CN115314643B - Method, system, equipment and storage medium for realizing net switching - Google Patents

Method, system, equipment and storage medium for realizing net switching Download PDF

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Publication number
CN115314643B
CN115314643B CN202210897058.5A CN202210897058A CN115314643B CN 115314643 B CN115314643 B CN 115314643B CN 202210897058 A CN202210897058 A CN 202210897058A CN 115314643 B CN115314643 B CN 115314643B
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cut
sequence number
path
rtp
rtp sequence
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CN115314643A (en
Inventor
姜文波
赵贵华
梅剑平
蔺飞
唐湜
汪刚果
张峰
赵浩宾
王丽霞
李鑫
邢伯敏
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China Media Group
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China Media Group
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/222—Studio circuitry; Studio devices; Studio equipment
    • H04N5/262—Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects
    • H04N5/268—Signal distribution or switching
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/63—Control signaling related to video distribution between client, server and network components; Network processes for video distribution between server and clients or between remote clients, e.g. transmitting basic layer and enhancement layers over different transmission paths, setting up a peer-to-peer communication via Internet between remote STB's; Communication protocols; Addressing
    • H04N21/643—Communication protocols
    • H04N21/6437—Real-time Transport Protocol [RTP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/222—Studio circuitry; Studio devices; Studio equipment
    • H04N5/262—Studio circuits, e.g. for mixing, switching-over, change of character of image, other special effects ; Cameras specially adapted for the electronic generation of special effects

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)

Abstract

The embodiment of the application provides a method, a system, equipment and a storage medium for realizing net switching, wherein the method comprises the following steps: the control system generates a net switching instruction according to the net switching operation information of the user and simultaneously transmits the net switching instruction to the A-path IP matrix equipment and the B-path IP matrix equipment; the A-path IP matrix equipment determines a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculates a first offset value of the RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream so as to finish net switching by using the first offset value; and meanwhile, the B-path IP matrix equipment determines a second RTP sequence number of the cut-out signal flow and a second RTP sequence number of the cut-in signal flow according to the net switching instruction, and calculates a second offset value of the RTP sequence number of the output signal flow relative to the second RTP sequence number of the cut-in signal flow so as to finish net switching by using the second offset value.

Description

Method, system, equipment and storage medium for realizing net switching
Technical Field
The present application relates to the field of broadcast television technologies, and in particular, to a method, a system, an apparatus, and a storage medium for implementing net switching.
Background
The seamless protection switching technology requires that a signal stream of the multicast network is transmitted by A, B two paths of IP streams with the same content but different IP header characteristics at the source end through copying. A. The IP 5 tuples of the two paths of signals B are different (mainly the destination IP addresses, namely multicast group addresses are necessarily different), but the load and the sequence number of RTP (one non-compressed video frame has a lot of information, and generally one frame has thousands of messages exceeding 1000 bytes, each second picture consists of 25-60 video frames, and the messages need to be subjected to sequence number allocation at the RTP layer) A, B paths of signals B are required to keep synchronous; A. the two paths B generally require that paths are not overlapped when in network transmission, and the passing nodes are not overlapped, so that A, B paths are prevented from being interrupted simultaneously when single-point faults occur; A. the two paths B do not distinguish between the main and the standby, and are effective at the same time; the media resource terminal equipment receives A, B two paths of signals simultaneously, and extracts specific load content from A, B paths according to rules before finally synthesizing a video frame; the different terminal implementations of the decimation rules are different, but the corresponding message of the expected sequence number is likely to be received in the path A, B according to the RTP time stamp information in the message, and the path A is selected when the message of the expected sequence number is received in the path A under the condition that the RTP time stamps of the path A, B are consistent, and the path B is selected when the message of the expected sequence number is received in the path B; according to the decimation rule, the final output signal can be kept stable when any one of A, B paths fails, and seamless protection switching is completed.
In addition, the traditional SDI matrix can realize net switching, and the requirement of net switching is naturally also put forward in the process of evolving to the IP matrix. However, an IP signal is transmitted on two different paths, and the IP devices on the different paths must be synchronously and net switched to avoid errors in the signal processing process of the downstream signal processing device. However, at present, no feasible technical solution is available for realizing the net switching in the technical scene of seamless protection switching on the IP matrix device.
Because the net switching based on SMPTE 2022-7 protection cannot be realized in the matrix in the current IP-based multicast network, only one device can be added independently to realize the net switching to avoid. The net switching device in fig. 1 receives the incoming and outgoing signal stream IP messages from A, B paths simultaneously, then restores them to the original picture signal, and finally repacks them to IP messages and transmits them downstream in SMPTE 2022-7, i.e. the output signal stream is transmitted downstream in a manner of regenerating the new signal stream. The IP message of the output signal stream transmitted downstream before switching includes the video information content in the switched-out signal stream, and the video information content of the switched-in signal stream is transmitted downstream after switching. In this process a net switching between the cut-in signal and the cut-out signal is accomplished on command. However, there are the following significant drawbacks:
1. the single point of failure of the signal net switching device in the figure is introduced, which is not in line with the seamless protection switching idea of the SMPTE 2022-7 protocol. The reliability is deteriorated.
2. For the IP matrix switch-in flows, the switch-out flows all need to be sent downstream, and occupy one time of bandwidth.
3. The inter-conversion of the IP message and the picture signal is required to be additionally carried out, and the transmission delay of the whole system is least increased by 1-2 frames.
4. And equipment is additionally added, so that the system investment is increased. In particular, the processing power of such devices is relatively small (much smaller than the IP matrix devices currently commercially available) and the investment is greatly increased in cases where the number of signals requiring a net handoff is relatively large.
5. Because the switching is not performed in the matrix, the traditional maintenance habit in the field of the multicast network is not met.
Disclosure of Invention
The embodiment of the application provides a method, a system, equipment and a storage medium for realizing net switching, which solve the problem that the A, B signal stream transmission paths required in seamless protection switching cannot be kept independent in the net switching realization process in the prior art.
According to a first aspect of an embodiment of the present application, there is provided a method for implementing a net handover, including:
the control system generates a net switching instruction according to net switching operation information of a user, and simultaneously transmits the net switching instruction to the A-path IP matrix device and the B-path IP matrix device;
the A-path IP matrix device determines a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculates a first offset value of the RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream so as to synchronously complete net switching with the B-path IP matrix device by utilizing the first offset value; at the same time
And the B-path IP matrix device determines a second RTP sequence number of the cut-out signal flow and a second RTP sequence number of the cut-in signal flow according to the net switching instruction, and calculates a second offset value of the RTP sequence number of the output signal flow relative to the second RTP sequence number of the cut-in signal flow so as to finish net switching synchronously with the A-path IP matrix device by using the second offset value.
According to a second aspect of an embodiment of the present application, there is provided a system for implementing a net handover, comprising:
the control system is used for generating a net switching instruction according to net switching operation information of a user and simultaneously transmitting the net switching instruction to the A-path IP matrix equipment and the B-path IP matrix equipment;
the path A IP matrix device is used for determining a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculating a first offset value of the RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream so as to synchronously complete net switching with the path B IP matrix device by utilizing the first offset value;
and the B-path IP matrix device is used for determining a second RTP sequence number of the cut-out signal flow and a second RTP sequence number of the cut-in signal flow according to the net switching instruction, and calculating a second offset value of the RTP sequence number of the output signal flow relative to the second RTP sequence number of the cut-in signal flow so as to finish net switching synchronously with the A-path IP matrix device by using the second offset value.
By adopting the technical scheme, the embodiment of the application has the following technical effects: the A, B signal flow transmission paths required in the seamless protection switching are kept independent in the net switching realization process, the reliability in the net switching scene is improved, and the traditional maintenance habit in the field of the multicast network can be kept under the condition that the bandwidth of an IP matrix output link is not additionally occupied, and net switching equipment, system deployment investment and system transmission delay are not additionally increased.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
fig. 1 is a system schematic diagram of a network for IP multicast provided in the prior art, in which a net handover based on SMPTE 2022-7 protection cannot be implemented in a matrix;
FIG. 2 is a flow chart of a method for implementing a clean handoff according to a first embodiment of the present application;
fig. 3 is a schematic diagram of a system for implementing a net handoff according to a second embodiment of the present application;
fig. 4 is a schematic diagram of a net switching scenario based on a seamless protection switching technology requirement in an IP multicast network system according to an embodiment of the present application;
fig. 5 is a flowchart of a method for implementing a net handoff according to a third embodiment of the present application;
fig. 6 is a flowchart of a method for implementing a net handoff according to a fourth embodiment of the present application.
Detailed Description
In order to make the technical solutions and advantages of the embodiments of the present application more apparent, the following detailed description of exemplary embodiments of the present application is provided in conjunction with the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application and not exhaustive of all embodiments. It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other.
Example 1
As shown in fig. 2, a method flowchart for implementing a net handover according to a first embodiment of the present application includes:
step S101: the control system generates a net switching instruction according to net switching operation information of a user, and simultaneously transmits the net switching instruction to the A-path IP matrix device and the B-path IP matrix device;
step S102: the A-path IP matrix device determines a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculates a first offset value of the RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream so as to synchronously complete net switching with the B-path IP matrix device by utilizing the first offset value; at the same time
Step S103: and the B-path IP matrix device determines a second RTP sequence number of the cut-out signal flow and a second RTP sequence number of the cut-in signal flow according to the net switching instruction, and calculates a second offset value of the RTP sequence number of the output signal flow relative to the second RTP sequence number of the cut-in signal flow so as to finish net switching synchronously with the A-path IP matrix device by using the second offset value.
Before the control system according to the embodiment of the application generates the net switching instruction according to the net switching operation information of the user, the control system further comprises: and carrying out time synchronization on the control system, the A-path IP matrix device and the B-path IP matrix device through a time synchronization system.
The determining, by the a-path IP matrix device, a first RTP sequence number of a hand-off signal stream and a first RTP sequence number of the hand-in signal stream according to the net switching instruction includes: the A-path IP matrix device determines a first cut-out RTP timestamp range of a last message of a cut-out signal flow and a first cut-in RTP timestamp range of a first message of the cut-in signal flow according to the time information of the net switching instruction and a preset first switching delay time; the A-path IP matrix device determines a first RTP sequence number of a last message of the cut-out signal flow according to the first cut-out RTP time stamp range and the pre-learned number of messages of each frame of the cut-out signal flow; simultaneously, according to the first cut-in RTP timestamp range and the number of each frame of messages of the cut-in signal flow learned in advance, determining a first RTP serial number of a first message of the cut-in signal flow; the time information refers to the sending time of the net switching instruction which is simultaneously issued to the A-path IP matrix device and the B-path IP matrix device by the control system and is contained in the net switching instruction; or the receiving time of the net switching instruction received by the A-path IP matrix device.
Wherein, the determining, by the B-path IP matrix device, the second RTP sequence number of the hand-out signal stream and the second RTP sequence number of the hand-in signal stream according to the net switching instruction includes: the B-path IP matrix device determines a second cut-out RTP timestamp range of a last message of a cut-out signal flow and a second cut-in RTP timestamp range of a first message of the cut-in signal flow according to the time information of the net switching instruction and a second switching delay time length which is preset; the B-path IP matrix device determines a second RTP sequence number of the last message of the cut-out signal flow according to the second cut-out RTP time stamp range and the pre-learned number of messages of each frame of the cut-out signal flow; determining a second RTP sequence number of a first message of the cut-in signal flow according to the second cut-in RTP time stamp range and the number of messages of each frame of the cut-in signal flow learned in advance; the first switching delay time length is the same as the second switching delay time length; the time information refers to the sending time of the control system for simultaneously sending the net switching instruction to the A-path IP matrix device and the B-path IP matrix device; or the receiving time of the net switching instruction received by the B-path IP matrix device.
The embodiment of the application also comprises the following steps: the A-path IP matrix device sends the first offset value to the control system, and the B-path IP matrix device sends the second offset value to the control system; the control system compares the first offset value with the second offset value; when the first offset value and the second offset value are different, the control system generates a net switching interrupt instruction and issues the net switching interrupt instruction to the A-path IP matrix device and the B-path IP matrix device at the same time, so that the A-path IP matrix device and the B-path IP matrix device terminate the net switching operation according to the net switching interrupt instruction.
The embodiment of the application also comprises the following steps: and after the net switching is completed, the A-path IP matrix equipment updates a preset first offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream to a first offset value of the RTP sequence number of the output signal stream relative to the first RTP sequence number of the cut-in signal stream. Meanwhile, after the net switching is completed, the B-path IP matrix equipment updates a second offset value of the RTP sequence number of the preset output signal flow relative to the RTP sequence number of the cut-out signal flow into a second offset value of the RTP sequence number of the output signal flow relative to the first RTP sequence number of the cut-in signal flow; wherein, the first offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream is the same as the second offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream.
Example two
As shown in fig. 2 and fig. 3, a system schematic diagram for implementing a net handover according to a second embodiment of the present application includes: the control system 201 is configured to generate a net switching instruction according to net switching operation information of a user, and send the net switching instruction to an a-path IP matrix device and a B-path IP matrix device at the same time; the path a IP matrix device 202 is configured to determine, according to the net switching instruction, a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream, and calculate a first offset value of an RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream, so as to complete net switching synchronously with the path B IP matrix device by using the first offset value; and the B-path IP matrix apparatus 203 is configured to determine a second RTP sequence number of the hand-out signal stream and a second RTP sequence number of the hand-in signal stream according to the net switching instruction, and calculate a second offset value of the RTP sequence number of the output signal stream relative to the second RTP sequence number of the hand-in signal stream, so as to complete net switching in synchronization with the a-path IP matrix apparatus by using the second offset value.
The device provided by the embodiment of the application comprises: a memory; a processor; a computer program; wherein the computer program is stored in the memory and configured to be executed by the processor to implement a method of achieving a net handoff.
A computer-readable storage medium provided by an embodiment of the present application has a computer program stored thereon; the computer program is executed by a processor to implement a method of achieving a net handoff.
By examining the principle of seamless protection switching of the multicast network, the application discovers that the reason that the current net switching on the IP matrix device can not be realized under the technical scene of seamless protection switching is mainly that the net switching can not be synchronously realized on two mutually independent A, B paths of IP matrix devices. The "synchronization" means that, after the last packet forwarding of the same frame of A, B paths of switch-out signal IP flows is finished, the A, B paths of matrices need to switch to the corresponding A, B paths of switch-in signal IP flows to start forwarding the first packet of the same frame, and then keep forwarding the packet of the switch-in signal IP flows.
In addition to the synchronization requirement, to achieve a net handoff effect guarantees:
1. in the switching process of the hand-in signal IP flow and the hand-out signal IP flow, 5-tuple of the IP message: the source IP address, the destination IP address, an upper layer protocol number (generally referred to as UDP) in the IP message header, a source port number of the UDP and destination port number information of the UDP are kept unchanged;
2. during the switching process of the hand-in signal IP flow and the hand-out signal IP flow, the time stamp of RTP in the IP message keeps increasing according to the frame time length (assuming that the signal code flow with 50 frame rate is 20ms, one frame is) in the positive (the increase of the time stamp is allowed to be kept within a certain range in the practical implementation);
3. the cut-in signal IP stream and the cut-out signal IP stream maintain a continuous positive growth between video frames during the handoff process with the RTP sequence numbers in the IP messages (including the RTP extension sequence numbers specified in SMPTE 2110).
Fig. 4 is a schematic diagram of a net switching scenario applied to an IP multicast network system based on a seamless protection switching technology requirement according to an embodiment of the present application, where, as shown in fig. 4, the method includes: the system comprises a cut-in signal source, a cut-out signal source, an A-path IP matrix, a B-path IP matrix and a control system.
The on/off signal source is used for generating A, B paths of IP signal flow messages, the IP signal flow messages respectively pass through A, B paths of IP matrixes, and then net switching between on/off signal flows is directly carried out on A, B paths of IP matrixes so as to keep the stability of the final output signal flow sent downstream.
Wherein, the A/B path IP matrix: the multicast replication and forwarding of the IP signal stream message are completed, and the switching or the net switching of matrix output signals among different input signals can be realized, generally, the network equipment capable of realizing the forwarding of the IP message in an IP multicast network, namely an IP matrix, such as a router, a switch, a virtual router, a virtual switch and the like; and (3) a control system: the signaling dispatch instruction is a device capable of completing issuing a net switching instruction in the IP multicast network, and is generally a control software system installed on a server.
Example III
Fig. 5 is a flowchart of a method for implementing a net handoff according to a third embodiment of the present application, as shown in fig. 5, including a preliminary action process before a handoff instruction is issued and a real handoff process.
Wherein, the preparation action before completing the switch instruction issue includes:
501. the control system, the A/B path IP matrix, the hand-in signal source equipment and the hand-out signal source equipment are all subjected to time synchronization in advance through the time synchronization system.
502. In order to determine the switching point during switching, the IP matrix device first learns features (such as a frame duration per frame, a number of messages per frame, etc.) of the hand-in signal flow and the hand-out signal flow in advance, and records an internal flow table entry.
503. The a/B path IP matrix has previously determined the same offset value (sn-offset 1) for the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream, which may be 0. The determination may be that the control system has issued the same sn-offset1 to the a/B-way IP matrix, or that the a/B-way IP matrix has negotiated the same sn-offset1 in advance, or that it was determined during a previous handoff, or other method.
504. The a/B path IP matrix has previously determined the same switching delay time length (time-delay), which may be 0. The method of determination may be that the control system has issued the same time-delay to the A/B path IP matrix, or that the A/B path IP matrix has been previously configured with the same time-delay, or other methods.
The switching is performed in the real switching process as follows:
511. the control system generates a switching instruction and simultaneously issues the switching instruction to the A-path and B-path IP matrix devices. The instruction contains timestamp (timestamp 1) information of the current moment (acquired by the time synchronization system) of the whole matrix system when the instruction is generated.
512. The A/B path IP matrix takes the time stamp1 in the switching instruction as a time reference, adds a time-delay, and independently determines the RTP timestamp range of the message at the cutting-out moment of the cutting-out signal flow.
513. The A/B path IP matrix independently determines the RTP timestamp range of the message of the cutting signal flow cutting moment determined by the previous step, and determines the RTP sequence number of the last message of the cutting signal flow sent at the cutting moment according to the number of each frame of the message of the cutting signal flow learned in advance, namely, calculates the real cutting switching point.
For example, according to the frame length of the outgoing stream (i.e., 20ms at 50 frames per second) learned before, calculate the RTP timestamp of the outgoing signal stream by taking the RTP timestamp of the outgoing message currently forwarded, which is the RTP timestamp of the outgoing signal stream, as the reference, and calculate the RTP timestamp of the outgoing signal stream by using the current timestamp of the outgoing signal stream as the reference.
N=0 is the cutoff-time 1=cutoff-time, and N > =1, the cutoff-time needs to be a timestamp value smaller than the timestamp1+time-delay that satisfies the maximum.
Assuming that the RTP sequence number of the currently forwarded cut-out signal stream packet is cut-in-sn 1, according to the number M1 of each frame of the cut-out signal stream packet determined previously, it may be determined that a cut-out signal stream packet including a frame end mark may be encountered between cut-in-sn 1 and cut-in-sn 1+m1, and the sequence number of the packet is predicted to be cut-in-sn 2. Then it can be determined that the message with RTP sequence number of cutout-stn2+nm1=cutout-sn 3 is the last message sent at the time of the cut-out signal stream cut-out, and the subsequent messages larger than the sequence number are discarded.
514. The A/B path IP matrix takes the time stamp1 in the switching instruction as a time reference, adds a time-delay, and independently determines the RTP timestamp range of the message at the switching moment of the switching signal flow.
515. The A/B path IP matrix independently determines the RTP timestamp range of the message of the hand-in signal flow hand-in moment determined by the previous step, and determines the RTP sequence number of the first message of the hand-in signal flow sent at the hand-in moment according to the number of each frame of the message of the hand-in signal flow learned in advance, namely, calculates the real hand-in switching point.
If the frame length of the cut-in stream is long (the frame rate of 50 frames per second is 20 ms) according to the previous learning, and the current RTP timestamp of the cut-in message subjected to discarding is taken as a reference to calculate the RTP timestamp of the cut-out signal stream, wherein the RTP timestamp of the cut-in message is calculated by taking the current RTP timestamp of the cut-in message subjected to discarding as a reference.
When n=0, it is the time 1=current-time, and when N > =1, current-time needs to be less than the time-delay value of the timestamp1+time-delay to be the largest.
Assuming that the RTP sequence number of the current cut-in signal stream message subjected to discarding processing is current-sn 1, according to the number M2 of each frame of the cut-in signal stream message determined before, it can be determined that a cut-in signal stream message containing a frame tail mark can be encountered between current-sn 1 and current-sn 1+M2, and the sequence number of the cut-in signal stream message is predicted to be current-sn 2. Then it can be determined that the message with RTP sequence number of current-sn 2+n×m1+1=current-sn 3 is the first message sent at the switching moment of the switching signal flow, and the subsequent messages with sequence number greater than or equal to this sequence number are not discarded but forwarded.
516. The a/B path IP matrix independently calculates the offset value (sn-offset 2) of the RTP sequence number for the output signal stream relative to the RTP sequence number of the hand-in signal stream.
If the RTP sequence number of the first message that the output signal stream is ready to send after switching is 131, but the RTP sequence number of the first message that the hand-in signal stream is ready to forward is 1258, in order to ensure that the RTP sequence number of the output signal stream can continuously increase after switching, the calculated sn-offset 2=131-1258= -1127.
517. The A/B path IP matrix feeds the sn-offset2 back to the control system so that the control system can timely perform error processing when the values of the two paths of feedback are different (if the non-net switching cannot be tolerated, the switching is timely terminated). When the values of the two feedback paths are the same, the control system will update the sn-offset1 stored by the control system with the value.
518. The A/B path matrix completes the switch independently and updates the value of sn-offset1 to sn-offset2.
Example IV
Fig. 6 is a flowchart of a method for implementing a net handoff according to a fourth embodiment of the present application, as shown in fig. 6, including a preliminary action process before a handoff instruction is issued and a real handoff process.
If the control system can be ensured to send a switching instruction to reach the A/B path IP matrix at the same time, the requirement on the control system can be simplified, and the preparation actions to be completed before the switching instruction is sent include:
601. the A/B path IP matrix, the hand-in signal source device and the hand-out signal source device are all subjected to time synchronization in advance through the time synchronization system. In contrast to the embodiment, the control system is no longer required to complete the time synchronization.
602. In order to determine the switching point during switching, the IP matrix device first learns features (such as a frame duration per frame, a number of messages per frame, etc.) of the hand-in signal flow and the hand-out signal flow in advance, and records an internal flow table entry.
603. The a/B path IP matrix has previously determined the same offset value (sn-offset 1) for the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream, which may be 0. The determination may be that the control system has issued the same sn-offset1 to the a/B-way IP matrix, or that the a/B-way IP matrix has negotiated the same sn-offset1 in advance, or that it was determined during a previous handoff, or other method.
604. The a/B path IP matrix has previously determined the same switching delay time length (time-delay), which may be 0. The method of determination may be that the control system has issued the same time-delay to the A/B path IP matrix, or that the A/B path IP matrix has been previously configured with the same time-delay, or other methods.
The switching is performed in the real switching process as follows:
611. the control system generates a switching instruction and simultaneously issues the switching instruction to the A-path and B-path IP matrix devices. In contrast to the embodiment, there is no longer a need to include the information of tiemstamp1 in the control system instructions.
612. The A/B path IP matrix takes the moment of receiving the switching instruction as a time reference, adds a time-delay, and independently determines the RTP timestamp range of the message of the cutting moment of the cutting signal flow.
613. The A/B path IP matrix independently determines the RTP timestamp range of the message of the cutting signal flow cutting moment determined by the previous step, and determines the RTP sequence number of the last message of the cutting signal flow sent at the cutting moment according to the number of each frame of the message of the cutting signal flow learned in advance, namely, calculates the real cutting switching point.
For example, according to the frame length of the outgoing stream (i.e., 20ms at 50 frames per second) learned before, calculate the RTP timestamp of the outgoing signal stream by taking the RTP timestamp of the outgoing message currently forwarded, which is the RTP timestamp of the outgoing signal stream, as the reference, and calculate the RTP timestamp of the outgoing signal stream by using the current timestamp of the outgoing signal stream as the reference.
N=0 is the cutoff-time 1=cutoff-time, and N > =1, the cutoff-time needs to be a timestamp value smaller than the timestamp1+time-delay that satisfies the maximum.
Assuming that the RTP sequence number of the currently forwarded cut-out signal stream packet is cut-in-sn 1, according to the number M1 of each frame of the cut-out signal stream packet determined previously, it may be determined that a cut-out signal stream packet including a frame end mark may be encountered between cut-in-sn 1 and cut-in-sn 1+m1, and the sequence number of the packet is predicted to be cut-in-sn 2. Then it can be determined that the message with RTP sequence number of cutout-stn2+nm1=cutout-sn 3 is the last message sent at the time of the cut-out signal stream cut-out, and the subsequent messages larger than the sequence number are discarded.
614. The A/B path IP matrix takes the moment of receiving the switching instruction as a time reference, adds a time-delay, and independently determines the RTP timestamp range of the message at the switching moment of the switching signal flow.
615. The A/B path IP matrix independently determines the RTP timestamp range of the message of the hand-in signal flow hand-in moment determined by the previous step, and determines the RTP sequence number of the first message of the hand-in signal flow sent at the hand-in moment according to the number of each frame of the message of the hand-in signal flow learned in advance, namely, calculates the real hand-in switching point.
If the frame length of the cut-in stream is long (the frame rate of 50 frames per second is 20 ms) according to the previous learning, and the current RTP timestamp of the cut-in message subjected to discarding is taken as a reference to calculate the RTP timestamp of the cut-out signal stream, wherein the RTP timestamp of the cut-in message is calculated by taking the current RTP timestamp of the cut-in message subjected to discarding as a reference.
When n=0, it is the time 1=current-time, and when N > =1, current-time needs to be less than the time-delay value of the timestamp1+time-delay to be the largest.
Assuming that the RTP sequence number of the current cut-in signal stream message subjected to discarding processing is current-sn 1, according to the number M2 of each frame of the cut-in signal stream message determined before, it can be determined that a cut-in signal stream message containing a frame tail mark can be encountered between current-sn 1 and current-sn 1+M2, and the sequence number of the cut-in signal stream message is predicted to be current-sn 2. Then it can be determined that the message with RTP sequence number of current-sn 2+n×m1+1=current-sn 3 is the first message sent at the switching moment of the switching signal flow, and the subsequent messages with sequence number greater than or equal to this sequence number are not discarded but forwarded.
616. The a/B path IP matrix independently calculates the offset value (sn-offset 2) of the RTP sequence number for the output signal stream relative to the RTP sequence number of the hand-in signal stream.
If the RTP sequence number of the first message that the output signal stream is ready to send after switching is 131, but the RTP sequence number of the first message that the hand-in signal stream is ready to forward is 1258, in order to ensure that the RTP sequence number of the output signal stream can continuously increase after switching, the calculated sn-offset 2=131-1258= -1127.
617. The A/B path IP matrix feeds the sn-offset2 back to the control system so that the control system can timely perform error processing when the values of the two paths of feedback are different (if the non-net switching cannot be tolerated, the switching is timely terminated). When the values of the two feedback paths are the same, the control system will update the sn-offset1 stored by the control system with the value.
618. The A/B path matrix completes the switch independently and updates the value of sn-offset1 to sn-offset2.
In summary, the present application synchronizes according to the net switching command sending time of the control system or the time when the two paths of IP matrices A, B receive the net switching command, and the two paths of IP matrices A, B in the seamless protection switching scene can independently calculate the synchronized net switching point. According to the preliminary action before the net switch and the calculation process of the net switch point, the A, B two paths of IP matrices can independently calculate the RTP sequence number offset of the same output signal stream relative to the hand-in signal stream, so that the messages of the same video content of the output signal stream independently transmitted in A, B paths have the same RTP sequence number. Thereby keeping the A, B signal flow transmission paths required in the seamless protection switch independent in the net switch implementation process.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (9)

1. A method of effecting a net handoff, comprising:
the control system generates a net switching instruction according to net switching operation information of a user, and simultaneously transmits the net switching instruction to the A-path IP matrix device and the B-path IP matrix device;
the A-path IP matrix device determines a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculates a first offset value of the RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream so as to synchronously complete net switching with the B-path IP matrix device by utilizing the first offset value; at the same time
The B-path IP matrix device determines a second RTP sequence number of a cut-out signal stream and a second RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculates a second offset value of the RTP sequence number of an output signal stream relative to the second RTP sequence number of the cut-in signal stream so as to synchronously complete net switching with the A-path IP matrix device by utilizing the second offset value;
the method for determining the first RTP sequence number of the cut-out signal flow and the first RTP sequence number of the cut-in signal flow by the A-path IP matrix device according to the net switching instruction comprises the following steps:
the A-path IP matrix device determines a first cut-out RTP timestamp range of a last message of a cut-out signal flow and a first cut-in RTP timestamp range of a first message of the cut-in signal flow according to the time information of the net switching instruction and a preset first switching delay time;
the A-path IP matrix device determines a first RTP sequence number of a last message of the cut-out signal flow according to the first cut-out RTP time stamp range and the pre-learned number of messages of each frame of the cut-out signal flow; simultaneously, according to the first cut-in RTP timestamp range and the number of each frame of messages of the cut-in signal flow learned in advance, determining a first RTP serial number of a first message of the cut-in signal flow;
the time information refers to the sending time of the control system for simultaneously sending the net switching instruction to the A-path IP matrix device and the B-path IP matrix device; or the receiving time of the net switching instruction received by the A-path IP matrix device.
2. The method of claim 1, wherein before generating the net switch command based on the net switch operation information of the user, the control system further comprises:
and carrying out time synchronization on the control system, the A-path IP matrix device and the B-path IP matrix device through a time synchronization system.
3. The method of claim 2, wherein the determining, by the B-way IP matrix device, the second RTP sequence number of the hand-in signal stream and the second RTP sequence number of the hand-in signal stream according to the net handover command comprises:
the B-path IP matrix device determines a second cut-out RTP timestamp range of a last message of a cut-out signal flow and a second cut-in RTP timestamp range of a first message of the cut-in signal flow according to the time information of the net switching instruction and a second switching delay time length which is preset;
the B-path IP matrix device determines a second RTP sequence number of the last message of the cut-out signal flow according to the second cut-out RTP time stamp range and the pre-learned number of messages of each frame of the cut-out signal flow; determining a second RTP sequence number of a first message of the cut-in signal flow according to the second cut-in RTP time stamp range and the number of messages of each frame of the cut-in signal flow learned in advance;
the first switching delay time length is the same as the second switching delay time length;
the time information refers to the sending time of the control system for simultaneously sending the net switching instruction to the A-path IP matrix device and the B-path IP matrix device; or the receiving time of the net switching instruction received by the B-path IP matrix device.
4. A method according to any one of claims 1-3, further comprising:
the A-path IP matrix device sends the first offset value to the control system, and the B-path IP matrix device sends the second offset value to the control system;
the control system compares the first offset value with the second offset value;
when the first offset value and the second offset value are different, the control system generates a net switching interrupt instruction and issues the net switching interrupt instruction to the A-path IP matrix device and the B-path IP matrix device at the same time, so that the A-path IP matrix device and the B-path IP matrix device terminate the net switching operation according to the net switching interrupt instruction.
5. A method according to any one of claims 1-3, further comprising:
and after the net switching is completed, the A-path IP matrix equipment updates a preset first offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream to a first offset value of the RTP sequence number of the output signal stream relative to the first RTP sequence number of the cut-in signal stream.
6. The method as recited in claim 5, further comprising:
after the net switching is completed, the B-path IP matrix device updates a preset second offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream to a second offset value of the RTP sequence number of the output signal stream relative to the first RTP sequence number of the cut-in signal stream;
wherein, the first offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream is the same as the second offset value of the RTP sequence number of the output signal stream relative to the RTP sequence number of the cut-out signal stream.
7. A system for effecting a net handoff, comprising:
the control system is used for generating a net switching instruction according to net switching operation information of a user and simultaneously transmitting the net switching instruction to the A-path IP matrix equipment and the B-path IP matrix equipment;
the path A IP matrix device is used for determining a first RTP sequence number of a cut-out signal stream and a first RTP sequence number of a cut-in signal stream according to the net switching instruction, and calculating a first offset value of the RTP sequence number of an output signal stream relative to the first RTP sequence number of the cut-in signal stream so as to synchronously complete net switching with the path B IP matrix device by utilizing the first offset value;
the path B IP matrix device is used for determining a second RTP sequence number of a cut-out signal flow and a second RTP sequence number of a cut-in signal flow according to the net switching instruction, and calculating a second offset value of the RTP sequence number of an output signal flow relative to the second RTP sequence number of the cut-in signal flow so as to synchronously complete net switching with the path A IP matrix device by utilizing the second offset value;
the method for determining the first RTP sequence number of the cut-out signal flow and the first RTP sequence number of the cut-in signal flow by the A-path IP matrix device according to the net switching instruction comprises the following steps:
the A-path IP matrix device determines a first cut-out RTP timestamp range of a last message of a cut-out signal flow and a first cut-in RTP timestamp range of a first message of the cut-in signal flow according to the time information of the net switching instruction and a preset first switching delay time;
the A-path IP matrix device determines a first RTP sequence number of a last message of the cut-out signal flow according to the first cut-out RTP time stamp range and the pre-learned number of messages of each frame of the cut-out signal flow; simultaneously, according to the first cut-in RTP timestamp range and the number of each frame of messages of the cut-in signal flow learned in advance, determining a first RTP serial number of a first message of the cut-in signal flow;
the time information refers to the sending time of the control system for simultaneously sending the net switching instruction to the A-path IP matrix device and the B-path IP matrix device; or the receiving time of the net switching instruction received by the A-path IP matrix device.
8. An apparatus, comprising: a memory; a processor; a computer program;
wherein the computer program is stored in the memory and configured to be executed by the processor to implement the method of any of claims 1-6.
9. A computer-readable storage medium, characterized in that a computer program is stored thereon; the computer program being executed by a processor to implement the method of any of claims 1-6.
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