Protocol conversion circuit and protocol conversion method

Abstract

The present disclosure relates to protocol conversion circuit and protocol conversion method. The present disclosure discloses a protocol conversion circuit and a protocol conversion method. The protocol conversion circuit comprises a DP signal receiver, a control analysis circuit, a downstream transmitter and a picture buffer. The DP signal receiver analyzes a DP signal to obtain video data and packet information. The control analysis circuit determines whether the packet information indicates that a live function or a panel replay (PR) function is started. When the live function is determined to be started, the control analysis circuit controls the picture buffer to store current video data received and transmit the current video data to the downstream transmitter. When the PR function is determined to be started, the control analysis circuit controls the picture buffer to discard the current video data received, or update previous video data stored in the picture buffer with a specified range in the current video data, and transmit the latest video data to the downstream transmitter, so as to output a target signal to a second electronic device.

Description

Technical Field

[0001] This invention relates to a circuit and a method, and more particularly to a protocol conversion circuit and a protocol conversion method. Background Technology

[0002] The existing DisplayPort (DP) standard declares a feature called Panel Replay, which allows the DP sink to operate in two different modes. One is a live mode that plays the video data provided by the current video source in real time, and the other is a panel replay (PR) mode that plays the video data stored in an internal buffer.

[0003] While this technology can effectively save power in specific situations, it is limited to the DP-related product ecosystem, and other products cannot enjoy the advantages offered by this feature. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a protocol conversion circuit and protocol conversion method to address the shortcomings of the prior art, which can extend the Panel Replay function to products beyond the DP specification.

[0005] To address the aforementioned technical problems, one technical solution adopted by this invention is to provide a protocol conversion circuit, including a DisplayPort (DP) signal receiver, a control and analysis circuit, a downstream transmitter, and a screen buffer. The DP signal receiver receives DP signals from a first electronic device and is configured to parse the DP signals to obtain video data and packet information. The control and analysis circuit is configured to determine whether the packet information indicates the activation of a live streaming function or a panel replay (PR) function. The downstream transmitter is connected to a second electronic device. The screen buffer receives video data. In response to determining that the live streaming function is activated, the control and analysis circuit executes a preset live streaming program to control the screen buffer to store the received current video data and simultaneously transmit the current video data to the downstream transmitter. In response to the determination that the PR function is activated, the control analysis circuit is configured to execute a preset PR program, including: controlling the screen buffer to discard the received current video data, or updating the previous video data stored in the screen buffer with content within a specified range of the current video data; and controlling the screen buffer to transmit the latest stored video data to the downstream transmitter. Specifically, when the live streaming function is enabled, the downstream transmitter converts the current video data from the screen buffer into a target signal in the target format and outputs it to the second electronic device; while when the PR function is enabled, the downstream transmitter converts the latest video data from the screen buffer into a target signal in the target format and outputs it to the second electronic device.

[0006] To address the aforementioned technical problems, another technical solution adopted by the present invention is to provide a protocol conversion method, comprising: configuring a DP signal receiver to receive a DP signal from a first electronic device and parsing the DP signal to obtain video data and packet information; configuring a screen buffer to receive video data; configuring a control analysis circuit to perform the following steps: determining whether the packet information indicates the activation of a live streaming function or a PR function; in response to determining that the live streaming function is activated, executing a preset live streaming program to control the screen buffer to store the received current video data and simultaneously transmit the current video data to a downstream transmitter; in response to determining that the PR function is activated, executing a preset PR program, including: controlling the screen buffer to discard the received current video data, or updating the previously stored video data in the screen buffer with content within a specified range of the current video data; and controlling the screen buffer to transmit the latest stored video data to the downstream transmitter; configuring the downstream transmitter to convert the current video data into a target signal of a target format and output it to a second electronic device when the live streaming function is activated, and to convert the latest video data from the screen buffer into a target signal of a target format and output it to the second electronic device when the PR function is activated.

[0007] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0008] Figure 1 This is a functional block diagram of the protocol conversion circuit according to an embodiment of the present invention.

[0009] Figure 2 This is a flowchart of the control flow of the control analysis circuit in an embodiment of the present invention.

[0010] Figure 3 This is another flowchart of the control flow of the control analysis circuit in an embodiment of the present invention. Detailed Implementation

[0011] The following specific embodiments illustrate the implementation of the "protocol conversion circuit and protocol conversion method" disclosed in this invention. Those skilled in the art can understand the advantages and effects of this invention from the content disclosed in this specification. This invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of this invention. Furthermore, the accompanying drawings of this invention are for simple illustrative purposes only and are not depictions of actual dimensions, as stated in advance. The following embodiments will further describe the relevant technical content of this invention in detail, but the disclosed content is not intended to limit the scope of protection of this invention. In addition, the term "or" used herein may, depending on the actual situation, include any combination of any one or more of the associated listed items.

[0012] Figure 1 This is a functional block diagram of the protocol conversion circuit according to an embodiment of the present invention. (See attached diagram.) Figure 1 As shown, this embodiment of the invention provides a protocol conversion circuit 100, which may include a DisplayPort (DP) signal receiver 1, a control analysis circuit 2, a screen buffer 3, a downstream transmitter 4, and a stagnation pattern generator 5, each of which can be implemented by a processing circuit including a processor and memory. The protocol conversion circuit 100 is electrically connected between a first electronic device 200 and a second electronic device 300. The first electronic device 200 may be, for example, a general-purpose computer that supports the DP standard, while the second electronic device 300 may be, for example, a display that does not support the DP standard, such as a display that only supports HDMI / VGA standards. Therefore, the protocol conversion circuit 100 is needed to convert the signal format.

[0013] The DP signal receiver 1 can receive the DP signal S1 from the first electronic device 200 and is configured to parse the DP signal S1 to obtain video data and packet information. Specifically, the first electronic device 200 is a source device, and the DP signal receiver 1 can be used to receive the DP signal S1 transmitted from the first electronic device 200. In some embodiments, the DP signal receiver 1 may include an 8 / 10b decoder conforming to the DP1.4 specification and a 128 / 132b decoder conforming to the DP2.0 specification. Furthermore, in addition to transmitting video in the Single Stream Transport (SST) mode typically supported by DP source devices, the DP signal receiver 1 can also support Multi Stream Transport (MST) applications.

[0014] Using the aforementioned decoder, the DP signal receiver 1 can parse the received DP signal S1 to obtain video data and packet information. The video data is transmitted to the picture buffer 3, and the packet information is transmitted to the control analysis circuit 2 for subsequent logical judgment processing. The packet information may be, for example, a Video Stream Configuration Secondary Data Packet (VSC SDP) located in the Blanking area of ​​the DP signal S1, but the invention is not limited to this.

[0015] It should be noted that packet information can be used to indicate whether the first electronic device 200 is operating in live mode or panel replay (PR) mode. For example, the source device (such as the first electronic device 200) can be indicated through the PR_STATE and Update_RFB fields of the VSC SDP.

[0016] According to the DP specification, in live streaming mode, the receiving device not only plays the video data sent by the source device through the panel, but also stores the video data of each frame in a buffer (which can be determined by the source device). This allows the video data previously stored in the buffer to be played when the source device switches to PR mode.

[0017] More specifically, PR mode can be divided into two replay modes: Entire Frame Replay and Selective Update. The former means the receiving device will perform panel replay for the entire frame. The latter means the source device instructs the receiving device to live stream within a specified area of ​​the frame, while the remaining areas continue to play existing frames stored in the buffer. This achieves the benefits of partial updates. Furthermore, in selective updates, the specified area to be updated within each frame is not limited to a single region. For example, frame buffer 3 can receive video data from multiple areas specified by the source device for selective updates and dynamically update and push the video to each frame accordingly.

[0018] More specifically, during selective updates, the DP signal receiver 1 synchronously updates the corresponding range in the buffer with the video data received within the specified range, and the content ultimately displayed in that range can be, for example, directly the image transmitted by the source device. Therefore, a primary objective of this invention is to extend the aforementioned live streaming function and the two panel replay functions to non-DP specification products.

[0019] It should be noted that, in order for the source device to know that the protocol conversion circuit 1 supports Panel Replay related functions, when the DP signal receiver 1 is electrically connected to the first electronic device 200, the DP signal receiver 1 and the first electronic device 200 will execute a first handshake procedure to inform the first electronic device 200 that the protocol conversion circuit 100 supports the PR function under the DP specification. Only after the first electronic device 200 knows that the protocol conversion circuit 100 supports the PR function will it include a packet indicating whether to enable the live streaming function or the PR function in the DP signal S1.

[0020] In other words, before transmitting the DP signal S1 containing valid information such as video and audio data, the source device (first electronic device 200) can access the DisplayPort configuration data (DPConfiguration Data, DPCD) of the DP signal receiver 1 via, for example, the AUX pin, to exchange messages before transmitting the signal. This message exchange may include handshake procedures related to the PanelReplay function and DP link training procedures, and is basically in accordance with the DP specification, so it will not be described in detail here.

[0021] Please refer to the following: Figure 1 The control and analysis circuit 2 can be electrically connected to the DP signal receiver 1, the image buffer 3, and the downstream transmitter 4.

[0022] To enable the smooth expansion of the PR function, a screen buffer 3 is set up on the video data transmission path. This buffer can store or update the entire frame or a specific area of ​​the input video data. The screen buffer 3 can be implemented using any memory or storage unit, such as DDR or SRAM. The behavior of the screen buffer 3 is controlled by the control and analysis circuit 2 to determine the content to be output to the downstream transmitter 4, or to update the stored video data therein with the received video data.

[0023] For clarity, the following description will focus on downstream transmitter 4. Downstream transmitter 4 is connected to the second electronic device 300 and is primarily used to transmit video signals from various output interfaces (e.g., HDMI, VGA, etc.) and packet information containing audio data and other auxiliary information to the downstream device (i.e., the second electronic device 300). Downstream transmitter 4 obtains the video data to be transmitted from the screen buffer 3 or the déjà vu generator mentioned below. It should be noted that although... Figure 1 Only one downstream transmitter 4 is shown in the diagram, but the number of downstream transmitters 4 can be determined according to the number of downstream devices to be connected by the protocol conversion circuit 100. Therefore, the number of output ports of the protocol conversion circuit 100 can be one or more, and the number of downstream transmitters 4 corresponds to the number of output ports, which can also be one or more.

[0024] When the downstream transmitter 4 is connected to the second electronic device 300, the downstream transmitter 4 and the second electronic device 300 will execute a second handshake procedure to obtain device information related to the second electronic device 300, such as device type, manufacturer, supported resolution and supported capabilities.

[0025] For example, the downstream transmitter 4 also includes a PR capability analyzer 40, which is configured to acquire extended display identification data (EDID) and status and control data channel (SCDC) data of the second electronic device 300 during the second handshake procedure.

[0026] Therefore, the packet information (e.g., VSC SDP information) parsed by the DP signal receiver 1 and the device information analyzed by the PR capability analyzer 40 are further input into the control analysis circuit 2 for analysis to determine the arbitration instruction corresponding to the live broadcast function or the RP function. The arbitration instruction can be used to control the screen buffer 3 and the stagnation pattern generator 5 mentioned below.

[0027] It should be noted that the present invention also provides a protocol conversion method, which can be applied to the protocol conversion circuit 100 mentioned in the foregoing embodiments. For clarity, the details already described above will not be repeated here, and the following will focus on the process in which the control analysis circuit 2 participates in the protocol conversion method. Figure 2 This is a flowchart of the control flow of the control analysis circuit 2 in an embodiment of the present invention.

[0028] like Figure 2 As shown, the control flow includes configuring the control analysis circuit 2 to perform the following steps:

[0029] Step S20: Determine if the packet information indicates that the live function or panel replay (PR) function should be started.

[0030] In response to the determination that the live streaming function is activated in step S20, the control flow proceeds to step S21: executing a preset live streaming program to control the screen buffer to store the received current video data and simultaneously transmit the current video data to the downstream transmitter. The stored current video data will transform into previous video data over time, thus providing previous footage for the PR function's replay mechanism.

[0031] In response to the determination that the PR function is activated in step S20, the control flow proceeds to step S22: execute the preset PR program.

[0032] like Figure 2 As shown, the default PR procedure includes the following steps:

[0033] Step S220: Determine whether the activated PR function is full-screen replay or selective update.

[0034] In response to the determination that the activated PR function is full-screen replay, step S221 is entered: control the screen buffer to discard the received current video data.

[0035] In response to the determination that the initiated PR function is a selective update, step S222 is entered: the control screen buffer updates the previous video data stored in the screen buffer with content within a specified range of the current video data. In a selective update, the source device (first electronic device 200) may, for example, use the coordinate indicator field in the VSC SDP to frame a specific live and replay range from the screen.

[0036] After completing step S221 or step S222, the control flow proceeds to step S223: the control screen buffer transmits the latest stored video data to the downstream transmitter.

[0037] In other words, if the PR function is set to full-screen replay, the previous video data (or its corresponding previous frame) stored in the video buffer 3 will be used as the latest stored video data. If the PR function is set to selective update, the video data of the live area that has already been updated will be used as the latest stored video data. Furthermore, in this case, the video buffer 3 will discard the currently received video data.

[0038] Therefore, when the live streaming function is enabled, the downstream transmitter 4 can convert the current video data from the video buffer 3 into a target signal S2 in the target format and output it to the second electronic device 300. When the PR function is enabled, the downstream transmitter 4 converts the latest video data from the video buffer 3 into a target signal S2 in the target format and outputs it to the second electronic device 300.

[0039] Therefore, by executing the control flow, the PR function can be extended to the non-DP specification second electronic device 300. That is, when the DP specification source device (first electronic device 200) is connected to the non-DP specification second electronic device 300 through the protocol conversion circuit 100 of the present invention, the PR function can still be used to achieve the advantages of power saving or flexible use.

[0040] On the other hand, the protocol conversion circuit 100 of the present invention also incorporates different signal transmission mechanisms designed for specific types of devices. For example, the downstream transmitter 4 can determine whether the second electronic device 300 is a specific type of device based on device information from the second electronic device 300. More precisely, the PR capability analyzer 40 can be configured to determine whether the second electronic device 300 is a specific type of device based on EDID and / or SCDC data during the second handshake process.

[0041] In response to the PR capability analyzer 40 determining that the second electronic device 300 is not a specific type of device, the configuration control analysis circuit 2 executes... Figure 2 The control process.

[0042] Please refer to Figure 3 , Figure 3 This is another flowchart of the control flow of the control analysis circuit 2 according to an embodiment of the present invention. In response to the PR capability analyzer 40 determining that the second electronic device 300 is a specific type of device, the control analysis circuit 2 is configured to execute... Figure 3 The control flow. It should be noted that when the second electronic device 300 is a specific type of device, it is a non-DP specification electronic device and has another built-in screen buffer, which can be used to implement the PR function.

[0043] Figure 3 The control process includes the following steps:

[0044] Step S30: Determine if the packet information indicates that the live streaming function or PR function should be started.

[0045] In response to the determination that the live streaming function is activated in step S30, the control flow proceeds to step S31: executing a specific live streaming program to control the screen buffer to directly transmit the received current video data to the downstream transmitter. Unlike the previous embodiment, in this step, the screen buffer 4 may not store the current video data; that is, it does not need to provide the previous video for the PR function's replay mechanism.

[0046] In response to the determination that the PR function is activated in step S20, the control flow proceeds to step S32: execute a specific PR program.

[0047] Please refer to the following: Figure 1 The protocol conversion circuit 100 also includes a stagnation pattern generator 5. The stagnation pattern generator 5 generates stagnation video data with a stagnation pattern based on the horizontal and vertical resolution information provided by the DP source device (first electronic device 200) and transmits it to the downstream transmitter 4. Whether or not to output the stagnation pattern depends on the arbitration result generated by the control analysis circuit 2.

[0048] like Figure 3 As shown, a specific PR procedure includes the following steps:

[0049] Step S320: Determine whether the activated PR function is full-screen replay or selective update.

[0050] In response to the determination in step S320 that the activated PR function is full-screen replay, the process proceeds to step S321: the control screen buffer discards the received current video data, the control stag pattern generator 5 generates stag video data with stag pattern, and the control downstream transmitter 4 generates a custom packet instructing the second electronic device 300 to enter the full-screen replay mode.

[0051] Please refer to the following: Figure 1 In response to the determination in step S320 that the activated PR function is selective update, the process proceeds to step S322: The previous video data stored in the screen buffer is updated with content within a specified range of the current video data; the screen buffer is controlled to transmit the latest stored video data to the downstream transmitter; and the stagnation pattern generator is controlled to generate stagnation video data with a stagnation pattern corresponding to the specified range for transmission to the downstream transmitter. That is, in Figure 3 In the selective update, the source device (first electronic device 200) can first use the coordinate indicator field in VSC SDP to frame a specific live range and replay range from the screen. The replay range is filled with a stationary pattern, while the live range is updated with the content within the specified range in the current video data.

[0052] After step S322 is completed, the downstream transmitter 4 obtains the video data to be transmitted from the image buffer 3 and the stagnation pattern generator 5, converts it into a target signal S2 in the target format, and outputs it to the second electronic device 300. Simultaneously, the downstream transmitter 4 is also controlled by the control analysis circuit 2 to generate a custom packet instructing the second electronic device 300 to enter selective update mode. Therefore, when only stagnation video data with a stagnation pattern is transmitted, the overall power consumption of the protocol conversion circuit 100 can be reduced. In some embodiments, the stagnation pattern can be implemented in ways other than transmitting video data. For example, the stagnation pattern generator 5 can generate a minimum power consumption signal capable of maintaining the physical channel, which is a digital signal capable of maintaining the link between the transmitter and receiver. The second electronic device 300 can generate a video signal itself upon receiving this minimum power consumption signal.

[0053] When the second electronic device 300 receives a custom packet indicating entry into full-screen playback mode, it can output the previous image stored in its built-in other image buffer. When the second electronic device 300 receives a custom packet indicating entry into selective update mode, it can update the previous image stored in its built-in other image buffer with video data from the area outside the stagnant pattern in the target signal S2, and display the updated video data. It should be noted that the aforementioned custom packet can be, for example, a Sony / Philips Digital Interconnect Format (S / PDIF) or an HDMI Vendor Specific InfoFrame (VSIF) packet, thereby allowing the downstream transmitter 4 to instruct the required operating mode for a specific type of device, achieving a PR function similar to DP.

[0054] In other embodiments, for certain types of devices with specific interfaces, the LFPS mechanism can be used to prevent downstream transmitter 4 from transmitting video signals during the time interval when the pausing pattern generator 5 generates pausing video data while the PR function is in full-screen replay mode. Therefore, for these specific types of devices, the relevant circuitry at their video receiver can be in a sleep state. When the downstream transmitter 4 needs to send valid video content (i.e., when the source device indicates the start of live streaming mode or the PR function switches to selective update), the downstream transmitter 4 can be controlled to transmit the LFPS wake-up signal in advance, thereby waking up the relevant circuitry at the video receiver of the specific type of device. This allows the protocol conversion circuitry and the specific type of device to operate in a more power-efficient manner.

[0055] [Beneficial Effects of the Examples]

[0056] One of the advantages of this invention is that, in the protocol conversion circuit and protocol conversion method provided by this invention, the PR function can be extended to a second electronic device that is not DP specification. This allows a DP specification source device to still use the PR function when connected to a non-DP specification electronic device through the protocol conversion circuit of this invention, thereby achieving the advantages of power saving or flexible use.

[0057] Furthermore, the protocol conversion circuit and protocol conversion method provided by this invention are designed with different video data transmission processes for specific types of devices. In live broadcast mode and full-screen replay mode, there is no need to store video data, and in selective update mode, only video data within the live broadcast range is stored. In addition to saving the power required for the overall protocol conversion circuit, it also allows specific types of devices to operate in a more energy-efficient manner.

[0058] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention specification and drawings are included in the scope of the patent application of the present invention.

[0059] [Symbol Explanation]

[0060] Protocol conversion circuit: 100

[0061] DP signal receiver: 1

[0062] Control and analysis circuit: 2

[0063] Screen buffer: 3

[0064] Downstream transmitters: 4

[0065] Stasis Pattern Generator: 5

[0066] First electronic device: 200

[0067] Second electronic device: 300 DP signal: S1 Target signal: S2

Claims

1. A protocol conversion circuit, comprising: A display port DP signal receiver receives a DP signal from a first electronic device that supports the DP specification. The DP signal includes both video data and packet information. The DP signal receiver is configured to parse the DP signal to obtain the video data and packet information. A control analysis circuit is configured to determine whether the packet information indicates the activation of a live streaming function or a panel replay (PR) function, thereby determining whether to activate the live streaming function or the PR function based on the packet information in the DP signal from the first electronic device. A downstream transmitter is connected to a second electronic device that does not support the DP specification; as well as A video buffer receives the video data. In response to determining that the live streaming function has been activated, the control analysis circuit executes a preset live streaming program to control the video buffer to store the received current video data and transmit the current video data to the downstream transmitter. In response to the determination that the PR function is activated, the control analysis circuit is configured to execute a preset PR program, including: Control the screen buffer to discard the received current video data, or update the previously stored video data in the screen buffer with content within a specified range of the current video data; and The control unit transmits the latest stored video data to the downstream transmitter. When the live streaming function is enabled, the downstream transmitter converts the current video data from the video buffer into a target signal in a target format and outputs it to the second electronic device. When the PR function is enabled, the downstream transmitter converts the latest video data from the video buffer into the target signal in the target format and outputs it to the second electronic device. Thus, the second electronic device extends the PR function to non-DP standard second electronic devices based on the packet information indicating whether to activate the live streaming function or the PR function and the corresponding video data from the downstream transmitter.

2. The protocol conversion circuit according to claim 1, wherein, When the DP signal receiver is connected to the first electronic device, the DP signal receiver and the first electronic device perform a first handshake procedure to inform the first electronic device that it supports the PR function under the DP specification.

3. The protocol conversion circuit as described in claim 1, wherein, When the downstream transmitter is connected to the second electronic device, the downstream transmitter and the second electronic device perform a second handshake procedure to determine whether the second electronic device is a specific type of device based on device information from the second electronic device.

4. The protocol conversion circuit as described in claim 3, wherein, In response to determining that the second electronic device is the specific type of device and that the live streaming function is activated, the control analysis circuit executes a specific live streaming program to control the screen buffer to directly transmit the current video data to the downstream transmitter without storing the received current video data.

5. The protocol conversion circuit as described in claim 3 further includes a stagnation pattern generator, wherein, In response to determining that the second electronic device is of the specific type and that the PR function is activated, the control analysis circuit executes a specific PR program, including: The system controls the screen buffer to discard the received current video data and controls the stasis pattern generator to generate stasis video data with a stasis pattern; or The previous video data stored in the screen buffer is updated with the content within a specified range of the current video data. The screen buffer is controlled to transmit the latest stored video data to the downstream transmitter. The stagnation pattern generator is also controlled to generate stagnation video data with a stagnation pattern for transmission to the downstream transmitter.

6. The protocol conversion circuit as described in claim 5, wherein, The downstream transmitter obtains the video data to be transmitted from one or more of the image buffer and the stagnation pattern generator, converts it into the target signal in the target format, and outputs it to the second electronic device.

7. The protocol conversion circuit as described in claim 5, wherein, The stagnation pattern generator also generates stagnation video data with the stagnation pattern based on the horizontal and vertical information provided by the first electronic device, or generates a minimum power consumption signal.

8. The protocol conversion circuit as described in claim 3, wherein, In response to determining that the second electronic device is the specific type of device, the downstream transmitter sends a custom packet when the live streaming function or the PR function is enabled to inform the second electronic device that it needs to operate the live streaming function or the PR function.

9. The protocol conversion circuit as described in claim 3, wherein, The downstream transmitter also includes a PR capability analyzer configured to determine, in the second handshake process, whether the second electronic device is the specific type of device based on the Extended Display Capability Identification Data (EDID) and / or Status and Control Data Channel (SCDC) data of the second electronic device.

10. A protocol conversion method, comprising: Configure a display port DP signal receiver to receive a DP signal from a first electronic device that supports the DP specification. The DP signal includes both video data and packet information. Parse the DP signal to obtain the video data and packet information. Configure a video buffer to receive the video data; Configure a control analysis circuit to perform the following steps: The packet information indicates whether to start a live streaming function or a panel replay PR function, and thus the packet information in the DP signal from the first electronic device determines whether to start a live streaming function or a PR function. In response to the determination that the live streaming function has been activated, a preset live streaming program is executed to control the screen buffer to store the received current video data and transmit the current video data to the downstream transmitter. and In response to the determination that the PR function is activated, a preset PR procedure is executed, including: Control the screen buffer to discard the received current video data, or update the previous video data stored in the screen buffer with content within a specified range of the current video data; and The control unit transmits the latest stored video data from the video buffer to the downstream transmitter; and The downstream transmitter is configured to convert the current video data into a target signal in a target format and output it to the second electronic device when the live streaming function is enabled, and to convert the latest video data from the picture buffer into the target signal in the target format and output it to the second electronic device when the PR function is enabled. Thus, the second electronic device extends the PR function to the non-DP specification second electronic device according to the packet information indicating whether to start the live streaming function or the PR function and the corresponding video data from the downstream transmitter.

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