Cross-screen bullet screen synchronization method and system

Abstract

The invention discloses a cross-screen bullet screen synchronization method and system, and mainly relates to the technical field of smart televisions and interactive media. The method comprises the following steps: establishing binding between a small-screen terminal and an IPTV terminal; the time offset of the two is calibrated through a bidirectional timestamp synchronization mechanism; the small screen end inputs and sends a bullet screen to the IPTV message base; the base obtains a program identifier currently played at the television end and an accurate playing time point in real time; binding the bullet screen with the progress information and then submitting the bullet screen and the progress information to a back end for storage; and when any terminal plays the program, searching and displaying the corresponding bullet screen according to the current playing time point. The system comprises a small screen terminal, an IPTV terminal, a message base module and a back-end service which are used for executing the steps. The method has the advantages that the core problem that the bullet screen time sequence is disordered due to the fact that the small screen end cannot sense the large screen playing progress is solved, and high-precision synchronization of the cross-screen bullet screens is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of intelligent television and interactive media technology, and particularly relates to a cross-screen bullet screen synchronization method and system based on dynamic binding of program progress of a network television message base. BACKGROUND

[0002] With the development of IPTV services, users' demand for interactive experience is increasing, and bullet screen, as a real-time comment and social interaction form, has been widely used in video websites. However, in the IPTV environment, since large-screen terminals (such as set-top boxes and smart televisions) usually do not have convenient text input capabilities, users cannot directly send bullet screens on the large screen.

[0003] In the prior art, there are solutions that use a mobile phone App or a small program as a small-screen input terminal to send bullet screen messages to a server, and then push the bullet screen messages to an IPTV terminal for display. For example, some patents (such as CN107666624B and CN105933748A) propose an architecture that receives bullet screens through an instant messaging platform and forwards the bullet screens to an IPTV system. However, these solutions generally have a key problem: the small-screen terminal cannot obtain the accurate playing progress of the program on the large screen. Therefore, when the bullet screen message is sent, the system cannot accurately bind the bullet screen message to a specific time point (such as "00:12:35") in the program. This leads to serious deviations in the following scenarios: 1. Live broadcast scenario: multiple users send bullet screens at different times, but since there is no unified time reference, the timing of displaying the bullet screens does not match the program content; 2. On-demand / replay scenario: when a user replays a program, the system cannot accurately restore the historical bullet screens according to the original program timeline, which seriously affects the viewing experience.

[0004] Although some solutions mention "associating bullet screens with program timestamps", they do not explicitly explain the source mechanism of the timestamps, especially the core problem of "lack of progress awareness on the small screen".

[0005] Therefore, there is an urgent need for a cross-screen bullet screen synchronization method and system based on dynamic binding of program progress of a network television message base to solve the above problems. SUMMARY

[0006] The present application aims to provide a cross-screen bullet screen synchronization method and system based on dynamic binding of program progress of a network television message base, which solves the core problem of bullet screen timing disorder caused by the small-screen terminal's inability to perceive the playing progress of the large screen, and achieves high-precision synchronization of cross-screen bullet screens.

[0007] To achieve the above-mentioned purpose, the present application realizes the following technical solutions: On the one hand, the present application provides a cross-screen bullet screen synchronization method, comprising the following steps: Establish a binding relationship between the small-screen terminal and the IPTV TV terminal; To synchronize the time between the small-screen terminal and the IPTV TV terminal, and to calibrate the timing device offset between the small-screen terminal and the IPTV TV terminal; The system receives user-inputted bullet comments via a small-screen terminal and sends them to the IPTV messaging dock deployed on the IPTV TV. Upon receiving the bullet screen content, the IPTV message dock retrieves the playback progress information of the program currently playing on the IPTV TV; the playback progress information includes, but is not limited to, the program identifier and the current playback time. The bullet screen content is bound to the obtained playback progress information to generate bound bullet screen data; The bound bullet screen data is sent to the backend server for storage, and indexed by the program identifier and playback time. When any terminal plays the program, it requests and retrieves the bound bullet screen data within the corresponding time range from the backend server based on the current playback time and displays it.

[0008] Preferably, establishing the binding relationship between the small-screen terminal and the IPTV television terminal includes: Display a binding QR code containing device identification and session information on the IPTV television; The device identifier and session information can be obtained by scanning the binding QR code on a small screen terminal; Send the device identifier, session information, and user account associated with the small screen terminal to the IPTV message base server for verification; After successful verification, the user account is linked to the IPTV television device.

[0009] Preferably, the time synchronization between the small-screen terminal and the IPTV television terminal specifically includes: The small-screen terminal and the IPTV messaging base server perform several bidirectional timestamp exchange processes, each of which includes: The master device sends a message carrying the first timestamp to the slave device. Synchronous messages; The secondary device records a local second timestamp when it receives a synchronization message. It then immediately sends a response message to the master device, the response message carrying a second timestamp. and third timestamp The third timestamp The local time when the secondary device sends the response message; The master device records a local fourth timestamp when it receives the response message. ; Calculate the estimated value of a single clock offset based on the timestamp obtained in each bidirectional timestamp exchange process. , is represented as: ,in, The sequence number of the swaps; Outlier removal and averaging are performed on several single clock offset estimates obtained from several calculations to obtain the final clock offset. ; Based on the final clock offset It corrects the local time of the small-screen terminal to align with the playback progress time reference of the IPTV TV terminal.

[0010] Preferably, the time synchronization between the small-screen terminal and the IPTV television terminal further includes adaptive calibration cycle adjustment: Set the initial calibration cycle; Record recent The standard deviation of the clock offset obtained from the second calibration ; like Greater than the first threshold This shortens the calibration cycle; If the absolute value of the difference between clock offsets obtained from several consecutive adjacent calibrations is less than the second threshold If so, the calibration cycle will be extended; The calibration cycle is adjusted within the preset upper and lower limit ranges; Based on the adjusted calibration period, the bidirectional timestamp exchange process is periodically repeated to update the clock offset. .

[0011] Preferably, in response to receiving the bullet screen content, the IPTV message base obtains the playback progress information of the program currently being played on the IPTV TV terminal, specifically as follows: The IPTV message dock calls the application programming interface of the local player on the IPTV TV to query the program identifier and absolute playback time in milliseconds or seconds for the current playback session. When switching programs or starting a new playback session, the IPTV TV client proactively notifies the small-screen terminal to trigger a new round of time synchronization.

[0012] Preferably, when the IPTV message base cannot obtain playback progress information from the local player in real time, one of the following fallback strategies is used sequentially to obtain the playback progress information, specifically: Use the playback progress information that was most recently successfully reported and cached by the IPTV TV client. The timestamp of the cached information must be within the preset valid time window. Based on the start time recorded in the program's electronic program guide and the system time on the IPTV television, the current playback time is estimated. If none of the above strategies work, the bullet screen content will be temporarily saved and a background retry mechanism will be initiated.

[0013] Preferably, the step of sending the bound bullet screen data to the backend server for storage specifically includes: storing the bound bullet screen data in the form of database records, each record containing at least a bullet screen content field, a program identifier field, and a playback time point field; The step of requesting and retrieving the bound bullet screen data within a corresponding time range from the backend server and displaying it when any terminal plays the program, based on its current playback time, specifically includes: The backend server receives information including the program identifier and the current playback time. Request to retrieve bullet comments; Based on the program identifier and the current playback time Determine the target time range ,in This is the preset time tolerance window; Retrieve all bullet comment records from the database that match the program identifier and whose playback time falls within the target time range, and return them to the requesting terminal.

[0014] The best options also include personalized bullet screen recommendations: The small-screen terminal identifies the time period characteristics of the program playback based on the current playback progress information synchronized from the IPTV TV terminal; the time period characteristics include the opening, ending, key plot points, black screen transitions, or advertising periods; Based on the identified time period characteristics, the system intelligently recommends preset bullet screen templates or related advertising content that match the currently playing content on the bullet screen input interface of the small screen terminal.

[0015] On the other hand, the present invention also provides a cross-screen bullet screen synchronization system for implementing the cross-screen bullet screen synchronization method described above, comprising: The small-screen terminal is used to provide a user interface for inputting bullet screen content and to bind and synchronize with the IPTV TV terminal. The IPTV television terminal includes a media player and an IPTV messaging base module deployed thereon; the media player is used to play programs and maintain playback progress; the IPTV messaging base module is used to communicate with the IPTV messaging base server and to obtain the current playback progress information of the media player. The binding and synchronization module is used to establish the account and device binding relationship between the small screen terminal and the IPTV TV terminal, and to execute the time synchronization algorithm between the small screen terminal and the IPTV TV terminal to calibrate the timing device offset. The IPTV messaging base server is used to manage the connection and message forwarding of the IPTV messaging base module, and participates in the time synchronization process as a coordinator. The bullet screen backend service is used to receive bullet screen data bound with playback progress information from the IPTV message base module and store it indexed by program identifier and playback time point; it is also used to respond to playback requests and return bullet screen data within the corresponding time range according to the requested playback time point.

[0016] Preferably, the IPTV message base module includes a degradation processing unit, used to attempt the following operations sequentially when the playback progress cannot be obtained from the media player in real time: Read the most recently valid playback progress information from the local cache; Estimate playback progress based on the electronic program schedule and system time; Trigger the process of temporarily storing and retrying bullet screen data.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses an IPTV message base server to perform average calculation and periodic calibration based on the timestamps of multiple devices under the same account. Combined with a multiple timing mechanism, it effectively eliminates the impact of clock drift and network latency between large and small screen devices, achieves millisecond-level playback progress synchronization, and ensures that the bullet comments sent by users on the small screen can be accurately bound to the corresponding time point of the program on the large screen, significantly improving the timeliness and semantic consistency of bullet comments.

[0018] 2. The system of the present invention not only supports users to send real-time bullet comments at the current playback time, but also allows users to preset "fixed-point bullet comments" at any historical or future time point based on the synchronized program progress timeline, breaking through the traditional one-way viewing limitation, providing users with a "time-traveling" interactive experience, and enhancing users' sense of participation and content co-creation capabilities.

[0019] 3. In this invention, the small screen terminal intelligently pushes matching preset bullet screen templates based on the current playback progress of the large screen (such as opening, climax, advertisement, black screen, etc.), and dynamically generates recommended content in combination with program semantics (such as characters, scenes, plot), reducing the input threshold for users, guiding high-quality and contextualized interaction, avoiding meaningless screen scrolling, and optimizing the overall bullet screen ecosystem.

[0020] 4. The system of the present invention can identify embedded advertising periods or specific content segments in programs and simultaneously display related personalized advertisements (such as products featured in the show or brand interactive activities) on a small screen, realizing precise marketing through the integration of "content-bullet comments-advertisements", improving advertising conversion rates, and opening up new commercialization models for IPTV operators.

[0021] 5. This invention separates the IPTV message base, message base server, and bullet screen backend service modules, with each component having a clear responsibility and efficient communication; bullet screens are stored in a structured manner according to (program ID + playback time), supporting high-concurrency read and write and fast retrieval, and the system can be easily expanded to a scale of millions of users, while ensuring the secure isolation of the IPTV main business network.

[0022] 6. This invention relies on QR code binding and unified account management to realize a natural interactive paradigm of "watching on a big screen and chatting on a small screen". It transforms the mobile phone from a source of interference into an interactive entry point that enhances the viewing experience. It not only optimizes the shared viewing experience in family scenarios, but also provides a technical foundation for interactive variety shows, live sports broadcasts, educational programs and other scenarios, helping IPTV evolve towards immersive, social and intelligent features. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0025] In this invention, terms such as "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "side," and "bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only to facilitate the description of the structural relationships of the various components or elements of this invention and do not specifically refer to any component or element in this invention. They should not be construed as limiting the invention.

[0026] Example: like Figure 1 As shown, this embodiment provides a cross-screen bullet screen synchronization method, including the following steps: Establish a binding relationship between the small-screen terminal and the IPTV TV terminal; To synchronize the time between the small-screen terminal and the IPTV TV terminal, and to calibrate the timing device offset between the small-screen terminal and the IPTV TV terminal; The system receives user-inputted bullet comments via a small-screen terminal and sends them to the IPTV messaging dock deployed on the IPTV TV. Upon receiving the bullet screen content, the IPTV message dock retrieves the playback progress information of the program currently playing on the IPTV TV. This playback progress information includes, but is not limited to, the program identifier and the current playback time. The bullet screen content is bound to the obtained playback progress information to generate bound bullet screen data; The bound bullet screen data is sent to the backend server for storage, and indexed by the program identifier and playback time. When any terminal plays the program, it requests and retrieves the bound bullet screen data within the corresponding time range from the backend server based on the current playback time and displays it.

[0027] like Figure 2 As shown, this embodiment also provides a cross-screen bullet screen synchronization system, including: The small-screen terminal is used to provide a user interface for inputting bullet screen content and to bind and synchronize with the IPTV TV terminal. The IPTV television terminal includes a media player and an IPTV messaging base module deployed thereon; the media player is used to play programs and maintain playback progress; the IPTV messaging base module is used to communicate with the IPTV messaging base server and to obtain the current playback progress information of the media player. The binding and synchronization module is used to establish the account and device binding relationship between the small screen terminal and the IPTV TV terminal, and to execute the time synchronization algorithm between the small screen terminal and the IPTV TV terminal to calibrate the timing device offset. The IPTV messaging base server is used to manage the connection and message forwarding of the IPTV messaging base module, and participates in the time synchronization process as a coordinator. The bullet screen backend service is used to receive bullet screen data bound with playback progress information from the IPTV message base module and store it indexed by program identifier and playback time point; it is also used to respond to playback requests and return bullet screen data within the corresponding time range according to the requested playback time point.

[0028] Below, this embodiment will provide a detailed description of the above method and system in conjunction with a real-world scenario.

[0029] The application scenarios presented in this embodiment are as follows: Large screen: A smart set-top box of a certain brand (running Android TV system) is connected to the TV and is playing live program B on channel A; Small screen: Users can install the "XX Video" App or run the mini-program on their mobile phones; Server-side components: IPTV message base server, bullet screen storage server, EPG program list database; Network: Home Wi-Fi, with the large and small screens on the same local area network.

[0030] The specific implementation process is as follows: 1. Establish the binding relationship between large and small screens: When a user turns on live TV program B and presses the "Interact" button on the remote control, a dynamic QR code (containing device ID, user account, session token, etc.) will be displayed on the screen. Users can scan the QR code using a mobile app or mini-program; The app sends the device ID, user account, and token to the IPTV message base server; After server verification, a user account is created. The binding relationship of set-top box devices; At this point, the system knows that the user's small screen operation should be associated with the content currently being played on the set-top box.

[0031] 2. Open the bullet screen interface in small mode to trigger initial time synchronization: Users can click the "Send Bullet Comment" button in the app to enter the bullet comment input page; The app or mini-program sends a "prepare to send bullet comments" request to the IPTV messaging dock; The message base immediately sends a time synchronization command to the set-top box; The set-top box performs the following operations: (1) Obtain current program information from the player kernel: program_id="Channel A_20251129_1900", play_offset=482000ms (meaning 8 minutes and 2 seconds have been played); Simultaneously initiate the two-way timestamp timing process (a total of 7 interactions); The message base server acts as a coordinator, instructing the large screen (set-top box) and small screen (mobile phone) to perform lightweight time exchange; Small screen records local time Send a "synchronization request" to the message base; The message dock immediately forwards it to the main screen; Record local time after receiving the data on the large screen. and send back a response; The small screen records the response. ; Calculate the clock offset: ; Processing of 7 offset samples [48, 50, 350, 49, 51, 50, -200] (unit: ms): After sorting, remove the maximum value (350) and the minimum value (-200); The average of the remaining 5 values ​​is: (48+49+50+50+51) / 5 = 49.6ms; Returning to the corrected local time base: the local time on the smaller screen is approximately 49.6 milliseconds faster than that on the larger screen; Small-screen apps or mini-programs store this offset in memory.

[0032] After that, when it is necessary to estimate the "current playback time on the large screen", the local time on the small screen can be reduced by 49.6 milliseconds for conversion; after the initial synchronization is completed, the small screen obtains the same time reference as the large screen.

[0033] 3. User sends bullet comments, system binding progress: The user typed the comment: "The host's hairstyle looks good today!" and clicked send; The app or mini-program uploads the bullet screen text to the IPTV messaging base via the IPTV messaging base server; Message base: Check the playback status of the currently bound set-top box; Get real-time progress: program_id = "Channel A_20251129_1900", offset = 485000 ms; The bullet comments are stored on the bullet comment server and recorded as follows: { "content": "The host has a nice hairstyle today!" "program_id": "Channel A_20251129_1900", "play_offset_ms": 485000, "user_id": "U12345", "bind_method": "realtime_player" }

[0034] 4. The bullet comments are accurately synchronized when other users are watching: Another user is watching the same live broadcast program B (on demand). When the set-top box plays to offset=485000 ms, the message base server queries the bullet screen server and pushes the bullet screen message. The comments appeared on screen precisely on time, perfectly matching the streamer's camera angles; The set-top box can also shift the playback time back a certain period to batch obtain bullet comments and reduce system pressure: for example, when the playback reaches 480000ms, it can obtain a list of bullet comments for 5 seconds between [480000, 485000] at once. The time interval can be adjusted, and the set-top box can accurately display the bullet comments on the screen based on the timestamp and the current playback progress.

[0035] 5. Troubleshooting (Player not responding): Suppose that in process 3 above, the set-top box failed to return to the playback progress due to system lag; IPTV message dock detected a timeout (greater than 1 second); System downgrade startup process: (1) Find the most recent cache progress reported by the set-top box (2 seconds ago: offset = 483000 ms); (2) Verify that the cache has not expired (less than 3 seconds), and use this value; (3) The bullet comments are stored as follows: {..., "play_offset_ms": 483000, "bind_method": "cached_fallback"}; Users are unaware of the situation, and the bullet comments remain largely aligned. If the cache also fails, the system can enter estimation mode, which estimates the offset to be approximately 485,000 ms based on the EPG start time (19:00:00) + the current system time (19:08:05). All bullet comments bound in this way are marked as bind_method: "estimated" in the metadata for subsequent precision-based processing.

[0036] 6. Periodic calibration maintains long-term synchronization: Over the next 30 seconds, the message base proactively initiates a lightweight time calibration every 15 seconds (7 interactions). (secondary sampling) The next calibration cycle is dynamically adjusted based on offset stability (if the network is stable, it is extended to 60 seconds). Ensures that even during extended viewing, comments sent from a small screen will still be accurately aligned with the large screen.

[0037] The above is a detailed description of the preferred embodiments of the present invention, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A cross-screen bullet screen synchronization method, characterized in that, Includes the following steps: Establish a binding relationship between the small-screen terminal and the IPTV TV terminal; To synchronize the time between the small-screen terminal and the IPTV TV terminal, and to calibrate the timing device offset between the small-screen terminal and the IPTV TV terminal; The system receives user-inputted bullet comments via a small-screen terminal and sends them to the IPTV messaging dock deployed on the IPTV TV. The IPTV message dock responds to received bullet screen content and obtains the playback progress information of the program currently being played on the IPTV TV. The playback progress information includes, but is not limited to: program identifier and current playback time. The bullet screen content is bound to the obtained playback progress information to generate bound bullet screen data; The bound bullet screen data is sent to the backend server for storage, and indexed by the program identifier and playback time. When any terminal plays the program, it requests and retrieves the bound bullet screen data within the corresponding time range from the backend server based on the current playback time and displays it.

2. The cross-screen bullet screen synchronization method according to claim 1, characterized in that, The process of establishing a binding relationship between the small-screen terminal and the IPTV television terminal includes: Display a binding QR code containing device identification and session information on the IPTV television; The device identifier and session information can be obtained by scanning the binding QR code on a small screen terminal; Send the device identifier, session information, and user account associated with the small screen terminal to the IPTV message base server for verification; After successful verification, the user account is linked to the IPTV television device.

3. The cross-screen bullet screen synchronization method according to claim 1, characterized in that, The time synchronization between the small-screen terminal and the IPTV TV terminal specifically involves: The small-screen terminal and the IPTV messaging base server perform several bidirectional timestamp exchange processes, each of which includes: The master device sends a message carrying the first timestamp to the slave device. Synchronous messages; The secondary device records a local second timestamp when it receives a synchronization message. It then immediately sends a response message to the master device, the response message carrying a second timestamp. and third timestamp The third timestamp The local time when the secondary device sends the response message; The master device records a local fourth timestamp when it receives the response message. ; Calculate the estimated value of a single clock offset based on the timestamp obtained in each bidirectional timestamp exchange process. , is represented as: ,in, The sequence number of the swaps; Outlier removal and averaging are performed on several single clock offset estimates obtained from several calculations to obtain the final clock offset. ; Based on the final clock offset It corrects the local time of the small-screen terminal to align with the playback progress time reference of the IPTV TV terminal.

4. The cross-screen bullet screen synchronization method according to claim 3, characterized in that, The time synchronization between the small-screen terminal and the IPTV TV also includes adaptive calibration cycle adjustment: Set the initial calibration cycle; Record recent The standard deviation of the clock offset obtained from the second calibration ; like Greater than the first threshold This shortens the calibration cycle; If the absolute value of the difference between clock offsets obtained from several consecutive adjacent calibrations is less than the second threshold If so, the calibration cycle will be extended; The calibration cycle is adjusted within the preset upper and lower limit ranges; Based on the adjusted calibration period, the bidirectional timestamp exchange process is periodically repeated to update the clock offset. .

5. The cross-screen bullet screen synchronization method according to claim 1, characterized in that, The IPTV message base responds to the received bullet screen content by obtaining the playback progress information of the program currently playing on the IPTV TV, specifically: The IPTV message dock calls the application programming interface of the local player on the IPTV TV to query the program identifier and absolute playback time in milliseconds or seconds for the current playback session. When switching programs or starting a new playback session, the IPTV TV client proactively notifies the small-screen terminal to trigger a new round of time synchronization.

6. The cross-screen bullet screen synchronization method according to claim 5, characterized in that, When the IPTV message base cannot obtain playback progress information from the local player in real time, it will use one of the following fallback strategies to obtain playback progress information in sequence: Use the playback progress information that was most recently successfully reported and cached by the IPTV TV client. The timestamp of the cached information must be within the preset valid time window. Based on the start time recorded in the program's electronic program guide and the system time on the IPTV television, the current playback time is estimated. If none of the above strategies work, the bullet screen content will be temporarily saved and a background retry mechanism will be initiated.

7. The cross-screen bullet screen synchronization method according to claim 1, characterized in that, The step of sending the bound bullet screen data to the backend server for storage specifically includes: storing the bound bullet screen data in the form of database records, each record containing at least a bullet screen content field, a program identifier field, and a playback time point field; The step of requesting and retrieving the bound bullet screen data within a corresponding time range from the backend server and displaying it when any terminal plays the program, based on its current playback time, specifically includes: The backend server receives information including the program identifier and the current playback time. Request to retrieve bullet comments; Based on the program identifier and the current playback time Determine the target time range ,in This is the preset time tolerance window; Retrieve all bullet comment records from the database that match the program identifier and whose playback time falls within the target time range, and return them to the requesting terminal.

8. A cross-screen bullet screen synchronization method according to claim 1, characterized in that, It also includes personalized bullet screen recommendations: The small-screen terminal identifies the time period characteristics of the program playback based on the current playback progress information synchronized from the IPTV TV terminal; the time period characteristics include the opening, ending, key plot points, black screen transitions, or advertising periods; Based on the identified time period characteristics, the system intelligently recommends preset bullet screen templates or related advertising content that match the currently playing content on the bullet screen input interface of the small screen terminal.

9. A cross-screen bullet screen synchronization system, used to implement the cross-screen bullet screen synchronization method as described in any one of claims 1-7, characterized in that, include: The small-screen terminal is used to provide a user interface for inputting bullet screen content and to bind and synchronize with the IPTV TV terminal. The IPTV television terminal includes a media player and an IPTV messaging base module deployed thereon; the media player is used to play programs and maintain playback progress; the IPTV messaging base module is used to communicate with the IPTV messaging base server and to obtain the current playback progress information of the media player. The binding and synchronization module is used to establish the account and device binding relationship between the small-screen terminal and the IPTV TV terminal, and to execute the time synchronization algorithm between the small-screen terminal and the IPTV TV terminal to calibrate the timing device offset. The IPTV messaging base server is used to manage the connection and message forwarding of the IPTV messaging base module, and participates in the time synchronization process as a coordinator. The bullet screen backend service is used to receive bullet screen data bound with playback progress information from the IPTV message base module and store it indexed by program identifier and playback time point; it is also used to respond to playback requests and return bullet screen data within the corresponding time range according to the requested playback time point.

10. A cross-screen bullet screen synchronization system according to claim 9, characterized in that, The IPTV message base module includes a degradation processing unit, used to attempt the following operations sequentially when the playback progress cannot be obtained from the media player in real time: Read the most recently valid playback progress information from the local cache; Estimate playback progress based on the electronic program schedule and system time; Trigger the process of temporarily storing and retrying bullet screen data.

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