Cross-domain media gateway supporting global accurate synchronization

Abstract

The invention belongs to the technical field of network communication, and particularly relates to a cross-domain media gateway supporting global accurate synchronization. The device comprises a network interface module, an audio and video transcoding module, a local clock receiving module, a synchronous packet generation module, a synchronous packet detection module, a clock phase-locked loop module and a clock output module. The media gateway realizes multi-domain division management of an audio and video network through organic combination and cooperative work with the service nodes in the audio and video domains and the service nodes among the audio and video domains, particularly, the media gateway supports precise clock synchronization of the whole domain, and can realize no tearing and no blocking during cross-domain display of video images.

Description

Technical Field

[0001] This invention belongs to the field of network communication technology, specifically, it relates to a cross-domain media gateway that supports precise synchronization across the entire domain. Background Technology

[0002] In the field of local audio and video systems based on network communication technology, as the scale of audio and video systems continues to expand, the problems faced are becoming increasingly prominent, such as: the increased system complexity makes system integration and management more difficult; various types of faults in the system make the localization problem more complicated; due to the increase in system scale, the transmission and processing latency cannot meet the real-time requirements of audio and video services; this requires the system to be divided into multiple domains to achieve an architecture of regional autonomy and inter-regional collaboration.

[0003] In implementing a multi-domain divide-and-conquer architecture, a crucial issue is achieving precise time synchronization across the entire domain. Precise clock synchronization between different devices on the network is essential for ensuring accurate data exchange, improving system performance, and enhancing security. However, in a multi-domain divide-and-conquer system, subdomains require physical isolation of broadcast domains via media gateways. Currently common clock synchronization protocols include NTP and PTP. Taking PTP as an example, it requires a clock server and network devices that support the protocol at the physical layer. This not only necessitates additional investment in equipment upgrades but also suffers from complex deployment and inflexible configuration, making it unsuitable for large-scale local audio and video systems. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing local large-scale audio and video network clock synchronization architectures and further improve them. To better adapt to the multi-domain architecture of large-scale local audio and video network services, this invention proposes a cross-domain media gateway that supports precise synchronization across all domains. This gateway enables the sharing of audio and video services while ensuring independence and integrity within each domain. Simultaneously, it supports precise synchronization of clocks across all domains, thereby ensuring complete consistency in the audio and video distribution, decoding, and display times of each subdomain.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] This invention provides a cross-domain media gateway supporting precise synchronization across the entire domain, comprising a local clock receiving module, a synchronization packet generation module, a synchronization packet detection module, a clock phase-locked loop module, a clock output module, and a clock master / backup arbitration module; wherein: The network interface module is divided into two parts. One part is connected to the basic network switching equipment within the domain, and the other part is connected to the basic network switching equipment between the domains, so as to achieve physical isolation between the intra-domain network and the inter-domain network. The clock master-slave arbitration module performs master-slave arbitration judgment based on the characteristic information of the audio and video media gateway node, and generates master-slave clock decision. The local clock receiving module receives clock pulse signals generated by the free oscillation of a crystal oscillator from this media gateway. The synchronization packet detection module receives the synchronization message sent by the main media gateway of the network interface module, decodes it, and outputs the clock information to the clock phase-locked loop module. The clock phase-locked loop module receives the clock pulse signal from the local clock receiving module and the clock information output by the synchronization packet detection module, and locks in and generates a new, precise clock pulse signal. The clock output module selects either the clock pulse signal from the local clock receiving module or the clock pulse signal from the clock phase-locked loop module for output, based on the master / standby status determined by the clock master / standby arbitration module. The synchronization packet generation module receives the clock signal sent by the clock output module, encapsulates it periodically to generate clock synchronization messages, and sends them to the network interface module.

[0007] In this invention, one end of the network interface module is connected to the audio and video network encoding node, audio and video network decoding node, and audio and video intra-domain service node in the intra-domain system, and the other end is connected to other audio and video media gateways and audio and video inter-domain service nodes in the inter-domain system.

[0008] This invention also includes a heartbeat module, which generates characteristic information of the local media gateway and broadcasts it to all nodes in the system for discovery by other devices. At the same time, it receives heartbeat packets from other audio and video media gateways and parses the characteristic information, which includes the priority of the audio and video media gateway node, the protocols supported by audio and video transcoding, and audio and video transcoding capabilities.

[0009] The present invention also includes an audio and video transcoding module, which receives parameter configurations from the audio and video inter-domain service nodes and converts the input audio and video bitstreams into output audio and video bitstreams in a specified format according to the transcoding protocol requirements.

[0010] In this invention, the characteristic information of the clock primary / backup arbitration module includes the MAC address and SN serial number of the media gateway; the primary / backup arbitration process is as follows: 1) Perform a hash algorithm on the MAC address and SN serial number of this media gateway to obtain the hash value H0; 2) Perform a hash algorithm on the MAC address and SN sequence number of other media gateways in the network to obtain a hash value Hi, i = 1,2,...N-1, where N is the number of media gateways in this domain; 3) Compare the size of H0 with each Hi. If H0 is smaller than any of the Hi, then this media gateway is considered a backup media gateway and will not send a synchronization message. 4) If H0 is the largest within period T, then this media gateway is considered the main media gateway, and a synchronization message is sent after period T ends.

[0011] Furthermore, this invention also provides a method for achieving precise time synchronization between multiple audio and video domains using the aforementioned cross-domain media gateway that supports full-domain precise synchronization. Each media gateway faces two network domains: a subdomain and a parent network domain. First, a master media gateway for each subdomain is selected through a clock master-slave arbitration module. Then, based on these master media gateways, the final master media gateway is selected in the parent network domain through the clock master-slave arbitration module. If it is the master media gateway, the clock output module outputs the clock from the local clock receiving module; if it is the backup media gateway, the clock output module outputs the clock locked by the clock phase-locked loop module. The specific process is as follows: (1.1) Media gateways belonging to the same subdomain send heartbeat information through the network interface connected to the subdomain; (1.2) Media gateways belonging to the same subdomain receive hop information from other media gateways in the same subdomain through the network interface connected to the subdomain; (1.3) The clock primary and backup arbitration module performs primary and backup arbitration judgment based on the collected hop information of other media gateways in the same subdomain; if the arbitration result determines that this media gateway is the primary media gateway in this subdomain, then the step goes to (1.4); if the arbitration result determines that this media gateway is the backup media gateway in this subdomain, then the step goes to (1.6). (1.4) The primary media gateway elected within the subdomain sends heartbeat information through the network interface connected to the upper-level network domain; (1.5) All primary media gateways within the upper-level network domain are subject to primary / backup arbitration by the clock primary / backup arbitration module based on the collected hop information of other primary media gateways in the same-level domain. If the arbitration result determines that this media gateway is the primary media gateway within the upper-level network domain, then proceed to (1.9). If the arbitration result determines that this media gateway is the backup media gateway of the upper-level network domain, then proceed to (1.6). (1.6) The synchronization packet detection module receives the clock synchronization message sent by the main media gateway, decodes it to generate clock synchronization information, and transfers it to the clock phase-locked loop module; (1.7) The clock phase-locked loop module locks the clock according to the clock synchronization information of the main media gateway and generates a new precise clock pulse signal; the locked clock pulse signal is then transferred to the clock output module. (1.8) The clock output module selects one path (the local clock pulse signal generated by the local clock receiving module or the clock pulse signal locked by the clock phase-locked loop module) to output to other service modules of the media gateway, such as the audio and video transcoding module, based on the arbitration result of the main and backup modules. (1.9) If this media gateway is the primary media gateway in this subdomain, the synchronization packet generation module generates synchronization messages at a certain period and sends them to other media gateways in this domain; if this media gateway is the primary media gateway in the upper-level network domain, the synchronization packet generation module generates synchronization messages at a certain period and sends them to other media gateways in the upper-level network domain.

[0012] Compared with existing technologies, the cross-domain media gateway that supports precise synchronization across the entire domain disclosed in this invention has the following beneficial effects: First, it eliminates the need for a dedicated clock server and network infrastructure (such as switches supporting the 1588 protocol) found in traditional clock synchronization architectures, reducing overall system costs and network equipment requirements. Second, the media gateway can achieve N+1 backup. If any media gateway fails or malfunctions, it will not affect the normal operation of the system as a whole. Third, the system has strong scalability and can flexibly realize the splitting or merging of subdomains. After splitting or merging, it can still achieve precise clock synchronization across the entire domain. Attached Figure Description

[0013] Figure 1 This is a block diagram of an audio / video system that supports multi-domain divide-and-conquer.

[0014] Figure 2 This is a block diagram of a media gateway. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0016] Example 1

[0017] like Figure 1 As shown, this invention is a cross-domain media gateway that supports precise synchronization across the entire domain, belonging to an audio-visual system that supports multi-domain governance. It includes audio-visual network encoding nodes, audio-visual network decoding nodes, audio-visual media gateways, intra-domain audio-visual service nodes, and inter-domain audio-visual service nodes. The audio-visual network encoding nodes, audio-visual network decoding nodes, audio-visual media gateways, intra-domain audio-visual service nodes, and inter-domain audio-visual service nodes are connected to the basic network switching equipment through standard network link interfaces.

[0018] For ease of description, this embodiment sets the basic network switching equipment to two levels, where the first level is an intra-domain switch and the second level is an inter-domain switch. The intra-domain switch of the first level and the inter-domain switch of the second level are interconnected through an audio and video media gateway. The audio and video network encoding node, audio and video network decoding node, and audio and video intra-domain service node are all connected to the intra-domain switch of the first level through network interfaces. The audio and video inter-domain service node is connected to the inter-domain switch of the second level.

[0019] In this embodiment, there are 3 audio and video domains, and 3 sets of audio and video media gateways are deployed in each audio and video domain.

[0020] This embodiment provides a cross-domain media gateway that supports precise synchronization across the entire domain. It includes a network interface module, an audio / video transcoding module, a local clock receiving module, a synchronization packet generation module, a synchronization packet detection module, a clock phase-locked loop module, a clock output module, a heartbeat module, and a clock master / backup arbitration module, wherein: 1) Network Interface Module In this embodiment, there are two network interface modules, one of which is connected to the intra-domain switch and the other is connected to the inter-domain switch. One end of the module is connected to the audio and video network encoding node, audio and video network decoding node, and audio and video intra-domain service node in the intra-domain system, and the other end is connected to other audio and video media gateways and audio and video inter-domain service nodes in the inter-domain system. The two parts are completely independent and do not affect each other, achieving physical isolation between intra-domain networks and inter-domain networks, preventing the spread of anomalies such as switch broadcast storms, and improving network convergence speed. (ii) Audio and video transcoding module The audio / video transcoding module receives configuration parameters from the parameter configuration module, transcodes the input audio / video bitstream according to the JPVC2 protocol, and converts it into an output audio / video bitstream in a specified format. (iii) Local clock receiving module The local clock receiving module receives clock pulse signals generated by the free oscillation of a crystal oscillator from this media gateway, and is a local clock source. (iv) Synchronization Packet Generation Module The synchronization packet generation module receives the clock signal sent by the clock output module, encapsulates it into a clock synchronization message at a certain period, and sends it to the network interface module. (v) Synchronization Packet Detection Module The synchronization packet detection module receives the synchronization message sent by the main media gateway from the network interface module, decodes it, and outputs the clock information to the clock phase-locked loop module. vi) Clock Phase-Locked Loop Module The clock phase-locked loop module receives the clock pulse signal from the local clock receiving module and the clock information output by the synchronization packet detection module, and locks in and generates a new, precise clock pulse signal. 7) Clock Output Module The clock output module selects either the clock pulse signal output by the local clock receiving module or the clock pulse signal output by the clock phase-locked loop module for output, based on the master / standby status determined by the clock master / standby arbitration module. (viii) Heartbeat Module The heartbeat module generates characteristic information of the audio and video media gateway node and broadcasts it to all nodes in the system for discovery by other devices. Important characteristic information includes the priority of the audio and video media gateway node, the protocols supported by audio and video transcoding, and audio and video transcoding capabilities. At the same time, it receives heartbeat packets from other audio and video media gateways and parses the characteristic information. ix) Clock master / slave arbitration module The master-slave clock arbitration module generates master-slave clock decisions based on the characteristic information of the audio and video media gateway nodes. In this embodiment, the characteristic information of the master-slave arbitration includes: the MAC address and SN serial number of the media gateway.

[0021] The process of primary and backup arbitration in this embodiment is as follows: 1. Perform a hash algorithm on the MAC address and SN serial number of this media gateway to obtain the hash value H0; 2. Perform a hash algorithm on the MAC address and SN sequence number of other media gateways in the network to obtain a hash value Hi (i = 1,2,...N-1, where N is the number of media gateways in this domain). 3. Compare the size of H0 with each Hi. If H0 is smaller than any of the Hi, then this media gateway is considered a backup media gateway and will not send a synchronization message. 4. If H0 is at its maximum within a certain period T (e.g., 10 seconds), then this media gateway is considered the primary media gateway, and a synchronization message is sent after the period T ends.

[0022] The three audio and video media gateways within each domain can work independently and back each other up. The idle status is automatically detected and services are allocated through the inter-domain service nodes for audio and video.

[0023] In this embodiment, the method for achieving precise time synchronization between multiple audio and video domains using a cross-domain media gateway that supports precise domain synchronization is as follows: For ease of description, the three subdomains are named DA, DB, and DC, and the media gateways within the subdomains are named MAi, MBi, and MCi (i=0,1,2). (1.1) Taking subdomain DA as an example, media gateway MAi (i=0,1,2) belonging to the same subdomain DA sends heartbeat information through the network interface connected to the subdomain; (1.2) Media gateways (DAs) belonging to the same subdomain receive hop information from other media gateways in the same subdomain through the network interface connected to the subdomain DA; (1.3) The clock primary and backup arbitration module performs primary and backup arbitration judgment based on the hop information of other media gateways in the same subdomain DA collected; if the arbitration result determines that this media gateway (e.g., MA0) is the primary media gateway in this subdomain, then the step goes to (1.4); if the arbitration result determines that this media gateway is the backup media gateway in this subdomain, then the step goes to (1.6). (1.4) The primary media gateway MA0 elected within the subdomain sends heartbeat information through the network interface connected to the upper-level network domain; (1.5) All primary media gateways within the upper-level network domain (e.g., MA0, MB0, MC0 are the primary media gateways elected by each subdomain) are subject to primary / backup arbitration by the clock primary / backup arbitration module based on the collected hop information of other primary media gateways in the same-level domain. If the arbitration result determines that this media gateway is the primary media gateway within the upper-level network domain (e.g., MA0), then proceed to (1.9). If the arbitration result determines that this media gateway is the backup media gateway of the upper-level network domain, then proceed to (1.6). (1.6) The synchronization packet detection module receives the clock synchronization message sent by the main media gateway (MA0), decodes it to generate clock synchronization information, and transfers it to the clock phase-locked loop module; (1.7) The clock phase-locked loop module locks the clock according to the clock synchronization information of the main media gateway and generates a new precise clock pulse signal; the locked clock pulse signal is then transferred to the clock output module. (1.8) The clock output module selects the clock pulse signal locked by the clock phase-locked loop module and outputs it to other service modules of the media gateway, such as the audio and video transcoding module, based on the arbitration result of the main and backup modules. (1.9) If this media gateway is the primary media gateway (MA0, MB0, MC0) within this subdomain, the synchronization packet generation module will generate synchronization messages and send them to other media gateways within this domain at a certain period of time; if this media gateway is the primary media gateway (MA0) of the upper-level network domain, the synchronization packet generation module will generate synchronization messages and send them to other media gateways within the upper-level network domain at a certain period of time.

[0024] Obviously, those skilled in the art will intentionally make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A cross-domain media gateway supporting precise synchronization across all domains, characterized in that, It includes a local clock receiving module, a synchronization packet generation module, a synchronization packet detection module, a clock phase-locked loop module, a clock output module, and a clock master / backup arbitration module; wherein: The network interface module is divided into two parts. One part is connected to the basic network switching equipment within the domain, and the other part is connected to the basic network switching equipment between domains, so as to achieve physical isolation between the local network and the inter-domain network. The local clock receiving module receives clock pulse signals generated by the free oscillation of a crystal oscillator from this media gateway. The clock master-slave arbitration module performs master-slave arbitration judgment based on the characteristic information of the audio and video media gateway node, and generates master-slave clock decision. The synchronization packet detection module receives the synchronization message sent by the main media gateway of the network interface module, decodes it, and outputs the clock information to the clock phase-locked loop module. The clock phase-locked loop module receives the clock pulse signal from the local clock receiving module and the clock information output by the synchronization packet detection module, and locks in and generates a new, precise clock pulse signal. The clock output module selects either the clock pulse signal from the local clock receiving module or the clock pulse signal from the clock phase-locked loop module for output, based on the master / standby status determined by the clock master / standby arbitration module. The synchronization packet generation module receives the clock signal sent by the clock output module, encapsulates it periodically to generate clock synchronization messages, and sends them to the network interface module.

2. The cross-domain media gateway supporting precise synchronization across all domains according to claim 1, characterized in that, It also includes a network interface module that connects one end to the audio and video network encoding nodes, audio and video network decoding nodes, and audio and video intra-domain service nodes in the intra-domain system, and the other end to other audio and video media gateways and audio and video inter-domain service nodes in the inter-domain system.

3. The cross-domain media gateway supporting precise synchronization across all domains according to claim 2, characterized in that, It also includes a heartbeat module, which generates characteristic information of the local media gateway and broadcasts it to all nodes in the system for discovery by other devices. At the same time, it receives heartbeat packets from other audio and video media gateways and parses the characteristic information, which includes the priority of the audio and video media gateway node, the protocols supported by audio and video transcoding, and audio and video transcoding capabilities.

4. The cross-domain media gateway supporting precise synchronization across all domains according to claim 2, characterized in that, It also includes an audio / video transcoding module, which receives parameter configurations from the audio / video inter-domain service nodes and converts the input audio / video bitstream into an output audio / video bitstream in a specified format according to the transcoding protocol requirements.

5. The cross-domain media gateway supporting precise synchronization across all domains according to claim 1, characterized in that, The characteristic information of the clock primary / backup arbitration module includes the MAC address and SN serial number of the media gateway; the primary / backup arbitration process is as follows: 1) Perform a hash algorithm on the MAC address and SN serial number of this media gateway to obtain the hash value H0; 2) Perform a hash algorithm on the MAC address and SN sequence number of other media gateways in the network to obtain a hash value Hi, i = 1, 2, ..., N-1, where N is the number of media gateways in this domain; 3) Compare the size of H0 with each Hi. If H0 is smaller than any of the Hi, then this media gateway is considered a backup media gateway and will not send a synchronization message. 4) If H0 is at its maximum during period T, which is the time of primary / backup contention set by the system, then this media gateway is considered the primary media gateway, and a synchronization message is sent after period T ends.

6. A method for achieving precise time synchronization between multiple audio and video domains using the cross-domain media gateway supporting full-domain precise synchronization as described in claim 1, characterized in that, Each media gateway faces two network domains: a subdomain and a parent network domain. First, the primary media gateway for each subdomain is selected through the primary and backup clock arbitration module. Then, based on these primary media gateways, the final primary media gateway is selected in the parent network domain through the primary and backup clock arbitration module. If it is the primary media gateway, the clock output module outputs the clock from the local clock receiving module. If it is the backup media gateway, the clock output module outputs the clock locked by the clock phase-locked loop module.

7. The method for achieving precise time synchronization among multiple audio and video domains according to claim 6, characterized in that, The specific process is as follows: (1.1) Media gateways belonging to the same subdomain send heartbeat information through the network interface connected to the subdomain; (1.2) Media gateways belonging to the same subdomain receive hop information from other media gateways in the same subdomain through the network interface connected to the subdomain; (1.3) The clock primary and backup arbitration modules make a primary and backup arbitration judgment based on the collected information on other media network jumps in the same subdomain; If the arbitration result determines that this media gateway is the primary media gateway in this subdomain, then proceed to step (1.4); if the arbitration result determines that this media gateway is the backup media gateway in this subdomain, then proceed to step (1.6). (1.4) The primary media gateway elected within the subdomain sends heartbeat information through the network interface connected to the upper-level network domain; (1.5) All primary media gateways within the upper-level network domain are subject to primary / backup arbitration by the clock primary / backup arbitration module based on the collected hop information of other primary media gateways in the same-level domain. If the arbitration result determines that this media gateway is the primary media gateway within the upper-level network domain, then proceed to (1.9). If the arbitration result determines that this media gateway is the backup media gateway of the upper-level network domain, then proceed to (1.6). (1.6) The synchronization packet detection module receives the clock synchronization message sent by the main media gateway, decodes it to generate clock synchronization information, and transfers it to the clock phase-locked loop module; (1.7) The clock phase-locked loop module locks the clock according to the clock synchronization information of the main media gateway and generates a new precise clock pulse signal; Once locked, the clock pulse signal is transferred to the clock output module. (1.8) The clock output module selects one of the local clock pulse signal generated by the local clock receiving module or the clock pulse signal locked by the clock phase-locked loop module to output to other service modules of the media gateway based on the arbitration result of the main and backup modules. (1.9) If this media gateway is the primary media gateway in this subdomain, the synchronization packet generation module generates synchronization messages at a certain period and sends them to other media gateways in this domain. If this media gateway is the primary media gateway of the parent network domain, the synchronization packet generation module generates synchronization messages at regular intervals and sends them to other media gateways within the parent network domain.

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