Camera system and switching device

A camera system includes a plurality of camera devices and a switching device. The switching device transmits a reference signal to the camera devices via a network. Each of the camera devices transmits a video signal based on the time when the camera device receives the reference signal. The switching device determines one or more priority images for transmitting video signals with priority, in accordance with operation by a user. The camera system has a configuration in which transmission of a video signal from each of one or more of the camera devices not capturing the one or more priority images is delayed relative to transmission of a video signal from each of one or more of the camera devices capturing the one or more priority images.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2013-046307 filed on Mar. 8, 2013, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

The present disclosure relates to camera systems using camera devices with network functions.

An example existing device transmits images captured by multiple cameras via a network and selects a desired image from the images.

Japanese Unexamined Patent Publication No. 2011-259365 describes, for example, a configuration including a plurality of camera devices that output video signals as packets and a relay device that relays video signals from the camera devices and selects and outputs a desired image from a plurality of images.

SUMMARY

The present disclosure provides a camera system that can reduce quality degradation of a necessary image even in a case where a network bandwidth is insufficient for video signal transmission.

An example camera system according to the present disclosure includes: a plurality of camera devices connectable to a network; and a switching device configured to transmit a reference signal for synchronizing video signals to the camera devices via the network and receive video signals from the camera devices, wherein each of the camera devices transmits the video signal based on a time when the camera device receives the reference signal, the switching device determines, in accordance with operation by a user, one or more priority images for transmitting video signals with priority among a plurality of images captured by the camera devices, and the camera system has a configuration in which a time of transmitting a video signal from each of one or more of the camera devices not capturing the one or more priority images is delayed relative to a time of transmitting a video signal from each of one or more of the camera devices capturing the one or more priority images.

A camera system according to the present disclosure is useful for reducing quality degradation of a necessary image even in a case where a network bandwidth is insufficient for video signal transmission.

DETAILED DESCRIPTION

Embodiments are described in detail below with reference to the attached drawings. However, unnecessarily detailed description may be omitted. For example, detailed description of well-known techniques or description of the substantially same elements may be omitted. Such omission is intended to prevent the following description from being unnecessarily redundant and to help those skilled in the art easily understand it.

Inventor provides the following description and the attached drawings to enable those skilled in the art to fully understand the present disclosure. Thus, the description and the drawings are not intended to limit the scope of the subject matter defined in the claims.

In an existing camera system, each camera device is connected to a switching device with a cable, and an analog video signal is transmitted through the cable. Thus, to use the camera system for broadcasting live concerts or sports, a large number of cables need to be extended inside and outside a venue for preparation of the camera system.

On the other hand, digitization of camera devices has proceeded in recent years, and a configuration in which a digital video signal subjected to compression coding is transmitted from a camera device to a switching device that decodes the video signal, has become a mainstream. In this configuration, each camera device is connected to a network, and the switching device receives a video signal via the network. In this case, the switching device only needs to be connected to, for example, a LAN cable. This configuration eliminates the necessity of extending a large number of cables, so that the camera system can be easily installed, and a cost for the system is significantly reduced.

In this configuration, however, a network bandwidth is not always sufficient for video signal transmission, which causes a possibility of quality degradation of a video signal. Specifically, in this camera system, a plurality of camera devices transmit video signals as packets in synchronization, and thus, a large number of packets are transmitted at the same time. Accordingly, a collision or a loss of packets often occurs. Consequently, packets need to be transmitted again, and a video signal is transmitted with a large delay. In particular, in a case where image data has a high bit rate or a case where a large number of camera devices are used, a large amount of packets are transmitted at the same time within a limited bandwidth of a network, and thus, the above-described phenomenon frequently occurs.

The number of cameras for use in a camera system and the resolution of cameras are expected to increase in future, and the amount of data of a video signal transmitted via a network is also expected to increase. Although the network bandwidth is, of course, also expected to increase technically, the above-described phenomenon occurs due to a correlation between the network bandwidth and the data amount of a video signal, and thus, measures against the phenomenon is still important in future.

A camera system according to the present disclosure can reduce quality degradation of an important image, such as an image output from a switching device, even in a case where a network bandwidth is insufficient for video signal transmission.

A first embodiment will be described with reference toFIGS. 1-5.

FIG. 1is a block diagram schematically illustrating a configuration of a camera system according to the first embodiment. The camera system illustrated inFIG. 1includes a plurality of camera devices10(a camera A, a camera B, a camera C, and a camera D), a relay150, and a switching device100. The camera devices10are cameras connectable to a network, i.e., network cameras, and are connected to the relay150via the network. The switching device100is connected to the relay150via the network. In this embodiment, the network is an Ethernet (registered trademark). That the term “connected” or “connectable,” as used herein, is defined as directly or indirectly coupled in an electrical manner.

The camera devices10packetize captured video signals into packets, and output the packets to the network. The image data may be data subjected to compression coding or uncompressed data. The relay150is a network device such as a switching hub, and a network can be constituted by connecting a plurality of network devices. A video signal from each of the camera devices10is transmitted to the switching device100from the relay150via the network.

The switching device100includes an interface section160, a multi-decoder165, an image display section170, a switching section175, a user operation section180, a reference signal generator185, and a priority image selector190.

The interface section160serves as an interface with the network, and receives video signals, audio signals, control signals, and other signals from the camera devices10via the network. The received video signals are transmitted to the multi-decoder165. The interface section160transmits signals such as a reference signal from the reference signal generator185and a selection signal from the priority image selector190via the network.

The multi-decoder165includes buffers (not shown) individually provided for the camera devices10, and temporarily stores transmitted video signals in the buffers. When a predetermined data amount or a predetermined image data unit is accumulated in one of the buffers, the multi-decoder165performs a decoding process. This decoding process is associated with an encoding process in the camera devices10, and can be performed in parallel on the buffers. The image data to which the decoding process has been completed is transmitted to the image display section170and the switching section175.

The image display section170displays the transmitted image data on a screen.FIG. 2illustrates an example of the screen of the image display section170. In the example ofFIG. 2, the image display section170has four screens71,72,73, and74. The screen71displays a main image to be output from the switching device100to the outside. The screen72displays a switching candidate image to be next switched to a main image. The screens73and74display standby images. InFIG. 2, the screens71,72,73, and74display images of the camera C, the camera D, the camera A, and the camera B, respectively.

The switching section175selects one of images decoded by the multi-decoder165, based on a switching instruction output from the user operation section180. The selected image is output as an image output of the switching device100. In general, a main image is selected as an image to be output to the outside.

The user operation section180allows the user to perform image selecting operation and switching operation. Although not shown inFIG. 1, the user operation section180includes a user interface including buttons and switches. An output of the user operation section180is sent to the image display section170, the switching section175, and the priority image selector190. The user can operate the user operation section180and switch the image between a main image and a switching candidate image at a desired timing, while watching the screen of the image display section170. The user can also select one of a plurality of standby images so as to replace the selected standby image with the switching candidate image.

InFIG. 2, images displayed on the screens71,72,73, and74can be switched by operation with the user operation section180. The main image displayed on the screen71is output from the switching device100and is used for, for example, broadcasting and recording. The switching candidate image displayed on the screen72can be switched to the main image by operation with the user operation section180. The user can switch the switching candidate image on the screen72to the main image at a desired timing, while watching the screens71and72. As a result, inFIG. 2, the image on the screen71is switched to the image of camera D, and the image of the camera D is output as a main image from the switching device100.

The user can also select a desired image as an image of a switching candidate from standby images on the screens73and74. Operation with the user operation section180can replace the switching candidate image displayed on the screen72with the standby images displayed on the screens73and74. A standby image becomes a switching candidate image through operation by the user, and the switching candidate image replaces the main image and is output by further operation by the user.

The reference signal generator185periodically generates a reference signal serving as a basis of the time of transmitting a video signal. This reference signal is a signal for synchronizing video signals from the camera devices10. The reference signal is transmitted from the interface section160to the camera devices10via the network. Examples of the reference signal include a frame signal, a field signal, a line signal of an image, and a timing signal for a fixed period. Each of the camera devices10that have received the reference signal via the network outputs a video signal to the network based on the time when the camera device10received the reference signal. Thus, images of the camera devices10are synchronized, and the images can be easily switched by the switching device100.

The priority image selector190receives an output of the user operation section180, and generates selection signals notifying the camera devices10whether images being captured are priority images or not. Here, the priority images are images that are important and have priority in transmitting video signals among images captured by the camera devices10. The selection signals are transmitted from the interface section160to the camera devices10via the network. The selection signals notify each of the camera devices10whether the image that is currently being captured is a priority image or not.

In this embodiment, the priority image selector190determines the main image and the switching candidate image as priority images. In the example ofFIG. 2, for example, images that are being captured by the cameras C and D are determined as the priority images. The selection signals may be in various forms. For example, different signal values may be sent to a camera device capturing a priority image and a camera device not capturing a priority image. Alternatively, a specific signal may be sent only to camera devices not capturing priority images. Signals may also be sent at various timings. For example, a selection signal may be periodically transmitted at the same time as the reference signal, or may be transmitted only when priority images are switched.

In this embodiment, each of the camera devices10is configured to change the time of transmitting a video signal depending on whether an image that is being captured by the camera device10is a priority image or not. Specifically, when being notified that an image that is being captured is not a priority image, each of the camera devices10sets a period from reception of a reference signal to start of transmission of a video signal longer than that when being notified that the image that is being captured is a priority image. That is, each of the camera devices10is configured to delay the time of transmitting a video signal when the image that is being captured is not a priority image.

FIG. 3is a timing chart showing an example of operation of the camera system of the first embodiment. The example ofFIG. 3is based on the assumption that the camera C is capturing a main image, the camera D is capturing a switching candidate image, and the image being captured by the cameras C and D are determined as priority images. In addition, it is assumed that each of the camera devices10(the cameras A-D) delays transmission of a video signals by a predetermined time Td when an image being captured is not a priority image. InFIG. 3, T1and T2denote times of receiving reference signals. InFIG. 3, the upper part (“Scheduled timing”) shows scheduled times necessary for transmitting video signals, and the lower part (“Actual timing”) shows times elapsed for actual transmission.

Each of the cameras A-D needs to output a predetermined unit of video signals to the network and transmit the predetermined unit to a receiver device, within a period from time T1of receiving a reference signal to time T2of receiving a next reference signal. Here, in a case where the network bandwidth is sufficiently large for the sum of the image bit rates of the cameras A-D, no significant problems occur even when the cameras A-D transmit video signals at the same time.

On the other hand, in a case where the network bandwidth is insufficient for the sum of the image bit rates of the cameras A-D, if the cameras A-D try to output video signals to the network at the same time, a large number of packets are transmitted at the same time, and consequently, a collision or a loss of the packets readily occur. As a result, packets need to be transferred again, and a large delay occurs in transmission of video signals. Insufficiency of the network bandwidth arises when a high-quality camera having a high image bit rate is used, when a larger number of cameras are connected, or when the network bandwidth is originally small, and so on.

To cope with this insufficiency, as illustrated inFIG. 3, the cameras A and B notified that images being captured are not priority images delay transmission of video signals by a predetermined time Td. That is, video signals only of the cameras C and D capturing priority images are output to the network at time T1of receiving the reference signal.

In this manner, as illustrated inFIG. 3, the video signals of the cameras C and D are transmitted to the receiver device within a period before time T2. Thus, no image disturbance occurs in the main image and the switching candidate image. On the other hand, transmission of video signals of the cameras A and B is delayed by the predetermined time Td, and thus, transmission is not completed before time T2of receiving the next reference signal in some cases, as illustrated inFIG. 3. In this case, although image disturbance occurs, this image disturbance has a small influence because the images of the cameras A and B are standby images. As a result, it is possible to avoid the problem that transmission of a priority image, i.e., an important video signal, is not completed within a predetermined period because of a network delay due to, for example, a packet collision.

The predetermined time Td may be a fixed value such as ½ or ⅓ of the period of a reference signal. The switching device100may adjust the value of the predetermined time Td in accordance with a network bandwidth, the number of cameras, or a parameter such as an image bit rate. Alternatively, the switching device100may be configured such that the predetermined time Td can be adjusted by user operation. In this case, the switching device100may be configured such that the user can finely adjust the predetermined time Td by using the user operation section180while checking the image quality. In addition, the predetermined time Td does not need to be the same among the camera devices10, and may differ from one another among the camera devices10.

FIG. 4is a timing chart showing an example of operation of a comparative example. In the example ofFIG. 4, the cameras A-D output video signals to the network at the same time in synchronization with a reference signal. Thus, a large number of packets are output to the network at the same time, and due to constraints on the network bandwidth, retransmission of packets resulting from a loss or a collision of packets, for example, is repeated. As a result, transmission of video signals takes a time several-fold that in the scheduled timing. In this comparative example, each of the cameras A-D fails to transmit predetermined units of video signals to a receiver device until time T2of receiving the next reference signal. Accordingly, all the images fail to be transmitted in synchronization with the reference signal, and image disturbance also occurs in a main image and a switching candidate image.

On the other hand, in the operation example ofFIG. 3, the cameras A and B that are not capturing priority images delay transmission of video signals by the predetermined time Td. Thus, the cameras C and D that are capturing priority images complete transmission of video signals within a period shorter than that in the comparative example illustrated inFIG. 4. As a result, no image disturbance occurs in a main image and a switching candidate image, and high quality of the images can be maintained.

FIG. 5is a timing chart schematically showing a change in operation of the camera system in accordance with user operation. InFIG. 5, T11-T15denote times of receiving reference signals. The lower part ofFIG. 5shows the state of the screen of the image display section170. In actual operation, the transmission cycle of video signals is much shorter than that in switching the screen of the image display section170.FIG. 5, however, schematically illustrates this transmission cycle.

In state (1), the image of the camera C is selected as a main image and the image of camera D is selected as a switching candidate image, by user operation. At this time, the images of the cameras C and D are determined as priority images. Thus, at time T11, the cameras A and B notified that images being captured are not priority images delay transmission of video signals.

Thereafter, suppose the user switches the main image to the image of the camera D and the switching candidate to the image of the camera B (state (2)). At this time, the images of the cameras B and D are determined as priority images. Thus, at time T12, the cameras A and C notified that image being captured are not priority images delay transmission of video signals. This operation continues until the user next switches images.

Then, suppose the user switches the main image to the image of the camera B and the switching candidate to the image of the camera C (state (3)). Then, images of the cameras B and C are determined as priority images. Thus, at time T14, the cameras A and D notified that images being captured are not priority images delay transmission of video signals. This operation continues until the user next switches images.

In this manner, in this embodiment, priority images for transmitting video signals with priority dynamically change in accordance with operation by the user, and selection of cameras for delaying transmission of video signals also dynamically changes accordingly. Thus, quality degradation of an important image caused by network congestion can be avoided.

As described above, the camera system of this embodiment includes the camera devices10and the switching device100. The switching device100transmits a reference signal for synchronizing video signals to the camera devices10and receives video signals from the camera devices10, via the network. Each of the camera devices10transmits a video signal based on the time when the reference signal is received. The switching device100determines priority images for transmitting video signals with priority, among images captured by the camera devices10. The switching device100notifies each of the camera devices10whether an image being captured is a priority image or not. When being notified that an image being captured is not a priority image, each of the camera devices10sets a period from reception of the reference signal to start of transmission of a video signal longer than that when being notified that an image being captured is a priority image. That is, the camera system is configured to delay the time of transmission of video signals from the camera devices10not capturing priority images relative to the time of transmission of video signals from the camera devices10capturing priority images.

In this manner, video signals from the camera devices10capturing priority images are transmitted before video signals from the camera devices10not capturing priority images. Thus, even if the network bandwidth is not sufficient for video signal transmission, the possibility of transmitting video signals of priority images without fail increases, whereas the possibility of occurrence of image disturbance decreases. As a result, quality degradation of a necessary image can be reduced.

In this embodiment, the switching device100may transmit a signal indicating the predetermined time Td, i.e., a waiting time from reception of a reference signal to start of transmission of a video signal, to the camera devices10that are not capturing priority images. For example, this signal may be included in a selection signal to be transmitted from the switching device100to the camera devices10.

A second embodiment will be described with reference toFIGS. 6-8.

FIG. 6is a block diagram schematically illustrating a configuration of a camera system according to the second embodiment. InFIG. 6, components substantially identical to those illustrated inFIG. 1may not be described. The camera system illustrated inFIG. 6includes a plurality of camera devices15(a cameras A, a camera B, a camera C, and a camera D), a relay150, and a switching device200. The camera devices15are cameras connectable to a network, i.e., network cameras, and are connected to the relay150via the network. The switching device200is connected to the relay150via the network. In this embodiment, the network is an Ethernet (registered trademark).

The camera devices15packetize captured video signals into packets, and output the packets to the network. The image data may be data subjected to compression coding or uncompressed data. The relay150is a network device such as a switching hub, and a network can be constituted by connecting a plurality of network devices. A video signal from each of the camera devices15is transmitted to the switching device200from the relay150via the network.

The switching device200includes an interface section260, a multi-decoder165, an image display section170, a switching section175, a user operation section180, a reference signal generator285, and a priority image selector290.

In the first embodiment, the switching device100notifies each of the camera devices10whether an image being captured is a priority image or not. In addition, each of the camera devices10changes the time of outputting a video signal depending on whether an image being captured is a priority image or not. On the other hand, in the second embodiment, the switching device200does not notify the camera devices15whether images being captured are priority images or not. That is, a selection signal used in the first embodiment is not transmitted to the camera devices15. Alternatively, the switching device200controls the time of transmitting a reference signal to each of the camera devices15, depending on whether an image being captured is a priority image or not.

In the configuration ofFIG. 6, in response to an output of the user operation section180, the priority image selector290generates a selection signal for specifying one or more of the camera devices15that are capturing priority images. The selection signal is sent to the reference signal generator285. Similarly to the first embodiment, the priority image selector290of the second embodiment determines a main image and a switching candidate image as priority images. For example, in the example ofFIG. 2, images being captured by the cameras C and D are determined as priority images.

Similarly to the reference signal generator185ofFIG. 1, the reference signal generator285periodically generates a reference signal serving as a basis of the time of transmitting a video signal. In this embodiment, the reference signal generator285receives a selection signal output from the priority image selector290. Based on this selection signal, the reference signal generator285can distinguish the camera devices15capturing priority images and the camera devices15not capturing priority images from each other.

The reference signal generator285transmits a normal reference signal to the camera devices15capturing priority images (e.g., the cameras C and D inFIG. 2). On the other hand, the reference signal generator285transmits a reference signal delayed by a predetermined time Td to the camera devices15not capturing priority images (e.g., cameras A and B inFIG. 2). These reference signals are transferred to the interface section260, and then to the camera devices15via the network.

The predetermined time Td may be a fixed value such as ½ or ⅓ of the period of a reference signal. The switching device200may adjust the value of the predetermined time Td in accordance with a network bandwidth, the number of cameras, or a parameter such as an image bit rate. Alternatively, the switching device200may be configured such that the predetermined time Td can be adjusted by user operation. In this case, the switching device200may be configured such that the user can finely adjust the predetermined time Td by using the user operation section180while checking the image quality. In addition, the predetermined time Td does not need to be the same among the camera devices15, and may differ from one another among the camera devices15.

FIG. 7is a timing chart showing an example of operation of the camera system of the second embodiment. The example ofFIG. 7is based on the assumption that the camera C is capturing a main image, the camera D is capturing a switching candidate image, and images being captured by the cameras C and D are determined as priority images. In addition, it is assumed that the reference signal generator285delays a reference signal by a predetermined time Td to the camera devices15that are not capturing priority images. InFIG. 7, T1and T2denote times of receiving reference signals, and T1X denotes a time of receiving a delayed reference signal. InFIG. 7, the upper part (“Scheduled timing”) shows a scheduled timing necessary for transmitting video signals, and the lower part (“Actual timing”) shows the time elapsed for actual transmission.

Each of the cameras A-D needs to output a predetermined unit of video signals to the network and transmit the predetermined unit to a receiver device, within a period from time T1of receiving a reference signal to time T2of receiving a next reference signal. Here, in a case where the network bandwidth is sufficiently large for the sum of the image bit rates of the cameras A-D, no significant problems occur even when the cameras A-D transmit video signals at the same time.

On the other hand, in a case where the network bandwidth is insufficient for the sum of the image bit rates of the cameras A-D, if the cameras A-D try to output video signals to the network at the same time, a large number of packets are transmitted at the same time, and consequently, a collision or a loss of the packets readily occurs. As a result, packets need to be transferred again, and a large delay occurs in transmission of video signals. Insufficiency of the network bandwidth arises when a high-quality camera having a high image bit rate is used, when a larger number of cameras are connected, or when the network bandwidth is originally small, and so on.

To cope with this insufficiency, as illustrated inFIG. 7, a reference signal delayed by the predetermined time Td is transmitted from the switching device200to the cameras A and B not capturing priority images. That is, video signals only of the cameras C and D capturing priority images are output to the network based on time T1of receiving the reference signal.

In this manner, as illustrated inFIG. 7, the video signals of the cameras C and D are transmitted to a receiver device within a period before time T2. Thus, no image disturbance occurs in the main image and the switching candidate image. On the other hand, transmission of video signals of the cameras A and B is delayed by the predetermined time Td, and thus, transmission is not completed before time T2of receiving the next reference signal in some cases, as illustrated inFIG. 7. In this case, although image disturbance occurs, the image disturbance has a small influence because the images of the cameras A and B are standby images. As a result, it is possible to avoid the problem that transmission of a priority image, i.e., an important video signal, is not completed within a predetermined period because of a network delay due to, for example, a packet collision.

FIG. 8is a timing chart schematically showing an example of operation of the camera system in accordance with user operation. InFIG. 8, T11-T15denote times of receiving reference signals, and T11X-T14X denote times of receiving delayed reference signals. The lower part ofFIG. 8shows a state of the screen of the image display section170. In actual operation, the transmission cycle of video signals is much shorter than that in switching the screen of the image display section170.FIG. 8, however, schematically illustrates this transmission cycle.

In state (1), the image of the camera C is selected as a main image and the image of camera D is selected as a switching candidate image, by user operation. At this time, the images of the cameras C and D are determined as priority images. Thus, at time T11X, a reference signal delayed relative to normal time T11is transmitted to the cameras A and B not capturing priority images.

Thereafter, suppose the user switches the main image to the image of the camera D and the switching candidate to the image of the camera B (state (2)). At this time, the images of the cameras B and D are determined as priority images. Thus, at time T12X, the cameras A and C not capturing priority images receive a reference signal delayed relative to normal time T12. This operation continues until the user next switches images.

Thereafter, suppose the user switches the main image to the image of the camera B and the switching candidate to the image of the camera C (state (3)). Then, images of the cameras B and C are determined as priority images. Thus, at time T14X, the cameras A and D not capturing priority images receive a reference signal delayed relative to normal time T14. This operation continues until the user next switches images.

In this manner, similarly to the first embodiment, priority images for transmitting video signals with priority dynamically change in accordance with operation by the user, and selection of cameras for delaying transmission of video signals also dynamically changes accordingly in this embodiment. Thus, quality degradation of an important image due to network congestion can be avoided.

In this embodiment, it is sufficient for the camera devices15to operate similarly to conventional camera devices, i.e., transmit video signals after receiving reference signals. Thus, in this embodiment, the configuration of the camera devices15does not need to be changed, and an existing camera device can be used.

As described above, the camera system of this embodiment includes the camera devices15and the switching device200. The switching device200transmits a reference signal for synchronizing video signals to the camera devices15and receives video signals from the camera devices15, via the network. Each of the camera devices15transmits a video signal based on the time when the reference signal is received. The switching device200determines priority images for transmitting video signals with priority, among images captured by the camera devices15. The switching device200delays the time of transmitting a reference signal to the camera devices15not capturing priority images, relative to the camera devices15capturing priority images. That is, the camera system is configured to delay the time of transmission of video signals from the camera devices15not capturing priority images relative to the time of transmission of video signals from the camera devices15capturing priority images.

In this manner, video signals from the camera devices15capturing priority images are transmitted before video signals from the camera devices15not capturing priority images. Thus, even if the network bandwidth is not sufficient for video signal transmission, the possibility of transmitting video signals of priority images without fail increases, whereas the possibility of occurrence of image disturbance decreases. As a result, quality degradation of a necessary image can be reduced.

The foregoing first and second embodiments have been described as example techniques disclosed in the present application. However, the techniques according to the present disclosure are not limited to these embodiments, and are also applicable to those where modifications, substitutions, additions, and omissions are made. In addition, elements described in the first and second embodiments may be combined to provide a different embodiment.

Other embodiments will now be described.

In the first and second embodiments, the camera devices are connected to the switching device via a wired network. However, the present disclosure is not limited to this configuration, and a wireless network as illustrated inFIG. 9may be used. InFIG. 9, camera devices17are connected to a relay250via a wireless network. The relay250may be wireless network equipment such as an access point of a wireless network. The configurationFIG. 9corresponds to the second embodiment, but the configuration of the first embodiment may employ a wireless network.

In the first embodiment, the relay150and the switching device100may be united together as one device. In the second embodiment, the relay150and the switching device200may be united together as one device. The image display section170and the user operation section180may be united with the switching devices100and200, or may be separate from the switching devices100and200and connected to the switching devices100and200via signal lines.

In the first and second embodiments, the main image and the switching candidate image are determined as priority images. However, the present disclosure is not limited to this. For example, only the main image may be determined as a priority image. Alternatively, a plurality of switching candidate images may be included in priority images. The user may determine a priority image for transmitting a video signal with priority, independently of selection of the main image and the switching candidate image.

In the first and second embodiments, main images and the switching candidate image output from the switching devices100and200are determined as priority images. However, determination of priority images is not limited to this. For example, the user may determine an image with which the camera angle is adjusted as a priority image. Some camera systems are configured to allow a switching device or a camera operating section near the switching device to adjust the angle (e.g., pan and tilt) of a remote camera. In adjusting the angle with such a configuration, image quality degradation of the camera undesirably hinders the adjustment. In view of this, when the user selects an adjustment target image with which the camera angle is adjusted, the adjustment target image may be determined as a priority image.

FIG. 10is a block diagram schematically illustrating a configuration of a camera system according to a variation of the first embodiment. InFIG. 10, a switching device110includes a camera operating section195for remotely operating a camera. The camera operating section195may be separate from a switching device110, and may be connected to the switching device110via a signal line. The priority image selector190receives an operation output from the camera operating section195. When the user adjusts the angle of a remote camera by operating the camera operating section195, the priority image selector190determines, as a priority image, an image of the camera whose angle is being adjusted. The subsequent operation is similar to that in the first embodiment. A similar variation is also applicable to the second embodiment.

In the first embodiment, the switching device100notifies the camera devices10whether images being captured are priority images or not, and transmission of video signals of the camera devices10not capturing priority images is delayed. In the second embodiment, the switching device150delays transmission of a reference signal to the camera devices15not capturing priority images. The present disclosure is not limited to these embodiments. Specifically, the camera system may have a configuration in which the switching device determines priority images in accordance with operation by the user and the camera system delays the time of transmission of video signals from camera devices not capturing priority image relative to the time of transmission of video signals from camera devices capturing priority images.

Various embodiments have been described above as example techniques of the present disclosure, in which the attached drawings and the detailed description are provided.

As such, elements illustrated in the attached drawings or the detailed description may include not only essential elements for solving the problem, but also non-essential elements for solving the problem in order to illustrate such techniques. Thus, the mere fact that those non-essential elements are shown in the attached drawings or the detailed description should not be interpreted as requiring that such elements be essential.

Since the embodiments described above are intended to illustrate the techniques in the present disclosure, it is intended by the following claims to claim any and all modifications, substitutions, additions, and omissions that fall within the proper scope of the claims appropriately interpreted in accordance with the doctrine of equivalents and other applicable judicial doctrines.

The present disclosure is applicable to camera systems that reduce quality degradation of necessary images. Specifically, the present disclosure is useful for, for example, camera systems for broadcasting or recording sports or live concerts.