Patent Publication Number: US-2018054345-A1

Title: Transmission apparatus and transmission method, reception apparatus and reception method, transmission system, and program

Description:
TECHNICAL FIELD 
     The present technology relates to a transmission apparatus and a transmission method, a reception apparatus and a reception method, a transmission system, and a program and particularly to a transmission apparatus and a transmission method, a reception apparatus and a reception method, a transmission system, and a program that efficiently use a transmission bandwidth such that power saving can be realized. 
     BACKGROUND ART 
     A standard of an interface that transmits image data to a display, which is called DisplayPort (trademark), is commonly used (e.g., see Non-Patent Literature 1). 
     CITATION LIST 
     Non-Patent Literature 
     Non-Patent Literature 1: DisplayPort (trademark) Version1.2a VESA (Video Electronics Standards Association) 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     By the way, in the DisplayPort (trademark) standard, a transmission scheme called Virtual Channel is defined. In the transmission scheme, a plurality of streams are transmitted through a single transmission channel to a plurality of streams sinks from a plurality of stream sources. 
     In the Virtual Channel, the plurality of streams are subjected to time division processing and transmitted by a stream transmission processing unit and a stream reception processing unit each of which processes a plurality of streams. At this time, respective processing timings are allocated as divided time slots. In addition, the stream transmission processing unit and the stream reception processing unit each transmit allocated streams through processing in four lanes at the respective processing timings. That is, in the Virtual Channel, a plurality of stream transmission processing units and a plurality of stream reception processing units each perform processing in four lanes at predetermined time-divided processing timings. In this manner, a plurality of streams are transmitted. 
     With such a configuration, in the Virtual Channel of the DisplayPort (trademark) standard, for example, if transmission of any stream of the plurality of streams is stopped, the stream transmission processing unit and the stream reception processing unit that process the stream whose transmission is stopped do not work at a timing for processing the stream whose transmission is stopped out of the allocated time slots since the time slot is also allocated to the stream whose transmission is stopped. However, since the bandwidth should be ensured, the stream transmission processing unit and the stream reception processing unit that process the stream whose transmission is stopped cannot be completely stopped and electric power continues to be consumed. 
     The present technology has been made in view of the above-mentioned circumstances particularly to efficiently use a bandwidth such that power saving can be realized even if transmission of any of a plurality of transmitted streams is stopped. 
     Solution to Problem 
     A transmission apparatus according to a first aspect of the present technology is a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the transmission apparatus including: a transmitter that transmits a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and a controller that assigns the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which the transmitter transmits the plurality of streams through the lanes assigned by the controller on the stream-by-stream basis. 
     The format for transmitting to the display can be a format defined by DisplayPort (trademark), and the transmitter can use a Virtual Channel defined by the DisplayPort (trademark) to transmit the plurality of streams formed of the visible image data to the respective stream sinks from the respective stream sources through the plurality of lanes in the single transmission channel. 
     If transmission of any stream of the plurality of streams is stopped, the controller can output, via the transmission channel, a stop signal for notifying that transmission through a corresponding lane is stopped. 
     The stop signal can be a signal in starting an ALPM (Advanced Link Power Management) state defined by DisplayPort (trademark). 
     The transmission apparatus can further include an auxiliary communication unit different from the transmission channel that communicates with a reception apparatus that receives the plurality of streams, in which if transmission of any stream of the plurality of streams is restarted, the controller can notify the reception apparatus of a restart signal via the auxiliary communication unit, the restart signal indicating that transmission through a corresponding lane is restarted. 
     The restart signal can be a signal in terminating an ALPM (Advanced Link Power Management) state defined by DisplayPort (trademark). 
     The transmission apparatus can further include an auxiliary communication unit different from the transmission channel that communicates with a reception apparatus that receives the plurality of streams, in which the controller can use the auxiliary communication unit to notify a reception apparatus that receives the plurality of streams of information indicating that the plurality of streams are assigned to the plurality of lanes on the stream-by-stream basis. 
     A transmission method according to the first aspect of the present technology is a transmission method for a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the transmission method including: a transmission step of transmitting a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which processing of the transmission step transmits the plurality of streams through the lanes assigned by processing of the control step on the stream-by-stream basis. 
     A program according to the first aspect of the present technology is a program that causes a computer that controls a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display to execute processing including: a transmission step of transmitting a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which the processing of the transmission step transmits the plurality of streams through the lanes assigned by the processing of the control step on the stream-by-stream basis. 
     A reception apparatus according to a second aspect of the present technology is a reception apparatus that receives visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the reception apparatus including: a receiver that receives a plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources, through the plurality of lanes in the single transmission channel; and a controller that assigns the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which the receiver receives the plurality of streams in the lanes assigned by the controller on the stream-by-stream basis. 
     The format for transmitting to the display can be a format defined by DisplayPort (trademark), and the receiver can use a Virtual Channel defined by the DisplayPort (trademark) to receive the plurality of streams formed of the visible image data to the respective stream sinks from the respective stream sources through the plurality of lanes in the single transmission channel. 
     The reception apparatus can further include an auxiliary communication unit different from the transmission channel that communicates with a transmission apparatus that transmits the plurality of streams, in which the controller can use the auxiliary communication unit to receive information indicating that the plurality of streams are assigned to the plurality of lanes on the stream-by-stream basis from the transmission apparatus that transmits the plurality of streams and to assign, on the basis of the received information, the plurality of streams to the plurality of lanes on the stream-by-stream basis. 
     A reception method according to the second aspect of the present technology is a reception method for a reception apparatus that receives visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the reception method including: a reception step of receiving a plurality of streams formed of the visible image data, which are transmitted to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream. 
     basis, in which processing of the reception step receives the plurality of streams in the lanes assigned by processing of the control step on the stream-by-stream basis. 
     A program according to the second aspect of the present technology is a program that causes a computer that controls a reception apparatus that receives visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display to execute processing including: a reception step of receiving a plurality of streams formed of the visible image data, which are transmitted to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which the processing of the reception step receives the plurality of streams in the lanes assigned by the processing of the control step on the stream-by-stream basis. 
     A communication system according to a third aspect of the present technology is a transmission system including: a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display; and a reception apparatus, in which the transmission apparatus includes a transmitter that transmits a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel, and a first controller that assigns the plurality of streams to the plurality of lanes on a stream-by-stream basis, the transmitter transmits the plurality of streams through the lanes assigned by the first controller on the stream-by-stream basis, the reception. apparatus includes a receiver that receives a plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources, through the plurality of lanes in the single transmission channel; and a second controller that assigns the plurality of streams to the plurality of lanes on the stream-by-stream basis, and the receiver receives the plurality of streams in the lanes assigned by the second controller on the stream-by-stream basis. 
     In the first aspect of the present technology, a plurality of streams formed of the visible image data to respective stream sinks are transmitted from respective stream sources through a plurality of lanes in a single transmission channel. The plurality of streams are assigned to the plurality of lanes on a stream-by-stream basis. The plurality of streams are transmitted through the lanes assigned on the stream-by-stream basis. 
     In the second aspect of the present technology, a plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources, are received through the plurality of lanes in the single transmission channel. The plurality of streams are assigned to the plurality of lanes on a stream-by-stream basis. The plurality of streams are received in the lanes assigned on the stream-by-stream basis. 
     In the third aspect of the present technology, by the transmission apparatus, a plurality of streams formed of the visible image data are transmitted to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel, the plurality of streams are assigned to the plurality of lanes on a stream-by-stream basis, and the plurality of streams are transmitted through the lanes assigned on the stream-by-stream basis. By the reception apparatus, a plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources, are received through the plurality of lanes in the single transmission channel, the plurality of streams are assigned to the plurality of lanes on a stream-by-stream basis, and the plurality of streams are received in the lanes assigned on the stream-by-stream basis. 
     The transmission apparatus and the reception apparatus that constitute the transmission apparatus according to the first aspect of the present technology, the reception apparatus according to the second aspect, and the transmission system according to the third aspect may be independent apparatuses or may be blocks that performs transmission processing. 
     Advantageous Effects of Invention 
     In accordance with the aspects of the present technology, it becomes possible to efficiently use a bandwidth such that power saving can be realized even if transmission of any of a plurality of transmitted streams is stopped. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       [ FIG. 1 ] A diagram showing a configuration example of an embodiment of a transmission system to which the present technology is applied. 
       [ FIG. 2 ] A diagram describing MSA and SDP. 
       [ FIG. 3 ] A diagram describing a Virtual Channel. 
       [ FIG. 4 ] A diagram describing a general transmission scheme. 
       [ FIG. 5 ] A diagram describing a transmission scheme to which the present technology is applied. 
       [ FIG. 6 ] A diagram describing a stop signal in stopping transmission and a restart signal in restarting. 
       [ FIG. 7 ] A flowchart describing transmission and reception processing by the transmission system of  FIG. 1 . 
       [ FIG. 8 ] A diagram describing a configuration example of a general-purpose personal computer. 
     
    
    
     MODE(S) FOR CARRYING OUT THE INVENTION 
     &lt;Configuration Example of Transmission System Using Virtual Channel&gt; 
       FIG. 1  shows a configuration example of an embodiment of a transmission system to which the present technology is applied. The transmission system of  FIG. 1  is a system that transmits image data generated (captured) by an image pickup apparatus (not shown). 
     More specifically, the transmission system of  FIG. 1  is constituted by a transmitter  21  and a receiver  22 . The transmitter  21  transmits, to the receiver  22 , visible image data supplied by the image pickup apparatus (not shown) by using a format called Virtual Channel of DisplayPort (trademark) that is a standard for transmitting to a display. The receiver  22  receives visible image data transmitted from the transmitter  21 . Note that, in the present specification, it is assumed that an image is constituted by a plurality of pixels and image data is constituted by pixel data that is data on pixel values and the like of a plurality of pixels. 
     Next, configurations of the transmitter  21  and the receiver  22  in the transmission system of  FIG. 1  will be described. 
     The transmitter  21  includes stream transmission processing units  41 - 1  to  41 - n , a multiplexer  42 , a controller  43 , and an AUX (auxiliary communication unit)  44 . Further, each of the stream transmission processing units  41 - 1  to  41 - n  includes an MSA generator  61 , an SDP generator  62 , and a multiplexer  63  and generates stream data formed of visible image data and outputs it to the multiplexer  42 . Note that, if the stream transmission processing units  41 - 1  to  41 - n  do not have to be distinguished from one another, they will be simply referred to as stream transmission processing units  41  and other configurations will be also referred in a similar way. 
     The multiplexer  42  transmits, to the receiver  22 , multiplexed data obtained by time division multiplexing the stream data formed of the visible image data supplied from a plurality of stream transmission processing units  41 - 1  to  41 - n.    
     The controller  43  comprehensively controls operations of the transmitter  21 . Further, when starting transmission of streams, the controller  43  assigns lanes on a stream-by-stream basis and instructs ail the stream transmission processing units  41  and notifies the receiver  22  by using the AUX (auxiliary communication unit)  44 . In addition, when stopping transmission of any of a plurality of transmitted streams to the receiver  22 , the controller  43  causes the multiplexer  42  to output a stop signal to the receiver  22  with the stop signal being included in multiplexed data. Further, when restarting transmission of streams whose transmission is stopped, the controller  43  notifies the receiver  22  of restart information by using the AUX (auxiliary communication unit)  44 . 
     The MSA generator  61  generates MSA (Main Stream Attributes) that are image property information such as the number of lines per frame, the number of pixels per line, the number of bits per pixel, and the like of image data (visible image data) formed of effective pixel data, which is to be transmitted, and supplies them to the multiplexer  63 . 
     On the basis of additional data such as audio data, the SDP generator  62  generates packets, which are called SDP (Secondary-Data Packets), according to a format for packetizing and transmitting in a horizontal blanking region and a vertical blanking region other than an effective pixel region and supplies them to the multiplexer  63 . 
     The multiplexer  63  multiplexes MSA supplied from the NSA generator  61 , SDP supplied from the SDP generator  62 , and image data (visible image data) formed of input effective pixel data and outputs them as multiplexed data. 
     The receiver  22  includes a division unit  81 , stream reception processing units  82 - 1  to  82 - n , a controller  83 , and an AUX (auxiliary communication unit)  84 . 
     The division unit  81  divides multiplexed data transmitted from the transmitter  21 , a plurality of pieces of stream data formed of a plurality of pieces of visible image data and supplies them to the stream reception processing units  82 - 1  to  82 - n.    
     Each of the stream reception processing units  82  includes a division unit  91 , an MSA reader  92 , an SDP reader  93 , and an image generator  94 . The stream reception processing unit  82  generates and outputs visible image data from stream data of the pieces of stream data formed of the plurality of pieces of visible image data, which is allocated. 
     The division unit  91  divides multiplexed data for each of streams supplied from the division unit  81  into MSA, SDP, and visible image data and supplies the MSA to the MSA reader  92 , the SDP to the SDP reader  93 , and the visible image data to the image generator  94 . 
     The MSA reader  92  reads, on the basis of the supplied MSA, the information on the number of lines per frame, the number of pixels per line, and the number of bits per pixel of the visible image data and supplies the read information to the image generator  94 . 
     The SDP reader  93  reads the SDP and extracts and outputs packetized additional data. 
     The image generator  94  acquires visible image data and reconfigures and outputs the visible image on the basis of the information on the MSA. 
     The controller  83  comprehensively controls operations of the receiver  22 . Further, when starting transmission of streams, the controller  83  uses the AUX (auxiliary communication unit)  84  to receive information indicating that lanes have been assigned on the stream-by-stream basis, which is notified by the transmitter  21 , and notifies all the stream reception processing units  82  of that fact. In addition, the controller  83  receives the stop signal included in the multiplexed data, which indicates that transmission of any of a plurality of streams transmitted from the transmitter  21  via the division unit  81  is to be stopped, and instructs all the stream reception processing units  82  of corresponding processing. Further, the controller  83  receives, via the AUX (auxiliary communication unit)  84 , information indicating that transmission of any is to be restarted for example and instructs the division unit  81  and the stream reception processing unit  82  to perform corresponding processing. 
     &lt;Regarding MSA (Main Stream Attributes) and SDP (Secondary-Data Packet)&gt; 
     Next, a structure of the image data and the NSA and SDP will be described with reference to  FIG. 2 . 
     The NSA is for using the vertical blanking region for each frame to packetize and transmit image property information of the stream. Further, the SDP is for using the horizontal blanking region and the vertical blanking region for each frame to packetize and transmit data other than the visible image data (effective pixel data). 
     Regarding the structure of the image data, as shown in  FIG. 2 , a lower right region ((number of effective pixels (Hwidth): X)×(number of effective lines (Vheight): Y)) is an the effective pixel region  71 . 
     Above the effective pixel region  71 , provided is a vertical blanking region (Vblank)  72  in which MSA  111  and SDP  112  are arranged. 
     Further, a horizontal blanking region (Hblank)  73  is provided on a left-hand side of the effective pixel region  71 . 
     &lt;Regarding Virtual Channel&gt; 
     Next, a transmission scheme using the Virtual Channel defined by the DisplayPort (trademark) will be described. The Virtual Channel is a scheme for transmitting a plurality of streams through a single transmission channel to a plurality of streams sinks from a plurality of stream sources. The transmission system of  FIG. 1  transmits a plurality of streams formed of visible image data that is a plurality of stream sources by using the Virtual Channel. 
     With the Virtual Channel, the time slot can be divided into 63 segments in accordance with requirements of DisplayPort (trademark). Therefore, for example, if streams formed of visible image data that are streams VC 1  and VC 2  having identical image quality are transmitted, 32 time slots (slots) are allocated to the stream VC 1  while 31 time slots are allocated to the stream VC 2  as shown in  FIG. 3  when time division multiplexing is performed at an approximately identical ratio. Note that one top slot is allocated to a header (MTP Header). 
     That is, by using the Virtual Channel, time division multiplexing and transmission are performed, and hence two streams are transmitted to two stream sinks (stream sinks of two visible images) from two stream sources (stream sources of two visible images) through one transmission channel. As a result, it becomes possible to transmit the visible image data of the two streams. 
     Note that, in  FIG. 3 , division into at most 63 slots is defined. Therefore, the number of streams that can be transmitted and received is at most 63. 
     &lt;Regarding General Transmission Method&gt; 
     In accordance with requirements of DisplayPort (trademark), the stream transmission processing units  41 - 1  to  41 - n  of the transmitter  21  and the stream reception processing units  82 - 1  to  82 - n  of the receiver  22  each perform transmission processing through processing through four lanes. Therefore, in a case where the two streams of the streams VC 1  and VC 2  are transmitted as shown in the upper part of  FIG. 4 , the stream transmission processing unit  41  and the stream reception processing unit  82  each execute processing on the basis of time slots as shown in the lower part of  FIG. 4 . That is, following one slot that is the header in each of Lane 0  to Lane 4 , the stream VC 1  in an amount corresponding to 32 slots is processed and the stream VC 2  in an amount corresponding to the remaining 31 slots is processed. 
     As a result, at a timing departing from a range surrounded with the dotted lines of  FIG. 4 , the processing is efficiently performed. Note that, in the upper section of  FIG. 4 , frames # 1  to # 5  that constitute the stream VC 1  and frames # 1  to # 3  that constitute the stream VC 2  are chronologically transmitted. Further, in the lower section, signals transmitted in each of Lane 0  to Lane 4  are shown. In the figures, MPT Header indicates a header, VC# 1  indicates a timing for processing of transmitting each of frame images of the stream VC 1 , and VC# 2  indicates a timing for processing of transmitting each of frame images of the stream VC 2 . 
     However, if transmission of the stream VC 2  is stopped in the middle as in the range surrounded with the dotted line, that in an amount corresponding to the late 31 slots of the time slots that are 64 slots at that timing is not processed. Note that, in the figure, they are expressed as Null. That is, despite the absence of data that should be transmitted, there is a need for ensuring a bandwidth and unnecessary power consumption continues. That is, in the transmission scheme using the Virtual Channel defined by DisplayPort (trademark), there is a fear that unnecessary power consumption may continue if transmission of some streams is stopped. 
     &lt;Regarding Transmission Method to which Present Technology is Applied&gt; 
     In view of this, in the transmission system of  FIG. 1  to which the present technology is applied, lanes are assigned for each stream and the stream whose transmission is stopped is brought into a halt state for each lane. At this time, for stopping and restarting transmission for each lane, ALPM (Advanced Link Power Management) that is a function of stopping stream transmission defined by DisplayPort (trademark) is used. 
     That is, for example, as shown in  FIG. 5 , Lane 0  and Lane 1  are assigned with respect to the stream VC 1  and Lane 2  and Lane 3  are assigned with respect to the stream VC 2 . By doing so, as in the range surrounded with the dotted line of  FIG. 5 , also if transmission of the stream VC 2  is stopped, it is only necessary to stop transmission in Lane 2  and Lane 3 . Therefore, it becomes possible to reduce power consumption corresponding to that amount. Note that, in the figure, the stop state is expressed as ALPM. 
     ALPM is a function of performing instructions of the stop and restart for each lane. For example, if input of any stream is stopped, the controller  43  of the transmitter  21  causes the multiplexer  42  to output, as shown in a range Z 1  of  FIG. 6 , information on a lane to be stopped as well as stop information indicating that transmission is to be stopped with they being included in multiplexed data. Correspondingly, the stop information obtained by the division unit  81  of the receiver  22  dividing the multiplexed data is supplied to the controller  83 . On the basis of this stop information, the controller  83  supplies information regarding which lane is to be stopped to the stream reception processing unit  82 . At a timing described as “Stop” surrounded with the dotted line in the figure, the controller  63  performs control to stop processing through a corresponding lane. 
     Further, if the input of any stream is restarted, the controller  43  of the transmitter  21  supplies a restart signal indicating the restart of transmission as shown in a range Z 2  of  FIG. 7 , to the receiver  22  via the AUX  44 . Note that  FIG. 7  describes a stop signal for starting the ALPM state and a restart signal for terminating the ALPM state. The upper section of the figure shows transmission of the restart signal in communication by the AUXs  44  and  84 . The lower section or the figure shows a stop signal multiplexed on the multiplexed data between the multiplexer  42  and the division unit  81  and transmitted and multiplexed data when transmission is restarted. 
     In addition, when receiving a restart signal from the AUX  84 , the controller  83  of the receiver  22  supplies the stream reception processing unit  82  with information on a lane in which reception is restarted and restart information. In addition, at a point of time t that is a timing at which a predetermined time has elapsed after the restart signal is transmitted, the multiplexer  42  generates a training pattern as shown by a range Z 3  and supplies it to a corresponding lane. After that, the multiplexer  42  continuously restarts transmission of the stream successively from a vertical blanking signal that is the top of data of each frame as shown by a range Z 4 . 
     Correspondingly, the controller  83  of the receiver  22  controls the stream reception processing unit  82  to receive the training pattern as shown by the range Z 3  from Lane in which transmission had been stopped and further to restart reception of the streams successively from the vertical blanking signal shown by the range Z 4 . 
     In the above-mentioned manner, for the four-lane processing on the plurality of streams defined by DisplayPort (trademark), the lanes are assigned for each stream and the ALPM (Advanced Link Power Management) that is the function of stopping transmission on a lane-by-lane basis is further used. Thus, it becomes possible to achieve power saving by stopping the operation on the lane-by-lane basis even if transmission of any stream is stopped, for example. 
     &lt;Transmission and Reception Processing&gt;. 
     Next, transmission and reception processing in transmitting the two streams VC 1  and VC 2  formed of the visible image data in the transmission system of  FIG. 1  will be described with reference to the flowchart of  FIG. 7 . Note that it is assumed that no additional data is transmitted here. 
     In Step S 11 , the controller  43  assigns streams that should be transmitted to Lane 0  to Lane 3  in each stream transmission processing unit  41  and notifies all the stream transmission processing units  41  of it. Further, the controller  43  supplies information indicating that Lane 0  to Lane 3  are assigned to the receiver  22  via the AUX  44 . 
     In Step S 12 , the controller  43  determines whether or not a lane that, stops transmission of any stream has been generated by transmission of any being stopped. For example, if transmission of any streams is not stopped, the processing of Steps S 13  and S 14  is skipped and the processing proceeds to Step S 15 . 
     In Step S 15 , the controller  43  determines whether or not a lane that restarts transmission of any stream has been generated by transmission of any being restarted. For example, if transmission of any streams is not restarted, the processing of Steps S 16  and S 17  is skipped and the processing proceeds to Step S 18 . 
     In Step S 18 , the MSA generator  61  of the stream transmission processing unit  41  generates MSA for image data of the assigned stream in each lane and outputs it to the multiplexer  63 . 
     In Step S 19 , the multiplexer  63  multiplexes, in each lane, each piece of image data of the assigned stream, which is supplied, with the NSA for each piece of image data to generate stream data and supplies it to the multiplexer  42 . 
     In Step S 20 , the multiplexer  42  performs time division multiplexing on the plurality of pieces of stream data formed of the visible image data, which are supplied, in accordance with the format of the Virtual Channel. 
     In Step S 21 , the multiplexer  42  transmits multiplexed data generated by multiplexing to the receiver  22 . 
     In Step S 22 , the transmitter  21  determines whether or not a next image signal is absent and an instruction to terminate the processing is performed. 
     If the instruction to terminate the processing is not performed, the processing returns to Step S 11  and the subsequent processing is repeated. Then, if the instruction to terminate the processing is performed in Step S 22 , the processing ends. 
     On the other hand, in the receiver  22 , in Step S 51 , the controller  83  receives the assignment information of Lane° to Lane 3  supplied from the transmitter  21  in the processing of Step S 11  via the AUX  84  and notifies each stream reception processing unit  82  of it. 
     In Step S 52 , the controller  83  determines whether or not the stream output from the division unit  81  in the previous processing contains a stop signal indicating the stop of transmission. In Step S 52 , for example, it is determined that it does not contain the stop signal indicating the stop of transmission in the previous processing, the processing of Step S 53  is skipped and the processing proceeds to Step S 54 . Note that since the previous processing does not exist in first processing, it is considered that it does not contain the stop signal. 
     In Step S 54 , the controller  83  determines whether or not the stream output from the division unit  81  in the previous processing contains a signal indicating the restart of transmission. For example, if it is determined that it does not contain the signal indicating the restart of transmission, the processing of Step S 55  is skipped and the processing proceeds to Step S 56 . 
     In Step S 56 , the division unit  81  of the receiver  22  receives the transmitted, multiplexed data. 
     In Step S 57 , the division unit  201  of the receiver  22  divides the received multiplexed data into the plurality of pieces of stream data formed of the visible image data in accordance with the format of the Virtual Channel and supplies each of them to the stream reception processing unit  82  and the controller  83 . 
     In Step S 58 , the division unit  91  of the stream reception processing unit  82  divides the stream data formed of the visible image data into the MSA for the visible image and the visible image data and outputs the MSA for the visible image to the MSA reader  92  and the visible image data to the image generator  94 . 
     In Step S 59 , the MSA reader  92  reads the MSA with respect to the stream assigned in each lane and supplies information on the read MSA to the image generator  94 . 
     In Step S 60 , the image generator  94  reconfigures the visible image from the visible image data on the basis of the information on the MSA of the stream assigned in each lane and outputs it. 
     In Step S 61 , the receiver  22  determines whether or not next image data is absent and an instruction to terminate the processing is performed. If the instruction to terminate the processing is not performed, the processing returns to Step S 51  and the subsequent processing is repeated. Then, if the instruction to terminate the processing is performed in Step S 61 , the processing ends. 
     In the above-mentioned processing, if the streams VC 1  and VC 2  are transmitted as in  FIG. 5 , the stream VC 1  is transmitted through Lane 0  and Lane 1  and the stream VC 2  is transmitted through Lane 2  and Lane 3 . 
     Further, for example, if transferring of the stream VC 2  is stopped, it is considered in Step S 12  that there is a lane that should be stopped and the processing proceeds to Step S 13 . 
     In Step S 13 , the controller  43  controls the multiplexer  42  to output a stop signal indicating the stop of transmission of the stream as the multiplexed data, which includes information on a corresponding lane whose transmission is stopped as shown in the range Z 1  in  FIG. 6 , for example. 
     Corresponding to this, in Step S 52 , if it contains the stop signal indicating the stop of transmission in the previous processing, the processing proceeds to Step S 53 . 
     In Step S 53 , the controller  83  notifies all the stream reception controllers  82  so as to stop the operation of the corresponding lane that is a target whose transmission is stopped, for stopping the operation. 
     After this series of processing, in Step S 14 , the controller  43  controls all the stream transmission processing units  41  to stop the output from the lanes allocated to the stream VC 2 . With this operation, as shown in the range surrounded with the dotted line in  FIG. 5 , the transmission in the stream VC 2  in Lane 2  and Lane  3  is stopped and enters the ALPM (Advanced Link Power Management) state. 
     In addition, for example, if the transferring of the stream VC 2  is restarted, it is considered in Step S 15  that there is a lane that should he restarted and the processing proceeds to Step S 16 . 
     In Step S 16 , the controller  43  performs control to multiplex and output a restart signal indicating the restart of transmission of the stream, which includes information on a corresponding lane whose transmission is restarted, for example, as shown in the range Z 2  in  FIG. 6  via the AUX  44 . 
     Corresponding to this, in Step S 54 , it is determined that it contains the restart signal indicating the restart of transmission for example and the processing proceeds to Step S 55 . 
     In Step S 55 , the controller  83  notifies all the stream reception controllers  82  so as to start the operation of the corresponding lane that is a target whose transmission is restarted, for restarting the operation. 
     After this series of processing, in Step S 17 , the controller  43  controls the stream transmission processing unit  41  to successively output signals shown in the ranges Z 3  and  24  of  FIG. 6  and restart the output from Lane 2  and Lane 3  allocated to the stream VC 2 . With this operation, as shown in the section following the range surrounded with the dotted line in  FIG. 5 , transmission in the stream VC 2  in Lane 2  and Lane 3  is restarted and the ALPM (Advanced Link Power Management) state is terminated. 
     In the above-mentioned processing, a stream is assigned for each Lane by making a plurality of streams formed of visible image data into a single piece of streaming data in a case where transmission is performed using the Virtual Channel. Therefore, even if transmission of any stream is stopped, it is possible to stop it on the Lane-by-Lane basis and to prevent unnecessary power consumption only for ensuring the bandwidth. Therefore, it becomes possible to realize power saving. 
     By the way, the above-mentioned series of processing may be executed by hardware or may be executed by software. If the series of processing is executed by software, programs that configure that software are installed, from the recording medium, in a computer incorporated in dedicated hardware or for example, a general-purpose personal computer capable of executing various functions by installing various programs. 
       FIG. 8  shows a configuration example of a general-purpose personal computer. This personal computer includes a built-in CPU (Central Processing Unit)  1001 . An input/output interface  1005  is connected to the CPU  1001  via a bus  1004 . A ROM (Read Only Memory)  1002  and a RAM (Random Access Memory)  1003  are connected to the bus  1004 . 
     A communication unit  1009  is connected to the input/output interface  1005 . The communication unit  1009  is constituted by an input unit  1006  constituted by input devices such as a keyboard and a mouse into which a user inputs operation commands, an output unit  1007  that outputs processing operation screens and images of processing results to a display device, a storage unit  1008  constituted by a hard disk drive that stores programs and various types of data and the like, a LAN (Local Area Network) adaptor, and the like. The communication unit  1009  executes communication processing via a network represented by the Internet. Further, a drive  1010  is connected thereto. The drive  1010  reads and writes data from/in the removable medium  1011  such as a magnetic disk (including flexible disk), an optical disc (including CD-ROM (Compact Disc-Read Only Memory) and DVD (Digital Versatile Disc)), a magneto-optical disk (including MD (Mini Disc)), and a semiconductor memory. 
     The CPU  1001  executes various types of processing in accordance with the programs stored in the ROM  1002  or programs read from a removable medium  1011  such as a magnetic disk, an optical disc, a magneto-optical disk, and a semiconductor memory, installed into the storage unit  1008 , and loaded into the RAM  1003  from the storage unit  1008 . Data and the like necessary for the CPU  1001  to execute various types of processing are further stored in the RAM  1003  if necessary. 
     In the thus configured computer, the CPU  1001  loads, for example, programs stored in the storage unit  1008  into the RAM  1003  via the input/output interface  1005  and the bus  1004  and executes them. In this manner, the above-mentioned series of processing is performed. 
     Programs executed by the computer (CPU  1001 ) can be, for example, recorded and provided in the removable medium  1011  that is a package medium. Further, the programs can be provided via a wired or wireless transmission medium such as a local area network, the Internet, and digital satellite broadcasting. 
     In the computer, the programs can be installed into the storage unit  1008  via the input/output interface  1005  by the removable medium  1011  being mounted on the drive  1010 . Further, the programs can be received by the communication unit  1009  via the wired or wireless transmission medium and installed into the storage unit  1008 . Otherwise, the programs can be installed into the ROM  1002  and the storage unit  1008  in advance. 
     Note that the programs executed by the computer may be programs are processed chronologically in the order described in the present specification or may be programs processed concurrently or at necessary timings, for example, upon calling. 
     Further, in the present specification, the system means a collection of a plurality of components (apparatuses, modules (parts), etc.) and it does not matter whether or not all the components are contained in an identical casing. Therefore, a plurality of apparatuses housed in separate casings and connected via a network and a single apparatus including a plurality of modules housed within a single casing are both systems. 
     Note that embodiments of the present technology are not limited to the above-mentioned embodiments and various modifications can be made without departing from the gist of the present technology. 
     For example, the present technology can take a cloud computing configuration in which a single function is shared and cooperatively processed by a plurality of apparatuses via a network. 
     Further, the respective steps described above with reference to the above-mentioned flowcharts can be shared and executed by a plurality of apparatuses rather than being executed by a single apparatus. 
     In addition, if a single step includes a plurality of processes, the plurality of processes of the single step can be shared and executed by a plurality of apparatuses rather than being executed by a single apparatus. 
     It should be noted that the present technology can also take the following configurations. 
     (1) A transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the transmission apparatus including:
         a transmitter that transmits a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and   a controller that assigns the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which   the transmitter transmits the plurality of streams through the lanes assigned by the controller on the stream-by-stream basis.       

     (2) The transmission apparatus according to (1), in which
         the format for transmitting to the display is a format defined by DisplayPort (trademark), and   the transmitter uses a Virtual Channel defined by the DisplayPort (trademark) to transmit the plurality of streams formed of the visible image data to the respective stream sinks from the respective stream sources through the plurality of lanes in the single transmission channel.       

     (3) The transmission apparatus according to (1), in which
         if transmission of any stream of the plurality of streams is stopped, the controller outputs, via the transmission channel, a stop signal for notifying that transmission through a corresponding lane is stopped.       

     (4) The transmission apparatus according to (3), in which
         the stop signal is a signal in starting an ALPM (Advanced. Link Power Management) state defined by DisplayPort (trademark).       

     (5) The transmission apparatus according to (1), further including
         an auxiliary communication unit different from the transmission channel that communicates with a reception apparatus that receives the plurality of streams, in which   if transmission of any stream of the plurality of streams is restarted, the controller notifies the reception apparatus of a restart signal via the auxiliary communication unit, the restart signal indicating that transmission through a corresponding lane is restarted.       

     (6) The transmission apparatus according to (5), in which
         the restart signal is a signal in terminating an ALP (Advanced Link Power Management) state defined by DisplayPort (trademark).       

     (7) The transmission apparatus according to ( 1 ), further including
         an auxiliary communication unit different from the transmission channel that communicates with a reception apparatus that receives the plurality of streams, in which   the controller uses the auxiliary communication unit to notify a reception apparatus that receives the plurality of streams of information indicating that the plurality of streams are assigned to the plurality of lanes on the stream-by-stream basis.       

     (8) A transmission method for a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the transmission method including:
         a transmission step of transmitting a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and   a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which   processing of the transmission step transmits the plurality of streams through the lanes assigned by processing of the control step on the stream-by-stream basis.       

     (9) A program that causes a computer that controls a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display to execute processing including:
         a transmission step of transmitting a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and   a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which   the processing of the transmission step transmits the plurality of streams through the lanes assigned by the processing of the control step on the stream-by-stream basis.       

     (10) A reception apparatus that receives visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the reception apparatus including:
         a receiver that receives a plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources, through the plurality of lanes in the single transmission channel; and   a controller that assigns the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which   the receiver receives the plurality of streams in the lanes assigned by the controller on the stream-by-stream basis.       

     (11) The reception apparatus according to (10), in which
         the format for transmitting to the display is a format defined by DisplayPort (trademark), and   the receiver uses a Virtual Channel defined by the DisplayPort (trademark) to receive the plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources.       

     (12) The reception apparatus according to (10), further including
         an auxiliary communication unit different from the transmission channel that communicates with a transmission apparatus that transmits the plurality of streams, in which   the controller uses the auxiliary communication unit to receive information indicating that the plurality of streams are assigned to the plurality of lanes on the stream-by-stream basis from the transmission apparatus that transmits the plurality of streams and to assign, on the basis of the received information, the plurality of streams to the plurality of lanes on the stream-by-stream basis.       

     (13) A reception method for a reception apparatus that receives visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display, the reception method including:
         a reception step of receiving a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and   a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which   processing of the reception step receives the plurality of streams in the lanes assigned by processing of the control step on the stream-by-stream basis.       

     (14) A program that causes a computer that controls a reception apparatus that receives visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display to execute processing including:
         a reception step of receiving a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel; and   a control step of assigning the plurality of streams to the plurality of lanes on a stream-by-stream basis, in which   the processing of the reception step receives the plurality of streams in the lanes assigned by the processing of the control step on the stream-by-stream basis.       

     (15) A transmission system, including:
         a transmission apparatus that transmits visible image data formed of effective pixel data of an image pickup apparatus by using a format for transmitting to a display; and   a reception apparatus, in which   the transmission apparatus includes
           a transmitter that transmits a plurality of streams formed of the visible image data to respective stream sinks from respective stream sources through a plurality of lanes in a single transmission channel, and   a first controller that assigns the plurality of streams to the plurality of lanes on a stream-by-stream basis,   
           the transmitter transmits the plurality of streams through the lanes assigned by the first controller on the stream-by-stream basis,   the reception apparatus includes
           a receiver that receives a plurality of streams formed of the visible image data, which are transmitted to the respective stream sinks from the respective stream sources, through the plurality of lanes in the single transmission channel; and   a second controller that assigns the plurality of streams to the plurality of lanes on the stream-by-stream basis, and   
           the receiver receives the plurality of streams in the lanes assigned by the second controller on the stream-by-stream basis.       

     REFERENCE SIGNS LIST 
       21  transmitter,  22  receiver,  41 ,  41 - 1  to  41 - n  stream transmission processing unit,  42  multiplexer, as controller,  44  AUX (auxiliary communication unit),  61  MSA generator,  62  SDP generator,  63  multiplexer,  81  division unit,  82 ,  82 - 1  to  82 - n  stream reception processing unit,  91  division unit,  92  MSA reader,  93  SDP reader,  94  image generator