Patent Application
20140104242
This application is directed, in general, to display of video content from a computer and, more specifically, to concurrent display of a video signal on a plurality of display devices.
In many applications, identical content is presented concurrently on a plurality of video displays or other video monitor devices. Such applications may include medical systems, where an x-ray, CAT scan, MRI, or other image or sequence of images (e.g., a video) is presented concurrently to a number of viewers in a plurality of locations. Such applications may also include digital signage at multiple locations in a public space. Such applications may include advertising and informational presentations in a train station or airport.
Currently, a programmer implementing such a system may be required to contend with operating system (OS) limitations on multiple displays, such as a maximum number of displays addressable by the OS. The programmer may also be required to become familiar with details and differing capabilities of individual display devices used in the system and adapt the content for display on the display devices of the system. Further, such a system may require modification when newer devices, or devices with differing capabilities, are added to an existing system.
One aspect provides a method for displaying a video signal concurrently on a plurality of display devices. The method includes identifying a subset of display devices connected to a system, where the subset includes two or more of the display devices connected to the system. The method also includes configuring the system to route a video signal to all of the subset of display devices.
Another aspect provides a system that includes an operating system (OS) and a device driver. The device driver is configured to identify a subset of display devices connected to the system, where the subset includes two or more of the display devices connected to the system. The device driver is also configured to connect to the OS a virtual display device that is representative of the subset of display devices. The device driver is further configured to configure the system to route a video signal to all of the subset of display devices.
Yet another aspect provides a non-transitory, computer readable medium that stores instructions. When executed by a processing system, the instructions cause the processing system to display a video signal concurrently on a plurality of display devices. Steps performed by the processing system include identifying a subset of display devices connected to the processing system, where the subset includes two or more of the display devices connected to the processing system. The steps also include configuring the processing system to route a video signal to all of the subset of display devices.
Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The processing system 100 includes an operating system (OS) 120 that may be resident in the host processor 102, in the GPU 104, or may be distributed across the host processor 102 and one or more GPUs 104. The OS 120 includes a device driver 122 according to the disclosure, which will be described in greater detail with reference to subsequent figures.
Coupled to the GPU 104 are a branch device 106a and a display device 108. While the branch device 106a and the display device 108 are shown coupled directly to the GPU 104, in other embodiments one or both of the branch device 106a and the display device 108 may be coupled to the GPU 104 via the host processor 102 or other suitable circuit.
The branch device 106a is coupled to display devices 110a, 110b, and 110c, as well as to a branch device 106b. The branch device 106b is coupled to display devices 110d, 112, and 114. The display devices 110a, 110b, 110c, and 110d are identical devices, while the display devices 108, 112 and 114 are non-identical devices. Display devices may differ in their capabilities relating to resolution, refresh rate, color format, pixel clock, color depth, audio, and other such characteristics.
The branch device 106a is coupled to the GPU 104 via an interface providing a plurality of video signals. One example of such an interface is a DisplayPort interface, providing as many as four video lanes. The lanes form a video link which can carry up to a 63 video streams. Each stream has a unique ID and utilizes a specified amount of bandwidth on the link. Each stream has a destination, which is programmed in a table in the branch device, The branch device allocates it an appropriate time-slice of the link to each stream and forwards it accordingly. Thus, the branch device 106a may receive and distribute individual video signals to each of the display devices 110a, 110b, and 110c, and for the branch device 106b.
The branch device 106a is also adapted to duplicate any received video stream and distribute the duplicated signal to more than one of the display devices 110a, 110b, and 110c, and for the branch device 106b. When a single stream ID has multiple destinations, the branch device, under the control of the device driver 122, clones this stream and sends it out to those destinations. Every link from the GPU to each of the final monitors sees only a single copy of this stream (and therefor utilizes the bandwidth just once per stream instead of once per target monitor).
The branch device 106a is coupled to the branch device 106b via a multi-lane interface and is also adapted to distribute video streams to the branch device 106b. In other embodiments, additional branch devices may be coupled to either or both of the branch devices 106a and 106b. The branch device 106b is also adapted to distribute an individual video stream to any connected display device or branch device, or to duplicate and distribute any individual video stream to two or more connected display devices or branch devices. The branch devices 106a and 106b are adapted to distribute one or more video streams to connected devices. In some embodiments, a monitor, as a physical device, may itself incorporate a branch device, for example to provide a picture-in-picture function.
While the devices 106a and 106b are identified herein as branch devices, it will be understood that any suitable video switching device may be used to couple the GPU 104 to a plurality of display devices in a system according to the disclosure.
The host processor 102 includes one or more subsystems adapted to receive programs stored on one or more types of computer readable medium. The phrase “computer readable medium” includes any type of non-transitory medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc or digital versatile disc (DVD), or any other type of medium. Instructions implementing part or all of the OS 120 and/or the device driver 122 may be stored on such a computer readable medium.
A user of the processing system 100 may want to display video content concurrently on some or all of the displays 108, 110a-d, 112, and 114 (i.e., on a subset of the display devices connected to the system 100). The user employs a control panel provided by the device driver 122 to specify one or more display device characteristics. The control panel (or the device driver 122) then selects a plurality of the displays 108, 110a-d, 112, and 114 that are have at least the specified characteristic(s). This plurality of display devices is referred to herein as a multi-stream clone cluster, or more simply as a cluster.
The device driver 122 then generates a descriptor (e.g., an extended display identification data (EDID)) of a virtual display device that is representative of the cluster and registers the representative device with the OS 120, along with the display port and video stream by which the OS will send video signals to the cluster. The driver 122 also sets up one or both of the branch devices 106a and 106b as required to duplicate and distribute the video signal sent via the registered port and lane to the display devices of the cluster.
In step 202, a user selects a GPU display output connector through which the cluster of display devices may be sent a video signal for concurrent display. In step 204, the control panel calls the device driver 122 repeatedly to build up a list of all display devices that are coupled to the selected connector. In building the list, the device driver determines the characteristics (or capabilities) of each connected display, such as resolution, refresh rate, color format, pixel clock, color depth, audio, and other such characteristics.
In step 206, the control panel aggregates the available values for each characteristic available from the connected display devices and presents the user with those available values. In step 208, the control panel receives, via the dialog box, the user's selection of which characteristics, and what characteristic values, are desired for appropriate display of the video content that will be displayed concurrently on the devices in the cluster. Such a selection may be referred to as a “pivot.”
In step 210, the control panel (in some embodiments, with support from the device driver 122) identifies which display devices that are coupled to the selected connector are capable of providing, at a minimum, the characteristic values included in the pivot in step 208. In step 212, the identified, qualified display devices are added to a list (or “clone group”) representing the multi-stream clone cluster.
In some embodiments, prior to step 212, a listing of the identified display devices is presented to the user and the user is permitted to deselect some of the identified devices. The devices remaining in the culled list are then added to the clone group in step 212.
In step 214, the device driver 122 generates a description of a virtual display (or “representative device”) that has the characteristic values selected by the user in step 208. The representative device descriptor also has values for other characteristics that are required to fully describe a display device to the OS 120, but for which the user did not indicate a preference in step 208. Such additional characteristics will typically be given a value representing a highest quality signal that can be supported by all display devices in the display group formed in step 212. However, other value-setting heuristics may also or additionally be employed; for example, where any one of the display devices in the group is capable of audio output—and where the provision of audio output to a non-audio-capable display device does not cause problems—the representative device descriptor may indicate that the virtual device is capable of audio output.
The descriptor of the representative device generated in step 214 may be in the form of an EDID or other standardized descriptor format. In step 216, the device driver 122 registers the EDID of the representative device with the OS 120 as being coupled to the connector selected in step 202.
Where individual displays in the clone group have previously been registered with the OS 120 as being connected, before the representative device is registered with the OS 120, the device driver 122 first unregisters (or “hot unplugs”) the individual displays in the clone group from the OS 120. After registration (or “hot plugging”) of the representative device, all display devices in the clone group will receive a common video signal via the virtual representative device and the device driver 122. Individual devices in the clone group are then added to the multi-stream clone cluster, and the cluster is placed in the “active” state, as will be described in greater detail with reference to
The dialog box 300 provides the user with an interface to select one or more desired (or required) characteristics that are to be provided by display devices in a multi-stream clone cluster, as described with reference to step 208 of the method 200.
The preset selector 302 allows the user to select among presets that, in turn, make initial selections among the characteristic values presented in the selectors 304-312. A “common native mode” preset selects values that would form a clone group having the same native display timing. Where more than one such group exists, this preset selects values forming the largest group of displays or, where such groups are of equal size, values forming the clone group with the highest resolution.
A “highest common mode” preset selects values for the selectors 304-312 that would form a clone group having one or more common timings. Where more than one such group exists, this preset selects values forming the largest group of displays or, where such groups are of equal size, values forming the clone group with the highest timing.
If the user changes the selection in one or more of the selectors 304-312, the preset selector 302 changes to the value “custom settings.”
As described with reference to
The refresh rate (RR) selector 306 will present all available RRs for the currently selected value in the resolution selector 304, with the initial RR selection set according to the preset selected in the selector 302. Again, the user may change the RR selected in the selector 306. If the user selects a different resolution in the selector 304, the values for RR presented in the selector 306 may change accordingly.
The pixel clock selector 310 presents all available pixel clock values supported for the currently selected resolution and refresh rate. The initial pixel clock selection may be based on either the preset selected in the selector 302 or the pixel clock selection that will result in the largest clone group. Selecting a different resolution or refresh rate may change the values presented in the pixel clock selector 310.
The color format selector 308 presents all available color format values supported by the currently selected resolution, refresh rate and pixel clock. The control panel may include an order of preference amongst possible color formats and, where more than one color format is listed in the selector 308, the color format having the highest preference is initially selected.
The color depth selector 312 presents all available color depths supported by the currently selected resolution, refresh rate, pixel clock and color format. The control panel may include an order of preference amongst possible color depths and, where more than one color format is listed in the selector 308, the color depth having the highest preference is initially selected.
While particular characteristics, types of selectors, selection methodologies for values displayed in the selectors, and initial selections among the displayed values have been described and shown herein, it will be understood that in other embodiments, other characteristics, selectors, selection methodologies, and initial selections may be provided without departing from the scope of this disclosure.
As mentioned with reference to
Subsequently, all displays that are included in the cluster may be disconnected from the system 100, at which time the cluster is placed into a “dormant” state, configuration of the branch devices 104a and 104b for the cluster is reversed, and the cluster's virtual representative device is disconnected from the OS 120. The cluster is still enabled, however, and when one or more displays that qualify for inclusion in the cluster are subsequently connected to the system 100, the newly connected devices are added to the cluster, the branch devices 104a and 104b are configured according to the physical connectivity of the new devices, the cluster is returned to the “active” state, and the cluster's representative device is re-connected to the OS 120.
In step 404, when a user creates a multi-stream clone cluster (as described with reference to
When the cluster is in the “enabled” state 406, in step 410 the device driver 122 may sense connection of a new display device to the video output port used for the cluster. In step 412, the device driver 122 determines whether the newly connected display device is qualified to participate in the cluster. If the device is not qualified, the cluster is returned to the “enabled” state 406.
If the newly connected display device is determined in step 412 to be qualified to participate in the cluster, in step 414 the device is added to the list or other data structure used to hold information about the devices included in the cluster. In step 416, the cluster's state is checked to determine whether the cluster is in the “dormant” state. If not, the cluster remains in the “active” state 420. If so, in step 418, the cluster's representative device is connected to the OS 120, one or both of the branch devices 104a and 104b are configured to route the video signal from the cluster's video output port to the newly connected device, and the cluster is placed into the “active” state 420.
If the unplugged device is determined in step 504 to be a member of the cluster, then in step 506 the device is removed from the cluster and configuration of the branch devices 104a and 104b is reversed that routed video signals to the newly disconnected device. In step 508, the device driver 122 determines whether the device just removed was the last device in the cluster, i.e., whether the cluster is now empty. If there are one or more devices remaining in the cluster, the cluster remains in the “active” state 420. However, if the cluster is now empty, in step 510 the cluster's representative device is disconnected from the OS 120 and the cluster is placed into the “dormant” state 512.
In the processing system 100, the definition of a cluster (e.g., its video output port, its pivot, and other defining information) persists through events such as the system 100 being powered off and back on again. More generally, the definition of a cluster persists across the device driver 122 being unloaded from the OS 120 and later reloaded.
However, if MSC parameters are found in the persistence database, in step 608 the device driver 122 reads the stored information relating to the MSC cluster(s) and identifies any display devices coupled to the cluster's video output port that meet the criteria of the cluster's pivot and are qualified to participate in the cluster. In step 610, the driver 122 determines whether the list of qualified devices is empty. If the list is empty, then the cluster is placed into the “dormant” state 512.
If the list of qualified devices is not empty, however, then in step 608 the qualified devices are added to the cluster, the branch devices 104a and 104b are configured according to the physical connectivity of the devices to duplicate and route video signals from the cluster's video output port to the qualified devices, the cluster is placed in the “active” state 420, and the cluster's representative device is connected (or “hot plugged”) to the OS 120.
Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.
