WO2008101443A1 - Procédé, système et dispositif pour acquérir un flux multimédia - Google Patents

Procédé, système et dispositif pour acquérir un flux multimédia Download PDF

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Publication number
WO2008101443A1
WO2008101443A1 PCT/CN2008/070322 CN2008070322W WO2008101443A1 WO 2008101443 A1 WO2008101443 A1 WO 2008101443A1 CN 2008070322 W CN2008070322 W CN 2008070322W WO 2008101443 A1 WO2008101443 A1 WO 2008101443A1
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WIPO (PCT)
Prior art keywords
endpoint
media stream
media
destination
source
Prior art date
Application number
PCT/CN2008/070322
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English (en)
French (fr)
Inventor
Yun He
Dongming Zhu
Peili Xu
Yuxia Zhang
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Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Publication of WO2008101443A1 publication Critical patent/WO2008101443A1/zh

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/46—Interconnection of networks
    • H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]

Definitions

  • the present invention relates to the field of multimedia communication technologies, and in particular, to a method, system and device for acquiring a media stream.
  • the Session Initiation Protocol is one of the multimedia communication system framework protocols developed by the Internet Engineering Task Force (IETF). It is a text-based application layer control protocol, which is independent of the underlying protocol. Used to create, modify, and terminate multimedia on the Internet.
  • SIP Session Initiation Protocol
  • a multimedia session consists of a set of multimedia senders and receivers and data flows between each other.
  • the multimedia session uses SIP for conversations and follows SIP rules when sending requests during a conversation.
  • the dialog refers to a SIP relationship between the two parties communicating, which provides the necessary state information upon which routing and message ordering between the communicating parties is based.
  • a User Agent (UA, User Agent) or terminal forms the endpoint of a conversation. It sends or receives SIP requests and responses, which is the end of the multimedia stream.
  • a UA is usually a User Equipment (UE), that is, an application on the terminal or a dedicated hardware device.
  • UE User Equipment
  • SIP Session Description Protocol
  • SDP Session Description Protocol
  • the provider provides the respondent with an SDP offer, which contains the media information supported by the provider and the media information to be used, including the type of media, media address and port, the type of codec used by the media, and some related parameter information.
  • the responder responds to the SDP offer based on a series of information such as the content of the SDP offer, its own media capabilities, the type of media that can or will be supported and used, and responds to the SDP offer via SDP answer.
  • the respondent returns the SDP answer to the provider, the media stream provided by the SDP offer needs to be answered one by one.
  • the response to each media stream includes whether the media stream is supported. If the support also needs to return the codec type and response selected by the respondent. The media address and port of the end, and some related parameter information. Eventually, the provider will establish a media channel based on the SDP answer and the respondent.
  • the provisioning/response interaction of the session description protocol is also called The media negotiation interaction, the media negotiation in the present invention refers to the process of using the protocol for interaction. Users sometimes need to obtain media streams between other devices. For example: The user originally used a personal digital assistant (PDA) and a friend video chat. He used the PDA's screen to receive and play the video stream sent by friends, using the PDA. The built-in camera sends its own video stream to friends.
  • PDA personal digital assistant
  • the user wants to obtain a better visual effect, so he wants to operate the projector to obtain the video stream originally received by the PDA, and play the video stream with the projector, but continues to use the camera built in the PDA to send the video stream.
  • the SDP offer/answer model media stream acquisition is not yet possible.
  • the prior art provides a session acquisition method. It is assumed that there is a session between UA2 and UA3, the session includes an audio stream and a video stream, and UA1 wants to switch the session from UA3 to itself.
  • the specific process includes the following steps. :
  • Step a UA1 sends an invite INVITE request message to UA2, the INVITE request message includes an alternate Replaces header field, and the content of the Replaces header field is an original tongue identifier between UA2 and UA3;
  • the INVITE request message is structured as follows:
  • INVITE sip ua2@example.com SIP/2.0
  • Step b UA2 obtains the session to be established by the INVITE request from the Replaces header field, and needs to replace the original session between UA2 and UA3, and UA2 returns a 200 OK response message, indicating Accept the INVITE request;
  • Step c UA1 sends an ACK request message indicating that the new session is successfully established;
  • Step d UA2 assigns the user interface and other resources originally allocated to the replaced session to the new INVITE session, and terminates the replaced session and sends A BYE request to UA3;
  • Step e UA3 returns a 200 OK response message indicating that the replaced session has terminated.
  • UA2 accepts the INVITE request containing the Replaces header field, it switches the entire session belonging to UA3 to UA1, but UA1 cannot obtain part of the media stream in the source session, and the INVITE request Medium UA1 cannot get media streams in multiple sessions. Therefore, in the process of creating the present invention, the inventor has found that at least the following problems exist in the prior art: the session obtaining method provided by the prior art can only acquire one session, cannot obtain part of the media stream in one session, or multiple The media stream in the session.
  • an embodiment of the present invention provides a method, system, and apparatus for acquiring a media stream to solve the problem of acquiring some or all media streams from one or more source tongues.
  • an embodiment of the present invention provides a method for acquiring a media stream, where the method includes:
  • the first endpoint switches the at least one media stream between the second endpoint and the second endpoint to the destination endpoint according to the request message.
  • the embodiment of the present invention further provides a media stream switching device, where the device includes: a receiving unit, configured to receive a media stream clearing message sent by a destination endpoint;
  • a switching unit configured to switch, according to the acquiring the media stream request message, the at least one media stream between the second endpoints that are in conversation with the media stream switching device to the destination endpoint.
  • the embodiment of the invention further provides a device for acquiring a media stream, which is used for acquiring a media stream between other devices, and the device includes:
  • a media stream information unit configured to obtain media stream information from a device that sends a media stream request message
  • a message construction unit configured to: according to the media stream information, construct a media stream request message; a signaling processing unit, configured to send the obtained media stream request message to another device; A media processing unit, configured to interact with other devices to obtain a media stream.
  • an embodiment of the present invention further provides a system for acquiring a media stream, including: a destination endpoint, a first endpoint, and a second endpoint, where
  • the destination endpoint is configured to send a media stream request message to the first endpoint, requesting to obtain at least one media stream between the first endpoint and the second endpoint;
  • the first endpoint is configured to switch at least one media stream between the second endpoint and the second endpoint to the destination endpoint according to the request message.
  • the request message for obtaining the media stream sent by the destination endpoint to the first endpoint includes the information of the media stream to be acquired, and the first endpoint according to the request The message switches the at least one media stream between it and the second endpoint to the destination endpoint, thus enabling partial or full media streams to be retrieved from one or more source sessions.
  • FIG. 1 is a signaling flowchart of a first preferred embodiment of a method for acquiring a media stream according to the present invention
  • FIG. 2 is a signaling flowchart of a second preferred embodiment of a method for acquiring a media stream according to the present invention
  • FIG. 3 is a signaling flowchart of a third preferred embodiment of a method for acquiring a media stream according to the present invention.
  • FIG. 4 is a signaling flowchart of a fourth preferred embodiment of a method for acquiring a media stream according to the present invention.
  • FIG. 5 is a structural diagram of a first preferred embodiment of a media stream obtaining system according to the present invention.
  • FIG. 6 is a structural diagram of a second preferred embodiment of a media stream obtaining system according to the present invention.
  • FIG. 7 is a structural diagram of a preferred embodiment of a media stream obtaining apparatus according to the present invention.
  • FIG. 8 is a structural diagram of a preferred embodiment of a media stream switching device according to the present invention.
  • FIG. 9 is a structural diagram of a third preferred embodiment of a media stream obtaining system according to the present invention.
  • the embodiment of the invention provides a method for acquiring a media stream, a system and a device thereof.
  • the step of the method for obtaining a media stream includes:
  • the first endpoint switches the at least one media stream between the second endpoint and the second endpoint to the destination endpoint according to the request message.
  • the first endpoint may be: a terminal that supports the SIP protocol or an application server in the IMS network
  • the second endpoint may be: a terminal that supports the SIP protocol
  • the destination endpoint may be a SIP support.
  • the terminal of the agreement may be: a terminal that supports the SIP protocol or an application server in the IMS network
  • the second endpoint may be: a terminal that supports the SIP protocol
  • the destination endpoint may be a SIP support.
  • the destination endpoint obtains the media stream information on the first endpoint before sending the media stream request message.
  • the obtaining the media stream request message includes at least the following information: a media stream obtaining indication, configured to indicate, to the first endpoint, a obtaining operation requested by the destination endpoint; and the identifier information of the media stream to be acquired, used for the first endpoint Locate the media stream to be obtained by the destination endpoint.
  • the method may further include: further including a media stream retention indication information or a reason indication.
  • the media stream retention indication information is used to indicate a processing manner of the remaining media streams in the session to which the media stream belongs to be obtained. If the media stream retention indication information requires that the remaining media streams are not retained, the first endpoint deletes the remaining in the identified session. Media stream.
  • the carrying reason indication is used to indicate the description information of the obtaining operation, and the first endpoint displays the information to the user.
  • the first endpoint When the media stream acquisition indication is a direct acquisition mode, the first endpoint performs media negotiation with the destination endpoint to add a media corresponding to the media to be obtained between the destination endpoint and the first endpoint; wherein, the media negotiation passes the A new session established between an endpoint and a destination endpoint or an update of the original session is implemented. After the destination endpoint performs media negotiation with the first endpoint, the first endpoint and the second endpoint interact to delete the media stream to be acquired by the endpoint of the destination.
  • the first endpoint controls and forwards media negotiation between the destination endpoint and the second endpoint, and replaces the first endpoint with the added media stream between the destination endpoint and the second endpoint.
  • the media negotiation between the first endpoint and the second endpoint determined by the identification information of the media stream to be acquired is performed.
  • the mediation between the first endpoint and the second endpoint by the destination endpoint includes one of the following manners: After receiving the media stream request sent by the destination endpoint, the first endpoint obtains the destination endpoint and the media stream to be obtained. Corresponding media information, and initiating media interaction with the second endpoint and subsequent media interaction; the destination endpoint provides the media information corresponding to the media stream to be acquired while obtaining the media stream request, and the first endpoint receives the request for obtaining the media stream After that, media interaction is directly performed with the second endpoint to complete media replacement.
  • the location relationship between the source endpoint, the endpoint, and the destination endpoint In the media session, the source endpoint and the peer endpoint can be understood as performing an end-to-end media stream session, and the destination endpoint acts as a third party. You can request to join the source endpoint and the session to the endpoint, or get the source endpoint and/or media stream to the endpoint: get the media stream of the source endpoint, or get the media stream to the endpoint, or get the source endpoint and the media to the endpoint flow.
  • the first endpoint may determine whether it is a source endpoint or a pair endpoint based on the received media stream clearing message. For example, if the media stream acquisition indication in the received media stream request message is the direct acquisition mode, the endpoint is a pair of endpoints. If the media stream acquisition indication in the message is an indirect acquisition mode, the endpoint is a source endpoint. The details are not described below.
  • the UAs participating in the media stream obtaining operation may be divided into a source endpoint, a pair endpoint, and a destination endpoint, where the source endpoint performs media stream interaction by using a source session established between the endpoints.
  • the destination endpoint obtains the media stream from the source session between the source endpoint and the pair endpoint.
  • the method for obtaining the media stream is divided into two methods: direct media stream acquisition and indirect media stream acquisition.
  • the direct media stream acquisition refers to the destination endpoint directly sending.
  • the SIP message to the endpoint requires that the media stream be obtained from the source session between the endpoint and the source endpoint, and the endpoint switches the media stream in the source session to the session between the endpoint and the destination endpoint according to the SIP message; the indirect media stream is obtained.
  • the destination endpoint sends a SIP message to the source endpoint, requesting to obtain the media stream from the source session between the endpoint and the source endpoint, and the source endpoint switches the media stream in the source session to the session between the endpoint and the destination endpoint according to the SIP message. in.
  • FIG. 1 is a signaling flowchart of a first preferred embodiment of a method for acquiring a media stream according to the present invention.
  • the first audio stream transmits a smooth background music
  • the second audio stream transmits the call between the two endpoints.
  • the destination endpoint obtains the required audio stream (in the present embodiment, the audio stream for transmitting background music) from a source session by using the direct media stream acquisition method, that is, the destination endpoint sends a SIP message to the pair of endpoints according to the SIP message.
  • the endpoint switches the first audio stream in the source session to the session with the destination endpoint, and the specific process includes:
  • Step 101 The destination endpoint obtains the information of the media stream that needs to be obtained, where the information of the media stream may include the media stream identifier of the media stream in the source session, the identifier of the source session where the media stream is located, and the like;
  • the related information of the media stream that needs to be acquired in this embodiment is related information of the first audio stream between the source endpoint and the pair of endpoints.
  • the destination endpoint may adopt one of the following methods, but is not limited to the disclosed method, and obtains information about the media stream that needs to be obtained:
  • the destination endpoint sends a SUBSCRIBE request to the source endpoint to subscribe to the media stream information by using the subscription/notification mechanism, and obtains information about the media stream that needs to be obtained according to the NOTIFY request returned from the source endpoint;
  • the destination endpoint uses the subscription/notification mechanism to send a subscription to the endpoint SUBSCRIBE request to subscribe to the media stream information, and obtain information about the media stream that needs to be obtained according to the notification NOTIFY request returned from the endpoint;
  • the destination endpoint sends a SUBSCRIBE request to the state agent to subscribe to the media stream information by using the subscription/notification mechanism, and obtains information about the media stream that needs to be obtained according to the NOTIFY request returned from the state agent;
  • the destination endpoint receives a reference REFER request sent by another UA (which may be an endpoint, a source endpoint, or another UA), and obtains information about the media stream that needs to be obtained according to the REFER request.
  • another UA which may be an endpoint, a source endpoint, or another UA
  • Step 102 The destination endpoint constructs a SIP message and sends it to the pair of endpoints, requesting to obtain a required media stream from the source session between the source endpoint and the peer endpoint, where the SIP message includes information about the media stream that needs to be acquired;
  • the SIP message may be a SIP request, such as an INVITE request (including an initial INVITE request and an INVITE request in the dialog), an update UPDATE request, or a SIP response, such as a 200 OK response for the INVITE request.
  • a SIP request such as an INVITE request (including an initial INVITE request and an INVITE request in the dialog)
  • an update UPDATE request such as an update UPDATE request
  • SIP response such as a 200 OK response for the INVITE request.
  • the SIP message may include preset operation indication information, an SDP offer provided by the destination endpoint, information of the media stream to be acquired, and cause information.
  • the operation indication information includes the acquisition mode indication information and the media stream retention indication information, where the acquisition mode indication information is used to indicate that the media stream acquisition mode is a direct media stream acquisition mode or an indirect media stream acquisition mode.
  • the obtaining mode indication information indicates that the media stream obtaining mode is a direct media stream obtaining mode.
  • the media stream retention indication information is used to indicate that the processing of the remaining media stream in the source session is performed by the endpoint or the source endpoint after receiving the SIP message, and the processing manner includes the source session continuing to retain the remaining media stream. , and delete the remaining media streams.
  • the operation indication information may be implemented by adding a SIP header field, or by extending an existing Replaces header field, or by extending a message body (SIP providing a message body) carried in the SIP message.
  • the SDP offer provided by the destination endpoint includes an SDP parameter of the media stream that the destination endpoint needs to obtain, and the destination endpoint supports or uses the SDP parameter.
  • the information of the media stream includes a source session identifier, a media stream identifier, and the like.
  • the source session identifier is used to indicate a source session to which the media stream belongs.
  • the media stream identifier may be used to distinguish the media stream from other media streams in the session, or may be used for
  • the identifier of the media stream to be distinguished from other media streams for example, may be the global unique identifier on the endpoint of the received media stream acquisition request.
  • the information of the media stream that needs to be obtained includes the source session identifier and the media stream identifier of the media stream that needs to be obtained;
  • the flow is the entire media stream in the source session between the source endpoint and the pair of endpoints, and the information of the media stream that needs to be obtained may include only the source session identifier, because the source session identifier may be used to indicate that the destination endpoint needs to be obtained only by the source session identifier.
  • the information of the media stream that needs to be obtained may include only the media stream that needs to be obtained.
  • the media stream identifier because the media stream identifier can be used to indicate the media stream that the destination endpoint needs to acquire and the source session to which the media stream belongs.
  • the information about the media stream that needs to be obtained may be located in the header field of the SIP message, or in the SDP offer, or in the header field of the SIP message and in the SDP offer.
  • the endpoint can assign a media stream identifier to each media stream in each session it participates in; if the endpoint is the party that initiated the SDP offer, then it needs to be configured for each SDP offer.
  • the media stream is assigned a media stream identifier; if the endpoint is the party that sends the SDP answer, if it finds that the media stream does not have a media stream identifier in the received SDP offer, then it can allocate for each media stream when answering the SDP answer A media stream identifier.
  • the source endpoint can assign a media stream identifier to each of the media streams in each session it participates in. If the source endpoint is the party that initiated the SDP offer, then it needs to assign a media stream identifier to each media stream when constructing the SDP offer; if the source endpoint is the party that sends the SDP answer, if it finds the media in the received SDP offer The stream does not have a media stream identifier assigned, so a media stream identifier can be assigned to each media stream when answering the SDP answer.
  • the media stream identifier may be in any form. If it is a globally unique identifier on the endpoint of the received media stream acquisition request, it may be a unique number on the requested endpoint generated by an algorithm or randomly generated, or The IP address and port number of the media unit that receives and sends the media stream. If it is The unique identifier in the session, then it may be the sequence number of the media stream in the tongue, or a tag, or the content attribute of the upper layer application to which the media stream belongs, or the type of the media stream.
  • the reason information is used to indicate the related text description information of the direct media stream acquisition or the indirect media stream acquisition operation, and may be located in the operation indication information, or may be located in other header fields.
  • the SIP message is an INVITE request message
  • the SDP offer carried in the INVITE request message includes SDP parameters of the media stream that the destination endpoint needs to obtain.
  • the SDP parameters are supported or intended to be used by the destination endpoint.
  • Media stream ID In this embodiment, the value of the media stream identifier is a sequence number of the media stream in the source session, and " indicates that the first media stream in the source session needs to be acquired.
  • the endpoint returns a "200 OK" response message to the destination endpoint, indicating that the endpoint accepts the INVITE session request, and the SDP carried in the response message
  • the answer includes the SDP parameter of the media stream that needs to be obtained, and the SDP parameter is supported or intended to be used by the endpoint.
  • Step 104 The destination endpoint sends a new session establishment success acknowledgement (ACK) message to the endpoint.
  • Step 105 Send a request to the source endpoint to update the source session, and request to delete the media stream that has been acquired by the destination endpoint.
  • ACK session establishment success acknowledgement
  • the request for updating the source session is an INVITE request, and the following describes the content of the INVITE request:
  • Step 106 The source endpoint accepts the request sent by the endpoint to update the source session, returns a "200 OK" response message to the endpoint, and deletes the media stream obtained by the destination endpoint in the source session;
  • Step 107 The source endpoint sends an acknowledgement message to the endpoint indicating that the source session is updated successfully.
  • the final result is that the new audio stream between the destination endpoint and the pair endpoint includes the first audio stream, and the source endpoint and the source session to the endpoint include the second audio stream.
  • FIG. 2 it is a signaling flowchart of a second preferred embodiment of the method for obtaining a media stream according to the present invention.
  • multiple source endpoints exist, and a media stream exists between each source endpoint and the pair of endpoints; for example, a source endpoint
  • There is an audio stream between the endpoint and the endpoint there is a video stream between the source endpoint 2 and the pair endpoint, and there may also be a source endpoint 3 (not shown).
  • the destination endpoint obtains the required audio stream and video stream from two or more source sessions by direct media stream acquisition.
  • the source endpoints 1 and 2 are described as an example.
  • the specific processes include:
  • Step 201 The target endpoint obtains related information of the media stream that needs to be obtained.
  • the related information of the media stream that needs to be obtained in this embodiment is related information of the audio stream between the source endpoint 1 and the pair endpoint, and related information of the source stream 2 and the video stream between the endpoints.
  • the method for obtaining the related information of the media stream that needs to be obtained by the destination endpoint is the same as that in the first preferred embodiment, and details are not described herein again.
  • Step 202 The destination endpoint constructs a SIP message and sends it to the pair of endpoints, requesting to obtain the required media stream from the source session between the source endpoint 1, the source endpoint 2, and the pair endpoint, where the SIP message includes the media stream that needs to be acquired.
  • the SIP message is an INVITE request message
  • the SDP offer carried in the INVITE request message includes an SDP parameter of the media stream that the destination endpoint needs to obtain, where the SDP parameter is supported or intended to be used by the destination endpoint,
  • the content of the INVITE request message INVITE sip: remote@example.com SIP/2.0
  • the value of the media stream identifier "12456784333224" is a globally unique identifier identifying a media stream on the requested endpoint, which represents the media stream in the source session between the endpoint and source endpoint 1; "876493826224565" is determined on the requested endpoint A globally unique identifier for a media stream that represents the media stream in the source session between the endpoint and source endpoint 2.
  • a preset Retrieval header field is used in the INVITE request to represent the operation indication information, indicating that this is a direct media stream acquisition operation.
  • the value of the first Retrieval header field "123;to-tag aaa;
  • the source session ID corresponds to the source between the endpoint and source endpoint 1.
  • Step 203 The endpoint returns a response message carrying the SDP answer to the destination endpoint according to the received SIP message.
  • a new session is established between the endpoint and the destination endpoint.
  • the new session includes the media stream that the destination endpoint needs to obtain.
  • the endpoint returns a "200 OK" response message to the destination endpoint, indicating that the endpoint accepts the INVITE request, and the response message carries the response to the endpoint.
  • the SDP answer includes the SDP parameters of the media stream that needs to be obtained, and the SDP parameters are supported or intended to be used by the endpoint.
  • Step 204 The destination endpoint sends a confirmation message that the new session is successfully established to the endpoint.
  • Step 205 The endpoint sends a request to the source endpoint 1 to terminate the source session between the two.
  • the request for terminating the source session between the two is a BYE request.
  • Step 206 The source endpoint 1 accepts the request sent by the endpoint to terminate the source session between the two, returns a "200 OK" response message to the endpoint, and terminates the source session between the two.
  • Step 207 The endpoint sends a request to the source endpoint 2 to terminate the source session between the two.
  • the request for terminating the source session between the two is a BYE request.
  • Step 208 The source endpoint 2 accepts the request sent by the endpoint to terminate the source session between the two, to the right The endpoint returns a "200 OK" response message and terminates the source session between the two.
  • the order in which the source endpoints 1 and 2 issue a request to terminate the source session between the two is not limited.
  • the source endpoint 2 may be sent to the source endpoint 2 and then sent to the source endpoint 1.
  • the final result is that the new session between the destination endpoint and the pair endpoint includes an audio stream and a video stream.
  • FIG. 3 is a signaling flowchart of a third preferred embodiment of a method for acquiring a media stream according to the present invention.
  • an audio stream and a video stream exist in the source session between the source endpoint and the pair endpoint, and the destination endpoint obtains the required audio stream from the source session by using the indirect media stream obtaining manner, that is, the destination endpoint sends the SIP message.
  • the source endpoint switches the audio stream in the source session to the session between the destination endpoint and the endpoint, and the specific process includes:
  • Step 301 The destination endpoint obtains related information of the media stream that needs to be obtained.
  • the related information of the media stream that needs to be obtained in this embodiment is related information of the audio stream between the source endpoint and the endpoint.
  • the method for obtaining the related information of the media stream that needs to be obtained by the destination endpoint is the same as that in the first preferred embodiment, and details are not described herein again.
  • Step 302 The destination endpoint constructs a SIP message and sends it to the source endpoint, requesting to obtain a required media stream from the source session between the source endpoint and the peer endpoint, where the SIP message includes information about the media stream to be acquired.
  • the SIP message is an INVITE request message
  • the first session description protocol providing message body (SDP offer 1 ) carried in the INVITE request message includes related SDP parameters of the media stream that the destination endpoint needs to obtain,
  • the SDP parameters are supported or intended to be used by the destination endpoint.
  • the obtaining mode indication information indicates that the media stream capturing mode is the indirect media stream obtaining mode.
  • label represents the media stream identifier.
  • the value of the media stream identifier is the sequence number of the media stream in the source session, and "1" indicates that the first media stream in the source session needs to be obtained.
  • Step 303 The source endpoint sends a request for updating the source session to the endpoint, where the request message includes related parameters of the media stream that the destination endpoint needs to obtain, and optionally, the related parameters of the media stream remaining in the source session.
  • the request for updating the source session is an INVITE request
  • the second session description protocol providing message body (SDP offer 2) carried in the INVITE request message includes related SDP parameters of the media stream that the destination endpoint needs to obtain, And the related SDP parameters of the remaining media streams in the source session.
  • SDP offer 2 the second session description protocol providing message body
  • the SDP offer 2 includes the information of the SDP offer 1, and for the audio stream that needs to be switched,
  • SDP offer 2 Listed in SDP offer 2 are the IP address of the destination endpoint, the port number, and the codec format to be used. These information are extracted from SDP offer 1; for the remaining video stream in the source session, SDP offer 2 The parameters such as the IP address of the source endpoint, the port number, and the codec format to be used are given.
  • Step 304 The endpoint returns a response message to the source endpoint according to the received request for the update source session, and carries the relevant parameters of the media stream that the destination endpoint needs to obtain.
  • the endpoint may further include related parameters of the media stream remaining in the source session.
  • the endpoint returns a "200 OK" response message to the source endpoint, where the response message carries an SDP answer 2 that responds to the endpoint, which includes parameters related to the media stream that the destination endpoint needs to acquire, and remaining in the source session.
  • SDP parameters of the media stream the SDP parameters are supported or intended to be used by the endpoint, and the following is an example of the content of the response message:
  • Step 305 The source endpoint sends an acknowledgment message to the endpoint, indicating that the source session is successfully updated.
  • Step 306 The source endpoint returns a response message carrying the SDP answer to the destination endpoint, and carries the SDP parameter of the media stream that needs to be obtained by the destination endpoint, and the SDP parameter.
  • the destination endpoint can learn the information of the SDP offer/answer interaction and establish a media channel between the endpoint and the endpoint. In order to get the required media stream;
  • the source endpoint returns a "200 OK" response message to the destination endpoint, where the response message carries the SDP answer 1 of the source endpoint response, which includes the relevant parameters of the media stream that the destination endpoint needs to obtain, and these parameters are answered from the SDP.
  • the response message carries the SDP answer 1 of the source endpoint response, which includes the relevant parameters of the media stream that the destination endpoint needs to obtain, and these parameters are answered from the SDP.
  • the following example illustrates the content of the response message: SIP/2.0 200 OK
  • Step 307 The destination endpoint sends an acknowledgement message to the source endpoint, indicating that the session between the destination endpoint and the source endpoint is successfully established.
  • the final result is that a media channel is established between the destination endpoint and the endpoint to transmit the media stream, if the destination endpoint again requests to obtain other media streams, destination endpoints, or addresses of the endpoints from the source endpoint and the endpoint.
  • the destination endpoint and the signaling of the interaction between the endpoints need to be forwarded through the source endpoint.
  • the destination endpoint may perform media negotiation with the endpoint through the source endpoint.
  • the source endpoint may obtain the SDP offer 1 of the destination endpoint through the media response request after receiving the media stream request. Subsequent media negotiation interaction process. Referring to FIG.
  • FIG. 4 it is a signaling flowchart of a method for obtaining a media stream according to a fourth preferred embodiment of the present invention.
  • a media stream exists between the source endpoint and the multiple endpoints.
  • there is an audio stream between the source endpoint and the endpoint 1 a video stream exists between the source endpoint and the endpoint 2, and there is also a peer 3 (not shown).
  • Streaming and video streaming, destination endpoints use indirect media stream retrieval to obtain from two or more source sessions The desired audio stream and video stream.
  • the specific process includes:
  • Step 401 The destination endpoint obtains related information of the media stream that needs to be obtained.
  • the related information of the media stream that needs to be obtained in this embodiment is related information of the audio stream between the source endpoint and the endpoint 1, and related information of the video stream between the source endpoint and the endpoint 2;
  • the method for obtaining the related information of the media stream that needs to be obtained by the destination endpoint is the same as that in the first preferred embodiment, and details are not described herein again.
  • Step 402 The destination endpoint constructs a SIP message and sends it to the source endpoint, requesting to obtain the required media stream from the source endpoint and the source session between the endpoint 1 and the endpoint 2, where the SIP message includes the media stream to be acquired.
  • Information
  • the SIP message is an INVITE request message
  • the SDP offer 1 carried in the INVITE request message includes an SDP parameter of the media stream that the destination endpoint needs to obtain, where the SDP parameter is supported or intended to be used by the destination endpoint.
  • INVITE sip source@example.com SIP/2.0
  • the obtaining mode indication information indicates that the media stream obtaining mode is an indirect media stream acquiring party.
  • the value of the media stream identifier "123abcgkeo224" is a globally unique identifier identifying the media stream on the source endpoint, which represents the media stream in the source session between the source endpoint and the endpoint 1; "zxywhi565dfddf is another media stream identified on the source endpoint Globally unique identifier, which represents the media stream in the source session between the source endpoint and the endpoint 2.
  • the media stream identifier is a globally unique identifier corresponding to the media stream. Therefore, the source session can be learned by the endpoint through the media stream identifier, so the source session identifier can be omitted in the SDP.
  • the preset Indirect-Retrieval header field is used in the INVITE request to represent the operation indication information, indicating that this is an indirect media stream acquisition operation.
  • Step 403 The source endpoint sends a request for updating the source session to the endpoint 1, where the request message is included in the packet.
  • the request for updating the source session is an INVITE request
  • the SDP offer 2 carried in the INVITE request message includes an SDP parameter of the media stream that the destination endpoint needs to obtain, where the SDP parameter is supported or intended to be used by the destination endpoint.
  • INVITE sip remotel@example.com SIP/2.0
  • the SDP offer 2 includes part of the information of the SDP offer 1.
  • the SDP offer 2 lists the IP address, the port number, and the codec format to be used. Extracted from SDP offer 1.
  • Step 404 The endpoint 1 returns a response message to the source endpoint according to the received request for updating the source session, and carries the relevant parameters of the media stream that the destination endpoint needs to retrieve;
  • the endpoint 1 returns a "200 OK" response message to the source endpoint, and the response message carries the SDP answer 2 that responds to the endpoint 1, which includes the SDP parameters of the media stream that the destination endpoint needs to obtain, the SDP
  • the parameter is the following example of the response message that is supported or intended to be used by Endpoint 1:
  • Step 405 The source endpoint sends an acknowledgment message to the endpoint, indicating that the source session is successfully updated.
  • Step 406 The source endpoint sends a request for updating the source session to the endpoint 2, where the request message includes related parameters of the media stream that the destination endpoint needs to obtain. ;
  • the order of the request to update the source session to the endpoints 1, 2 is not limited.
  • the endpoint 2 may be sent to the endpoint 2 and then to the endpoint 1.
  • the request for updating the source session is an INVITE request
  • the SDP offer 3 carried in the INVITE request message includes related SDP parameters of the media stream that the destination endpoint needs to obtain, where the SDP parameter is the destination endpoint support or desire.
  • the following example illustrates the contents of the INVITE request message:
  • the SDP offer 3 includes part of the information of the SDP offer 1.
  • the IP address, the port number, and the codec format to be used are listed in the SDP offer 3. Extracted from SDP offer 1.
  • Step 407 The endpoint 2 returns a response message to the source endpoint according to the received request for updating the source session, and carries the relevant parameters of the media stream that the destination endpoint needs to obtain.
  • the endpoint 2 returns a "200 OK" response message to the source endpoint, and the response message carries the SDP answer 3 that responds to the endpoint 2, and includes the SDP parameter of the media stream that the destination endpoint needs to obtain, the SDP The parameters are supported or intended for Endpoint 2.
  • the following examples illustrate the contents of the response message: SIP/2.0 200 OK
  • Step 408 The source endpoint sends an acknowledgment message to the endpoint 2, indicating that the source session is successfully updated.
  • the source endpoint returns a "200 OK" response message to the destination endpoint, where the response message carries the SDP answer 1 of the source endpoint response, which includes the relevant parameters of the media stream that the destination endpoint needs to obtain, and these parameters are answered from the SDP.
  • SDP answer 1 of the source endpoint response which includes the relevant parameters of the media stream that the destination endpoint needs to obtain, and these parameters are answered from the SDP.
  • SDP answer 3 which is supported or intended for Endpoint 1 or Endpoint 2
  • the following examples illustrate the contents of the response message:
  • Step 410 The destination endpoint sends an acknowledgement message to the source endpoint, indicating that the session between the destination endpoint and the source endpoint is successfully established.
  • the final result is that the destination endpoint and the media channel for endpoint 1 contain one audio stream, and the destination endpoint and the media channel for endpoint 2 contain a video stream.
  • the destination endpoint again requires that other media streams, destination endpoints, or endpoints 1, and endpoint 2 addresses be changed from the source endpoint to either endpoint 1 or pair endpoint 2, the destination endpoint and pair endpoint 1 or pair endpoint 2
  • the signaling of the interaction needs to be forwarded through the source endpoint.
  • the destination endpoint may perform media negotiation with the endpoint through the source endpoint.
  • the source endpoint may obtain the SDP offer 1 of the destination endpoint by using the media response request after receiving the media stream request. Subsequent media negotiation interaction process.
  • FIG. 5 is a structural diagram of a first preferred embodiment of a media stream obtaining system according to the present invention.
  • the media stream obtaining system includes a source end point 51, a pair of end points 52, and a destination end point 53. It should be noted that the pair of end points 52 in the embodiment are after receiving the media stream clearing message sent by the destination end point 53. Determining, according to the media stream acquisition indication of the obtained media stream request message, the processing of the endpoint 52, that is, the first endpoint, and the pair of endpoints 52 corresponding to the direct switching mode of the switching device; the corresponding source endpoint 51 is the second Endpoints, for ease of description, embodiments of the present invention are directly described in terms of the relative concepts of endpoints and source endpoints.
  • the destination endpoint 51 is configured to send a media stream request message to the endpoint 52 or the source endpoint 53 to obtain a media stream in at least one source between the source endpoint 51 and the endpoint 52.
  • the destination endpoint 51 is configured to send, to the endpoint 52 or the source endpoint 53, a request message that needs to obtain media stream information, and obtains a media stream in at least one source session between the source endpoint and the pair endpoint; receiving the request message And an endpoint, configured to switch the media stream in the at least one source session between the source endpoint and the pair endpoint to the destination endpoint and the session to the endpoint according to the request message.
  • the destination endpoint 51 is configured to send, to the endpoint 52, a request message that needs to obtain media stream information, and obtains a media stream in at least one source session between the source endpoint and the pair of endpoints;
  • the pair of endpoints 52 of the request message are configured to switch the media stream in the at least one source session between the source endpoint and the pair endpoint to the destination endpoint and the session to the endpoint according to the request message.
  • the destination endpoint 51 is configured to send, to the source endpoint 53, a request message that needs to obtain media stream information, and obtains a media stream in at least one source session between the source endpoint and the pair endpoint; and receiving the request message
  • the source endpoint 53 is configured to switch the media stream in the at least one source session between the source endpoint and the pair endpoint to the destination endpoint and the session to the endpoint according to the request message.
  • the source endpoint 51 includes a signaling processing unit 511 and a media processing unit 512.
  • the opposite end point 52 includes a media stream identification generating unit 521, a media processing unit 522, a signaling processing unit 523, and an operation processing unit 524.
  • the destination endpoint 53 includes a media stream information unit 531, a message construction unit 532, a signaling processing unit 533, and a media processing unit 534.
  • the media stream information unit 531 of the destination endpoint 53 is configured to obtain the information of the media stream that the destination endpoint needs to obtain.
  • the specific acquisition method and the content included in the information of the media stream may refer to step 101 of the first preferred implementation method.
  • the message construction unit 532 is configured to construct an acquisition media path according to the information of the media stream that the destination endpoint needs to obtain, which is obtained by the media stream information unit 531.
  • the signaling processing unit 533 is configured to send the location.
  • the request message for obtaining the media stream is sent to the pair of endpoints 52; the media processing unit 534 is configured to interact with the endpoint 52 to obtain the media stream that needs to be acquired.
  • the signaling processing unit 511 of the source endpoint 51 is configured to interact with the endpoint 52 for signaling; the media processing unit 512 is configured to interact with the endpoint 52 to interact with the media stream.
  • the media stream identifier generating unit 521 of the endpoint 52 is configured to allocate a media stream identifier to the media stream in the session in which the endpoint participates in advance;
  • the signaling processing unit 522 is configured to receive the media stream sent by the destination endpoint 53. a request message;
  • the operation processing unit 524 acquires a request message of the media stream according to the signaling processing unit 522, and switches the media stream that needs to be acquired by the destination endpoint in the source session with the source endpoint 51 to the destination endpoint 53.
  • the media processing unit 523 is configured to exchange media streams with the source endpoint 51 and the destination endpoint 53.
  • the destination endpoint may obtain the media stream that needs to be obtained from one or more sessions between the one or more source endpoints and the pair of endpoints.
  • FIG. 6 is a structural diagram of a second preferred embodiment of a media stream obtaining system according to the present invention.
  • the media stream acquisition system includes a source endpoint 61, a pair of endpoints 62, and a destination endpoint 63.
  • the source Point 61 is a first endpoint, which is determined to be a source endpoint according to the content of the message after receiving the media stream request message sent by the destination endpoint, and where the source endpoint 61 corresponds to the indirect switching mode of the switching device;
  • the corresponding pair of endpoints 62 is the second endpoint.
  • the embodiments of the present invention directly describe the relative concepts of endpoints and source endpoints.
  • the source endpoint 61 includes a media stream identification generating unit 611, a signaling processing unit 612, a media processing unit 613, and an operation processing unit 614.
  • the pair of endpoints 62 includes a signaling processing unit 621 and a media processing unit 622.
  • the destination endpoint 63 includes a media stream information unit 631, a message construction unit 632, a signaling processing unit 633, and a media processing unit 634.
  • the media stream information unit 631 of the destination endpoint 63 is configured to obtain the information of the media stream that the destination endpoint needs to obtain; the message construction unit 632 is configured to obtain the information of the media stream that needs to be acquired according to the destination endpoint obtained by the media stream information unit 631.
  • the request message for acquiring the media stream is configured; the signaling processing unit 633 is configured to send the request message for acquiring the media stream to the source endpoint 61; and the media processing unit 634 is configured to obtain the required media stream from the endpoint 62.
  • the media stream identifier generating unit 611 of the source endpoint 61 is configured to allocate a media stream identifier to the media stream in the session in which the source endpoint participates in advance;
  • the signaling processing unit 612 is configured to receive the obtained media stream sent by the destination endpoint 63. a request message;
  • the operation processing unit 614 switches the media stream that needs to be acquired by the source endpoint 61 and the destination endpoint in the source session between the endpoints 62 to the request message for obtaining the media stream received by the signaling processing unit 612 to
  • the destination endpoint 63 is in a session with the endpoint 62.
  • the media processing unit 613 is configured to interact with the endpoint 62 to media streams.
  • the signaling processing unit 621 of the pair of endpoints 62 is configured to exchange signaling with the source endpoint 61; the media processing unit 622 is configured to interact with the destination endpoint 63 and the source endpoint 61.
  • the destination endpoint may obtain the media stream that needs to be obtained from one or more sessions between the source endpoint and one or more pairs of endpoints.
  • FIG. 7 is a structural diagram of a preferred embodiment of the apparatus for acquiring a media stream according to the present invention.
  • the acquiring media stream device 70 may be a user terminal or an application server in a network.
  • a media stream information unit 71, a message construction unit 72, a signaling processing unit 73, and a media processing unit 74 are included.
  • the media stream information unit 71 is configured to obtain the information of the media stream that needs to be acquired.
  • the message construction unit 72 is configured to construct a request message for acquiring the media stream according to the information of the media stream that needs to be obtained obtained by the media stream information unit.
  • FIG. 8 is a structural diagram of a media stream switching apparatus according to an embodiment of the present invention.
  • the method for obtaining a media stream according to an embodiment of the present invention, the embodiment of the present invention provides a media stream switching apparatus, where the media stream is switched.
  • the device may be a terminal that supports the SIP protocol or an application server in the IMS network, and specifically includes: a receiving unit 81 and a switching unit 82.
  • the receiving unit 81 is configured to receive a media stream clearing message sent by the destination endpoint, where the switching unit 82 is configured to perform a second session with the media stream switching device according to the acquiring the media stream request message. At least one media stream between the endpoints switches to the destination endpoint.
  • the switching unit 82 includes at least one of the following:
  • the direct switching unit 821 is configured to increase media corresponding to the media to be acquired between the media stream switching device and the destination endpoint, to establish a media channel between the destination endpoint and the media stream switching device, and perform corresponding media transmission;
  • Media negotiation for adding media information establishes a new session or updates an original session between the media stream switching device and the destination endpoint;
  • the indirect switching unit 822 is configured to control media negotiation between the destination endpoint and the second endpoint in the session of the media stream switching device, and replace the media stream between the destination endpoint and the second endpoint to replace the media stream switching device and the second endpoint.
  • the media stream is to be obtained, so that the destination endpoint obtains the media stream; wherein media negotiation between the destination endpoint and the media stream switching device is implemented by establishing a new session or updating the original session; between the media stream switching device and the second endpoint
  • the media negotiation is implemented by the media stream switching device determining the session between the media stream switching device and the second endpoint according to the received identification information of the media stream to be acquired.
  • the media stream switching device further includes at least one of the following:
  • the first deleting unit 83 is connected to the direct switching unit, and configured to delete the media stream to be acquired by the destination endpoint on the media stream switching device after the media stream switching device performs media negotiation with the target endpoint;
  • the second deleting unit 84 is connected to the receiving unit, and configured to determine, according to the media stream reservation indication information carried in the media stream request message, the processing manner of the remaining media stream in the session to which the media stream belongs to be obtained, if the media stream retains the indication information request If the remaining media stream is not retained, the remaining media streams in the identified session are deleted.
  • the media stream switching apparatus further includes: a media stream identifier generating unit, configured to allocate a media stream identifier for the media stream in the participating session in advance.
  • a media stream identifier generating unit configured to allocate a media stream identifier for the media stream in the participating session in advance.
  • a structural diagram of a third preferred embodiment of a system for media stream acquisition includes: a destination endpoint 91, a first endpoint 92, and a second endpoint 93, wherein the destination endpoint 91.
  • the method is configured to send a media stream request message to the first endpoint, requesting to obtain at least one media stream between the first endpoint and the second endpoint, where the first endpoint 92 is configured to send the media stream according to the request message. At least one media stream between the second endpoint is switched to the destination endpoint.
  • the destination endpoint 91 may include: a media stream information unit 911, a message construction unit 912, a signaling processing unit 913, and a media processing unit 914.
  • the media stream information unit 911 is configured to obtain media stream information of the first endpoint;
  • the message constructing unit 912 is configured to: obtain a media stream request message according to the media stream information;
  • the signaling processing unit 913 And the sending the media stream request message to the first endpoint;
  • the media processing unit 914 configured to interact with the first endpoint or the second endpoint to obtain a corresponding media stream.
  • the first endpoint 92 has the same function and function as the media stream switching device, and specifically includes: a receiving unit 921 and a switching unit 922, wherein the switching unit 922 includes at least one of the following: a direct switching unit 9221, indirect switching Unit 9222.
  • the first endpoint 92 may further include a first deleting unit 923 and a second deleting unit 924.
  • the first endpoint 92 may further include a media stream identifier generating unit.
  • the embodiment of the present invention provides a method for acquiring a media stream, which is a method for acquiring a media stream directly or indirectly.
  • the destination endpoint constructs a SIP message and sends it to the peer node, requesting to obtain the desired media stream from the source session between the peer node and the source endpoint.
  • the destination endpoint constructs a SIP message and sends it to the source endpoint, requesting to obtain a desired media stream from the source session between the source endpoint and the peer node; then, the source endpoint accepts the destination endpoint to send After the incoming SIP message, according to the instructions therein, the media stream in the source ⁇ is switched to the session between itself and the peer node.
  • the embodiment of the present invention further provides a media stream obtaining system and device, where the destination endpoint can obtain the media stream identifier of the media stream as needed, from one or more source sessions between the source endpoint and the pair of endpoints.
  • the media stream corresponding to the media stream identifier is obtained, so that some or all of the media streams can be obtained from one or more source sessions.
  • the present invention can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware.
  • the technical solution of the present invention which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a storage medium, including a plurality of instructions for causing a A computer device (which may be a personal computer, server, or network device, etc.) performs the methods described in various embodiments of the present invention.

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Description

媒体流获取方法、 系统及装置
本申请要求于 2007 年 2 月 16 日提交中国专利局、 申请号为 200710079398.2、 发明名称为"媒体流获取方法及其系统、 装置"的中国专利申 请的优先权， 其全部内容通过引用结合在本申请中。
技术领域
本发明涉及多媒体通信技术领域，特别涉及一种媒体流获取方法、 系统及 装置。
背景技术
舌发起协议 (SIP, Session Initiation Protocol)是因特网工程任务组 (IETF, Internet Engineering Task Force)制定的多媒体通信系统框架协议之一， 它是一 个基于文本的应用层控制协议， 它独立于底层协议， 用于建立、修改和终止互 联网上的多媒体^舌。在 SIP中， 多媒体会话是由一组多媒体发送者和接收者 及彼此之间的数据流组成，多媒体会话采用 SIP进行对话并在对话期间发送请 求时遵循 SIP规则。 所述对话指通信双方之间的一种 SIP关系， 它提供了在通 信双方之间进行路由和消息排序时所依据的必要的状态信息。 用户代理 (UA, User Agent)或终端构成对话的端点， 它发送或者接收 SIP请求和响应， 是多媒 体流的终点。 UA通常是用户设备 ( UE, User Equipment )， 即终端上的一个应 用或一个专用的硬件设备。
SIP通常使用^舌描述协议 (SDP, Session Description Protocol)提供 /应答 (offer/answer)模型进行媒体能力的交互， 同时也完成承载能力的协商和承载的 建立。 比如： 提供者向应答者提供一个 SDP offer, 其中包含提供者支持和欲 使用的媒体信息， 包括媒体的类型， 媒体地址和端口， 媒体所采用的编解码类 型以及相关的一些参数信息。应答者根据 SDP offer的内容、 自身的媒体能力、 可以或愿意支持和使用的媒体类型等一系列信息对 SDP offer做出应答， 并且 通过 SDP answer对 SDP offer做出应答。 在应答者向提供者返回 SDP answer 时需要对 SDP offer提供的媒体流逐个进行应答， 对每个媒体流的应答包括是 否支持该媒体流，如果支持还需要返回应答者选用的编解码类型、应答端的媒 体地址和端口、 以及相关的一些参数信息。 最终， 提供者会根据 SDP answer 和应答者建立媒体通道。 一般情况下， 会话描述协议的提供 /应答交互也称为 媒体协商交互， 本发明中的媒体协商就是指使用该协议进行交互的过程。 用户有时需要获取其他设备之间的媒体流，例如： 用户原本使用个人数字 助理器 (PDA, Personal Digital Assistant)和朋友视频聊天，他利用 PDA的屏幕接 收并播放朋友传来的视频流， 利用 PDA内置的摄像头发送自己的视频流给朋 友。 这时， 用户希望获取更好的视觉效果， 于是他想操作投影仪获取原本是 PDA收到的视频流， 并用投影仪播放该视频流， 但继续用 PDA内置的摄像头 发送视频流。通过使用 SDP offer/answer模型，还无法实现媒体流的获取操作。
现有技术提供了一种会话获取方法， 假设 UA2和 UA3之间有一个会话， 该会话包含一个音频流和一个视频流， UA1想把会话从 UA3切换到自己这里， 所述具体过程包括以下步骤：
步骤 a: UA1发送一个邀请 INVITE请求消息给 UA2 , 所述 INVITE请 求消息包括替代 Replaces头域， Replaces头域的内容是 UA2和 UA3之间的原 有 ^舌标识；
所述 INVITE请求消息结构如下：
INVITE sip: ua2@example.com SIP/2.0
To: <sip: ua2@example.com>
From: <sip: ual @example.com>; tag=uvw
Call-ID: 123
Replaces: 456; to-tag=abc; from-tag=def
Contact: <sip: ual @example.com>
Content-Type: application/sdp
v=0
c=IN IP4 192.168.0.10
m=audio 4400 RTP/AVP 0 8
a=sendonly
m=video 5400 RTP/AVP 31 34
a=sendrecv
步驟 b: UA2从 Replaces头域中获得所述 INVITE请求欲建立的会话， 需 要替代 UA2和 UA3之间的原有会话， UA2返回一个 200 OK响应消息， 表明 接受所述 INVITE请求；
步驟 c: UA1发送一个 ACK请求消息， 表明新会话建立成功； 步骤 d: UA2把原来分配给被替代的会话的用户接口和其它资源分配给新 的 INVITE会话 , 并中止被替代的会话 , 并发送一个 BYE请求给 UA3； 步骤 e: UA3返回 200 OK响应消息， 表明被替代的会话已经终止。 从上述会话获取过程可以看出： 当 UA2接受了包含 Replaces 头域的 INVITE请求后， 它把属于 UA3的整个会话切换给了 UA1 , 但是 UA1无法获 取源会话中的部分媒体流， 而且在 INVITE请求中 UA1不能获取多个会话中 的媒体流。 因此， 在进行本发明创造过程中，发明人发现现有技术中至少存在 如下问题：现有技术提供的会话获取方法只能够获取一个会话， 不能够获取一 个会话中的部分媒体流， 或者多个会话中的媒体流。
发明内容
有鉴于此， 本发明实施例提出一种媒体流获取方法、 系统及装置， 以解决 从一个或多个源^舌中获取部分或全部媒体流的问题。
为解决上述技术问题，本发明实施例提供一种媒体流获取的方法，所述方 法包括：
第一端点接收到目的端点发送的获取媒体流请求消息；
第一端点 据所述请求消息将其与第二端点间的至少一个媒体流切换至 目的端点。
另外， 本发明实施例还提供一种媒体流切换装置， 所述装置包括： 接收单元， 用于接收目的端点发送的获取媒体流清求消息；
切换单元，用于根据所述获取媒体流请求消息将与该媒体流切换装置进行 会话的第二端点间的至少一个媒体流切换至目的端点。
本发明实施例再提供一种媒体流获取的装置，用于获取其它设备之间的媒 体流， 所述装置包括：
媒体流信息单元，用于从发送获取媒体流请求消息的设备中获取媒体流信 息；
消息构造单元， 用于根据所述媒体流信息， 构造获取媒体流请求消息； 信令处理单元， 用于向其它设备发送所述获取媒体流请求消息； 媒体处理单元， 用于与其它他设备交互需要获取的媒体流。
此外， 本发明实施例还提供一种媒体流获取的系统， 包括： 目的端点和第 一端点、 第二端点， 其中
所述目的端点， 用于向第一端点发送获取媒体流请求消息，要求获取第一 端点与第二端点之间至少一个媒体流；
所述第一端点，用于根据所述请求消息将其与第二端点之间的至少一个媒 体流切换到目的端点。
通过本发明实施例提供的媒体流获取方法及其系统、装置， 目的端点发送 给第一端点的获取媒体流的请求消息中包括需要获取的媒体流的信息，第一端 点根据所述请求消息将其与第二端点间的至少一个媒体流切换至目的端点，因 此能够实现从一个或多个源会话中获取部分或全部的媒体流。
附图说明
图 1为本发明媒体流获取方法第一较佳实施例的信令流程图；
图 2为本发明媒体流获取方法第二较佳实施例的信令流程图；
图 3为本发明媒体流获取方法第三较佳实施例的信令流程图；
图 4为本发明媒体流获取方法第四较佳实施例的信令流程图；
图 5为本发明媒体流获取系统第一较佳实施例的结构图；
图 6为本发明媒体流获取系统第二较佳实施例的结构图；
图 7为本发明媒体流获取装置较佳实施例的结构图；
图 8为本发明媒体流切换装置较佳实施例的结构图；
图 9为本发明媒体流获取系统第三较佳实施例的结构图。
具体实施方式
本发明实施例提供一种媒体流获取方法及其系统、 装置。 其中， 所述获取 媒体流的方法的步骤包括：
第一端点接收到目的端点发送的获取媒体流请求消息；
第一端点才艮据所述请求消息将其与第二端点间的至少一个媒体流切换至 目的端点。
其中， 所述第一端点可以是： 支持 SIP协议的终端或者 IMS 网络中的应 用服务器， 第二端点可以是： 支持 SIP协议的终端， 目的端点可以是支持 SIP 协议的终端。
优选的， 目的端点在发送获取媒体流请求消息之前，获取第一端点上的媒 体流信息。
其中， 所述获取媒体流请求消息至少包括下述信息： 媒体流获取指示， 用 于向第一端点指示目的端点所请求的获取操作；待获取媒体流的标识信息，用 于第一端点定位目的端点所要获取的媒体流。进一步还可以包括：还包括媒体 流保留指示信息或携带原因指示。所述媒体流保留指示信息，用于指示对待获 取媒体流所属会话中剩余媒体流的处理方式，如果媒体流保留指示信息要求不 保留剩余媒体流，则第一端点删除所标识会话中的剩余媒体流。所述携带原因 指示， 用于表示获取操作的说明信息， 第一端点将该信息显示给用户。
当所述媒体流获取指示为直接获取方式时，第一端点与目的端点进行媒体 协商， 以在目的端点和第一端点间增加待获取媒体对应的媒体； 其中， 所述媒 体协商通过第一端点与目的端点之间建立的新会话或者更新原会话来实现。所 述目的端点与第一端点进行媒体协商后，第一端点和第二端点交互删除其上目 的端点所要获取的媒体流。
当所述媒体流获取指示为间接获取方式时，第一端点控制并转发目的端点 与第二端点间的媒体协商，将目的端点与第二端点间增加的媒体流替代第一端 点与第二端点间的待获取媒体流， 使目的端点获取所述媒体流； 其中， 目的端 点与第一端点间的媒体协商通过建立新会话或者更新原会话来实现；第一端点 与第二端点间的媒体协商通过待获取媒体流的标识信息所确定的第一端点与 第二端点间的 ^舌进行。
其中，所述目的端点通过第一端点与第二端点间进行媒体协商包括下述方 式之一： 第一端点收到目的端点发送的获取媒体流请求后，获取目的端点和待 获取媒体流对应的媒体信息， 并发起与第二端点的媒体交互以及后续媒体交 互； 目的端点在获取媒体流请求的同时提供待获取媒体流对应的媒体信息，第 一端点收到所述获取媒体流请求后，直接与第二端点进行媒体交互，完成媒体 替换。
为了便于本领域技术人员的理解， 以及使本发明的技术方案更加清楚明 白， 请参照附图及实施例， 对本发明做进一步的说明。 需要说明的是， 在本发 明实施例中， 所述源端点、 对端点以及目的端点之间的位置关系： 在媒体会话 中， 源端点和对端点可以理解为进行的是端对端的媒体流会话， 而目的端点作 为第三方， 可以请求加入源端点与对端点的会话， 或者获取源端点和 /或对端 点的媒体流： 即获取源端点的媒体流， 或获取对端点的媒体流， 或获取源端点 和对端点的媒体流。
此外，第一端点可以根据接收到的获取媒体流清求消息来确定自身是源端 点或是对端点。 比如， 如果接收到的获取媒体流请求消息中媒体流获取指示为 直接获取方式， 则该端点为对端点， 如果该消息中的媒体流获取指示为间接获 取方式， 则该端点为源端点。 下述不再赘述。
在下面列举的几个本发明实施例中，参与媒体流获取操作的 UA可分为源 端点、 对端点以及目的端点， 其中， 源端点通过与对端点之间建立的源会话进 行媒体流交互， 目的端点从源端点与对端点之间的源会话中获取媒体流， 所述 获取媒体流方法分为直接媒体流获取和间接媒体流获取两种方式：直接媒体流 获取指的是目的端点直接发送 SIP消息至对端点，要求从对端点与源端点之间 的源会话中获取媒体流，对端点根据 SIP消息把源会话中的媒体流切换至对端 点与目的端点的会话中；间接媒体流获取指的是目的端点发送 SIP消息至源端 点， 要求从对端点与源端点之间的源会话中获取媒体流， 源端点根据 SIP消息 把源会话中的媒体流切换至对端点与目的端点的会话中。
请参照图 1， 为本发明媒体流获取方法第一较佳实施例的信令流程图。 本 实施例中， 源端点与对端点之间存在两个音频流： 比如， 第一个音频流传传输 的是一支动听的背景音乐， 而第二个音频流传输的是两个端点间的通话， 目的 端点采用直接媒体流获取方式从一个源会话中获取需要的音频流（在本实施例 中为传输背景音乐的那个音频流）， 即目的端点发送 SIP消息给对端点， 根据 所述 SIP 消息， 对端点将源会话中的第一个音频流切换至与目的端点的会话 中， 具体过程包括：
步骤 101 : 目的端点获得需要获取的媒体流的信息， 所述媒体流的信息可 以包括媒体流在源会话中的媒体流标识、 媒体流所在源会话的标识等；
本实施例中需要获取的媒体流的相关信息为源端点与对端点之间第一个 音频流的相关信息。 目的端点可以采用以下几种方法之一，但并不限于所公开的方法，获得需 要获取的媒体流的相关信息：
目的端点利用订阅 /通知机制， 向源端点发送 SUBSCRIBE请求订阅媒体 流信息， 并根据从源端点返回的 NOTIFY请求中获得需要获取的媒体流的相 关信息；
目的端点利用订阅 /通知机制 , 向对端点发送订阅 SUBSCRIBE请求订阅 媒体流信息， 并根据从对端点返回的通报 NOTIFY请求中获得需要获取的媒 体流的相关信息；
目的端点利用订阅 /通知机制， 向状态代理发送 SUBSCRIBE请求订阅媒 体流信息， 并根据从状态代理返回的 NOTIFY请求中获得需要获取的媒体流 的相关信息；
目的端点收到另一个 UA (；可以是对端点、源端点或其它 UA)发送来的查阅 REFER请求， 根据 REFER请求中获得需要获取的媒体流的相关信息。
步骤 102: 目的端点构造 SIP消息， 并发送给对端点， 要求从源端点与对 端点之间的源会话中获取需要的媒体流，所述 SIP消息包括需要获取的媒体流 的信息；
所述 SIP消息可以是一个 SIP请求， 例如 INVITE请求（包括初始 INVITE 请求和对话内的 INVITE请求）、更新 UPDATE请求， 也可以是一个 SIP响应， 例如针对 INVITE请求的 200 OK响应等。
所述 SIP消息可以包括预设的操作指示信息、 目的端点提供的 SDP offer. 需要获取的媒体流的信息、 以及原因信息等。
操作指示信息包括获取方式指示信息以及媒体流保留指示信息，所述获取 方式指示信息用于指示媒体流获取方式为直接媒体流获取方式或者间接媒体 流获取方式。本实施例中，获取方式指示信息指示媒体流获取方式为直接媒体 流获取方式。媒体流保留指示信息用于指示执行媒体流获取操作后，收到所述 SIP消息的对端点或源端点对源会话中的剩余媒体流的处理方式， 处理方式包 括源会话继续保留剩余的媒体流， 以及删除剩余的媒体流。所述操作指示信息 可以通过新增 SIP头域来实现， 也可以通过扩展已有的 Replaces头域来实现， 还可以通过扩展 SIP消息中至少携带的消息体（SIP提供消息体）来实现。 所述目的端点提供的 SDP offer, 包括目的端点需要获取的媒体流的 SDP 参数， 目的端点支持或者使用所述 SDP参数。
媒体流的信息包括源会话标识、媒体流标识等， 源会话标识用于指示媒体 流所属于的源会话； 媒体流标识可以用于区别媒体流和所属会话中其他媒体 流，也可以是用于所要获取媒体流区别其他媒体流的一个标识， 比如可以是收 到媒体流获取请求端点上的全局唯一标识。如果需要获取的媒体流为源端点与 对端点之间源会话中部分媒体流，所述需要获取的媒体流的信息包括源会话标 识和需要获取的媒体流的媒体流标识；如果需要获取的媒体流为源端点与对端 点之间源会话中全部媒体流，所述需要获取的媒体流的信息可以仅包括源会话 标识，因为所述 SIP消息中可以仅通过源会话标识来指示目的端点需要获取的 所有媒体流；如果需要获取的媒体流在源会话中的媒体流标识为收到媒体流获 取请求端点上的全局唯一标识，所述需要获取的媒体流的信息可以仅包括需要 获取的媒体流的媒体流标识，因为所述 SIP消息中可以仅通过媒体流标识来指 示目的端点需要获取的媒体流和媒体流所属的源会话。
所述需要获取的媒体流的信息可以位于 SIP消息的头域中 ,或者位于 SDP offer中， 也可以位于 SIP消息的头域中和 SDP offer中。
为实现直接媒体流获取方法，对端点可以为它参与的每个会话中的每个媒 体流分配媒体流标识；假如对端点是发起 SDP offer的一方，那么它在构建 SDP offer时需要为每个媒体流分配一个媒体流标识；如果对端点是发送 SDP answer 的一方， 如果它在收到的 SDP offer中发现媒体流没有分配媒体流标识， 那么 可以在应答 SDP answer时 , 为每个媒体流分配一个媒体流标识。
为实现间接媒体流获取方法，源端点可以为它参与的每个会话中的每个媒 体流分配媒体流标识。假如源端点是发起 SDP offer的一方，那么它在构建 SDP offer时需要为每个媒体流分配一个媒体流标识；如果源端点是发送 SDP answer 的一方， 如果它在收到的 SDP offer中发现媒体流没有分配媒体流标识， 那么 可以在应答 SDP answer时 , 为每个媒体流分配一个媒体流标识。
媒体流标识可以采用任何一种形式，如果它是收到媒体流获取请求端点上 的全局唯一标识，那么它可以是采用某种算法或者随机生成的该被请求端点上 的唯一数， 也可以是收发媒体流的媒体单元的 IP地址和端口号等。 如果它是 在会话中唯一的标识，那么它可以是该媒体流在^舌中的顺序号，也可以是一 个标记，也可以是媒体流所属上层应用的内容属性，也可以是该媒体流的类型 等。
所述原因信息用于指明直接媒体流获取或者间接媒体流获取操作的相关 说明性文字描述信息， 可以位于操作指示信息中， 也可以位于其他头域中等。
本实施例中， 所述 SIP消息为 INVITE请求消息， 所述 INVITE请求消息 携带的 SDP offer中包括目的端点需要获取的媒体流的 SDP参数， 这些 SDP 参数是目的端点支持或欲使用的， 下面举例说明 INVITE消息的内容：
INVITE sip: remote@example.com SIP/2.0
To: <sip: remote@example.com>
From: <sip: destination@example . com>; tag=xyz
Call-ID: 456
Replaces: 123; to-tag=aaa; from-tag=bbb; media-retrieval
preserve-direction=true
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 RTP/AVP 0 96
a=sendrecv
a=label:l
本实施例中，所述 INVITE请求消息通过扩展的 Replaces头域表示操作指 示信息， 其中的参数 media-retrieval表示这是一个直接媒体流获取操作； Replaces头域中的" 123; to-tag=aaa; fiOm-tag=bbb，，指明了源会话标识，源会话标 识对应的源会话标签" preserve-direction"表示媒体流保留指示信息， "true"表示 媒体流获取操作结束后， 将保留源会话中的剩余媒体流。
所述 SDP中， "c= "行代表的是目的端点的 IP地址； "m = "行代表的是目 的端点欲获取的媒体流； "a=label"代表的是目的端点欲获取的媒体流的媒体流 标识。 在本实施例中， 媒体流标识的取值是媒体流在源会话中的顺序号， " 表明需要获取的是源会话中的第一个媒体流。 步骤 103: 对端点根据接收的 SIP消息， 向目的端点返回携带 SDP answer 的应答消息 , 经过目的端点与对端点之间的 SDP offer/answer交互后， 对端点 与目的端点之间建立新会话， 所述新会话中包括目的端点需要获取的媒体流； 本实施例中， 对端点向目的端点返回 "200 OK"响应消息， 表明对端点接 受了所述 INVITE会话请求， 所述响应消息中携带的 SDP answer中包括所述 需要获取的媒体流的 SDP参数， 所述 SDP参数是对端点支持或欲使用的， 下 面举例说明响应消息的内容：
SIP/2.0 200 OK
To: <sip: remote@example.com>; tag=lmn
From: <sip: destination@example . com>; tag=xyz
Call-ID: 456
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.3
m=audio 2000 TP/AVP 0 96
a=sendrecv
在所述 SDP中， "c= "行代表的是对端点的媒体处理单元的 IP地址； "m = " 行代表的是需要获取的媒体流。
步驟 104: 目的端点向对端点发送新会话建立成功的确认 (ACK)消息； 步骤 105: 对端点向源端点发送要求更新源会话的请求， 要求删除目的端 点已经获取的媒体流；
本实施例中， 所述更新源会话的请求为 INVITE请求， 下面举例说明 INVITE请求的内容：
INVITE sip: source@example.com SIP/2.0
To: <sip: source@example.com>; tag=bbb
From: <sip: remote @example . com>； tag=aaa
Call-ID: 123
Content-Type: application/sdp
v=0 c=IN IP4 192.0.0.3
m=audio 0 RTP/AVP 96
m=audio 5500 RTP/AVP 98 99
a=sendrecv
步骤 106: 源端点接受对端点发送的要求更新源会话的请求， 向对端点返 回 "200 OK"响应消息， 并在源会话中删除目的端点获取的媒体流；
步骤 107: 源端点向对端点发送确认消息， 表明源会话更新成功。
本实施例中，最终结果为目的端点与对端点之间新建的 舌中包含第一个 音频流， 源端点与对端点的源会话中包含第二个音频流。
请参照图 2， 为本发明获取媒体流方法第二较佳实施例的信令流程图， 本 实施例中， 存在多个源端点， 各源端点与对端点之间存在媒体流； 例如源端点 1与对端点之间存在一个音频流， 源端点 2与对端点之间存在一个视频流， 还 可以存在一源端点 3 (图未示）， 源端点 3与对端点之间存在一个音频流和一 个视频流。目的端点采用直接媒体流获取方式从两个或多个源会话中获取需要 的音频流以及视频流。 但为描述的方便， 下述以源端点 1、 2为例进行说明， 具体过程包括：
步骤 201 : 目的端点获得需要获取的媒体流的相关信息；
本实施例中需要获取的媒体流的相关信息为源端点 1 与对端点之间音频 流的相关信息， 以及源端点 2与对端点之间的视频流的相关信息。
目的端点获得需要获取的媒体流的相关信息的方法与第一较佳实施中相 同， 这里不再赘述。
步骤 202: 目的端点构造 SIP消息， 并发送给对端点， 要求从源端点 1、 源端点 2与对端点之间的源会话中获取需要的媒体流，所述 SIP消息包括需要 获取的媒体流的信息；
本实施例所述 SIP 消息的类型和包括的内容，可以参考第一较佳实施中步 骤 102中对 SIP消息的类型及其包括内容的描述， 在此不再赘述。
本实施例中， 所述 SIP消息为 INVITE请求消息， 所述 INVITE请求消息 携带的 SDP offer中包括目的端点需要获取的媒体流的 SDP参数， 所述 SDP 参数是目的端点支持或欲使用的， 下面举例说明 INVITE请求消息的内容： INVITE sip: remote@example.com SIP/2.0
To: <sip: remote@example . com>
From: <sip: destination@example . com>; tag=xyz
Call-ID: 456
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 TP/AVP 0 96
a=sendrecv
a=unique-id: 12456784333224
m=video 5400 RTP/AVP 97 98
a=sendrecv
a=unique-id: 876493826224565
本实施例中，获取方式指示信息指示媒体流获取方式为直接媒体流获取方 式，在所述 SDP中的 "a=unique-id"表示这是一个直接媒体流获取操作。媒体流 标识的值" 12456784333224"是所请求端点上确定一个媒体流的全局唯一标识， 它代表对端点和源端点 1之间的源会话中的媒体流； "876493826224565"是所 请求端点上确定另一个媒体流的全局唯一标识，它代表对端点和源端点 2之间 的源会话中的媒体流。 "c= "行代表的是目的端点的媒体处理单元的 IP地址； "m = "行代表的是目的端点欲获取的媒体流。 由于媒体流标识是在对端点中对应 媒体流的全局唯一标识， 因此对端点通过媒体流标识能够获知源会话， 所以 INVITE消息中可以省略源 舌标识。
下面举例说明 INVITE请求消息另一种内容：
INVITE sip: remote@example.com SIP/2.0
To: <sip: remote@example . com>
From: <sip: destination@example.com>; tag=xyz
Call-ID: 456
Retrieval: 123; to-tag=aaa; from-tag=bbb
Retrieval: 135; to-tag=efg; from-tag=hij Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 TP/AVP 0 96
a=sendrecv
m=video 5400 RTP/AVP 97 98
a=sendrecv
在所述 INVITE请求中使用了预设的 Retrieval头域代表操作指示信息，表 明这是一个直接媒体流获取操作。 第一个 Retrieval头域的值" 123; to-tag=aaa;
Figure imgf000015_0001
该源会话标识对应的是对端点和源端点 1 之间的源^ ^舌。另一个 Retrieval头域的值" 135; to-tag=efg; from-tag=hij"代表另 一个源会话标识，该源会话标识对应的是对端点和源端点 2之间的源会话。 因 为目的端点需要获取两个源会话中的全部媒体流， 因此 INVITE消息中可以省 略媒体流标识。
步骤 203: 对端点根据接收的 SIP消息， 向目的端点返回携带 SDP answer 的应答消息， 经过目的端点与对端点之间的 SDP offer/answer交互后， 对端点 与目的端点之间建立新会话， 所述新会话中包括目的端点需要获取的媒体流； 本实施例中， 对端点向目的端点返回 "200 OK"响应消息， 表明对端点接 受了所述 INVITE请求，所述响应消息中携带对端点应答的 SDP answer,其中 包括所述需要获取的媒体流的 SDP参数， 所述 SDP参数是对端点支持或欲使 用的。
步骤 204: 目的端点向对端点发送新会话建立成功的确认消息；
步骤 205: 对端点向源端点 1发出终止两者间的源会话的请求， 本实施例 中终止两者间的源会话的请求为 BYE请求；
步骤 206: 源端点 1接受对端点发送的终止两者间的源会话的请求， 向对 端点返回 "200 OK"响应消息 , 并终止两者间的源会话；
步骤 207: 对端点向源端点 2发出终止两者间的源会话的请求， 本实施例 中终止两者间的源会话的请求为 BYE请求；
步驟 208: 源端点 2接受对端点发送的终止两者间的源会话的请求， 向对 端点返回 "200 OK"响应消息， 并终止两者间的源会话。
上述向源端点 1、 2发出终止两者间的源会话的请求的顺序并不限定， 例 如可以先向源端点 2发， 再向源端点 1发。
本实施例中，最终结果为目的端点和对端点之间新建会话中包含一个音频 流和一个视频流。
请参照图 3， 为本发明媒体流获取方法第三较佳实施例的信令流程图。 本 实施例中， 源端点与对端点之间的源会话存在一个音频流和一个视频流， 目的 端点采用间接媒体流获取方式从所述源会话中获取需要的音频流，即目的端点 发送 SIP消息给源端点， 根据所述 SIP消息， 源端点将源会话中的音频流切换 至目的端点与对端点之间的会话中， 具体过程包括：
步骤 301: 目的端点获得需要获取的媒体流的相关信息；
本实施例中需要获取的媒体流的相关信息为源端点与对端点之间音频流 的相关信息。
目的端点获得需要获取的媒体流的相关信息的方法与第一较佳实施中相 同， 这里不再赘述。
步骤 302: 目的端点构造 SIP消息， 并发送给源端点， 要求从源端点与对 端点之间的源会话中获取需要的媒体流，所述 SIP消息包括需要获取的媒体流 的信息；
本实施例所述 SIP 消息的类型和包括的内容，可以参考第一较佳实施中步 骤 102中对 SIP消息的类型及其包括内容的描述， 在此不再赘述。
本实施例中， 所述 SIP消息为 INVITE请求消息， 所述 INVITE请求消息 携带的第一会话描述协议提供消息体（ SDP offer 1 ) 中包括目的端点需要获取 的媒体流的相关 SDP参数， 所述 SDP参数是目的端点支持或欲使用的， 下面 举例说明 INVITE请求消息的内容：
INVITE sip: source@example.com SIP/2.0
To: <sip: source@example.com>
From: <sip: destination@example . com>; tag=xyz
Call-ID: 135
Indirect-Retrieval： 789; to-tag=abc; from-tag=def; preserve-direction=true Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 TP/AVP 0 96
a=sendrecv
a=label:l
本实施例中，获取方式指示信息指示媒体流莰取方式为间接媒体流获取方 式， 在所述 INVITE请求中， Indirect-Retrieva头域中 1代表操作指示信息， 表 明这是一个间接媒体流获取操作； Indirect-Retrieval头域中的" 789; to-tag=abc; from-tag=def'指明了源会话标识， 所述源会话标识对应的是源端点和对端点之 间的源会话； 标签" preserve-direction"代表保留指示， "true"代表媒体流获取操 作结束后， 将保留源会话中的剩余媒体流。
在 SDP 中， "a=label，，代表媒体流标识， 媒体流标识的取值是媒体流在源 会话中的顺序号， "1"表明需要获取的是源会话中的第一个媒体流。
步骤 303: 源端点向对端点发送更新源会话的请求， 所述请求消息中包括 目的端点需要获取的媒体流的相关参数，可选地，还可以包括源会话中剩余的 媒体流的相关参数；
本实施例中， 所述更新源会话的请求为 INVITE请求， 所述 INVITE请求 消息携带的第二会话描述协议提供消息体（SDP offer 2 )中包括目的端点需要 获取的媒体流的相关 SDP参数，以及源会话中剩余的媒体流的相关 SDP参数， 下面举例说明 INVITE消息的内容：
INVITE sip: remote@example.com SIP/2.0
To: <sip: remote@example.com>; tag=def
From: <sip: source@example.com>; tag=abc
Call-ID: 789
Content-Type: application/sdp
v=0
m=audio 4400 RTP/AVP 0 96
a=sendrecv c=IN IP4 192.0.0.1
m=video 5500 TP/AVP 98 99
a=sendrecv
c=IN IP4 192.0.0.2
所述 SDP offer 2中包含了 SDP offer 1的信息， 对于需要切换的音频流，
SDP offer 2中列出的是目的端点的 IP地址、 端口号和欲使用的编解码格式等 参数， 这些信息是从 SDP offer 1中提取的； 对于源会话中剩余的视频流， SDP offer 2中给出的是源端点的 IP地址、 端口号和欲使用的编解码格式等参数。
步骤 304:对端点根据接收的更新源会话的请求，向源端点返回响应消息， 携带目的端点需要获取的媒体流的相关参数，可选地，还可以包括源会话中剩 余的媒体流的相关参数；
本实施例中， 对端点向源端点返回 "200 OK"响应消息， 所述响应消息中 携带对端点应答的 SDP answer 2,其包括目的端点需要获取的媒体流的相关参 数， 以及源会话中剩余的媒体流的 SDP参数， 所述 SDP参数是对端点支持或 欲使用的， 下面举例说明响应消息的内容：
SIP/2.0 200 OK
To: <sip: remote@example.com>; tag=def
From: <sip: source@example.com>; tag=abc
Call-ID: 789
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.3
m=audio 5000 RTP/AVP 0 96
a=sendrecv
m=video 6000 RTP/AVP 98 99
a=sendrecv
步骤 305: 源端点向对端点发送确认消息， 表明源会话更新成功； 步驟 306:源端点向目的端点返回携带 SDP answer的应答消息，携带目的 端点需要获取的媒体流的 SDP参数， 所述 SDP参数原本是对端点支持或欲使 用的 , 但经过目的端点与源端点、 源端点与对端点之间的 SDP offer/answer交 互后 , 目的端点就可获知该 SDP offer/answer交互的信息并据此与对端点之间 建立媒体通道以便获取需要的媒体流；
本实施例中， 源端点向目的端点返回 "200 OK"响应消息， 所述响应消息 中携带源端点应答的 SDP answer 1 ,其包括目的端点需要获取的媒体流的相关 参数， 这些参数从 SDP answer 2中获取， 下面举例说明响应消息的内容： SIP/2.0 200 OK
To: <sip: source@example.com>; tag=uvw
From: <sip: destination@example . com>; tag=xyz
Call-ID: 135
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.3
m=audio 5000 TP/AVP 0 96
a=sendrecv
步骤 307: 目的端点向源端点发送确认消息， 表明目的端点与源端点之间 的对话建立成功。
本实施例中，最终结果为目的端点和对端点之间建立媒体通道来传送媒体 流， 如果目的端点再次要求从源端点与对端点之间获取其他媒体流、 目的端点 或对端点的地址发生变化等， 目的端点和对端点之间交互的信令需要经过源端 点来转发。本实施例中的目的端点通过源端点与对端点进行媒体协商还可以有 其它方式，如源端点收到获取媒体流请求后通过媒体的提供应答向目的端点获 取目的端点的 SDP offer 1， 再进行后续的媒体协商交互过程。 请参照图 4, 为本发明获取媒体流方法第四较佳实施例的信令流程图， 本 实施例中， 对端点有至少两个， 源端点与多个对端点之间分别存在媒体流， 例 如源端点与对端点 1之间存在一个音频流，源端点与对端点 2之间存在一个视 频流， 还可以存在对端的 3 (图未示）， 源端点与对端点 3之间存在一个音频 流和视频流， 目的端点采用间接媒体流获取方式从两个或多个源会话中获取需 要的音频流以及视频流。 但为描述的方便， 下述以对端点 1、 2为例进行说明， 具体过程包括：
步骤 401 : 目的端点获得需要获取的媒体流的相关信息；
本实施例中需要获取的媒体流的相关信息为源端点与对端点 1 之间音频 流的相关信息， 以及源端点与对端点 2之间的视频流的相关信息；
目的端点获得需要获取的媒体流的相关信息的方法与第一较佳实施中相 同， 这里不再赘述。
步骤 402: 目的端点构造 SIP消息， 并发送给源端点， 要求从源端点分别 与对端点 1、 对端点 2之间的源会话中获取需要的媒体流， 所述 SIP消息包括 需要获取的媒体流的信息；
本实施例所述 SIP 消息的类型和包括的内容,可以参考第一较佳实施中步 骤 102中对 SIP消息的类型及其包括内容的描述， 在此不再赞述。
本实施例中， 所述 SIP消息为 INVITE请求消息， 所述 INVITE请求消息 携带的 SDP offer 1中包括目的端点需要获取的媒体流的 SDP参数， 所述 SDP 参数是目的端点支持或欲使用的 , 下面举例说明 INVITE请求消息的内容： INVITE sip: source@example.com SIP/2.0
To: <sip: source@example.com>
From: <sip: destination@example . com>; tag=xyz
Call-ID: 456
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 TP/AVP 0 96
a=sendrecv
a=uid: 123abcgkeo224
m=video 5400 RTP/AVP 97 98
a=sendrecv
a=uid: zxywhi565dfddf
本实施例中，获取方式指示信息指示媒体流获取方式为间接媒体流获取方 式， 在所 SDP中的 "a=uid"表明这是一个间接媒体流获取操作。 媒体流标识的 值" 123abcgkeo224 "是源端点上确定一个媒体流的全局唯一标识， 它代表源 端点和对端点 1之间的源会话中的媒体流； "zxywhi565dfddf是源端点上确定 另一个媒体流的全局唯一标识，它代表源端点和对端点 2之间的源会话中的媒 体流。 "c= "行代表的是目的端点的 IP地址； "m = "行代表的是目的端点欲获取 的媒体流。 由于媒体流标识是对应媒体流的全局唯一标识， 因此对端点通过媒 体流标识能够获知源会话， 所以 SDP中可以省略源会话标识。
下面举例说明 INVITE请求消息另一种内容：
INVITE sip: source@example.com SIP/2.0
To: <sip: source@example.com>
From: <sip: destination@example . com>; tag=xyz
Call-ID: 456
Indirect-Retrieval： 111; to-tag=hhh; from-tag=jjj
Indirect-Retrieval： 335; to-tag=xcv; lrom-tag=zxd
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 TP/AVP 0 96
a=sendrecv
m=video 5400 RTP/AVP 97 98
a=sendrecv
在所述 INVITE请求中使用了预设的 Indirect-Retrieval头域代表操作指示 信息， 表明这是一个间接媒体流获取操作。 第一个 Indirect-Retrieval头域的值 "111 ; to-tag=hhh; from-tag=jjj"代表一个源会话标识 , 该源会话标识对应的是源 端点和对端点 1 之间的源会话。 另一个 Indirect-Retrieval 头域的值" 335; to-tag=xcv from-tag=zxd"代表另一个源会话标识 , 该源会话标识对应的是源端 点和对端点 2之间的源 舌。因为目的端点需要获取两个源会话中的全部媒体 流 , 因此 SIP消息中可以省略媒体流标识。
步驟 403: 源端点向对端点 1发送更新源会话的请求， 所述请求消息中包 括目的端点需要获取的媒体流的相关参数；
本实施例中， 所述更新源会话的请求为 INVITE请求， 所述 INVITE请求 消息携带的 SDP offer 2中包括目的端点需要获取的媒体流的 SDP参数， 所述 SDP参数是目的端点支持或欲使用的 ,下面举例说明 INVITE请求消息的内容： INVITE sip: remotel@example.com SIP/2.0
To: <sip: remote 1 @example.com>; tag=jjj
From: <sip: source@example.com>; tag=hhh
Call-ID: 111
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=audio 4400 TP/AVP 0 96
a=sendrecv
所述 SDP offer 2中包含了 SDP offer 1的部分信息， 对于需要切换的音频 流， SDP offer 2中列出的是目的端点的 IP地址、 端口号和欲使用的编解码格 式， 这些信息是从 SDP offer 1中提取的。
步骤 404: 对端点 1根据接收的更新源会话的请求， 向源端点返回响应消 息， 携带目的端点需要莰取的媒体流的相关参数；
本实施例中， 对端点 1向源端点返回 "200 OK"响应消息， 所述响应消息 中携带对端点 1应答的 SDP answer 2, 其包括目的端点需要获取的媒体流的 SDP参数， 所述 SDP参数是对端点 1支持或欲使用的下面举例说明响应消息 的内容：
SIP/2.0 200 OK
To: <sip: remote 1 @example.com>; tag=jjj
From: <sip: source@example.com>; tag=hhh
Call-ID: 111
Content-Type: application/sdp
v=0
c=IN IP4 192.168.99.1 m=audio 1000 RTP/AVP 0 96
a=sendrecv
步骤 405: 源端点向对端点发送确认消息， 表明源会话更新成功； 步骤 406: 源端点向对端点 2发送更新源会话的请求， 所述请求消息中包 括目的端点需要获取的媒体流的相关参数；
上述向对端点 1、 2发出更新源会话的请求的顺序并不限定， 例如可以先 向对端点 2发， 再向对端点 1发。
本实施例中， 所述更新源会话的请求为 INVITE请求， 所述 INVITE请求 消息携带的 SDP offer 3中包括目的端点需要获取的媒体流的相关 SDP参数， 所述 SDP参数是目的端点支持或欲使用的， 下面举例说明 INVITE请求消息 的内容：
INVITE sip: remotel@example.com SIP/2.0
To: <sip: remote 1 @example.com>; tag=zxd
From: <sip: source@example.com>; tag=xcv
Call-ID: 335
Content-Type: application/sdp
v=0
c=IN IP4 192.0.0.1
m=video 5400 RTP/AVP 97 98
a=sendrecv
所述 SDP offer 3中包含了 SDP offer 1的部分信息， 对于需要切换的音频 流， SDP offer 3中列出的是目的端点的 IP地址、 端口号和欲使用的编解码格 式 , 这些信息是从 SDP offer 1中提取的。
步驟 407: 对端点 2根据接收的更新源会话的请求， 向源端点返回响应消 息， 携带目的端点需要获取的媒体流的相关参数；
本实施例中， 对端点 2向源端点返回 "200 OK"响应消息， 所述响应消息 中携带对端点 2应答的 SDP answer 3 , 其包括目的端点需要获取的媒体流的 SDP参数， 所述 SDP参数是对端点 2支持或欲使用的， 下面举例说明响应消 息的内容： SIP/2.0 200 OK
To: <sip: remote 1 @example.com>; tag=zxd
From: <sip: source@example.com>; tag=xcv
Call-ID: 335
Content-Type: application/sdp
v=0
c=IN IP4 192.168.99.2
m=video 2000 TP/AVP 97 98
a=sendrecv
步骤 408: 源端点向对端点 2发送确认消息， 表明源会话更新成功； 步骤 409: 源端点向目的端点返回携带 SDP answer的应答消息，携带目的 端点需要获取的媒体流的相关参数， 经过目的端点与源端点、 源端点分别与对 端点 1、对端点 2之间的 SDP offer/answer交互后， 目的端点与对端点 1、对端 点 2之间分别建立媒体通道以便获取需要的媒体流；
本实施例中， 源端点向目的端点返回 "200 OK"响应消息， 所述响应消息 中携带源端点应答的 SDP answer 1 ,其包括目的端点需要获取的媒体流的相关 参数， 这些参数从 SDP answer 2和 SDP answer 3中获取， 是对端点 1或对端 点 2支持或欲使用的， 下面举例说明响应消息的内容：
SIP/2.0 200 OK
To: <sip: source@example.com>; tag=oppe3edd
From: <sip: destination@example.com>; tag=xyz
Call-ID: 456
Content-Type: application/sdp
v=0
m=audio 1000 RTP/AVP 0 96
a=sendrecv
c=IN IP4 192.168.99.1
m=video 2000 RTP/AVP 97 98
a=sendrecv c=IN IP4 192.168.99.2
步驟 410: 目的端点向源端点发送确认消息， 表明目的端点与源端点之间 对话建立成功。
本实施例中，最终结果是目的端点和对端点 1的媒体通道中包含一个音频 流， 目的端点和对端点 2的媒体通道中包含一个视频流。 如果目的端点再次要 求从源端点与对端点 1或对端点 2之间获取其他媒体流、目的端点或对端点 1、 对端点 2的地址发生变化等， 目的端点和对端点 1或对端点 2之间交互的信令 需要经过源端点来转发。本实施例中的目的端点通过源端点与对端点进行媒体 协商还可以有其它方式，如源端点收到获取媒体流请求后通过媒体的提供应答 向目的端点获取目的端点的 SDP offer 1 , 再进行后续的媒体协商交互过程。
请参照图 5， 为本发明媒体流获取系统第一较佳实施例的结构图。 所述媒 体流获取系统包括源端点 51、 对端点 52以及目的端点 53， 需要说明的是，本 实施例中的对端点 52,是在接收到目的端点 53发送的获取媒体流清求消息后， 根据该获取媒体流请求消息的媒体流获取指示来确定是对端点 52的,即第一端 点， 且这里的对端点 52对应切换装置直接切换方式的处理； 相应的源端点 51 就为第二端点， 为了描述方便， 本发明实施例直接采用对端点和源端点这样相 对的概念来描述。
所述目的端点 51， 用于向对端点 52或源端点 53发送需要获取媒体流请 求消息，要求获取源端点 51与对端点 52之间至少一个源^舌中的媒体流； 所 述源端点 52或对端点 53 , 用于 4艮据所述请求消息将源端点 51与对端点 52之 间的至少一个源会话中的媒体流切换到目的端点 53和对端点 52的会话中，即 用于根据所述请求消息将其与第二端点之间的至少一个媒体流切换到目的端 点。
所述目的端点 51， 用于向对端点 52或源端点 53发送需要获取媒体流信 息的请求消息，要求获取源端点与对端点之间至少一个源会话中的媒体流； 接 收所述请求消息的端点 ,用于根据所述请求消息将源端点与对端点之间的至少 一个源会话中的媒体流切换到目的端点和对端点的会话中。
例如， 所述目的端点 51 , 用于向对端点 52发送需要获取媒体流信息的请 求消息，要求获取源端点与对端点之间至少一个源会话中的媒体流； 接收所述 请求消息的所述对端点 52， 用于根据所述请求消息将源端点与对端点之间的 至少一个源会话中的媒体流切换到目的端点和对端点的会话中。
例如， 所述目的端点 51 , 用于向源端点 53发送需要获取媒体流信息的请 求消息，要求获取源端点与对端点之间至少一个源会话中的媒体流；接收所述 请求消息的所述源端点 53 , 用于根据所述请求消息将源端点与对端点之间的 至少一个源会话中的媒体流切换到目的端点和对端点的会话中。
所述源端点 51 包括信令处理单元 511 以及媒体处理单元 512。 所述对端 点 52包括媒体流标识生成单元 521、 媒体处理单元 522、 信令处理单元 523 以及操作处理单元 524。所述目的端点 53包括媒体流信息单元 531、消息构造 单元 532、 信令处理单元 533以及媒体处理单元 534。
所述目的端点 53的媒体流信息单元 531用于获得目的端点需要获取的媒 体流的信息，其具体的获取方法以及该媒体流的信息所包括的内容可以参考方 法第一较佳实施的步骤 101， 在此不再赞述； 所述消息构造单元 532用于根据 媒体流信息单元 531获得的目的端点需要获取的媒体流的信息，构造获取媒体 程； 所述信令处理单元 533用于发送所述获取媒体流的请求消息给对端点 52; 所述媒体处理单元 534用于与对端点 52交互需要获取的媒体流。
所述源端点 51的信令处理单元 511用于与对端点 52交互信令；所述媒体 处理单元 512用于与对端点 52交互媒体流。
所述对端点 52的媒体流标识生成单元 521用于预先为对端点所参与的会 话中的媒体流分配媒体流标识； 所述信令处理单元 522用于接收目的端点 53 发送的获取媒体流的请求消息；所述操作处理单元 524根据所述信令处理单元 522获取媒体流的请求消息， 将与源端点 51之间的源会话中的目的端点需要 获取的媒体流切换至与目的端点 53之间的会话中； 所述媒体处理单元 523， 用于与源端点 51和目的端点 53交互媒体流。
本实施例中，目的端点可以从一个或多个源端点与对端点之间的一个或多 个会话中获得需要获取的媒体流。
请参照图 6， 为本发明媒体流获取系统第二较佳实施例的结构图。 所述媒 体流获取系统包括源端点 61、对端点 62以及目的端点 63。需要说明的是源端 点 61为第一端点， 是在接收到目的端点发送的获取媒体流请求消息后， 根据 该消息的内容来确定是源端点的， 且这里的源端点 61对应切换装置间接切换 方式的处理； 相应的对端点 62即为第二端点， 为了描述方便， 本发明实施例 直接采用对端点和源端点这样相对的概念来描述。 所述源端点 61包括媒体流 标识生成单元 611、 信令处理单元 612、 媒体处理单元 613以及操作处理单元 614。 所述对端点 62包括信令处理单元 621和媒体处理单元 622。 所述目的端 点 63包括媒体流信息单元 631、消息构造单元 632、信令处理单元 633以及媒 体处理单元 634。
所述目的端点 63的媒体流信息单元 631用于获得目的端点需要获取的媒 体流的信息；所述消息构造单元 632用于根据媒体流信息单元 631获得的目的 端点需要获取的媒体流的信息，构造获取媒体流的请求消息； 所述信令处理单 元 633用于发送所述获取媒体流的请求消息给源端点 61 ; 所述媒体处理单元 634用于从对端点 62获取需要的媒体流。
所述源端点 61的媒体流标识生成单元 611用于预先为源端点所参与的会 话中的媒体流分配媒体流标识； 所述信令处理单元 612用于接收目的端点 63 发送的获取媒体流的请求消息；所述操作处理单元 614根据所述信令处理单元 612接收的获取媒体流的请求消息， 将源端点 61与对端点 62之间的源会话中 的目的端点需要获取的媒体流切换至目的端点 63与对端点 62之间的会话中。 所述媒体处理单元 613用于与对端点 62交互媒体流。
所述对端点 62的信令处理单元 621用于与源端点 61交互信令；所述媒体 处理单元 622用于与目的端点 63和源端点 61交互媒体流。
本实施例中，目的端点可以从源端点与一个或多个对端点之间的一个或多 个会话中获得需要获取的媒体流。
请参照图 7， 为本发明获取媒体流装置较佳实施例的结构图。 所述获取媒 体流装置 70, 所述获取媒体流装置 70可以是一个用户终端或者网络中的应用 服务器。 包括媒体流信息单元 71、 消息构造单元 72、 信令处理单元 73、 媒体 处理单元 74。 所述媒体流信息单元 71用于获得需要获取的媒体流的信息； 所 述消息构造单元 72 用于根据媒体流信息单元获得的需要获取的媒体流的信 息， 构造获取媒体流的请求消息； 所述信令处理单元 73用于发送所述获取媒 体流的请求消息； 所述媒体处理单元 74用于从其他设备获取需要的媒体流。 请参阅图 8， 为本发明实施例媒体流切换装置较佳实施例的结构图， 根据 本发明实施例获取媒体流的方法，本发明实施例提供一种媒体流切换装置，所 述媒体流切换装置可以是支持 SIP协议的终端或者 IMS网络中的应用服务器， 具体包括可以包括： 接收单元 81和切换单元 82。 其中， 所述接收单元 81 , 用 于接收目的端点发送的获取媒体流清求消息； 所述切换单元 82， 用于根据所 述获取媒体流请求消息将与该媒体流切换装置进行会话的第二端点间的至少 一个媒体流切换至目的端点。
优选的， 所述切换单元 82至少包括下述一种：
直接切换单元 821 , 用于增加该媒体流切换装置与目的端点间和待获取媒 体对应的媒体，以建立目的端点和该媒体流切换装置间的媒体通道并进行相应 媒体的传输；其中，所述增加媒体信息的媒体协商通过该媒体流切换装置与目 的端点之间建立新会话或者更新原会话；
间接切换单元 822, 用于控制目的端点与该媒体流切换装置进行会话的第 二端点间的媒体协商，并将目的端点与第二端点间增加的媒体流替代媒体流切 换装置和第二端点间的待获取媒体流， 使目的端点获取所述媒体流； 其中， 目 的端点与该媒体流切换装置间的媒体协商通过建立新会话或者更新原会话来 实现；该媒体流切换装置和第二端点间的媒体协商，是由该媒体流切换装置根 据接收到的待获取媒体流的标识信息确定其与第二端点间的会话来实现的。
优选的， 所述媒体流切换装置至少还包括下述一种：
第一删除单元 83 , 与直接切换单元相连， 用于在该媒体流切换装置与目 的端点进行媒体协商后 , 删除该媒体流切换装置上目的端点所要获取的媒体 流； 或者
第二删除单元 84， 与接收单元相连， 用于根据获取媒体流请求消息中携 带的媒体流保留指示信息 ,决定待获取媒体流所属会话中剩余媒体流的处理方 式，如果媒体流保留指示信息要求不保留剩余媒体流，则删除所标识会话中的 剩余媒体流。
优选的， 所述媒体流切换装置还包括： 媒体流标识生成单元， 用于预先为 参与会话中的媒体流分配媒体流标识。 对于本发发明所述媒体流切换装置中各个单元的功能和作用 ,详见上述对 应实施例的具体过程， 在此不再赞述。
请参见提 9， 为本发明实施例媒体流获取的系统第三较佳实施例的结构 图， 所述系统包括： 目的端点 91、 第一端点 92和第二端点 93 , 其中所述目的 端点 91 , 用于向第一端点发送获取媒体流请求消息， 要求获取第一端点与第 二端点之间至少一个媒体流； 所述第一端点 92, 用于根据所述请求消息将其 与第二端点之间的至少一个媒体流切换到目的端点。
优选的， 所述目的端点 91 可以包括： 媒体流信息单元 911、 消息构造单 元 912、 信令处理单元 913和媒体处理单元 914。 其中， 所述媒体流信息单元 911 , 用于获得第一端点的媒体流信息； 所述消息构造单元 912 , 用于根据媒 体流信息， 构造获取媒体流请求消息； 所述信令处理单元 913， 用于向第一端 点发送所述获取媒体流请求消息； 所述媒体处理单元 914， 用于与第一端点或 第二端点交互获取对应的媒体流。
所述第一端点 92与上述媒体流切换装置的功能和作用相同， 具体包括： 接收单元 921和切换单元 922， 其中所述切换单元 922至少包括下述一种： 直 接切换单元 9221 , 间接切换单元 9222。
优选的，所述第一端点 92还可包括第一删除单元 923和第二删除单元 924。 优选的， 所述第一端点 92还可包括媒体流标识生成单元。
对于本发发明所述媒体流切换系统中各个单元的功能和作用，详见上述对 应实施例的具体过程， 在此不再赘述。
由此可见，本发明实施例提供了媒体流获取的方法，分别是通过直接或间 接获取媒体流的方法。在直接媒体流获取方法中： 目的端点构造 SIP消息并发 送给对端结点， 要求从对端结点与源端点之间的源会话中获取希望的媒体流。 在间接媒体流获取方法中： 首先， 目的端点构造 SIP消息并发送给源端点， 要 求从源端点与对端结点之间的源会话中获取希望的媒体流； 然后， 源端点接受 目的端点发来的 SIP消息后，根据其中的指示把源^ ^中的媒体流切换到自己 和对端结点的会话中。
为此，本发明实施例还提供了的媒体流获取系统及装置， 目的端点可以根 据需要获取媒体流的媒体流标识，从源端点与对端点之间的一个或多个源会话 中获得与媒体流标识对应的媒体流，因此能够实现从一个或多个源会话中获取 部分或全部的媒体流。
通过以上的实施方式的描述，本领域的技术人员可以清楚地了解到本发明 可借助软件加必需的通用硬件平台的方式来实现， 当然也可以通过硬件实现。 基于这样的理解，本发明的技术方案本质上或者说对现有技术做出贡献的部分 可以以软件产品的形式体现出来， 该计算机软件产品存储在一个存储介质中， 包括若干指令用以使得一台计算机设备（可以是个人计算机， 服务器， 或者网 络设备等）执行本发明各个实施例所述的方法。
以上对本发明所提供的一种媒体流获取方法及其系统、 装置行了详细介 例的说明只是用于帮助理解本发明所揭示的技术方案； 同时，对于本领域的一 般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之 处， 综上所述， 本说明书内容不应理解为对本发明的限制。

Claims

权 利 要 求
1、 一种获取媒体流的方法， 其特征在于， 包括步驟：
第一端点接收到目的端点发送的获取媒体流请求消息；
第一端点根据所述请求消息将其与第二端点间的至少一个媒体流切换至 目的端点。
2、 根据权利要求 1所述的获取媒体流的方法， 其特征在于， 所述媒体流 请求消息至少包括下述信息：
媒体流获取指示， 用于向第一端点指示目的端点所请求的获取操作； 待获取媒体流的标识信息， 用于第一端点定位目的端点所要获取的媒体 流。
3、 根据权利要求 2所述的获取媒体流的方法， 其特征在于， 当所述媒体 流获取指示为直接获取方式时，所述第一端点根据所述请求消息将其与第二端 点间的至少一个媒体流切换至目的端点的具体方式为：
第一端点与目的端点进行媒体协商，以在目的端点和第一端点间增加待获 取媒体对应的媒体。
4、 根据权利要求 3所述的媒体流获取的方法， 其特征在于， 所述目的端 点与第一端点进行媒体协商后，第一端点和第二端点交互删除其上目的端点所 要获取的媒体流。
5、 根据权利要求 2所述的媒体流获取的方法， 其特征在于， 当所述媒体 流获取指示为间接获取方式时，所述第一端点根据所述请求消息将其与第二端 点间的至少一个媒体流切换至目的端点的具体方式为：
第一端点控制目的端点通过第一端点与第二端点进行媒体协商，将目的端 点与第二端点间增加的媒体流替代第一端点与第二端点间的待获取媒体流，使 目的端点获取所述媒体流。
6、 根据权利要求 5所述的媒体流获取的方法， 其特征在于， 所述第一端 点控制目的端点与第二端点间进行媒体协商包括下述方式之一：
第一端点收到目的端点发送的获取媒体流请求后，获取目的端点和待获取 媒体流对应的媒体信息，发起与第二端点的媒体协商以及完成目的端点与第二 端点间通过第一端点进行的媒体交互， 以使该媒体替换待获取的媒体； 目的端点在获取媒体流请求的同时提供待获取媒体流对应的媒体信息，第 一端点收到所述获取媒体流请求后，发起与第二端点的媒体协商及后续目的端 点与第二端点间通过第一端点进行的媒体协商的交互， 以完成媒体替换。
7、 根据权利要求 3或 5所述的获取媒体流的方法， 其特征在于， 所述媒 体流请求消息中还包括媒体流保留指示信息，用于指示对待获取媒体流所属会 话中剩余媒体流的处理方式。
8、 根据权利要求 2所述的媒体流获取的方法， 其特征在于， 所述媒体流 请求消息还包括： 携带原因指示， 用于表示获取操作的说明信息。
9、 根据权利要求 1所述的媒体流获取的方法， 其特征在于， 所述方法还 包括： 目的端点在发送获取媒体流请求消息之前，获取第一端点上的媒体流信
'&。
10、根据权利要求 1所述的媒体流获取的方法， 其特征在于， 所述方法还 包括： 第一端点预先为参与会话中的媒体流分配媒体流标识。
11、 一种媒体流切换装置， 其特征在于， 包括：
接收单元， 用于接收目的端点发送的获取媒体流请求消息；
切换单元，用于根据所述获取媒体流请求消息将与该媒体流切换装置进行 会话的第二端点间的至少一个媒体流切换至目的端点。
12、 根据权利要求 11所述的媒体流切换装置， 其特征在于， 所述切换单 元至少包括下述一种：
直接切换单元，用于增加该媒体流切换装置与目的端点间和待获取媒体对 应的媒体， 以建立目的端点和该设备间的媒体通道并进行相应媒体的传输； 间接切换单元，用于控制目的端点与该媒体流切换装置进行会话的第二端 点间的媒体协商，并将目的端点与第二端点间增加的媒体流替代媒体流切换装 置的第二端点间的待获取媒体流， 使目的端点获取所述媒体流。
13、 根据权利要求 12所述的媒体流切换装置， 其特征在于， 所述媒体流 切换装置至少还包括下述一种：
第一删除单元， 与直接切换单元相连，用于在该媒体流切换装置与目的端 点进行媒体协商后， 删除该媒体流切换装置上目的端点所要获取的媒体流； 第二删除单元， 与接收单元相连，用于根据获取媒体流请求消息中携带的 媒体流保留指示信息， 决定待获取媒体流所属会话中剩余媒体流的处理方式， 如果媒体流保留指示信息要求不保留剩余媒体流，则删除所标识会话中的剩余 媒体流。
14、 根据权利要求 11所述的媒体流切换装置， 其特征在于， 所述媒体流 切换装置还包括：媒体流标识生成单元，用于预先为参与会话中的媒体流分配 媒体流标识。
15、 一种媒体流获取的装置， 其特征在于， 所述装置包括：
媒体流信息单元，用于从发送获取媒体流请求消息的设备中获取媒体流信 白 - 消息构造单元， 用于根据所述媒体流信息， 构造获取媒体流请求消息； 信令处理单元， 用于向其它设备发送所述获取媒体流请求消息； 媒体处理单元， 用于与其它他设备交互需要获取的媒体流。
16、 一种媒体流获取的系统， 其特征在于， 包括： 目的端点、 第一端点和 第二端点， 其中
所述目的端点，用于向第一端点发送获取媒体流请求消息，要求获取第一 端点与第二端点之间至少一个媒体流；
所述第一端点，用于根据所述请求消息将其与第二端点之间的至少一个媒 体流切换到目的端点。
17、 根据权利要求 16所述的媒体流获取的系统， 其特征在于， 所述目的 端点包括：
媒体流信息单元， 用于获得第一端点的媒体流信息；
消息构造单元， 用于根据媒体流信息， 构造获取媒体流请求消息； 信令处理单元， 用于向第一端点发送所述获取媒体流请求消息； 媒体处理单元 , 用于与第一端点或第二端点交互获取对应的媒体流。
18、 根据权利要求 16所述的媒体流获取的系统， 其特征在于， 所述第一 端点包括：
接收单元， 用于接收目的端点发送的获取媒体流清求消息；
切换单元，用于根据所述获取媒体流请求消息将与该媒体流切换装置进行 会话的第二端点间的至少一个媒体流切换至目的端点。
19、 根据权利要求 18所述的媒体流获取系统， 其特征在于， 所述切换单 元至少包括下述一种：
直接切换单元， 用于增加该设备与目的端点间和待获取媒体对应的媒体， 以建立目的端点和该设备间的媒体通道并进行相应媒体的传输；
间接切换单元， 用于控制目的端点通过第一端点与第二端点间的媒体协 商，并将目的端点与第二端点间增加的媒体流替代第一端点和第二端点间的待 获取媒体流， 使目的端点获取所述媒体流。
20、 根据权利要求 19所述的媒体流获取系统， 其特征在于， 所述系统还 包括：
第一删除单元， 与直接切换单元相连，用于在该设备与目的端点进行媒体 协商后， 删除该设备上目的端点所要获取的媒体流；
第二删除单元， 与接收单元相连，用于根据获取媒体流请求消息中携带的 媒体流保留指示信息， 决定待获取媒体流所属会话中剩余媒体流的处理方式， 如果媒体流保留指示信息要求不保留剩余媒体流，则删除所标识会话中的剩余 媒体流。
21、 根据权利要求 16所述的媒体流获取系统， 其特征在于， 所述系统还 包括:媒体流标识生成单元，用于预先为参与会话中的媒体流分配媒体流标识。
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CN1738267A (zh) * 2004-08-20 2006-02-22 华为技术有限公司 实现媒体流旁路的方法
CN1848885A (zh) * 2005-04-13 2006-10-18 华为技术有限公司 通信系统中的呼叫代答方法
CN1874380A (zh) * 2005-11-09 2006-12-06 华为技术有限公司 通话的实现方法

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CN1848885A (zh) * 2005-04-13 2006-10-18 华为技术有限公司 通信系统中的呼叫代答方法
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