TWI485618B - Kvm switch of transmitting video signal to remote consoles and method thereof - Google Patents

Description

Multi-computer switcher and method for transmitting image signals to multiple remote control computers

The invention relates to a KVM switch for transmitting image signals from a computer to a plurality of remote control computers, in particular to a KVM switch and method for transmitting image signals through a network to a plurality of remote control computers.

The far-reaching network technology has brought convenience to human beings. Multi-computer switchers with network interfaces on the market have gradually become one of the main network management tools. Moreover, more and more KVM switches use special application integrated circuit (ASIC) chips or field programmable gate array (FPGA) chips, etc., to process the compression of image signals, and on the other hand to improve the KVM switch. The overall system performance, on the one hand, can reduce the cost of the multi-computer switcher and shorten the time course of technology development. According to the VESA standard, the image signal is composed of continuous image frames. For example, when the update frequency is 60 Hz, the image source generates 60 image frames per second for the screen. On the other hand, when performing JPEG compression encoding. Each image frame can be divided into a plurality of blocks, for example, 16 pixels by 16 pixels as a block. The baseline model contains most of the basic features of this JPEG standard, and has become the industry standard for digital signal controller (DSC) systems.

Simply put, the JPEG baseline mode is an architecture that uses transform coding. Perform a color space conversion step of converting RGB to YCrCb. Basically, it can be roughly divided into three parts: DCT (discrete cosine transform), quantization and entropy coding. First, the linear transformation (DCT) is used to convert the pixels in the space into a frequency space, and then the spatial coefficients are further quantized and entropy coding is further compressed. Entropy coding still involves two steps. First, the image components are scanned in a zigzag zigzag and Huffman coding. Therefore, the JPEG baseline mode combines techniques such as DCT, quantization, zigzag scan, and Huffman coding. Huffman coding is a JPEG compression coding of video signals in a DSC system. The last step. The JPEG decoding system is similar to its encoding system, and is only the inverse of the encoding process. First, Huffman decoding is performed, the header is processed first, and then Variable Length Decoding (VLD) is performed, after inverse quantization (IQ) and inverse two-dimensional discrete cosine transform (IDCT), and finally Then, the YCbCr→RGB conversion can be performed to restore the image signal.

Moreover, if the video signal is JPEG compression encoded as described above, the compressed image data is generally stored in two ways. The first way is that each image change block uses independent data storage and does not affect each other. The second way is that all image change blocks are stored continuously in bits. The former requires a larger memory space, while the latter can further reduce the use of memory.

In a multi-computer switching system, the individual transmission speeds between multiple remote control computers (multi-user mode) and multi-computer switching may vary depending on the network environment, for example, with optical fiber, ADSL modem or dial-up data. There is a significant difference in the transmission speed between the remote control computer and the multi-computer switch connected to the Modem. However, storing the image change block in the foregoing continuous manner, a part of the bit (byte) belongs to the previous change block, and a part of the bit belongs to the latter change block. The situation. Therefore, according to the prior art, when the KVM switch transmits a computer image signal to a plurality of remotely operated computers through the network, it is necessary that the remote control computer with the slowest transmission speed completely receives the image of the entire image frame. After the data is processed, the next image frame can continue to be processed. For a remotely controlled computer user with a faster transmission speed, it is necessary to wait for a remotely controlled computer user with a faster transmission speed, which is quite inconvenient to use.

The present invention proposes an effective solution to the shortcomings of the prior art.

The object of the present invention is to provide a KVM switch and method for transmitting video signals from a computer to a plurality of remote control computers. When transmitting video signals through the network, the receiving speed of the user with a faster transmission speed is subject to the need to accommodate Users with slower transmission speeds increase efficiency and convenience.

The object of the present invention is to provide a computer image signal to a plurality of remote ends. The multi-computer switcher and the method for controlling the computer, when transmitting the image signal through the network, decode the block data of the image signal by means of fast Huffman decoding, thereby improving the transmission speed of the image signal.

The KVM switch of the present invention is coupled to at least one controlled computer, and transmits the image signal from the controlled computer to the first remote control computer and the second remote control computer through the network, and the image signal is continuous image frame. The image frame is divided into a plurality of blocks. The KVM switch of the present invention includes at least an image data processing component, a first user index table, and a second user index table. The image data processing component compares the previous image frame with the current image frame to confirm whether the blocks are changed individually. The first user index table corresponds to the first remote control computer and the blocks. The second user index table corresponds to the second remote control computer and the blocks. The image data processing component respectively adds a plurality of tags to the first user index table and the second user index table according to whether the blocks are changed. The KVM switch of the present invention further includes an image data storage area for storing data of the blocks in the blocks that generate changes.

Then, the first remote control computer and the second remote control computer are simultaneously sent to transmit video signals. After transmitting the data of the changed blocks, the image data processing component changes the marks added to the first user index table and the second user index table. The image data processing component processes the previous image frame and the current image frame in a complete JPEG encoding/compression process before comparing the previous image frame with the current image frame, and then the region is fast Huffman decoding. The data of the block is decoded. Moreover, in the process of encoding/compressing JPEG, after performing the color space conversion step of converting RGB to YCrCb, the Cr/Cb component can be reduced to reduce the amount of data (for example, sampling in a 4:1:1 manner). . The Y component represents the brightness of one pixel, and the Cr/Cb component collectively represents the hue and saturation of a pixel. The KVM switch of the present invention can also process the Y component of the block when the image data processing component is decoded according to the instruction of the specific remote control computer user, and only transmit the image signal to the specific remote control computer. Grayscale data.

Please refer to FIG. 1 , which is a simplified diagram of a multi-computer switch connected to one or more controlled computers according to the present invention and connected to a plurality of remote control computers via a network. The KVM switch 10 of the present invention has an image data processing component 20, a network interface 25, a computer interface 26 and an image data storage area 30, and is connected to a local end manipulation device 40. A plurality of remote control computers 110, 120, 130 can connect to the KVM switch 10 via the network 50. For example, users A, B, and C operate the remote control computers 110, 120, and 130, respectively. The remote control computers 110 and 130 are respectively connected to the network 50 through the ADSL modems 111 and 131, and the remote control computer 120 is connected to the network 50 through a dial-up modem (Modem). Therefore, the user B or the remote control computer 120 is a user whose image receiving speed (download speed) is slow.

The KVM switch 10 of the present invention is simultaneously connected to the controlled computers 210, 220, 230, 240 via the computer interface 26. This computer interface can include an image port (such as a DB15 connector) and a keyboard/mouse port (such as a PS/2 or USB connector). Through the path arrangement between the central processing unit 27 and the switching unit 28 of the KVM switch 10, the controlled computers 210, 220, 230, 240 can be controlled by the local side operating computer 40 or the remote control computer 110, 120, 130. The KVM switch 10 transmits video signals to the remote control computer 110, 120, 130 through a network interface 25 and the network 50. The network interface may include a Network Interface Chip and an RJ-45 connector. When the users A, B, and C are both connected to the controlled computer 210 (the same image source in the multi-user mode), the KVM switch 10 can simultaneously transmit the image signal of the computer 210 to the plurality of remote control computers 110, 120, 130. On the other hand, the keyboard/mouse signal of the remote control computer 110, 120, 130 can also be transmitted to the controlled computer 210, 220, 230, 240 via the network 50 and the KVM switch 10 to enable the remote control computer 110. 120, 130 can control the controlled computers 210, 220, 230, 240, respectively.

Referring to FIG. 2, after the image data processing component of the present invention compares successive image frames of the image signal, the computer switcher 10 of FIG. 1 generates a corresponding correspondence for the plurality of remote control computers 110, 120, and 130. Schematic diagram of the steps of the user index tables A, B and C (in other words, the number of index tables and the number of users the same). As described above, for example, the video signal from the computer 210 is composed of continuous video frames (first, second, third video frames, etc.) as shown in the second figure in the time axis direction. After the image signal is converted into digital data, the integrated image processing chip can be used, for example, an application specific integrated circuit (ASIC) chip or a field programmable gate array (FPGA) chip to process image data compression, decoding, encoding, and the like. Decompress to improve system performance and reduce system cost, such as JPEG encoding/compression. The compressed HUFFMAN decoding method is used to decode the compressed image data. The reason why the fast HUFFMAN decoding is performed at the transmitting end (that is, the KVM switch 10) is because the original image frame may generate some empty bits after JPEG encoding/compression (in which the HUFFMAN is encoded as the last step). Yuan (that is, the total number of bits in each block will be less or different), and the transmitting end is stored and transmitted as a continuous bit, so that the receiving end (ie, the console computer) can be correct and The image data is quickly received, so the fast HUFFMAN decoding is first used to restore the complete number of bits, so that the receiving end can correctly determine which block the received image data belongs to.

As shown in FIG. 2, in step 500, the first, second, and third image frames are each divided into a plurality of blocks. In the case of an image signal having a resolution of 1024x768, one block can be a 16x16 dot matrix, and an image frame is divided into 3072 blocks. In general, all image change blocks can be continuously stored in the form of bits to further reduce the space of the image data storage area 30 required for image data processing. In step 510, the image data processing component 20 compares the previous (first) image frame obtained at the first time with the current (second) image frame obtained at the second time to confirm each block. Whether there is a change. In step 520, if the block indicating the black dot is displayed as shown in the figure, the image change is generated, and then the image data storage area 30 stores the data of the changed block (which is encoded by JPEG). In step 530, the plurality of computer switches 10 as shown in the first figure are respectively connected to the computer 210, and the remote control computers 110, 120, 130 that are receiving the image data of the computer 210 are prepared for the user index tables A, B, C and raise the mark corresponding to the change block. It should be noted that the present invention decodes and compresses image data by using fast HUFFMAN decoding on the transmitting end. because The data of the blocks in which the changes are stored are all data that are not completely decoded. Then, after the image signal is transmitted, the user index tables A, B, and C are updated.

Please refer to FIG. 3, which is an explanatory diagram of the user index table A, B, and C corresponding to the remote control computer 110, 120, 130 according to the present invention, with respect to the change of the block partition and the content of the mark. The user index tables A, B, and C respectively correspond to the above-mentioned divided 3072 blocks, and respectively have corresponding 3072 fields for marking when the image changes of the blocks are generated. As shown in the figure, a flag is indicated by a change of 1 representing a block change. Please refer to Figure 1, Figure 2, Figure 3 and Figure 4 together. Fig. 4 is an explanatory diagram of the user index table A corresponding to the image data storage area 30 of the present invention. The image data storage area 30 stores data of the changed blocks in the 3072 blocks. The image data processing component 20 thus marks the user index table A (also the user index tables B, C). In a preferred embodiment, 1 in the index table represents a change in some of the blocks of the two consecutive images, 0 means that the block data has not changed or the block data has been transmitted.

When there is a change in the block in the image frame in step 510, the image data storage area 30 in step 520 stores the data of the block that produces the change. The image data processing component 20 thus instructs the user index tables A, B, and C to mark the corresponding change blocks. Then, the remote control computer 110, 120, 130 is simultaneously transmitted with the video signal (that is, the block data in the image frame). After transmitting the data of the changed blocks, in step 530, the image data processing component 20 changes the marks added to the user index tables A, B, and C, and changes from 1 to 0.

Since the image data processing component 20 processes the transmission of the image data in units of image data blocks, in the case shown in FIG. 1, the remote control computers 110 and 130 are respectively connected through the ADSL modems 111 and 131. The network 50 has a faster receiving speed, and the remote control computer 120 is connected to the network 50 through a dial-up modem (Modem), and the receiving speed is slow. However, according to the present invention, the remote control computer 120 does not receive a slower speed, and the remote control computer 120 (user B), which has a slower reception speed, is required to operate the computer at the remote end as in the prior art. 120 After receiving all the data of an image frame, the KVM switch can transmit the data of the next image frame, so that the end of the faster receiving computer 110, 130 (users A, C) need to cooperate with the receiving speed. The slow remote controls the computer 120. In the KVM switch 10 of the present invention, since the user index tables A, B, and C are individually provided for the remote control computers 110, 120, 130, when the image data processing component 20 is sent according to the user index tables A, C, After the image data is sent to the remote control computer 110, 130, the image data storage area 30 and the user index tables A, B, and C are all updated. On the other hand, the remote computer receiving the fast speed (for example, the remote control computer 110) after receiving all the changed block data, although the remote computer receiving the slow speed (for example, the remote control computer 120) has not been completely received. To all of the changed block data, the remote control computer 110 will still notify the image data processing component 20 to continue digital sampling to obtain the next image frame. The image data processing component 20 repeats the steps of sampling, comparison, (encoding) compression, marking blocks, decoding, and transmission (described in more detail later). Therefore, the KVM switch 10 of the present invention can mainly control the remote control computers 110 and 130 with faster receiving speed, thereby improving the overall performance of the system.

It should be noted that the image data storage area 30 stores the data of the changed image blocks in a compressed (for example, JPEG code compression mode) and continuously stored. Moreover, the data of the image block includes the start bit, the length of the block data, and the length of the brightness (Y) data. In the JPEG encoding/compression process, after the color space conversion step of converting RGB to YCrCb, the Cr/Cb component can be reduced to reduce the amount of data. The Y component represents the brightness of one pixel, and the Cr/Cb component collectively represents the hue and saturation of a pixel. In the process of decoding the compressed image data by using the method of fast HUFFMAN decoding, the present invention can process only the Y components of the blocks. For example, when the receiving speed of the remote receiving computer 120 is sent, only the image signal needs to be transmitted. Grayscale data (ie, when black and white images are required), the image data processing component 20 transmits only the Y component to the remote control computer 120 based on the user index table B.

Please refer to FIG. 5, which is a flow chart of a method for transmitting an image signal to a plurality of remote control computers according to the present invention. The invention transmits image signals to a plurality of remote control computers The method includes the following steps: Step 510: Decode data of a plurality of blocks, and compare the previous (first) image frame obtained at the first time with the current (second) image frame obtained at the second time. Confirming whether the blocks are changed individually; in step 520, storing the data of the blocks in the blocks that generate the change; and in step 530, respectively filling the user index tables according to whether the blocks are changed. Step 540: transmitting the data of the changed blocks to the corresponding remote control computers; and step 550, changing the marks added to the user index tables.

Therefore, according to the present invention, when the image signal is transmitted through the network, the receiving speed of the user with a faster transmission speed is taken as the standard, and the user with a slower transmission speed does not need to be accommodated, thereby improving the use efficiency and convenience.

While the invention has been described above in terms of preferred embodiments, it is not intended to limit the invention. Various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

10‧‧‧Multicomputer switcher

20‧‧‧Image data processing components

30‧‧‧Image data storage area

40‧‧‧Local control computer

50‧‧‧Network

110, 120, 130‧‧‧ Remote control computer

111, 131‧‧‧ADSL data machine

121‧‧‧Dial-type data machine

210, 220, 230, 240‧‧‧ controlled computers

500, 510, 520, 530‧ ‧ steps

FIG. 1 is a simplified diagram of a multi-computer switch connected to a plurality of computers connected to a plurality of remote control computers via a network according to the present invention.

FIG. 2 is a schematic diagram showing the steps of generating a corresponding index table for a plurality of remote control computers after the image data processing component of the present invention compares successive image frames of the image signal.

Fig. 3 is an explanatory diagram showing the change of the block division and the content of the mark in the respective corresponding index table of the present invention.

Figure 4 is an explanatory diagram of an image data storage area corresponding to an index table of the present invention.

Figure 5 is a flow chart of a method for transmitting an image signal to a plurality of remotely operated computers according to the present invention.

10‧‧‧Multicomputer switcher

20‧‧‧Image data processing components

25‧‧‧Network interface

26‧‧‧Computer interface

27‧‧‧Central processor

30‧‧‧Image data storage area

40‧‧‧Local control computer

50‧‧‧Network

110, 120, 130‧‧‧ Remote control computer

111, 131‧‧‧ADSL data machine

121‧‧‧Dial-type data machine

210, 220, 230, 240‧‧‧ computers

Claims (39)

A KVM switch is coupled to at least one controlled computer to transmit an image signal from the controlled computer to a plurality of remote control computers through a network, wherein the image signal is composed of continuous image frames, each image frame The system is divided into a plurality of blocks, and the blocks include a plurality of blocks for generating changes. The KVM switch includes at least: an image data processing component, and compares the previous image frame with the current image frame to confirm the Whether the blocks are changed individually or not; and a plurality of user index tables respectively corresponding to the remote control computer and each of the blocks; wherein the image data processing component respectively changes according to whether the blocks are changed The user index table is filled with a plurality of tags; wherein the image data processing unit transmits the changed blocks to the corresponding remote control computers according to the user index tables to which the tags are added The image data processing unit updates the markers added by the user index tables and performs comparison of the remaining image frames. The KVM switch of claim 1, further comprising an image data storage area for storing data of the changed blocks in the blocks. The KVM switch of claim 1, wherein the image data processing component changes the tags added to the user index tables after transmitting the data of the changed blocks. The KVM switch of claim 2, wherein the data of the changed blocks is processed by the image data processing component and compressed and stored in the image data storage area. For example, the KVM switch according to Item 1 of the patent application, wherein The image data processing component is an integrated image processing chip that can compress, decode, encode, and decompress the data of the blocks. The KVM switch of claim 1, wherein the image data processing component decodes the data of the blocks by Huffman decoding before comparing the previous image frame with the current image frame. . The KVM switch of claim 6, wherein the image data processing component performs decoding to process the Y component of the blocks to transmit the grayscale data of the image signal to the remote control computer. The KVM switch of claim 1, wherein the data of the blocks includes a start bit, a block data length, and a brightness (Y) component. The KVM switch of claim 1, wherein the data of the blocks is stored in a continuous storage manner. A KVM switch coupled to a controlled computer for transmitting an image signal from the controlled computer to a first remote control computer and a second remote control computer via a network, wherein the first remote control computer The receiving speed is greater than the receiving speed of the second remote control computer. The image signal is composed of a plurality of consecutive image frames, each image frame is divided into a plurality of blocks, and the blocks include a plurality of generated blocks. The changed block, the KVM switch includes at least: an image data processing component, and compares the previous image frame with the current image frame to confirm whether the blocks are changed respectively; a first user index table corresponds to Controlling the computer and the blocks at the first remote end; and a second user index table corresponding to the second remote control computer and the blocks; wherein the image data processing component is based on the blocks Generating a change, respectively filling the first user index table and the second user index table with a plurality of Marking; wherein the image data processing unit updates the first image after the image data processing unit transmits the changed blocks to the first remote control computer according to the user index table to which the marks are added The user index table and the mark added by the second user index table perform comparison of the remaining image frames. The KVM switch according to claim 10, further comprising an image data storage area for storing data of the changed blocks in the blocks. The KVM switch of claim 10, wherein the first user index table or the second user index table is added after the data of the changed blocks is transmitted. The tag will be changed. The KVM switch of claim 11, wherein the data of the changed blocks is stored in the image data storage area in a compressed manner. The KVM switch of claim 10, wherein the image data processing component is an integrated image processing chip capable of compressing, decoding, encoding, and decompressing the data of the blocks. The KVM switch of claim 10, wherein the image data processing component performs Huffman decoding on the data of the blocks before the previous image frame and the current image frame. decoding. The KVM switch of claim 15, wherein the image data processing component performs decoding to process the Y component of the blocks to control the first remote control computer and the second remote control computer. The gray scale data of the image signal is transmitted. The KVM switch according to claim 10, wherein The data of the blocks includes the start bit, the block data length, and the lightness (Y) component. The KVM switch of claim 10, wherein the data of the blocks is stored in a continuous storage manner. A KVM switch for transmitting an image signal from a controlled computer to a first remote control computer and a second remote control computer through a network, the image signal being composed of a plurality of consecutive image frames, each An image frame is divided into a plurality of blocks, and the first remote control computer receives the image signal faster than the second remote control computer, and the KVM switch controls the first remote end The computer or the second remote control computer keyboard/mouse signal is transmitted to the controlled computer. The KVM switch includes at least: a computer interface coupled to the controlled computer; and a network interface through the network The image signal from the controlled computer is transmitted to the first remote control computer and the second remote control computer; an image data processing component for processing and compressing the image signal; and an image data storage area for storing the image signals a data block of the block in the block; a central processing unit coupled to the computer interface, the network interface, the image data storage area, and controlling the image data processing component; wherein the image resource The material processing component compares the first image frame obtained at the first time with the second image frame obtained at the second time, and confirms whether the blocks respectively change; a first user index table corresponds to Controlling the computer and the blocks at the first remote end; and a second user index table corresponding to the second remote control computer and the blocks; The image data processing component respectively adds a plurality of tags to the first user index table and the second user index table according to whether the blocks are changed. The central processor may determine the flag according to the tags. Whether the data of the blocks has changed or has been transmitted to the first remote control computer or the second remote control computer; wherein when the data of the changed blocks is completely transmitted to the first remote control computer Even if the data of the changed blocks has not been completely transmitted to the second remote control computer, a comparison between the third image frame and the second image frame is performed, and the block with the changed block is performed. The data is stored in the image data storage area. The KVM switch of claim 19, wherein the first user index table or the second user after the data of the changed blocks is transmitted to the first remote control computer These tags added to the index table will be changed. The KVM switch of claim 19, wherein the data of the changed blocks is stored in the image data storage area in a compressed manner. The KVM switch of claim 19, wherein the image data processing component is Huffman-decoded before the first image frame and the second image frame, and the blocks are The data is decoded. The KVM switch of claim 22, wherein the image data processing component performs decoding to process Y components of the blocks to control the first remote control computer and the second remote control computer. The gray scale data of the image signal is transmitted. For example, the KVM switch described in claim 19, wherein The data of the blocks includes the start bit, the block data length, and the lightness (Y) component. The KVM switch of claim 19, wherein the data of the blocks is stored in a continuous storage. A multi-computer switcher transmits a video signal from a controlled computer to a plurality of remotely operated computers through a network. The image signal is composed of a plurality of consecutive image frames, and each image frame is divided into a plurality of blocks. The method at least includes the steps of: comparing a previous image frame with a current image frame to confirm whether the blocks are changed individually; storing data of the blocks in the blocks that generate changes; according to the blocks Whether a change is made to a plurality of user index tables corresponding to the remote control computer and the blocks, and the plurality of tags are added according to the user index tables to which the tags are added; Blocking to the corresponding remote control computers; and updating the markers added by the user index tables and performing comparison of the remaining image frames. The method of claim 26, after the step of adding the markings, further includes the step of transmitting the data of the changed blocks to the corresponding remote control computers. The method of claim 27, wherein the step of comparing the previous image frame with the current image frame is compared to the Y component of the block to transmit the data of the changed block. In the step, the gray scale data of the image signal is transmitted. The method of claim 26, after the step of transmitting the data of the changed blocks, further includes changing the index of the users. The steps of the markings added to the table. The method of claim 26, further comprising the step of decoding the data of the blocks before the step of comparing the previous image frame with the current image frame. The method of claim 30, wherein the step of decoding the data of the blocks is to decode the data of the blocks by means of Huffman decoding. The method of claim 31, wherein the decoding of the blocks is performed by processing the Y components of the blocks to transmit the image signals in the step of transmitting the data of the changed blocks. Grayscale data. The method of claim 26, wherein the information of the blocks includes a start bit, a block data length, and a brightness (Y) component. The method of claim 26, wherein the data of the blocks is stored in a continuous storage. A multi-computer switcher transmits a video signal from a controlled computer to a first remote control computer and a second remote control computer via a network, and the first remote control computer receives the image signal The speed is higher than the second remote control computer. The image signal is composed of a plurality of consecutive image frames, and each image frame is divided into a plurality of blocks. The method includes at least the following steps: (a) providing a first a user index table and a second user index table, the first user index corresponding to the first remote control computer and the blocks, the second user index corresponding to the second remote control computer and the Block (b) comparing the first image frame obtained at the first time with the second image frame obtained at the second time, and confirming whether the blocks are changed individually; (c) at the first The user index table and the second user index table The blocks in the blocks are marked with changes; (d) storing the data of the blocks in the blocks; (e) respectively controlling the computer to the first remote end and the second remote control computer Transmitting the data of the changed blocks; and (f) after step (e), if the data of the changed blocks has been completely transmitted to the first remote control computer, repeating step (b) to Step (e). The method of claim 35, further comprising a step after the step (e): (g), changing the first user index table and the mark added by the second user index table . The method of claim 35, wherein in step (b), the Y component of the block is used to transmit the grayscale data of the image signal in the step (e). The method of claim 35, wherein the information of the blocks includes a start bit, a block data length, and a brightness (Y) component. The method of claim 35, wherein the data of the blocks is stored in a continuous storage.