JP2005033607A - Video synchronization method and video synchronization program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video synchronization method and a video synchronization program by which two video transmitters prepare for the transmission of frames with a matched display time and coincidentally transmit transmission timing. <P>SOLUTION: A video synchronization system 1 makes both video transmitters prepare for the transmission of the frames with a matched display time and transmits the frames at matched timing. A video transmitter 70a and a video transmitter 70b synchronize internal times, both video transmitters prepare for transmission at a display time based on the internal time, a phase comparator part 30 compares the transmission timings of both video transmitters whenever the completion of preparation for transmission is detected by a transmission preparation completion detection part 20 of the video transmitter 10, a frame delay execution part 40 delays the output of the video transmitter 70a by a time of one frame when the video transmitter 70a is earlier, outputs the frames as they are in other cases and a frame synchronization part 50 synchronizes the output of the video transmitter 70b with the output. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a video synchronization method and a video synchronization program that synchronize video on a frame-by-frame basis when transmitting left-eye video and right-eye video constituting a three-dimensional stereoscopic video from individual video transmission devices.

  A three-dimensional stereoscopic video display device that does not have a function capable of automatically adjusting the frame display timing (phase) of the right (left) eye video in accordance with the frame display timing of the left (right) eye video (for example, left When using a separate commercially available video projector for the video display for the eye and the video display for the right eye, etc.), when constructing a system that simultaneously displays the video for the left eye and the video for the right eye on one screen, The left-eye video and the right-eye video to be displayed are prepared, and the vertical refresh timing, that is, the frame transmission timing (phase) is matched (synchronized), and then this three-dimensional stereoscopic video display device is used. Must be sent out. If the frame is not transmitted in this way, a state in which accurate stereoscopic viewing cannot be presented to the viewer occurs. In order to send the left-eye video and the right-eye video in synchronism in units of frames from the video transmission device of one personal computer to the three-dimensional stereoscopic video display device, for example, the frame transmission timing is used as an external reference signal. There is a method of using a graphics card (video card) having a matching function (genlock function; see Patent Document 1). This graphics card is installed in the left-eye and right-eye personal computers, and the same reference signal is externally applied to match the transmission timing (phase) of the left-eye and right-eye frames. Can be sent out.

In addition to the genlock function, there is also a method of using a graphics card (video card) having a function of confirming that a graphics card (video card) on another personal computer has completed preparation for sending frames. By using a video transmission device such as a personal computer equipped with the graphics card (video card), it is possible to transmit the frames after matching the transmission timing after completing the frame transmission preparation.
JP-A-10-84519 (paragraphs 0007 to 0011, FIGS. 1 and 2)

  With the development of computer games, etc., many types of general-purpose personal computer graphics cards (video cards) used for computer game equipment have been sold, and the transmission speed (drawing speed) has been increased. It has been realized. However, these graphics cards (video cards) have generally completed preparations for sending frames from the conventional technology (1) Genlock function and (2) Graphics cards (video cards) on other personal computers. And confirming the transmission timing and sending out with the same sending timing. In addition, it is difficult to provide the function (1) or (2) by modifying the circuit by integration.

  Furthermore, in addition to graphics cards with genlock functions and graphics functions, there are limited models of graphics cards (video cards) that have the function of confirming that frames have been prepared for transmission from other graphics cards (video cards). In addition, there is a problem in that selection of a model for a required performance such as a sending speed (drawing speed) and an application is limited.

  Accordingly, the object of the present invention is to confirm that the frame transmission preparation from the conventional technology described above, that is, (1) genlock function, (2) graphics card (video card) on another personal computer has been completed, is transmitted. Even if a video transmission device such as a personal computer equipped with a general-purpose graphics card (video card) that does not have a function for transmitting the signals at the same timing is used, images are simultaneously displayed on the video transmission device for each frame. Provided video synchronization method and video synchronization program capable of preparing a left-eye video and a right-eye video to be output and outputting them to a 3D stereoscopic video display device with the same vertical refresh timing, that is, the frame transmission timing (phase) There is to do.

  The present invention was devised to achieve the above object, and the video synchronization method according to claim 1 is a first and second video transmission for transmitting left and right eye images constituting a three-dimensional stereoscopic image. A video synchronization method for causing a device to transmit images to be displayed simultaneously for each frame and simultaneously outputting the frames to be displayed at the same time. A time synchronization step, a frame transmission preparation completion detection step, and a phase comparison The method includes a step, a frame delay execution step, and a frame synchronization step.

  According to this configuration, the video synchronization method matches the internal times of the first video transmission device and the second video transmission device in the time synchronization step.

  The first video transmission device and the second video transmission device prepare to transmit a frame whose display time (time when the frame (image) should be displayed) is matched according to the internal time matched in this time synchronization step. The sending preparation is a frame (data) in which screen data in the first video sending device and the second video sending device can be sent to the 3D stereoscopic video display device by each video sending device. To prepare for the conversion. This transmission preparation may be shorter than the time of one frame, or may take more than the time of one frame. When the time required for preparation for transmission overlaps with the timing for starting transmission of a frame as described above, the video transmission apparatus retransmits the frame prepared and transmitted first at that timing.

  The video synchronization method is a frame transmission preparation completion detection step. Even if it takes longer than the time of one frame as described above to prepare for transmission of a frame having the same display time by the time synchronization step, Upon receiving a signal indicating that the transmission is being prepared from the video transmission device and the second video transmission device, the timing at which both the first video transmission device and the second video transmission device are ready to transmit is detected from the signal. To do. That is, it is detected that preparation for sending a frame at the next display time can be started. After the detected timing, the first video transmission device and the second video transmission device prepare to transmit frames with the same display time according to the internal time synchronized in the time synchronization step. In other words, the first video transmission device and the second video transmission device are synchronized at the time synchronization step after the completion of frame transmission preparation detection at the frame transmission preparation completion detection step. The preparation for sending the frame at the internal time is repeated.

  The video synchronization method compares the transmission start timings of the frames transmitted from the first video transmission device and the second video transmission device after the timing detected in the frame transmission preparation completion detection step in the phase comparison step.

  The video synchronization method is a frame delay execution step, and the comparison result of the phase comparison step indicates that the transmission start timing of the frame transmitted from the first video transmission device is the transmission start timing of the frame transmitted from the second video transmission device. If the result is earlier, a frame delayed by one frame is output to the frame transmitted from the first video transmission apparatus, and if not, the frame is output as it is without delay. The transmission start timing of the frame from the first video transmission device, which is the output of this frame delay execution step, is delayed by a certain time compared to the transmission start timing of the frame from the second video transmission device to be displayed simultaneously with this frame. It will be a thing. This time is shorter than the time of one frame.

  The video synchronization method is a frame synchronization step, in which a frame transmitted from the second video transmission device is simultaneously transmitted and transmitted as an output of the frame delay execution step. In this way, the video synchronization method prepares to transmit the left-eye video frame and the right-eye video frame to be displayed at the same time on the first video transmission device and the second video transmission device, respectively. Frame sending start timing (phase) can be matched and sent to the 3D stereoscopic moving image display apparatus.

  Furthermore, the video synchronization program according to claim 2 simultaneously transmits the images transmitted by the first video transmission device and the second video transmission device, which transmit the left and right eye images constituting the three-dimensional stereoscopic image, and whose internal times are synchronized with each other. In order to input and simultaneously output frames to be displayed, the computer functions as a frame transmission preparation completion detection unit, a phase comparison unit, a frame delay execution unit, and a frame synchronization unit.

  According to this configuration, first, based on the internal time at which the first video transmission device and the second video transmission device are synchronized with each other, a frame having the same display time (time when the frame (image) should be displayed) is prepared for transmission. . The sending preparation is a frame (data) in which screen data in the first video sending device and the second video sending device can be sent to the 3D stereoscopic video display device by each video sending device. To prepare for the conversion. This transmission preparation may be shorter than the time of one frame, or may take more than the time of one frame. When the time required for preparation for transmission overlaps with the timing for starting transmission of a frame as described above, the video transmission apparatus retransmits the frame prepared and transmitted first at that timing.

  The video synchronization program is a frame transmission preparation completion detection means, and even if the frame preparation at the same display time may take longer than the time of one frame as described above, Upon receiving a signal indicating that transmission preparation is in progress from the two video transmission devices, the timing at which both the first video transmission device and the second video transmission device are ready for transmission is detected from the signal. That is, it is detected that preparation for sending a frame at the next display time can be started. After the detected timing, the first video transmission device and the second video transmission device prepare to transmit frames with the same display time according to the internal time synchronized by the time synchronization means. That is, the first video transmission device and the second video transmission device detect when the frame transmission preparation completion detection means detects the completion timing of frame transmission, and at internal times synchronized with each other after the completion timing. Based on this, the preparation for sending out the frames whose display times coincide with each other is repeated.

  Then, the video synchronization program compares the transmission start timing of the frames transmitted from the first video transmission device and the second video transmission device after the timing detected by the frame transmission preparation completion detection unit by the phase comparison unit.

  The video synchronization program is a frame delay execution unit, and the comparison result of the phase comparison unit indicates that the transmission start timing of the frame transmitted from the first video transmission device is the transmission start timing of the frame transmitted from the second video transmission device. If the result is earlier, a frame delayed by one frame is output to the frame transmitted from the first video transmission apparatus, and if not, the frame is output as it is without delay. The transmission start timing of the frame from the first video transmission device, which is the output of the frame delay execution means, is delayed by a certain time compared to the transmission start timing of the frame from the second video transmission device to be displayed simultaneously with this frame. It will be a thing. This time is shorter than the time of one frame.

  Then, the video synchronization program is a frame synchronization means, which simultaneously starts sending out the frames sent from the second video sending device to the output of the frame delay execution means. In this way, the video synchronization program sends the transmission start timing (phase) of the left-eye video frame and the right-eye video frame to be displayed at the same time sent by the first video transmission device and the second video transmission device. Can be matched and sent to the three-dimensional stereoscopic video display device.

  The video synchronization method and the video synchronization program according to the present invention have the following excellent effects.

  According to the first aspect of the present invention, the frames sent from the two video sending devices can be sent by matching the display times of the frames, and the sending start timing can be matched, that is, sent in synchronism. it can. As a result, by connecting to two video transmission devices such as a personal computer equipped with a general-purpose graphics card (video card), the display times of the frames to be transmitted are matched and transmitted, and the transmission start timing is set. The three-dimensional images that can be transmitted in a matched manner and can be accurately stereoscopically displayed can be displayed on the three-dimensional stereoscopic moving image display device.

  According to the second aspect of the present invention, the frames transmitted from the two video transmission apparatuses whose display times coincide with each other can be transmitted in synchronism with the transmission start timing. As a result, by connecting to two video transmission devices such as a personal computer equipped with a general-purpose graphics card (video card), the display times of the frames to be transmitted are matched and transmitted, and the transmission start timing is set. The three-dimensional images that can be transmitted in a matched manner and can be accurately stereoscopically displayed can be displayed on the three-dimensional stereoscopic moving image display device.

  Accordingly, by using the inventions of claims 1 and 2, when a three-dimensional stereoscopic moving image system for simultaneously displaying a left-eye image and a right-eye image on a screen is established, (1) Many models do not have a genlock function and (2) a function for confirming that frame preparation from a graphics card (video card) on another personal computer has been completed and sending the frames at the same timing. Since a graphics card (video card) for a personal computer with the same can be selected as an option, it is possible to select a more appropriate graphics card (video card) in consideration of performance aspects such as drawing speed. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment)
FIG. 1 is a block diagram of a video synchronization system showing an embodiment of the video synchronization method of the present invention. The video synchronization system 1 is a system that synchronizes a left-eye video and a right-eye video that constitute a three-dimensional stereoscopic video, and sends them to a video receiving device (three-dimensional stereoscopic video display device) 80. The receiving device 80 is a three-dimensional stereoscopic moving image display device or the like, and receives a frame synchronized by the video synchronization system 1 and displays a three-dimensional stereoscopic moving image on a screen. The video synchronization system 1 includes a video synchronization device 10 and two video transmission devices 70 (70a and 70b). As shown in FIG. 1, the video transmission device 70 (70a) corresponds to the first video transmission device, the video transmission device (70b) corresponds to the second video transmission device, and the video transmission device 70 (70a, 70b) corresponds to the video. The frame is sent to the synchronization device 10, and the video synchronization device 10 sends the frame to the video reception device 80.

  The video transmission device 70 (70a, 70b) prepares to transmit frames and continuously transmits frames of a certain length. As shown in FIG. 1, the video transmission device 70 (70a, 70b) includes a frame transmission preparation transmission unit 71 (71a, 71b) and a control unit 72 (72a, 72b).

  The frame sending preparation sending unit 71 (71a, 71b) prepares sending a frame and continuously sends a frame of a certain length that is ready for sending. The frame sending preparation sending unit 71 (71a, 71b) includes a frame sending preparation unit 711 (711a, 711b) and a frame sending unit 712 (712a, 712b). The frame sending preparation unit 711 (711a, 711b) prepares to send a frame, and the frame sending unit 712 (712a, 712b) sends a frame of a certain length prepared for sending. The control unit 72 (72a, 72b) controls operations of the frame transmission preparation unit 711 (711a, 711b) and the frame transmission unit 712 (712a, 712b).

  The control unit 72 (72a, 72b) outputs a logical low value when the frame transmission preparation unit 711 (711a, 711b) is preparing for frame transmission, and a logical high value signal (not preparing for frame non-transmission). Signal) is output to the outside of the video transmission device. When the video transmission device is a computer, the control unit 72 corresponds to a control program for the graphic card, and outputs a frame non-transmission ready signal to the outside via the I / O port. In the present embodiment, a video transmission device having this function is assumed.

  In the video synchronization system 1, the video transmission device 70 (70a) (first video transmission device) and the video transmission device 70 (70b) (second video transmission device) are synchronized with the internal time for starting frame transmission preparation. Synchronizing the internal time here means that the other video transmission device is generated within one frame time with respect to the frame transmission start timing of one video transmission device (the internal time tn at this timing). The internal time at the frame transmission start timing is set to the same tn.

  Here, with reference to FIG. 2 (refer to FIG. 1), the principle of synchronizing the internal time between the first video transmission device and the second video transmission device will be described. FIG. 2 is a timing diagram showing the principle of synchronizing the internal time. The video transmission device 70 (70a) corresponding to the first video transmission device is a time series Tn (T0, T1) of the internal time of the first video transmission device at the frame transmission start timing of the first video transmission device in FIG. , T2,... Tn) at a frame transmission start timing. The second video transmission device transmits the frame transmission timing of the first video transmission device (FIG. 2 (a) the time series of the internal time of the first video transmission device at the frame transmission start timing of the first video transmission device (T0, T1,. T2,... Tn)) are detected from the vertical refresh signal of the frame transmitted from the first video transmission apparatus.

  It is assumed that the detection of the vertical refresh signal of the first video transmission device in this second video transmission device is performed in such a short time that it can be regarded as instantaneous compared to the time of one frame. When the second video transmission device is a personal computer or the like and has an interrupt input function, the vertical refresh signal is detected by this interrupt input function, so that the detection of the vertical refresh signal can be performed in a short time so that it can be regarded as an instant. Can do. Thereafter, in both the first video transmission device and the second video transmission device, it is assumed that the detection of the vertical refresh signal is performed in such a short time that it can be regarded as instantaneous compared to the time of one frame.

  Accordingly, the time series Tn of the internal time of the first video transmission device at the frame transmission start timing of the first video transmission device in FIG. 2A is the vertical refresh signal of the first video transmission device in the second video transmission device. It coincides with the timing at which is detected. Further, the time series Tn ′ of the internal time of the second video transmission device at the frame transmission start timing of the second video transmission device in FIG. 2C is the vertical refresh signal of the second video transmission device itself in the second video transmission device. It coincides with the timing at which is detected.

  The first video transmission device detects the internal time information I (T) at the frame transmission timing of the first video transmission device itself, detects the vertical refresh signal of the frame transmitted by the first video transmission device itself, Generated by counting. The detection of the vertical refresh signal can be considered to be performed instantaneously based on the above assumption, and it can be considered that no extra time (delay time, etc.) is added to the count (clocking), but the internal time information I (T) is used. A transfer time is required to transfer from the second video transmission device to the first video transmission device via a LAN or the like between the first video transmission device and the second video transmission device. Accordingly, as shown in FIG. 2B, the internal time information I (T) of the first video transmission device arrives at the second video transmission device via a LAN between the first video transmission device and the second video transmission device. The time series t (I (Tn)) of arrival times to be transmitted is compared with the time series Tn of the internal time of the first video transmission apparatus at the frame transmission start timing of the first video transmission apparatus in FIG. Etc., the transfer time will be delayed.

  Then, the frame transmission timing of the first video transmission device (FIG. 2 (a) the time series Tn of the internal time of the first video transmission device at the frame transmission start timing of the first video transmission device) and the frame of the second video transmission device Depending on the phase state of the transmission timing (FIG. 2C, the time series Tn ′ of the internal time of the second video transmission device at the frame transmission start timing of the second video transmission device), the time tn as in case 1 of FIG. 2 in the order of the frame transmission timing of the first video transmission device, the arrival timing of t (I (Tn)), the frame transmission timing of the second video transmission device at time tn ′, and the case 2 of FIG. As described above, the frame transmission timing of the first video transmission device at time tn, the frame transmission timing of the second video transmission device at time tn ′, and the arrival timing of t (I (Tn)) If occurs that.

  Therefore, as shown in FIG. 2 (b), the second video transmission device has internal time information I (T) of the first video transmission device between the first video transmission device and the second video transmission device. , The time series t (I (Tn)) (t (I (T0)), t (I (T1)), t (I (T2)),. ... (T (I (Tn))) is prepared, and when the frame transmission start timing of the first video transmission device is detected, this flag is reset.

  Then, the second video transmission device sends the frame transmission timing of the second video transmission device itself (FIG. 2C) the time series of the internal time of the second video transmission device at the frame transmission start timing of the second video transmission device (T0). ′, T1 ′, T2 ′,... Tn ′)) is detected from the vertical refresh signal of the frame of the second video transmission device itself, the flag is determined at this timing, and the flag is set if the flag is set. Case 1 of 2 and case 2 are determined if the flag is reset.

  Then, in the case of case 1, the second video transmission device uses the time Tn ′ obtained from the internal time information I (Tn) of the first video transmission device as the frame transmission start timing time Tn ′ of the second video transmission device itself. Set. Further, in the case 2, the second video transmission device receives the time of the frame transmission start timing time Tn ′ of the second video transmission device itself as internal time information I ( T (n-1)) is obtained by adding one frame time to time T (n-1) obtained from T (n-1)), that is, time Tn. In this way, the second video transmission device can synchronize with the first video transmission device the internal time at which frame transmission starts.

Returning to FIG. 1, the description will be continued.
Even if one or both of the video transmission device 70 (70a) and the video transmission device 70 (70b) may take more than one frame time to prepare for transmission of the frame, the video synchronization device 10 is able to The frames prepared for transmission so that the display times of the left-eye video and the right-eye video coincide with each other are transmitted to the three-dimensional stereoscopic video display device 80 with the vertical refresh timing, that is, the frame transmission timing (phase) matched. To do.

  The video synchronization apparatus 10 includes a frame transmission preparation completion detection unit 20, a phase comparison unit 30, a frame delay execution unit 40, and a frame synchronization unit 50.

  The frame transmission preparation completion detection unit 20 has a basic function and an operation recovery function. As described above, the basic function is that the first video transmission device and the second video transmission device may take a frame that is an image at the same display time to prepare for frame transmission longer than one frame time. The video transmission device 70 (70a) (first video transmission device) and the video transmission device 70 (70b) (second video transmission device) both detect completion of transmission preparation. That is, the frame transmission preparation completion detection unit 20 detects that it is possible to start transmission preparation for a frame at the next display time. The operation recovery function means that the frame transmission preparation completion detection unit 20 is actually ready for frame transmission by both of the video transmission devices due to noise or the like when the video transmission device 10 is turned on or in operation. Both of the video transmission devices are in the state of detecting that the frame is being prepared for transmission, or that at least one of the video transmission devices has not completed the frame transmission preparation. This is a function for recovering from a state in which it is detected that a transmission preparation has been completed.

  Here, with reference to FIG. 3 (refer to FIG. 1 as appropriate), a detailed configuration of the frame transmission preparation completion detection unit 20 will be described. FIG. 3 is a block diagram showing a detailed configuration of the frame transmission preparation completion detection unit 20. As shown in FIG. 3, the frame transmission preparation completion detection unit 20 includes a basic operation unit 20A having a basic function and an operation recovery unit 20B. The basic operation unit 20A detects completion of frame transmission preparation, and the operation recovery unit 20B recovers a state in which the basic operation unit 20A malfunctions.

  The basic operation unit 20A includes a one-shot pulse generator 21 (21a, 21b), an RS flip-flop 22 (22a, 22b), a logical product 23 (23a, 23b), and a transmission start timing detection unit 24 (24a , 24b) and an OR circuit 25 (25a). The operation recovery unit 20B includes a logical product 23 (23c, 23d), a logical sum 25 (25b, 25c), a binary counter 26, and a logical negator 27. Hereinafter, each configuration of the basic operation unit 20A and the operation recovery unit 20B will be described.

(Configuration of basic operation part of frame transmission preparation completion detection part)
The one-shot pulse generator 21 (21a, 21b) detects UpEdge of a signal that is a logic low value during frame transmission preparation and is a logic high value when frame transmission preparation is not being performed (frame non-transmission preparation signal). The output is a one-shot pulse whose UpEdge is the same time. This timing of UpEdge is the timing when the transmission preparation for the corresponding video transmission apparatus is completed.

  The RS flip-flops 22 (21a, 21b) operate as shown in the truth table of FIG. 6, and are set by UpEdge of one-shot pulse output from the one-shot pulse generator 21 (21a, 21b), respectively. The output is a logical high value. Further, the RS flip-flop 22 (22a, 22b) is reset by the output UpEdge of the logical product 23 (23a) and outputs the logical low value. The logical product 23 (23a) will be described later. The output of the AND circuit 23 (23a) is sent to the RS flip-flop 22 (22a, 22b) via the OR circuit 25 (25b) that adds the signal of the operation restoration unit 20B as a logical sum (AND). Entered. Since the signal of the operation restoration unit 20B added as a logical sum (AND) to the logical sum 25 (25b) is a logic low value unless the basic operation unit 20A malfunctions, if the basic operation unit 20A does not malfunction, The output of the logical adder 25 (25b) is the same as the output of the logical product 23 (23a).

  The logical product 23 (23b) outputs the logical product of the RS flip-flops 22 (22a, 22b). That is, when both the RS flip-flop 22 (22a) and the RS flip-flop 22 (22b) output a logical high value (the video transmission device 70 (70a) (first video transmission device) and the video transmission device 70 (70b) (first). The logical product 23 (23b) outputs a logical high value (at the time when the two video transmission device) completes frame transmission preparation, and is reset by the output UpEdge of the logical product 23 (23a). Value.

  The transmission start timing detector 24 (24a, 24b) detects the transmission start time for each frame from the vertical refresh signal of the transmission frame of the video transmission device 70 (70a, 70b) and outputs one shot pulse. is there. The transmission start timing detection unit 24 (24a) detects the output start timing of the frame from the video transmission device 70 (70a). The transmission start timing detection unit 24 (24b) detects the output start timing of the frame from the video transmission device 70 (70b).

  The OR circuit 25 (25a) outputs a logical sum of the one-shot pulses output from the transmission start timing detection unit 24 (24a) and the transmission start timing detection unit 24 (24b). That is, the output of the OR circuit 25 outputs a one-shot pulse at any timing of the output start timing of the frame from the video transmission device 70 (70a) and the output start timing of the frame from the video transmission device 70 (70b). Output.

  The logical product 23 (23a) outputs a logical product of the output of the logical sum 25 (25a) and the output of the logical product 23 (23b). That is, if both the RS flip-flop 22 (22a) and the RS flip-flop 22 (22b) output a logical high value (when the logical product 23 (23b) outputs a logical high value), the video transmission device At any timing of the output start timing of the frame from 70 (70a) and the output start timing of the frame from the video transmission device 70 (70b) (the output of the OR circuit 25 outputs a one-shot pulse at this timing). The output of the logical product 23 (23a) outputs one shot pulse.

  Therefore, the output of the AND circuit 23 (23b), which is the output of the frame transmission preparation completion detection unit 20, is logical when both the video transmission device 70 (70a) and the video transmission device 70 (70b) have completed frame transmission preparation. It becomes a High value, and thereafter, it becomes a logical low value at any timing of the output start timing of the frame from the video transmission device 70 (70a) and the output start timing of the frame from the video transmission device 70 (70b). Then, the timing of the output UpEdge is the timing when both the video transmission device 70 (70a) and the video transmission device 70 (70b) are ready for transmission.

(Internal operation of basic operation part of frame transmission preparation completion detection part)
Here, with reference to FIG. 4, the internal operation of the basic operation unit 20A of the frame transmission preparation completion detection unit will be described (see FIG. 1 and FIG. 3 as appropriate). FIG. 4 is a timing chart showing the internal operation of the basic operation unit 20A of the frame transmission preparation completion detection unit 20. In FIG. 4, the horizontal axis represents time.

  FIG. 4A shows a frame transmission cycle in the video transmission device 70 (70a) corresponding to the first video transmission device. The first video transmission device transmits a frame at a constant frame period Tp as shown in FIG. 4A, and starts frame transmission preparation at the start timing of this period. FIG. 4B shows a frame transmission preparation time in the first video transmission apparatus. Arrows P (t0) to P (t2) in FIG. 4B represent frame transmission preparation time, the start point of which corresponds to the frame transmission preparation start time, and the end point thereof corresponds to the frame transmission preparation completion time.

  FIG. 4E shows a frame transmission cycle in the video transmission device 70 (70b) corresponding to the second video transmission device. Similarly, the second video transmission device transmits a frame at a constant frame period Tp as shown in FIG. 4F, and starts frame transmission preparation at the start timing of this period. FIG. 4F shows the frame transmission preparation time in the second video transmission apparatus. Arrows P (t0) to P (t2) in FIG. 4 (f) represent frame transmission preparation times, the start point of which corresponds to the frame transmission preparation start time, and the end point thereof corresponds to the frame transmission preparation completion time. In FIG. 4, the arrow P (t0) at the first video transmission device and the arrow P (t0) at the second video transmission device are frames whose display time is based on the internal time t0 of the first video transmission device. Is expressed. The same applies to the arrow P (t1) and the arrow P (t2).

  Here, it will be described that the arrow P (tn) of the first video transmission device and the arrow P (tn) of the second video transmission device are frames at the same display time. As described above, the time tn (t 0, t 1, t 2, etc.) at the timing of starting the transmission of the frame in the first video transmission device and the second video transmission device generated within the time Tp of one frame from the timing. The internal time tn ′ (t0 ′, t1 ′, t2 ′, etc.) at the timing when frame transmission is started is the same internal time tn (t0, t1, t2, etc.). Therefore, after both the first video transmission device and the second video transmission device have completed frame transmission preparation, the first video transmission device has a timing to start transmission of frames earlier than the first video transmission device. Starts to send a frame whose display time is a time based on the internal time tn (for example, tn + b (b is a constant)) from the start of sending the frame. The timing based on the internal time tn (= tn ′) (for example, tn + b) is set as the display time at the timing at which the first video transmission device starts sending the frame after the timing. If the frame transmission preparation is started, these two frames become frames at the same display time.

  In addition, when both the first video transmission device and the second video transmission device are ready for frame transmission, when the timing of starting the transmission of the frame of the first video transmission device is late (including simultaneous cases) The second video transmission device starts preparation for transmitting a frame based on the internal time tn at the timing (for example, tn + b (b is a constant)), and the first video transmission device By starting preparation for sending a frame whose display time is a time (such as tn + b) based on the internal time tn at the first time t (n + 1) after the timing, the two frames are Frames with the same display time.

  As described above, the first video transmission device for creating the frame at the same display time includes the first video after the first video transmission device and the second video transmission device are both ready for frame transmission. A frame for which preparation for transmission is started depending on whether the timing at which the transmission device starts to transmit the frame is earlier at the timing at the internal time tn or at the later timing (including the simultaneous timing) at the internal time t (n + 1). Is required to determine whether the display time is based on the same time tn as the internal time or based on the internal time tn one hour before one frame. This information corresponds to the output of the phase comparison unit 30, which will be described later, after both the first video transmission device and the second video transmission device have completed frame transmission preparation, This is the output of the comparison result of whether the timing to start sending is earlier or later. As shown in FIG. 1, the first video transmission apparatus obtains this information by inputting this output to the control unit 72 (72a), and determines the display time of the frame to start transmission preparation as described above. Can be changed.

  The description of the internal operation of the basic operation unit 20A of the frame transmission preparation completion detection unit will be continued. The first video transmission device frame transmission preparation completion pulse shown in FIG. 4C and the second video transmission device frame transmission preparation completion pulse shown in FIG. (21a, 21b) is a one-shot pulse signal output upon completion of frame transmission preparation output. In FIG. 4C, a one-shot pulse that becomes UpEdge at time tp (t0), time tp (t1), etc., and in FIG. 4G, UpEdge at time tp (t0) ′, time tp (t1) ′, etc. It becomes 1 shot pulse.

  The RS edge of the one-shot pulse is detected by the RS flip-flop 22 (22a) and the RS flip-flop 22 (22b), and the output is set to a logical high value. That is, at the output of the RS flip-flop 22 (22a) in FIG. 4D, the time tp (t0) and the time tp (t1), and at the output of the RS flip-flop 22 (22b) in FIG. Like 'and time tp (t1)', each video transmission device has a logical high value every time frame transmission preparation is completed. It is assumed that the RS flip-flop 22 (22a, 22b) is reset first and the output value is a logic low value.

  The RS flip-flop 22 (22a) and the RS flip-flop 22 (22b) are output from the time tp (t0) to t1 and from the time tp (t1) to t2 ′ of the logical product 23 (23b) in FIG. ) Both output a logic high value, the output of the AND circuit 23 (23b) becomes a logic high value.

  Like the output start timing detection unit 24 (24a) of the first video transmission device output in FIG. 4 (j), the transmission start timing detection unit 24 (24a) transmits the transmission frame of the first video transmission device 70 (70a). From this, the output start timing for each frame is detected and one shot pulse is output. Similarly, like the output start timing detection unit 24 (24b) of the second video transmission device output in FIG. 4 (k), the transmission start timing detection unit 24 (24b) starts from the transmission frame of the second video transmission device. The output start timing for each frame is detected and one shot pulse is output.

  Like the output of the logical adder 25 (25a) in FIG. 4 (l), the output of the logical adder 25 (25a) is the transmission start timing detector 24 (24a) of the first video transmission device output in FIG. 4 (j). ) Output and a plurality of one-shot pulses that are the logical sum of the output of the second video transmission device output in FIG. 4 (k) and the output start timing detection unit 24 (24b).

  The output of the logical product 23 (23a) outputs a logical product of the logical product 23 (23b) output of FIG. 4 (i) and the logical sumr 25 (25a) output of FIG. Thus, the RS flip-flop 22 (22a) and the RS flip-flop 22 (22b) are reset. As shown at time t1, time t2 ', and time t4 in FIG. 4, the output of the logical product 23 (23b) in FIG. 4 (i) is a logical high value, and the logical sum 25 in FIG. 4 (l). (25a) A one-shot pulse such as an output is generated, and the output of the AND circuit 23 (23a) is UpEdge at which the logic High value is set, and the RS flip-flop 22 (22a) and the RS flip-flop 22 (22b) are reset. The output of the RS flip-flop 22 (22a) in FIG. 4D, the output of the RS flip-flop 22 (22b) in FIG. 4H, and the output of the logical product 23 (23b) in FIG. It becomes. As a result, the output of the logical product 23 (23a) also becomes a logical low value, and becomes a logical high value like the time t1, time t2 ′, and time t4 of the logical product 23 (23a) in FIG. Immediately after that, the logic low value is obtained.

  As apparent from FIG. 4, the timing of UpEdge at which the output of the AND circuit 23 (23b) in FIG. 4 (i) becomes a logical high value is the same display in the first video transmission device and the second video transmission device. This is the timing when preparation for sending a frame of time is completed.

(Configuration of operation recovery unit of frame transmission preparation completion detection unit)
Here, returning to FIG. 3, the description of the configuration of the frame transmission preparation completion detection unit 20 will be continued. The operation restoration unit 20B causes the RS flip-flops 22 (22a, 22b) of the basic operation unit 20A to malfunction together when the video transmission device 10 is powered on or during operation, and the video transmission devices complete preparation for transmission. If the state where the logic high value is not output continues after that, that is, if the frame transmission preparation is not detected due to malfunction, the RS flip-flop 22 (22a, 22b) is counted after counting the frame transmission start timing up to a preset number of times. Is reset to restore the operation of the basic operation unit 20A (reset function).

  Furthermore, although at least one of the video transmission devices has not completed the frame transmission preparation, both of the video transmission devices are erroneously detecting that they have completed the frame transmission preparation, that is, When the output of the RS flip-flop 22 (22a, 22b) has a logic high value, the output of the AND circuit 23 (23d) is forcibly set to a logic low value, thereby preventing malfunction. (Output limiting function).

  Further, the frame transmission preparation completion detection unit 20 also outputs a signal for resetting the RS flip-flops 22 (22a and 22b) to the output of the frame transmission preparation completion detection unit 20 at the time of reset by the reset function. The logical sum is output at (25c) and output. In the case of normal operation, when both video transmission apparatuses complete the frame transmission preparation, the output of the RS flip-flop 22 (22a, 22b) becomes a logical high value, so that the output of the frame transmission preparation completion detection unit 20 The output of the logical adder 25 (25c) becomes a logical high value, but when it is in a malfunctioning state that is reset by the reset function, the frame is forcibly prepared for transmission in both video transmission devices, and the RS flip-flop A logical high value signal for resetting the group 22 (22a, 22b) is logically summed by the logical summing unit 25 (25c) and output as the output of the frame transmission preparation completion detecting unit 20. The state of outputting a signal of this logical high value continues until the timing at which one video transmission device starts preparation for frame transmission. (Transmission preparation completion alternative output function)

  The logical product unit 23 (23c) receives the frame non-sending ready signal of the first video sending device and the second video sending device, and becomes a logical high value when both the video sending devices are both not ready for sending. Output.

  The binary counter 26 receives the output of the logical product 23 (23c), which is a logical high value when both video transmission devices are in preparation for non-transmission, as a count permission signal, and outputs the first video transmission device transmission frame. UpEdge of a plurality of one-shot pulses from the logical adder 25 (25a) that is the logical sum of the output of the transmission start timing detection unit 24 (24a) and the output of the second video transmission device transmission frame transmission start timing detection unit 24 (24b). Is to count.

  Then, the logical negator 27 inverts the output of the logical product unit 23 (23c) and outputs a signal that becomes a logical high value to the binary counter 26 when either or both of the video transmission devices are preparing for transmission. Is output as a reset signal. Therefore, the binary counter 26 is reset at UpEdge which becomes a logical high value when either or both of the video transmission devices are preparing for transmission. That is, the binary counter 26 determines the transmission frame transmission start timing of the first video transmission device and the transmission frame transmission start timing of the second video transmission device when both the video transmission devices are preparing for non-transmission. Count.

  The binary counter 26 outputs a logic high value signal when it counts a preset count number. This preset count number is set in the binary counter 26. If this count is a power of 2, for example 2, 4, 8, etc., the counter output should output the corresponding bit of the binary output (for example, the third bit from the bottom if it is 4). Thus, a signal having a logical high value can be output.

  In order to add the output signal which becomes the logical high value of the binary counter 26 as a logical sum to the output side of the AND circuit 23 (23a) as a signal for resetting the RS flip-flop 22 (22a, 22b) A summer 25 (25b) is provided, and the RS flip-flop 22 (22a, 22b) is reset by a logical sum of the output of the binary counter 26 and the output of the AND circuit 23 (23a). By doing so, the reset function described above is realized.

  The logical adder 25 (25c) outputs the logic of the binary counter 26 to the output of the logical product 23 (23d), which is the output limited by the previous output limiting function (the output of the frame transmission preparation completion detection unit 20B). A high value signal is added as a logical sum. By doing so, when at least one of the RS flip-flops 22 (22a, 22b) malfunctions and both the video transmission apparatuses complete the preparation for transmission, and the state where the logical high value is not output continues, When the transmission start timing of the preset number of times is counted, the output of the binary counter 26 becomes a logical high value, and this output resets the RS flip-flop 22 (22a, 22b), and also the frame transmission preparation completion detection unit 20 Is set to a logical high value (transmission preparation completion alternative output function).

Returning to FIG. 1, the description of the video synchronizer 10 will be continued.
The phase comparison unit 30 transmits the frame by the video transmission device 70 (70a) (first video transmission device) after the timing when the transmission preparation is completed by both the video transmission devices detected by the frame transmission preparation completion detection unit 20. The timing to start and the timing to start sending a frame in the video sending device 70 (70b) (second video sending device) are compared.

  Here, the configuration of the phase comparison unit 30 will be described with reference to FIG. FIG. 5 is a block diagram showing the configuration of the phase comparison unit 30. Here, the phase comparison unit 30 includes a transmission start timing detection unit 31 (31a, 31b), an RS flip-flop 32, a binary counter 33, a D latch 34, and a one-shot pulse generator 35. .

  The transmission start timing detection unit 31 (31a, 31b) detects the transmission start timing of the frame from the vertical refresh signal of the transmission frame of the video transmission device 70 (70a, 70b) and outputs one shot pulse. . The transmission start timing detection unit 31 (31a) detects the transmission start timing of the frame from the first video transmission device. The transmission start timing detection unit 31 (31b) detects the transmission start timing of the frame from the second video transmission device.

  The one-shot pulse generator 35 detects UpEdge at the timing when frame transmission preparation is completed from the output of the frame transmission preparation completion detection unit 20, and outputs a one-shot pulse at which UpEdge has the same time. .

  The RS flip-flop 32 operates as shown in the truth table of FIG. 6, and is set with a one-shot pulse that becomes UpEdge at the timing when the preparation for sending a frame from the one-shot pulse generator 35 is completed. It becomes a High value, and is reset by a one-shot pulse that becomes UpEdge at the transmission start timing of the frame of the first video transmission device from the transmission start timing detection unit 31 (31a), and the output becomes a logical low value.

  The binary counter 33 receives the output of the RS flip-flop 32 as a count permission signal, counts the 1-shot pulse UpEdge that is the output of the transmission start timing detection unit 31 (31b) from the second video transmission device, The output value changes from 0 to 1 (counting operation). Further, the binary counter 33 is reset by a one-shot pulse that becomes UpEdge at a timing when preparation for sending a frame from the one-shot pulse generator 35 is completed, and the output value returns from 1 to 0 (reset operation). . Since the binary counter 33 outputs the least significant bit, a 1-bit counter that can count from 0 to 1 is sufficient.

  The D latch 34 latches (holds) the least significant bit value of the output of the binary counter 33 at the timing of 1-shot pulse UpEdge which is the output value of the transmission start timing detection unit 31 (31b).

(Internal operation of phase comparator)
Here, the internal operation of the phase comparison unit 30 will be described with reference to FIG. 7 (see FIG. 5). FIG. 7 is a timing chart showing the internal operation of the phase comparator 30. In FIG. 7, the horizontal axis represents time.

  FIG. 7A shows a frame transmission cycle in the video transmission device 70 (70a) corresponding to the first video transmission device. The first video transmission apparatus transmits frames at a fixed frame period Tp as shown in FIG. 7A, and starts frame transmission preparation at the start timing of this period. FIG. 7B shows the frame transmission preparation time in the first video transmission apparatus. Arrows P (t0) to P (t2) in FIG. 7B represent frame transmission preparation time, the start point of which corresponds to the frame transmission preparation start time, and the end point thereof corresponds to the frame transmission preparation completion time.

  FIG. 7C shows a frame transmission cycle in the video transmission device 70 (70b) corresponding to the second video transmission device. The second video transmission apparatus also transmits a frame at a fixed frame period Tp as shown in FIG. 7C, and starts frame transmission preparation at the start timing of this period. FIG. 7D shows the frame transmission preparation time in the second video transmission apparatus. Arrows P (t0) to P (t2) in FIG. 7D represent frame transmission preparation time, the start point of which corresponds to the frame transmission preparation start time, and the end point thereof corresponds to the frame transmission preparation completion time. Note that the arrow P (t0) in the first video transmission device and the arrow P (t0) in the second video transmission device in FIG. 7 are frames whose display time is based on the internal time t0 of the first video transmission device. Is expressed. The same applies to the arrow P (t1) and the arrow P (t2).

  FIG. 7E shows the output of the frame transmission preparation completion detection unit 20. The one-shot pulse generator 35 output in FIG. 7 (f) is generated from the output of the frame transmission preparation completion detection unit 20 (the output that becomes UpEdge when the frame transmission preparation in both video transmission apparatuses is completed). 1 represents a one-shot pulse in which UpEdge generated by the device 35 is at the same time.

  Like the output of the transmission start timing detection unit 31 (31a) in the first video transmission device in FIG. 7G, the transmission start timing detection unit 31 (31a) Each output start time is detected and one shot pulse is output. It should be noted that the timing of this one-shot pulse UpEdge coincides with the start timing of the first video transmission apparatus frame transmission cycle of FIG. Similarly, like the transmission start timing detection unit output in the second video transmission device in FIG. 7 (h), the transmission start timing detection unit 31 (31b) starts from the transmission frame of the second video transmission device for each frame. Is output and one shot pulse is output. It should be noted that the timing of this one-shot pulse UpEdge coincides with the start timing of the second video transmission apparatus frame transmission cycle of FIG. 7B.

  The output of the RS flip-flop 32 in FIG. 7 (i) represents the output of the RS flip-flop 32, and the frame is transmitted by both video transmission devices at the time Tp (t1) at the output of the one-shot pulse generator 35 in FIG. 7 (f). The RS flip-flop 32 is set with a one-shot pulse that becomes UpEdge when the preparation for sending out is completed, and the output becomes a logical high value at the same time Tp (t1), and the first video shown in FIG. It is reset by a one-shot pulse at time t3 at the output of the transmission start timing detection unit 31 (31a) in the apparatus, and the output is logically low like the output of the RS flip-flop 32 in FIG. 7 (i) at the same time t3. Value.

  The output of the binary counter 33 in FIG. 7 (j) represents the output of the binary counter 33, and the output of the RS flip-flop 32 in FIG. 7 (i) is a logical high value from time Tp (t1) to time t3. When the binary counter 33 receives the signal as a count permission signal and there is a timing at which the second video transmission device starts to transmit a frame while the count permission is present, that is, the second video in FIG. In the case of time t2 ′ output from the transmission start timing detection unit 31 (31b) in the transmission device, the binary counter 33 counts this timing and the output value becomes 0 to 1. (Counting operation)

  The output of the binary counter 33 in FIG. 7 (j) is the time Tp (t0), Tp (t1), Tp (t2) when the binary counter 33 becomes the output of the one-shot pulse generator 35 in FIG. 7 (f). ) And the output value returns from 1 to 0 (reset operation).

  The output of the D latch 34 in FIG. 7 (k) represents the output of the D latch 34, and the output of the binary counter 33 in FIG. 7 (j) becomes the UpEdge at times t1, t2, and t3. This is latched by UpEdge of one shot pulse at time t3 of the output of the transmission start timing detector 31 (31a) in one video transmission device. The output of the D latch 34 becomes the output of the phase comparison unit 30.

  As described above, after the frame transmission preparation completion time detected by the frame transmission preparation completion detection unit 20 (time Tp (t1) in FIG. 7), the frame transmission timing of the second video transmission device (time t2 ′ in FIG. 7). Occurs earlier than the frame transmission timing (time t3 in FIG. 7) of the first video transmission device (including the simultaneous case), the phase comparison unit 30 prepares to transmit the frame detected by the frame transmission preparation completion detection unit 20. During the transmission of a frame from the first video transmission apparatus after the completion time (time Tp (t1) in FIG. 7) to the transmission completion time for the next frame (time Tp (t2) in FIG. 7) That is, a signal having a logical high value is output for the time of one frame from the time t3 of the output of the D latch 34 in FIG.

  Conversely, the phase comparison unit 30 outputs an output that is a logical low value in the following case. That is, after the frame transmission preparation completion time detected by the frame transmission preparation completion detection unit 20 (time Tp (t0) in FIG. 7), the frame transmission timing (time t1 in FIG. 7) of the first video transmission device is the second video. When this occurs earlier than the frame transmission timing (time t1 ′ in FIG. 7) of the transmission device, the phase comparison unit 30 is after the frame transmission preparation completion time detected by the frame transmission preparation completion detection unit 20 (time Tp (t0 in FIG. 7). )) To the next frame transmission preparation completion time (time Tp (t1) in FIG. 7), during the transmission of the frame from the first video transmission device, that is, the D latch 34 in FIG. 7 (k). A signal having a logic low value is output like the time of two frames from time t1 to time t3.

Returning to FIG. 1, the description of the video synchronizer 10 will be continued.
The frame delay execution unit 40 receives the output of the phase comparison unit 30, receives the output from the video transmission device 70 (70a) (first video transmission device), and delays the frame by one frame. The frames that are not to be switched (that is, the frames that are transmitted from the first video transmission device) are switched and output.
The frame delay execution unit 40 includes a frame delay unit 41 and a switch unit 42. The frame delay unit 41 transmits a frame obtained by delaying one frame time from the frame transmitted from the first video transmission device. The frame delay unit 41 is composed of a delay line.

  The delay line delays the video signal and the like. For example, two frame memories that can store one frame are prepared, and while the other frame memory records input data, the other frame memory The previously recorded frame is output with a time delay of one frame from the point of recording, and this is alternately repeated.

  The switch unit 42 is a switch that switches between two inputs depending on whether the output of the phase comparator 30 is a logical high value or a logical low value. As described above, by configuring the frame delay execution unit 40, when the phase comparison unit 30 outputs a logic low value, the frame delay execution unit 40 outputs a frame transmitted from the frame delay unit 41. When the switch unit 42 is switched and output, and the phase comparison unit 30 outputs a logical high value, the frame transmitted from the video transmission device 70 (70a) (first video transmission device) is switched and output as it is. can do.

  The frame synchronization unit 50 outputs the frame sent from the video transmission device 70 (70b) (second video transmission device) to the output of the frame delay execution unit 40 in frame synchronization (delay synchronization). The frame synchronization unit 50 includes a frame transmission start time difference detection unit 51, a delay time calculation unit 52, and a variable time delay unit 53.

  The frame transmission start time difference detection unit 51 inputs both frames transmitted from the video transmission device 70 (70a) and the video transmission device 70 (70b) and detects the transmission start time of each frame. The delay time calculation unit 52 calculates a time for delaying the frame transmitted from the video transmission device 70 (70b) based on the start time of each frame detected by the frame transmission start time difference detection unit 51. It is. Further, the variable time delay unit 53 delays the frame transmitted from the video transmission device 70 (70b) by the time calculated by the delay time calculation unit 52. With this configuration, the frame synchronization unit 50 synchronizes the frame transmitted from the video transmission device 70 (70b) (second video transmission device) with the output of the frame delay execution unit 40 (delay synchronization). Can be output.

  By configuring the video synchronization device 10 in this manner, the video synchronization device 10 prepares the first video transmission device and the second video transmission device to transmit frames to be displayed at the same time, and transmits the frames at the same transmission timing. Will be able to.

(Operation of video synchronizer)
Here, with reference to FIG. 8, the operation of the video synchronizer 10 will be described (appropriately, see FIG. 1). FIG. 8 is a timing chart showing the operation of the video synchronizer 10.

  In FIG. 8, the horizontal axis represents time. The video sending device 70 (70a) (first video sending device) starts sending a frame at a fixed frame period Tp as shown in FIG. 8A, and starts frame sending preparation at the start timing of this period. The arrows P (t0), P (t1), P (t3), P (t4), and P (t7) in FIG. 8B represent frame transmission preparation time, the start point is the frame transmission preparation start time, and the end point is the frame. Corresponds to the transmission preparation completion time. Arrows P (t0), P (t1), P (t3), and P (t4) in FIG. 8C represent frame transmission times, with the start point corresponding to the frame transmission start time and the end point corresponding to the frame transmission completion time.

  The video transmission device 70 (70b) (second video transmission device) also starts transmitting frames at a fixed frame period Tp as shown in FIG. 8E, and starts frame transmission preparation at the timing of this period. In FIG. 8F, arrows P (t0), P (t1), P (t3), P (t4), and P (t7) represent frame transmission preparation times, the start point is the frame transmission preparation start time, and the end point is the frame. Corresponds to the time to complete sending preparation Arrows P (t0), P (t1), P (t3), and P (t4) in FIG. 8G represent frame transmission times, with the start point corresponding to the frame transmission start time and the end point corresponding to the frame transmission completion time. The arrow P (t0) in the first video transmission device and the arrow P (t0) in the second video transmission device are the first video transmission device synchronized with the first video transmission device and the second video transmission device. The frame of the display time based on the internal time t0 is represented. The same applies to the arrows P (t1), P (t3), P (t4), and P (t7).

  The first video transmission device and the second video transmission device use the synchronized internal time t0 to prepare for transmission of the frame P (t0) at the same display time. Accordingly, the arrow P (t0) of the first video transmission device transmission preparation frame in FIG. 8B and the arrow P (t0) of the second video transmission device transmission preparation frame in FIG. That is, it represents a frame that is sent synchronously (time synchronization step). Note that preparation for sending a frame may take less time than one frame, or may take more than one frame. Then, after the frame transmission preparation completion detecting unit 20 detects the frame transmission preparation at the same display time in both video transmission apparatuses, the frame transmission start timing is earlier or later ( The video synchronizer operates differently (including the simultaneous case). First, the case where the frame transmission start timing of the first video transmission device is earlier will be described, and the case where the frame transmission start timing of the first video transmission device is later will be described.

  A case will be described in which the frame transmission start timing of the first video transmission device is earlier after the timing of completing the frame transmission preparation. First, P (t0) of the first video transmission device transmission preparation frame in FIG. 8B and P (t0) of the second video transmission device transmission preparation frame in FIG. The transmission preparation completion detection unit 20 detects Tp (t0). (Frame transmission preparation completion detection step)

  Then, the frame P (t0) that is detected to be ready for transmission is transmitted at the frame transmission start timing of each video transmission device. That is, the frame P (t0) is transmitted as P (t0) from time t1 and P (t0) from time t2 of the first video transmission device transmission frame in FIG. Also, the frame P (t0) is transmitted as P (t0) from the time t1 ′ and P (t0) from the time t2 ′ of the second video transmission device transmission frame in FIG. (The video transmission device continuously transmits the frames detected to be ready for transmission until the first transmission start timing after the completion of the creation of a new frame.)

  Then, after time Tp (t0) when the preparation for sending the frame P (t0) is completed in FIG. 8, the phase comparison unit 30 compares the frame sending start timings of the first video sending device and the second video sending device. The frame transmission start timing at time t1 of the first video transmission device transmission frame in FIG. 8C is higher than the frame transmission start timing at time t1 ′ of the second video transmission device transmission frame in FIG. Outputs the result of being fast. (Phase comparison step)

  Then, the frame delay execution unit 40 receives the result of the phase comparison unit 30, and the frame delay unit 41 delays the first video transmission device transmission frame of FIG. 8C by the time Tp of one frame period. Output. The frame P (t0) is P (t0) from time t2 at the output of the frame delay execution unit in FIG. (Frame delay execution step)

  Then, the frame synchronization unit 50 outputs to the output of the frame delay execution unit 40 (the output of the frame delay execution unit of FIG. 8D) from the output of the second video transmission device (send of the second video transmission device of FIG. 8G). The frame (frame) (frame synchronization) (delay synchronization) and output is P (t0) from time t2 at the frame synchronization unit output of FIG. 8 (i). 8 (h), P (t0) from time t2 at the output of the frame synchronization unit in FIG. 8 (i) is the delay time added by the frame synchronization unit 50. Is smaller than one frame time (t2−t1 ′) = (t1−t0 ′), and the transmission time coincides with P (t0) from time t2 of the frame delay execution unit output in FIG. Is (ie synchronized). (Frame synchronization step)

  In this way, after the timing of completing the frame transmission preparation, if the transmission start timing of the first video transmission device is earlier than the transmission start timing of the second video transmission device, the transmission frame of the first video transmission device is The transmission frame of the second video transmission device is transmitted in frame synchronization (delay synchronization) to the frame delayed by one frame time so that the transmission start timings of the frames from both video transmission devices can be transmitted. become. As will be described later, the same applies to frames transmitted from the frame synchronization unit 50 at time t3 and time t4 following the frame transmitted from the frame synchronization unit 50 at time t2 described above.

  Here, it will be described that the frame P (t1) is prepared for transmission at the same display time in the video transmission device and the second video transmission device. The first frame P (t1) is prepared for transmission only once at each video transmission device after the time Tp (t0) when it is detected that the frame transmission preparation is completed. That is, P (t1) from time t1 of the first video transmission device transmission preparation frame in FIG. 8B and P (t1) from time t1 ′ of the second video transmission device transmission preparation frame in FIG. As described above, the frame P (t1) is prepared for transmission. It should be noted that after the first video transmission device and the second video transmission device are both ready to transmit the previous frame P (t0), the timing at which the first video transmission device starts to transmit the frame is earlier. The first video transmission device determines this based on the output of the comparison result of the phase comparison unit 30, and from the timing of starting transmission of the frame, P (t1) of the frame whose display time is the time based on the internal time t1 ) Is prepared for transmission, a frame having the same display time as P (t1) of the frame based on the internal time t1 (= t1 ′) at which the second video transmission apparatus starts transmission preparation is prepared. (Since the frame is prepared for transmission once after the time Tp (t0) when the completion of frame transmission preparation is detected, the frame is transmitted from the time t2 ′ of the second video transmission device transmission preparation frame in FIG. 8 (f). Not prepared.)

  Now, with reference to FIG. 8, a frame transmitted from the frame synchronization unit 50 at time t3 and time t4 following the frame transmitted from the frame synchronization unit 50 at time t2 described above will be described. The frame transmission preparation completion detection unit 20 transmits the frame P (t1) detected that the transmission preparation is completed at the frame transmission start timing of each video transmission device. That is, P (t1) from time t3 of the first video transmission device transmission frame in FIG. 8C and P (t1) from time t3 ′ of the second video transmission device transmission frame in FIG. Frame P (t1) is sent out to.

  Then, after time Tp (t1) when the preparation for transmission of the frame P (t1) in FIG. 8 is completed, the phase comparison unit 30 compares the frame transmission start timings of the first video transmission device and the second video transmission device, and The result that the time t3 of the first video transmission device transmission frame in FIG. 8C is earlier than the time t3 ′ of the second video transmission device transmission frame in FIG. 8G is output. (Phase comparison step)

  Then, the frame delay execution unit 40 receives the result of comparison by the phase comparison unit 30, and the frame delay unit 41 delays the first video transmission device transmission frame of FIG. 8C by one frame time Tp. Are P (t0) from time t3 and P (t1) from time t4 at the output of the frame delay execution unit in FIG. 8D. (Delayed execution step)

  Then, the frame synchronization unit 50 outputs to the output of the frame delay execution unit 40 (the output of the frame delay execution unit of FIG. 8D) from the output of the second video transmission device (send of the second video transmission device of FIG. 8G). Frames (frames) output in frame synchronization (delay synchronization) are P (t0) from time t3 and P (t1) from time t4 in the frame synchronization unit output of FIG. 8 (i). As indicated by the arrow of the frame synchronization unit application delay time in FIG. 8 (h), P (t0) from time t3 and P (t1) from time t4 at the frame synchronization unit output in FIG. 8 (i). The delay time added by the frame synchronizer 50 is less than one frame time (t4−t3 ′) = (t3−t2 ′) = (t1−t0 ′), and the frame delay shown in FIG. The transmission time coincides with P (t0) from time t3 of the execution unit output and P (t1) from time t4 (that is, synchronized). (Frame synchronization step)

  As described above, in FIG. 8, the frames sent from the frame synchronization unit 50 at time t3 and time t4 subsequent to the frame sent from the frame synchronization unit 50 at time t2 described above are also prepared for frame transmission. If the transmission start timing of the first video transmission device is earlier than the transmission start timing of the second video transmission device after the completion timing, the transmission start timings of the frames from both video transmission devices should be matched. Will be able to.

  Now, a case will be described where the frame transmission start timing of the first video transmission device is later (including the simultaneous case) after the timing at which the frame transmission preparation is completed. This is the case of sending frames sent from the frame synchronization unit 50 at time t5 and time t6 following the frames sent from the frame synchronization unit 50 at time t3 and time t4 described above. First, similarly to the frame P (t1), the frame P (t3) is prepared for transmission at the same display time by the first video transmission device and the second video transmission device. Then, at time Tp (t3), the frame P (t3) that is detected to be ready for transmission is transmitted at the frame transmission start timing of each video transmission device. That is, the frame P (t3) is transmitted as P (t3) from the time t5 and P (t3) from the time t6 of the first video transmission device transmission frame in FIG. 8 (g), P (t3) from time t4 ′, P (t3) from time t5 ′, and P (t3) from time t6 ′. (T3) is sent out. (The video transmission device continuously transmits the frames detected to be ready for transmission until the first transmission start timing after the completion of the creation of a new frame.)

  Then, after time Tp (t3) when the preparation for transmission of the frame P (t3) in FIG. 8 is completed, the phase comparison unit 30 compares the frame transmission start timings of the first video transmission device and the second video transmission device, and FIG. The result that the time t5 of the first video transmission device transmission frame in FIG. 8C is later than the time t4 ′ of the second video transmission device transmission frame in FIG. 8G is output. (Phase comparison step)

  Then, the frame delay execution unit 40 receives the result of comparison by the phase comparison unit 30 and outputs the first video transmission device transmission frame of FIG. 8C as it is without delaying the frame of FIG. 8D. P (t3) from time t5 and P (t3) from time t6 at the delay execution unit output. (Delayed execution step)

  Then, the frame synchronization unit 50 outputs to the output of the frame delay execution unit 40 (the output of the frame delay execution unit of FIG. 8D) from the output of the second video transmission device (send of the second video transmission device of FIG. 8G). The output of the frame) after delay synchronization is P (t3) from time t5 and P (t3) from time t6 at the output of the frame synchronization unit in FIG. 8 (i). As indicated by the arrow of the frame synchronization unit application delay time in FIG. 8 (h), P (t3) from time t5 and P (t3) from time t6 at the output of the frame synchronization unit in FIG. 8 (i). The delay time added by the frame synchronizer 50 is less than one frame time (t5−t4 ′) = (t6−t5 ′) = (t1−t0 ′), and the frame delay shown in FIG. The transmission time coincides with P (t3) from time t5 of the execution unit output and P (t3) from time t6 (that is, synchronized). (Frame synchronization step)

  As described above, even when the transmission start timing of the first video transmission device is later than the transmission start timing of the second video transmission device after the timing of completing the frame transmission preparation (including the simultaneous case), Send the frame of the second video transmission device in frame synchronization (delay synchronization) to the frame as it is without delaying the transmission frame of the video transmission device, and match the transmission start timing of the frames from both video transmission devices for transmission Will be able to.

  Note that if the transmission start timing of the first video transmission device is later than the transmission start timing of the second video transmission device after the timing of completing the frame transmission preparation, the same frame prepared for transmission after that timing is used. Since the operation for setting the display time of the frame P (t4) is different, the preparation for sending the frame P (t4) will be described as an example. The frame P (t4) is prepared for transmission only once at each video transmission device after time Tp (t3) when it is detected that preparation for transmission of the frame P (t3) is completed. After the first video transmission device and the second video transmission device are both ready to transmit the previous frame P (t3), the timing at which the first video transmission device starts to transmit the frame is later. The first video transmission device makes a determination based on the output of the comparison result of the phase comparison unit 30 and displays a time based on the internal time t4 one frame before the internal time t5 of the timing at which the transmission of the frame is started. The frame having the same display time as P (t4) of the frame based on the internal time t4 (= t4 ′) at which the second video transmission apparatus starts the transmission preparation by starting the transmission preparation of the frame P (t4) Prepare to send.

  As is clear from the above description, the transmission frame of the first video transmission device and the transmission frame of the second video transmission device can be transmitted with the transmission start timing matched (synchronized).

  As described above, in this embodiment, the first video transmission device and the second video transmission device prepare to transmit frames so that their display times coincide with each other, and match the transmission start timing (phase) of those frames. Then, it can be sent out to the 3D stereoscopic moving image display device, that is, sent out in synchronization.

  It is also possible to operate the functions of each unit in the video synchronization apparatus 10 of the video synchronization system 1 in the present embodiment as a video synchronization program in a computer.

1 is a block diagram showing a configuration of a video synchronization system (first video transmission device, second video transmission device, and video synchronization device) according to an embodiment of the present invention, together with a video reception device (such as a three-dimensional stereoscopic video display device). . It is a timing diagram for demonstrating the principle of the time synchronization which concerns on embodiment of this invention. It is a block diagram which shows the structure of the frame transmission preparation completion detection part which concerns on embodiment of this invention. It is a timing diagram which shows operation | movement of the flame | frame transmission preparation completion detection part which concerns on embodiment of this invention. It is a block diagram which shows the structure of the phase comparison part which concerns on embodiment of this invention. FIG. 6 is a truth table of RS flip-flops in the block diagrams of FIGS. 3 and 5. FIG. It is a timing diagram which shows operation | movement of the phase comparison part which concerns on embodiment of this invention. It is a timing diagram which shows operation | movement of the video synchronization system which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Video synchronization system 10 Video synchronization apparatus 20 Frame transmission preparation completion detection part 21 (21a, 21b) 1 shot pulse generator 22 (22a, 22b) RS flip-flop 23 (23a, 23b, 23c, 23d) Logical product 24 ( 24a, 24b) Transmission start timing detection unit 25 (25a, 25b, 25c) OR circuit 26 Binary counter 27 Logical negator 30 Phase comparison unit 31 (31a, 31b) Transmission start timing detection unit 32 RS flip-flop 33 Binary Counter 34 D latch 35 1 shot pulse generator 40 Frame delay execution unit 41 Frame delay unit 42 Switch unit 43 Correction delay unit 44 Correction signal delay unit 50 Frame synchronization unit 51 Frame transmission start time difference detection unit 52 Delay time calculation unit 53 Variable time Delay unit 70 (70a 70b) Video transmission device 71 (71a, 71b) Frame transmission preparation transmission unit 711 (711a, 711b) Frame transmission preparation unit 712 (712a, 712b) Frame transmission unit 72 (72a, 72b) Control unit 80 Video reception device (three-dimensional) 3D video display device)

Claims (2)

Video that sends the video to be displayed simultaneously for each frame to the first and second video sending devices that send the left and right eye images constituting the 3D stereoscopic video, and simultaneously outputs the frames to be displayed simultaneously A synchronization method,
A time synchronization step of synchronizing internal times of the first video transmission device and the second video transmission device;
A frame transmission preparation completion detecting step for detecting a timing at which transmission preparation of a frame to be simultaneously displayed on the first video transmission device and the second video transmission device is completed by the internal time synchronized in the time synchronization step;
After the timing detected in the frame transmission preparation completion detection step, a phase comparison step for comparing transmission start timings of frames transmitted from the first video transmission device and the second video transmission device;
Based on the comparison result of the phase comparison step, frame delay execution is performed to select whether to output the frame output by the first video transmission device as it is or to output by delaying the time of one frame. Steps,
A frame synchronization step for simultaneously sending frames sent from the second video sending device in time with the frames output in the frame delay execution step;
A video synchronization method comprising: In order to input and simultaneously output frames to be displayed at the same time of the images transmitted from the first image transmission device and the second image transmission device which transmit the images for the left and right eyes constituting the 3D stereoscopic image and whose internal times are synchronized with each other Computer
A frame transmission preparation completion detection means for detecting a timing at which transmission preparation of a frame to be displayed simultaneously on the first video transmission device and the second video transmission device is completed;
Phase comparison means for comparing the transmission start timing of the frames transmitted from the first video transmission apparatus and the second video transmission apparatus after the timing detected by the frame transmission preparation completion detection means,
Based on the comparison result of the phase comparison means, a frame delay is executed to select whether to output the frame output by the first video transmission device as it is or to output the frame by delaying the time of one frame. means,
Frame synchronization means for simultaneously sending frames sent from the second video sending device in time with the frames output by the frame delay execution means;
A video synchronization program characterized by functioning as

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