WO2011076121A1

WO2011076121A1 - Signaling processing method in which, control server issues session record to decoder and encoder

Info

Publication number: WO2011076121A1
Application number: PCT/CN2010/080126
Authority: WO
Inventors: Di Zhou; Bo Huang
Original assignee: Hangzhou H3C Technologies Co., Ltd.
Priority date: 2009-12-22
Filing date: 2010-12-22
Publication date: 2011-06-30
Also published as: CN102104505B; CN102104505A

Abstract

A signaling processing method is provided. The method includes: a control server establishes a session between a Decoder (DC) and an Encoder (EC) according to an EC playing request transmitted by the DC to the control server; the control server creates a session record according to the session which has been established; the control server issues the session record to the EC and DC respectively to enable the DC and the EC to perform subsequent session establishment and session release operations directly according to the session record.

Description

SIGNALING PROCESSING METHOD IN WHICH, CONTROL SERVER ISSUES SESSION RECORD TO DECODER AND

ENCODER

BACKGROUND OF THE INVENTION

At present, many advanced IT application systems, such as IP surveillance systems, are centrally controlled, i.e., one control server (or a control server together with a backup control server) is responsible for centralized control of session establishment and session release procedures between terminals in the system. In a centrally controlled IP surveillance system, the central server controls the signal processing procedure between Encoders and Decoders of the surveillance system. This kind of centralized control is good at permission control and signaling interaction restriction. However, it is difficult to scale such systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.l is a flowchart illustrating a signaling processing procedure between devices in an IP surveillance system according to the prior art.

FIG.2 is a flowchart illustrating a signaling processing procedure according to one example

FIG.3 is a schematic diagram illustrating a structure of a control server according to one example.

FIG.4 is a schematic diagram illustrating a structure of a DC according to one example

FIG.5 is a schematic diagram illustrating a structure of an EC according to one example

DETAILED DESCRIPTION

An example of a signal processing procedure in an IP surveillance system having centralized control will now be described. The IP surveillance system includes a control server, an Encoder (EC) and a Decoder (DC). In practical applications, the EC and the DC may respectively have multiple tunnels which are working independently. For simplicity, one EC or one DC in the following represents one tunnel of the EC or the DC but not one physical entity of the EC or the DC.

FIG.l is a flowchart illustrating a signaling processing procedure between devices in the existing IP surveillance system. As shown in FIG.l, the EC and the DC respectively register with the control server and inform the control server of their respective IP address, ID and other necessary information.

After the registration of the EC and the DC, the IP surveillance system may operate normally. When the DC in the IP surveillance system requests video content encoded by the EC, the signaling processing procedure is as follows.

Step 101, the DC transmits an EC playing request to the control server.

When the DC requests video streams encoded by one or more ECs, the DC will transmit an EC playing request to the control server. The EC playing request includes an EC list containing the ECs being requested. If only one video stream is requested, the EC playing request may include only information of the EC corresponding to this video stream. If multiple video streams are requested, the EC playing request may include, besides the EC list, a switch plan. The switch plan includes relevant information of the ECs being requested, relevant information of the DC requesting the video streams and a time period that each EC plays its video stream.

Step 102, the control server assigns a call_ID for the DC.

Step 103, the DC returns a receiving port number used for receiving video streams to the control server.

Step 104, the control server also assigns a call_ID for the EC, transmits the call_ID and an IP address and the receiving port number of the DC to the EC, requesting the EC to transmit its video stream to the DC.

Step 105, the EC informs the control server of a transmitting port number of the EC used for transmitting the video stream.

Step 106, the control server informs an IP address and the transmitting port number of the EC to the DC, and requests the DC to receive the video stream.

The control server will save a session record for the request. The session record is as follows.

Table 1

With respect to different sessions, the control server will assign different call_IDs for the DC or the EC.

When the DC requests to stop playing a certain video stream, the signaling processing procedure is as follows.

Step 107, the DC transmits a message to the control server, requesting to stop playing the video stream of the EC. The message includes the call_ID of the DC.

Step 108, the control server informs the DC to release the call_ID and informs the DC to close its receiving port.

Step 109, the control server finds the session record according to the call_ID of the DC and requests, according to the session record, the EC to release its call_ID, close the video stream and the corresponding transmitting port. At this time, the control server deletes the session record as shown in the above table 1 saved in the control server.

As to the switch, the procedure is slightly different. The EC playing request transmitted by the DC to the control server further includes a switch plan. The switch plan includes the information of the DC, the information of all relevant ECs and a time period that each EC plays its video. As to a certain DC, if the control server finds that a play ending time of an EC arrives, the control server transmits messages to the EC and the DC at the same time requesting them to release their call_IDs, close their ports and deletes the session record. Then, the control server transmits messages to the next EC and the DC to assign call_IDs for them. The next EC and the DC return their port numbers to the control server. The control server informs a transmitting port number and an IP address of the next EC to the DC, informs the receiving port number and the IP address of the DC to the next EC, requests the next EC to transmit its video stream and creates a new session record.

In the existing IP surveillance system, the establishment and release of the session between the EC and the DC are both centrally controlled by the control server. But when the system has a larger scale, if a large amount of DCs frequently switch and change the ECs being requested, the amount of signaling which needs to be processed by the control server will increase dramatically, which is a big challenge to the processing ability of the control server. However, existing control servers are often deficient in their processing abilities, and may become a bottle neck for the performance of the whole IP surveillance system.

One idea described in the following examples is that, the control server issues the session record to the EC and the DC for storage by the EC and the DC. As such, the EC and the DC may directly perform subsequent session establishment and session release operations according to the session record without the participation of the control server. Therefore, the amount of signaling that needs to be processed by the control server may be reduced dramatically. At the same time, since the establishment and the release of the session between the EC and the DC are performed according to the session record issued by the control server and are under the restriction of the session record, the control server still has the power of managing and controlling the EC and DC. Thus, the system is still centrally controlled.

FIG.2 is a flowchart illustrating a signaling processing procedure according to one example. As shown in FIG.2, the flowchart includes the following steps.

Step 201, the control server establishes a session between the DC and the EC according to an EC playing request transmitted to the control server by the DC.

Step 202, the control server creates a session record according to the session established.

Step 203, the control server respectively issues the session record to the EC and the DC.

Step 204, the DC and the EC perform subsequent session establishment and session release operations according to the session record.

The process of the control server establishing the session between the DC and the EC according to the EC playing request in step 201 may be the same as that in the prior art. Reference may be made to steps 101 to 106 shown in FIG.l for an example of the detailed process.

In step 202, the session record created by the control server may be the same as that in the prior art. However, in addition, in order to facilitate the DC and the EC to find their respective counterpart during the subsequent session establishment or session release procedure, an additional item may be added into the session record. The additional item is an EC ID used for identifying the EC. A detailed session record may be as shown in table 2.

Table 2

At step 203 the session record is issued by the control server to the EC and the DC and the EC and the DC save the session record. By saving the session record in the DC and the EC, sessions may subsequently be established between the DC and the EC without the control server (e.g. the DC and the EC can send messages to each other to set-up or end sessions, without needing to communicate via the control server). This effectively reduces the amount of signaling needs to be processed by the control server. At the same time, the establishment and the release of the session are restricted by the session record created and issued by the control server. Thus, the system is still ultimately centrally controlled by the control server.

In step 204, after saving the session record issued by the control server, the DC and the EC may respectively know the port number and the IP address of the EC or the DC they are connected with. At this time, it is ready to perform the subsequent session establishment and session release operations according to the session record.

For example, when the DC requests to stop playing the video stream of an EC, the DC may find a corresponding session record according to the "EC ID" field and directly transmit a message to notify the EC to close the video stream. The message may carry a session ID, such that the EC may know that which session that the DC requests to release. At this time, the DC may reserve the receiving port number. Thus, when the DC requests the video stream of the EC again, the receiving port number may be used directly. Certainly, it is also possible to release the receiving port number. But when the DC requests the video stream of the EC again, the receiving port number may have been occupied by another session. And this session may be affected if the DC still directly uses this receiving port number. After receiving a video stream close message, the EC may further determine whether the session is a unicast session. If it is a unicast session, the EC directly closes the video stream but reserves the transmitting port number. If it is a multicast session, the EC determines whether there are other DCs receiving the video stream. If there is no other DC, the EC closes the video stream; otherwise, the EC does not close the video stream.

When requesting the video stream of the EC again, the DC finds the corresponding session record according to the "EC ID" field and directly transmits an EC playing request to the EC. The EC playing request may include a session ID for facilitating the EC to determine the session. The DC opens its receiving port and prepares to receive the video stream at the same time. After receiving the EC playing request, the EC finds the corresponding session record according to the session ID, opens a corresponding transmitting port and starts to transmit the video stream. In addition, if the number of video streams exceeds the ability of the EC, the EC may return a failure message to the DC and give a relevant prompt.

Although the communication procedure between the DC and the EC in step 204 does not involve the control server, all processing is executed based on the session record issued by the control server at the beginning. Therefore, the control server still has the power of the centralized control. And processing of a large amount of messages such as session establishment and session release in steps 101-105 and 108 in FIG.l is reduced at the same time.

The control server, the DC and the EC save the session record and this occupies some storage space. In order to avoid wasting storage space, when issuing the session record to the DC and the EC, the control server may set an aging time for the session record at the same time. After the DC stops playing the video stream of the EC, an aging timer starts. If the DC requests the video stream of the EC again before the aging timer reaches the aging time, the aging timer of the session record is reset. If the aging timer reaches the aging time, the DC or the EC may transmit a notification to the control server notifying the control server that the aging timer has reached the aging time. After receiving the notification, the control server instructs the EC and the DC to delete the session record. The control server then deletes the session record saved by the control server itself after receiving acknowledgements from the EC and the DC. The control server also requests the DC and the EC to release their call_IDs and close their ports.

If the control server receives a switch plan of the DC, the control server may assign a call_ID respectively to the DC and all relevant ECs following an existing method. The DC and all the relevant ECs return their port numbers to the control server. The control server adds playing information of the DC and all the relevant ECs, i.e. IP addresses and port numbers of the DC and all the relevant ECs, in the existing switch plan. The switch plan in the present example includes the following elements: the DC providing the switch plan, EC IDs arranged in an order of being requested, call_IDs, IP addresses and port numbers of the DC and all the relevant ECs, playing time period of each EC. The control server issues the new switch plan to the DC and each relevant EC. The EC ranking in the first transmits its video stream to the DC first. After the playing time period, the EC stops transmitting the video stream and notifies a next EC to transmit its video stream to the DC. The next EC starts to transmit the video stream to the DC after receiving the notification. The process proceeds similarly until the last EC.

In addition, in order to deal with the situation that an intermediate EC fails, when one EC notifies a next EC, the next EC may return an acknowledgment. If the EC does not receive the acknowledgement, it may directly notify a further next EC to transmit its video stream, the subsequent procedure is similar as the above.

As to other special events, e.g. when the control server changes, such as deleting, the permission of the DC for requesting the video stream of an EC, the control server may find the corresponding session record according to the DC and the EC and transmit a message including a session ID to the DC and the EC, requesting the DC and the EC to release their call_IDs and close their corresponding ports. If there is a switch plan, the control server may transmit the message to all the relevant ECs in the switch plan, requesting these ECs to delete the session record corresponding to the session ID.

For another example, if the DC or the EC fails to keep registered or quit the registration initiatively, the control server may find the session record corresponding to the DC or the EC, finds a relevant counterpart EC or DC, and transmits a message to the counterpart EC or DC, requesting it to delete the corresponding session record, release its call_ID and close its port.

In accordance with the above method, further examples provide a control server, an EC and a DC for implementing the above method.

FIG.3 is a schematic diagram illustrating a structure of a control server according to one example. As shown in FIG.3, the control server includes: a session establishing module 301, adapted to establish a session between a DC and an EC according to an EC playing request transmitted to the control server by the DC; a session record creating module 302, connected with the session establishing module 301 and adapted to create a session record according to the session established; and a session record issuing module 303, connected with the session record creating module 302 and adapted to issue the session record respectively to the EC and the DC.

The control server may further include: a switch plan modifying module 304, connected with the session establishing module 301 and adapted to add, according to a switch plan received from the DC, playing information of the DC and each relevant EC in the switch plan into the switch plan; and a switch plan issuing module 305, connected with the switch plan modifying module 304 and adapted to issue the switch plan added with the playing information to the DC and each relevant EC.

The control server may further include: an aging configuring module 306, connected with the session record issuing module 303 and adapted to configure an aging time for the session record transmitted to the EC and the DC.

In addition, the control server may further include: a session record deleting module 307, connected with the session record creating module 302, adapted to instruct the EC and the DC to delete the session record after receiving a notification from the DC or the EC indicating that an aging timer reaches the aging time, and adapted to delete the session record saved in the control server after receiving acknowledgements from the EC and the DC; and adapted to instruct, when the control server changes the permission of the DC for playing the video stream of the EC, the DC and the EC to delete the session record, release their call_IDs and close their ports; and adapted to instruct, if the DC or the EC fails to keep registered or quit the registration initiatively, a relevant counterpart EC or DC to delete the corresponding session record, release its call_ID and close its port.

FIG.4 is a schematic diagram illustrating a structure of a DC according to one example. As shown in FIG.4, the DC includes: a session record module 401, adapted to receive and save a session record issued by a control server; and a session controlling module 402, connected with the session record module 401 and adapted to directly perform subsequent session establishment and session release operations with the EC according to the session record.

The DC may further include: a session record aging module 403, connected with the session record module 401, adapted to start an aging timer when the DC stops playing a video stream of the EC, and adapted to reset the aging timer of the session record if the DC requests the video stream of the EC again before the aging timer reaches the aging time.

The DC may further include: a session record deleting module 404, connected with the session record module 401, and adapted to transmit a notification to the control server when the aging timer of the session record reaches the aging time; delete the session record saved by the DC after receiving a session record delete instruction and return an acknowledgement to the control server.

FIG.5 is a schematic diagram illustrating a structure of an EC according to one example. As shown in FIG.5, the EC includes: a session record module 501, adapted to receive and save a session record issued by the control server; and a session controlling module 502, connected with the session record module 501, and adapted to directly perform subsequent session establishment and session release operations with the DC according to the session record.

The EC may further include: a session record aging module 503, connected with the session record module 501, and adapted to start an aging timer when the DC stops playing a video stream of the EC, and adapted to reset the aging timer if the DC requests video stream of the EC again before the aging timer reaches the aging time.

The EC may further include: a session record deleting module 504, connected with the session record module 501, and adapted to transmit a notification to the control server when the aging timer of the session record reaches the aging time; and delete the session record saved by the EC when receiving a session record delete instruction and return an acknowledgement to the control server.

Reference may be made to the previously described methods for the detailed operations and functions of each module in the control server, the DC and the EC. Those will not be repeated herein.

It can be seen from the above that, in the signaling processing method, the control server, the DC and the EC provided by the above examples, through saving the session record in the DC and the EC, the session may be established directly between the DC and the EC without the control server, which effectively reduces the amount of signaling needs to be processed by the control server. At the same time, the establishment and the release of the session is restricted by the session record created and issued by the control server. Thus, the control of the control server in the centralized system will not be affected.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims

1. A signaling processing method, applied in an IP surveillance system comprising a control server, an Encoder (EC) and a Decoder (DC), the method comprising: the control server establishing a session between the DC and the EC according to an EC playing request transmitted by the DC to the control server; the control server creating a session record according to the session established; and the control server issuing the session record to the EC and the DC respectively, to enable the DC and the EC to perform subsequent session establishment and session release operations by communication with each other, according to the session record, without participation of the control server.

2. The signaling processing method of claim 1, wherein the DC and the EC directly performing the subsequent session establishment and session release according to the session record comprises: when the DC requests to stop playing a video stream of the EC, notifying, by the DC, the EC to close a video stream directly according to the session record; when the DC requests the video stream of the EC again, requesting, by the DC, the EC to transmit the video stream directly according to the session record.

3. The signaling processing method of claim 2, wherein the session record comprises an EC ID; and the method further comprises: before requesting to stop the video stream of the DC or requesting the EC to transmit the video stream, finding, by the DC, the session record according to the EC ID.

4. The signaling processing method of claim 1, further comprising: when the control server issues the session record to the EC and the DC respectively, configuring, by the control server, an aging time for the session record issued to the EC and the DC; and starting, by the DC, an aging timer when stopping playing a video stream of the EC; if the DC requests the video stream of the EC again before the aging timer reaches the aging time, resetting the aging timer of the session record.

5. The signaling processing method of claim 4, further comprising: instructing, by the control server, the EC and the DC to delete the session record according to a notification transmitted by the DC or the EC notifying that the aging timer reaches the aging time, and deleting, by the control server, the session record saved in the control server after receiving acknowledgements from the EC and the DC.

6. The signaling processing method of claim 1, further comprising: receiving, by the control server, a switch plan transmitted by the DC, adding playing information of the DC and each relevant EC in the switch plan into the switch plan, and issuing the switch plan with the added playing information to the DC and each relevant EC; and transmitting, by a first EC in the switch plan, a video stream to the DC, stopping transmitting the video stream after a playing time period, and notifying a next EC to transmit its video stream to the DC.

7. The signaling processing method of claim 6, wherein the playing information comprises: an IP address and a port number of the DC and each relevant EC.

8. The signaling processing method of claim 1, further comprising: if the control server changes a permission of the DC for playing a video stream of the EC, instructing, by the control server, the DC and the EC to delete the session record, release their call_IDs and close their ports; if the DC or the EC fails to keep registered or quits the registration on its own initiative, instructing, by the control server, a relevant counterpart EC or DC, to delete the session record, release a corresponding call_ID and close a corresponding port.

9. A control server, applied in an IP surveillance system comprising the control server, an Encoder (EC) and a Decoder (DC), comprising: a session establishing module, adapted to establish a session between the EC and the DC according to an EC playing request transmitted by the DC to the control server; a session record creating module, connected with the session establishing module and adapted to create a session record according to the session established; and a session record issuing module, connected with the session record creating module, and adapted to issue the session record to the EC and the DC respectively to enable the EC and the DC to perform subsequent session establishment and session release operations according to the session record without participation of the control server.

10. The control server of claim 9, further comprising: a switch plan modifying module, connected with the session establishing module, and adapted to add to a switch plan received from the DC, playing information of the DC and playing information of each relevant EC in the switch plan ; and a switch plan issuing module, connected with the switch plan modifying module, and adapted to issue the switch plan, with the added playing information, to the DC and each relevant EC.

11. The control server of claim 9, further comprising: an aging configuring module, connected with the session record issuing module, and adapted to configure an aging time for the session record issued to the EC and the DC; a session record deleting module, adapted to instruct the EC and the DC to delete the session record, after receiving a notification from the DC or the EC notifying that the aging timer reaches the aging time, and deleting the session record saved in the control server after receiving acknowledgements from the EC and the DC; adapted to instruct, if the control server changes a permission of the DC for playing a video stream of the EC, the DC and the EC to delete the session record, release their call_IDs and close their ports; and adapted to instruct, if the DC or the EC fails to keep registered or quits the registration, a relevant counterpart EC or DC, to delete the session record, release a corresponding call_ID and close a corresponding port.

12. A Decoder (DC), applied in an IP surveillance system comprising a control server, an Encoder (EC) and the DC, comprising: a session record module, adapted to receive and save a session record issued by the control server; and a session controlling module, connected with the session record module, and adapted to perform subsequent session establishment and session release operations with the EC according to the session record without participation of the control server.

13. The DC of claim 12, further comprising: a session record aging module, connected with the session record module, and adapted to start an aging timer when the DC stops playing a video stream of the EC, and reset the aging timer of the session record if the DC requests video stream of the EC again before the aging timer reaches the aging time; and a session record deleting module, connected with the session record module, and adapted to transmit, when the aging timer of the session record reaches the aging time, a notification to the control server notifying that the aging timer reaches the aging time; delete the session record saved in the DC after receiving a session record delete instruction from the control server and return an acknowledgement to the control server.

14. An Encoder (EC), applied in an IP surveillance system comprising a control server, the EC and a Decoder (DC), comprising: a session record module, adapted to receive and save a session record issued by the control server; and a session control module, connected with the session record module, and adapted to perform subsequent session establishment and session release operations with the DC according to the session record without participation of the control server.

15. The EC of claim 14, further comprising: a session record aging module, connected with the session record module, and adapted to start an aging timer when the DC stops playing a video stream of the EC, and reset the aging timer of the session record if the DC requests the video stream of the EC again before the aging timer reaches the aging time; and a session record deleting module, connected with the session record module, adapted to transmit, when the aging timer reaches the aging time, a notification to the control server notifying the control server that the aging timer reaches the aging time; delete the session record saved in the EC after receiving a session record delete instruction from the control server and return an acknowledgement to the control server.