have the same functions as the video transmission stop time code generation unit 340 and the video transmission start time code generation unit 350 of the video reception device 300 according to the first embodiment.

  FIG. 10 is a sequence chart of the operation in the second embodiment of the present invention.

  Steps S201 to S202 are the same as the operations of steps S101 and S102 in the first embodiment described above, and thus description thereof is omitted.

  Steps S203 to S205 are the same as the operations of steps S103 to S105 in the first embodiment described above, and the video receiving device 300 may be replaced with the video receiving device 400, and thus description thereof is omitted.

In step S206, the calculated measurement time codes OT _A and OT _B are transmitted from the measurement time code transmission unit 440 to the control device 500.

In step S207, in control device 500, video transmission stop time code generation unit 510 receives OT _A , and video transmission start time code generation unit 520 receives OT _B.

In step S208, the video transmission stop time code generation unit 510, in the same manner as step S104 of FIG. 8 to generate a video transmission stop time code ET _A, is transmitted to the video transmission apparatus 100A.

  In step S209, the video transmission start time code generation unit 520 generates a video transmission start time code STB by the same method as in step S105 of FIG. 8, and transmits the video transmission start time code STB to the video transmission device 100B.

In step S210, the video transmission stop portion 150A of the video transmission devices 100A, receives the ET _A from the control unit _500, and T A = ET _A when stopping the video transmission simultaneously.

In step S210, in parallel, the video transmission start unit 160B of the video transmission device 100B receives ST _B from the control device 500, and starts video transmission at the same time as T _B = ST _B.

In step S211, the video receiving apparatus 400, and at the same time the time code of the video from the video transmission apparatus 100A is ET _A, the received video is switched to the image from the video transmission apparatus 100B.

Referring to FIGS. 11 to 13, the number of lines constituting one frame of the image is L _MAX = 1125, the line number L satisfies 0 ≦ L ≦ 1124, and the measurement time code calculation period dRT in the video reception device is one frame. A case will be described.

  Information necessary for the switching timing control is a difference between time codes transmitted from the transmitting video transmitting apparatus A and the switching destination video transmitting apparatus B. Therefore, the value of this difference is measured with the accuracy of the number of video lines, so that accurate switching timing can be calculated. For example, even when the accuracy of the time code transmitted from the video transmission device A or B is one frame of video, the time when the video reception device receives the time code packet is accurately recorded, and the difference in the reception time is used. Thus, the difference can be measured with an accuracy of less than one frame of video.

  As a characteristic of the system process in the video reception apparatus, every time one stream packet is received, the video stream reception routine interprets the packet header and copies the data to an appropriate memory location in the reception buffer. Here, focusing on the fact that the received packet is the data of which video line of which video frame, the time code packet is received during the stream reception routine, and when the time code packet is further received The value of the video line counter of the video stream is recorded. When the accuracy of the time code transmitted from each video transmission device is in units of one frame of video, the video reception device may receive the time code packet from each server once per frame. Since it is only necessary to add processing to record the value of the video line counter at the time of reception to this time code packet reception processing, the processing load is reduced and the time code is measured with the accuracy of the number of video lines, and the difference between them is measured. Can be calculated.

11, the time code and the value of the transmission stream A in the video transmission apparatus A showing the relation between the time code packets T _A. FIG. 11 shows a case where the transmission buffer amount is 1 frame + 1025 lines. From Figure 11, when the stream A timecode 101.100 is transmitted, the time code _{T A} is seen that the time code packets 103.0 is delivered.

FIG. 12 shows an example of measuring the time code with the accuracy of the number of lines in the video receiver. The video receiver internal time code includes a video receiver internal frame number that is a frame number held in the video receiver and a video receiver internal line number that is a line number held in the video receiver. The video receiver internal time code is equivalent to the time code of the stream A being received. The value T _A timecode packet is a value conforming to HD-SDI input in the video transmitting apparatus A, a value obtained by adding the transmission buffer amount of the internal video transmission device A to the value of the time code of the stream A.

In Figure 12, the value _{T A} is received when the time code packet video receiver internal time code of 101.100 is 103.0, the value _{T B} is the time code packet video receiving device internal time is 86.0 It is received when the code is 101.950. Therefore,
T _A = 103.0, RT _A = 101.100
T _B = 86.0, RT _B = 101.950
It is. When the video receiver internal time code is 102.0, the measurement time codes OT _A and OT _B are calculated as follows using the above-mentioned numerical values:
_{OT A = T A + (RT} (n) -RT A)
= 103.0+ (102.0-101.100)
= 103.1025
OT _B = T _B + (RT _(n) −RT _B )
= 86.0 + (102.0-101.950)
= 86.175
That is, the measurement time code _OT A, OT _B shall be added to 1025 lines which is a difference from the receiving timing for calculating timing _{T A,} adds the 175-line, which is the difference from the reception timing for calculating timing _{T B} Is obtained. Even when the number of video transmission devices is three or more, all measurement time codes can be obtained by the same method. In the case of [Second Embodiment] described with reference to FIGS. 9 and 10, the obtained measurement time-coded OT _A and OT _B are notified to the control device 500.

FIG. 13 shows a process when the video receiving apparatus receives or does not receive a time code packet a plurality of times within one video frame period. Video receiver internal frame number is received twice timecode packet T _A at 101. When receiving a plurality of times, the measurement time code OT _A is calculated using the value of the last received time code packet. With timecode packet _{T A} received the second time when the video receiver internal line number 1015, obtain a measurement time code _OT A = 104.110. The video receiving apparatus internal frame number is not received timecode packet T _B at the time of 102. If no time code packet is received, dRT = 1 frame is added to the measured time code obtained in the previous frame. That is, OT _B = 86.175 + 1.0 = 87.175 is obtained. Further, when the time code packet is not continuously received, the video transmitting apparatus B is considered to have stopped, and the calculation of the measured time code OT _B may be stopped.

  When the transmission interval of the time code packet from the video transmission apparatus is one frame, the line number information in the time code packet may be omitted and the line number may be always regarded as a constant value. Further, by reducing the time code packet transmission interval and the measurement time code calculation interval (dRT) of the video receiver, it is possible to realize more accurate time code measurement.

  Note that the functions of the video transmission device and the video reception device described above can be constructed as a program, installed in a computer used as these devices and executed, or distributed via a network.

  Further, the constructed program can be stored in a portable storage medium such as a hard disk, a flexible disk, or a CD-ROM, and can be installed or distributed in a computer.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

  As described above, according to the present invention, the time code measuring means receives the time code from the video transmitting apparatus in parallel with the video stream receiving process in the video receiving means, and receives the time code and the time code. The measurement time code can be calculated based on the time code counted inside the video receiver at the time. Thereby, the time granularity of the time code can be shortened to the video line unit, and as a result, the video switching time can be shortened.

  The present invention is applicable to a video transmission / reception system that relays and transmits video.

It is a principle block diagram of this invention. It is a figure for demonstrating the principle of this invention. It is a figure for demonstrating the operation principle of the video transmission start time code production | generation process of this invention. It is a figure which shows the bit rate of the video signal of the video transmission apparatus of this invention. It is a figure which shows transition of the buffer amount of the video transmission apparatus and video reception apparatus of this invention. It is a figure which shows the fluctuation | variation of the total bit rate of this invention. It is a block diagram of the video transmission / reception system in the 1st Embodiment of this invention. It is a sequence chart of the operation | movement in the 1st Embodiment of this invention. It is a block diagram of the video transmission / reception system in the 2nd Embodiment of this invention. It is a sequence chart of operation in a 2nd embodiment of the present invention. It shows the relationship between the time code and the time code packets T _A transmission streams A in the video transmitting apparatus A. An example of measuring the time code with the accuracy of the number of lines in the video receiving apparatus will be shown. A process when the video receiving apparatus receives a time code packet a plurality of times within one video frame period or when it does not receive the time code packet is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Video transmission device 110 Video input means, Video input part 120 Video transmission means, Video transmission part 130 Time code generation means, Time code generation part 140 Time code transmission means, Time code transmission part 150 Video transmission stop means, Video transmission stop part 160 video transmission start means, video transmission start section 300 video reception apparatus 310 video reception means, video reception section 320 video output means, video output section 330 time code measurement means, time code measurement section 340 video transmission stop time code generation means, video Transmission stop time code generation unit 350 Video transmission start time code generation means, video transmission start time code generation unit 400 Video reception device 410 Video reception unit 420 Video output unit 430 Time code measurement unit 440 Measurement time code transmission unit 500 Control device 510 Video Send Stop the time code generator 520 video transmission start time code generator

Claims (10)

A video transmission / reception system in which a video reception device switches received video from one video transmission device to another video transmission device among a plurality of video transmission devices,
The video transmission device includes:
Video input means;
Video transmission means for transmitting a video signal to the video receiver;
Time code generation means for generating a time code T;
Time code transmitting means for transmitting the time code T to the video receiver;
Video transmission stop means for receiving video transmission stop time code ET and stopping video transmission when T = ET or video transmission start time code ST is received, and video transmission is performed when T = ST Video transmission start means for starting
With
The video receiver is
Video receiving means for receiving the video signal from the video transmitting device via a transmission path;
Video output means;
In response to the reception of the video signal, the video reception device starts counting the internal time code in units of video lines, receives the time code T, and receives the time code T and the time code T when the time code T is received. A time code measuring means for obtaining a measurement time code based on the internal time code;
To movies image switching source of the video transmission apparatus, a video transmission stop time code generating means for generating and transmitting said video transmission stop time code ET,
To movies image switching destination of the video transmission apparatus, a video transmission start time code generating means for generating and transmitting said video transmission start time code ST using the the measuring time code the video transmission stop time code ET,
A video transmission / reception system that switches received video from the plurality of video transmission devices. A video transmission / reception system that switches a received video from one video transmission device to another video transmission device among a plurality of video transmission devices by transmitting a measurement time code to the control device from the video reception device,
The video receiver is
Inside the video reception device in response to receiving the movies image signal starts counting the internal time code of the video line unit receives the time code T, the at the time of receiving the time code T to the time code T time code measuring means for determining the measurement time code based on the internal time code, includes a,
The controller is
To movies image switching source of the video transmission apparatus, a video transmission stop time code generating means for generating and transmitting video transmission stop time code ET,
Video transmission start time code generation means for generating and transmitting a video transmission start time code ST using the measurement time code and the video transmission stop time code ET to the video transmission device of the video switching destination, Video transmission / reception system characterized by this. The video transmission start time code generation means of the control device,
Wherein the video transmission stop time code ET, the measured time code of the video switching destination transmitted from the video receiving apparatus, by adding the difference between the measured time code Film image switching source transmitted from the video receiving device, Means for generating the video transmission start time code ST;
The video transmission / reception system according to claim 2. Of the plurality of video transmission devices, only two video transmission devices of a video switching source and a switching destination transmit the time code T to the video reception device.
The video transmission / reception system according to claim 1 or 2. The video receiver is
Means for measuring the delay time between the video switching source and the switching destination video transmission device,
The video transmission stop time code generating means includes
A value obtained by adding the time code T from the switching source video transmission apparatus and the longer one of the delay times, measured at the time of receiving the video switching request from the user, is the video transmission stop time code ET. Including means to
The video transmission / reception system according to claim 1 or 2. The video receiver is
Including means for measuring a difference between measurement time codes of a video switching destination and a switching source video transmission device a plurality of times,
The video transmission start time code generating means is
6. The video transmission / reception system according to claim 1, further comprising means for adding the average value to the video transmission start time code ET to generate a video transmission start time code ST. The video transmission means, the time code transmission means, the video reception means, the time code measurement means, the video transmission stop time code generation means, the video transmission start time code generation means,
Send and receive packets via a packet transmission network,
The video transmission / reception system according to claim 1. The measurement time code transmission means, the video transmission stop time code generation means, the video transmission start time code generation means,
Send and receive packets via a packet transmission network,
The video transmission / reception system according to claim 2. A video switching method in which a video receiving device switches received video from one video transmitting device to another video transmitting device among a plurality of video transmitting devices,
In each video transmission device,
Generating a time code;
A step of transmitting a time code to a video receiver via a video transmission path regardless of whether or not video is transmitted;
In the video receiver,
Receiving a movies image signal via a transmission path from the video transmission device,
In response to the reception of the video signal, the video reception device starts counting the internal time code in units of video lines, receives the time code T, and receives the time code T and the time code T when the time code T is received. Obtaining a measurement time code based on the internal time code;
To movies image switching source of the video transmission device, the steps of generating and transmitting said video transmission stop time code ET,
A video switching method comprising: generating and transmitting the video transmission start time code ST using the measurement time code and the video transmission stop time code ET to a video transmission device as a video switching destination. A video switching method for switching received video from one video transmission device to another video transmission device among a plurality of video transmission devices by transmitting a measurement time code to the control device from the video reception device,
In the video receiver,
Inside the video reception device in response to receiving the movies image signal starts counting the internal time code of the video line unit receives the time code T, the at the time of receiving the time code T to the time code T determining the measurement time code based on the internal time code, includes a,
In the control device,
To movies image switching source of the video transmission apparatus, a video transmission stop time code generating means for generating and transmitting video transmission stop time code ET,
To movies image switching destination of the video transmission apparatus, and a step of generating and transmitting a video transmission start time code ST using the measurement time code and the video transmission stop time code ET,
Video switching method.

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