A multi-call audio and video forwarding method and device based on voice energy detection

Abstract

This invention discloses a method and apparatus for multi-call audio and video forwarding based on voice energy detection, relating to the field of SIP monitoring equipment technology. The method includes a bridging marking process, an audio and video stream identification process, a multicast copying process, an energy detection and source switching process, and a selective routing process. By selectively forwarding audio and video media streams in multi-call scenarios, only the currently active SIP terminal is allowed to output audio and video to the called device, while blocking audio communication between other SIP terminals. This invention provides a method and apparatus for multi-call audio and video forwarding based on voice energy detection, effectively avoiding crosstalk, noise interference, and privacy leaks caused by traditional multi-party mixing methods, significantly improving the privacy and call quality during communication.

Description

Technical Field

[0001] This invention relates to the field of SIP monitoring equipment technology, and in particular to a method and apparatus for multi-channel call audio and video forwarding based on voice energy detection. Background Technology

[0002] In existing multi-party audio and video calls (such as SIP-based soft mixing or MCU / SFU multi-party conferencing bridging systems) or video surveillance scenarios, conventional solutions typically decode and mix the audio and video signals of all participants before distributing them uniformly. However, in application scenarios where "the called device (e.g., a centralized display or monitored object) simultaneously communicates with multiple SIP terminals," the mixing and broadcasting mechanisms have the following serious drawbacks: 1. Mutual interference problem: The audio from multiple SIP terminals is mixed before being sent to the called device, which can easily cause noise and interference. At the same time, the audio from each SIP terminal can also be heard by each other, which not only lacks privacy but also introduces unnecessary environmental noise.

[0003] 2. Waste of computing power: In many-to-one communication scenarios, the indiscriminate global media collection, mixing and distribution consume a large amount of DSP (digital signal processing) and CPU computing resources of the system server.

[0004] 3. Unclear visual focus: Traditional video streams usually only display a fixed image or use split-screen display, and cannot intelligently and smoothly switch the main visual image of the called device in real time according to "who is speaking".

[0005] 4. Susceptible to noise-induced false triggering: Ordinary speech activation detection (VAD) algorithms are prone to frequent false switching when there is a lot of background noise, resulting in frequent video flickering and a very poor viewing experience. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and apparatus for multi-channel call audio and video forwarding based on voice energy detection. The method establishes call and channel role recognition based on SIP, and determines the current active source channel by extracting the voice energy of the channel and combining it with preset rules to achieve accurate switching. At the same time, it avoids interference between multiple SIP terminals, reduces computing power waste, and improves user experience.

[0007] In a first aspect, the present invention provides a method for multi-channel call audio and video forwarding based on voice energy detection, comprising: Bridging marking process: In response to a SIP call request, a media bridge is established, the called device in the bridge is identified and its session channel is marked, and the video forwarding mode of the bridging gateway is set to single-source mode. Audio / video stream identification process: When an audio / video data frame is received from a SIP terminal, it is determined whether the current data frame originates from the called device. If so, the copy-and-multicast process is executed; otherwise, the power detection and source switching process is executed. Multicast copy process: The audio and video data frames of the called device are directly multicast copied and sent to other SIP terminals in the bridging environment; Energy detection and source switching process: Extract the absolute value of the current voice energy of the SIP terminal channel. If it is greater than the preset energy threshold and the channel is not the current active source channel, then mark the channel as an active source channel; if it is less than the preset energy threshold, then keep the current active source channel marking unchanged. Selective routing process: Based on the current active source channel label, a selective routing policy is executed so that the audio and video of the active source channel are sent only to the called device.

[0008] Furthermore, the energy detection and source switching process is also used to automatically trigger the traversal of the remaining SIP terminal session channels when the current active source channel is hung up or leaves the current bridge; after skipping the channels in the suspended state and the called device, one of the online SIP terminal channels that support video format attributes in the current media capability negotiation is selected as the new active source channel, and then a media update request is sent.

[0009] In the selective routing process, the selective routing strategy specifically includes: Video strategy: Only extract video frames from active source channels and forward them separately to the called device; Audio strategy: Only extract audio frames from the active source channel and forward them separately to the called device; Bypass Mixing: In bridged polling, once the target receiver is detected as a tagged called device, the underlying media system completely skips the regular audio decoding, mixing, re-encoding, collection, and distribution process for the corresponding channel.

[0010] Furthermore, the session channel of the called device is marked as a peer_channel pointer, and the active source channel is marked as a chan_vsrc pointer.

[0011] Secondly, the present invention provides a multi-channel call audio and video forwarding device based on voice energy detection, comprising: The bridging tagging module is used to establish a media bridge in response to a SIP call request, identify the called device in the bridge and tag its session channel, and set the video forwarding mode of the bridging gateway to single-source mode. The audio / video stream recognition module is used to determine whether the current data frame originates from the called device when it receives an audio / video data frame from a SIP terminal. If so, it executes the copy-and-multicast process; otherwise, it executes the energy detection and source switching process. The multicast copy module is used to directly multicast and copy the audio and video data frames of the called device and send them to other SIP terminals in the bridging environment. The energy detection and source switching module is used to extract the current absolute value of voice energy of the SIP terminal channel. If it is greater than the preset energy threshold and the channel is not the current active source channel, the channel is marked as an active source channel; if it is less than the preset energy threshold, the current active source channel marking remains unchanged. The selective routing module is used to execute a selective routing policy based on the current active source channel label, so that the audio and video of the active source channel are sent only to the called device.

[0012] Furthermore, the energy detection and source switching module is also used to automatically trigger the traversal of the remaining SIP terminal session channels when the current active source channel is hung up or leaves the current bridge; after skipping the channels in the suspended state and the called device, it selects one from the online SIP terminal channels that support video format attributes in the current media capability negotiation as the new active source channel, and then sends a media update request.

[0013] Furthermore, in the selective routing module, the selective routing strategy specifically includes: Video strategy: Only extract video frames from active source channels and forward them separately to the called device; Audio strategy: Only extract audio frames from the active source channel and forward them separately to the called device; Bypass Mixing: In bridged polling, once the target receiver is detected as a tagged called device, the underlying media system completely skips the regular audio decoding, mixing, re-encoding, collection, and distribution process for the corresponding channel.

[0014] Furthermore, the session channel of the called device is marked as a peer_channel pointer, and the active source channel is marked as a chan_vsrc pointer.

[0015] The technical solutions provided in the embodiments of the present invention have at least the following technical effects: 1. By selectively forwarding audio and video media streams in multi-call scenarios, only the currently active SIP terminal is allowed to output audio and video to the called device, while blocking audio communication between other SIP terminals. This effectively avoids crosstalk, noise interference, and privacy leaks caused by traditional multi-party mixing methods, and significantly improves the privacy and call quality during communication.

[0016] 2. By introducing a DSP-based voice energy detection mechanism and combining it with a preset energy threshold to determine the speaking status of each SIP terminal, the active source is switched only when a valid human voice is detected. This effectively suppresses false triggers caused by non-target sounds such as ambient noise and slight abnormal noises, avoids frequent switching and flickering of the screen on the called device, and improves the stability of audio and video interaction and viewing experience.

[0017] 3. By bypassing the regular mixing, decoding, re-encoding, and full media distribution processes directly at the bridging layer through the media gateway, targeted forwarding is only performed on the target active source, thereby significantly reducing the processing burden on the server-side DSP and CPU, reducing system resource consumption and deployment costs, and improving the overall carrying capacity in multi-concurrency scenarios.

[0018] 4. When the current active source channel goes offline, is disconnected, or exits abnormally, a new active source can be automatically selected from the remaining online SIP terminals with video capabilities, and a media update can be triggered to realize the automatic sequential switching of audio and video on the called device, avoiding black screen, mute, or service interruption, thereby improving the continuity, reliability, and fault tolerance of system operation.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This is a flowchart illustrating the overall process of the method in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the overall control flow of the multi-channel call audio and video selective forwarding method in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the judgment process based on DSP speech energy detection and dynamic switching of video sources in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the follow-up compensation process after the source node fails to connect or leaves the bridge in Embodiment 1 of the present invention. Figure 5 This is a schematic diagram of the device in Embodiment 2 of the present invention. Detailed Implementation

[0022] This invention provides a method and apparatus for multi-channel call audio and video forwarding based on voice energy detection. It establishes call and channel role recognition based on SIP, and determines the current active source channel by extracting the voice energy of the channel and combining it with preset rules to achieve precise switching. At the same time, it avoids interference between multiple SIP terminals, reduces computing power waste, and improves user experience. Example 1

[0023] This embodiment provides a method for multi-channel call audio and video forwarding based on voice energy detection, such as... Figure 1 and Figure 2 As shown, it includes: S1. Bridging Marking Process: In response to a SIP call request, a media bridge is established. Based on SIP, a call and channel role identification is established. The called device in the bridge is identified and its session channel is marked (peer_channel pointer, which points to only one channel). At the same time, the video forwarding mode of the bridging gateway is set to single-source mode. Single-source mode is for the called device, which only receives audio and video from one party at a time.

[0024] S2. Audio and video stream identification process: When an audio and video data frame is received from a SIP terminal, it is determined whether the current data frame comes from the called device. If yes, the S3-1 copy and multicast process is executed; if no, the S3-2 energy detection and source switching process is executed.

[0025] S3-1, Multicast Copying Process: When the audio and video data frame comes from the called device, the audio and video data frame of the called device is directly multicast copied and sent to other SIP terminals in the bridging environment to realize downlink broadcast of audio and video on the called device. S3-2, Energy Detection and Source Switching Procedure: Please refer to... Figure 3 When audio / video data frames come from other SIP terminals, the absolute value of the current speech energy (cur_energy) of the SIP terminal channel is extracted. If cur_energy is greater than the preset energy threshold (the preset energy threshold is generally set to a high energy isolation threshold, such as 2000, to determine that the speech in the current channel is valid human voice and avoid noise interference causing false switching), and the channel is not the current active source channel, then the channel is marked as an active source channel (chan_vsrc pointer, pointing to only one channel), and then a video keyframe update instruction (VIDUPDATE) is sent down through the SIP INFO or RTCP (such as FIR / PLI) mechanism; if cur_energy is less than the preset energy threshold, it is determined to be background noise or background noise, and the current active source channel mark chan_vsrc remains unchanged.

[0026] S4. Selective Routing Process: Execute a selective routing policy based on the current active source channel label, so that the audio and video of the active source channel are sent only to the called device.

[0027] In the selective routing process, the selective routing strategy specifically includes: Video strategy: Only extract video frames that match the active source channel chan_vsrc and forward them separately to the called device; Audio strategy: Only extract audio frames that match the active source channel chan_vsrc and forward them separately to the called device; Bypass Mixing: In bridged polling, once the target receiver is detected as the marked called device (peer_channel), the underlying media system completely skips the regular audio decoding, mixing, re-encoding, collection, and distribution process for the corresponding channel.

[0028] For a better option, please refer to Figure 4 Therefore, the energy detection and source switching process is also used to automatically trigger a traversal of the remaining SIP terminal session channels when the current active source channel is disconnected or leaves the current bridge; after skipping channels in a suspended state and the called device, a new active source channel is selected from the online SIP terminal channels that support video format attributes in the current media capability negotiation, and then a media update request is sent. This enables the automatic selection of a new active source from the remaining online SIP terminals with video capabilities when the current active source channel goes offline, is disconnected, or abnormally exits, and triggers a media update, realizing automatic sequential switching of audio and video on the called device end, avoiding black screen, mute, or service interruption, thereby improving the continuity, reliability, and fault tolerance of system operation.

[0029] To make the implementation of this invention more specific and clear, the communication process and details are explained below in conjunction with a specific distributed communication application scenario (such as a remote audio and video monitoring system developed based on the SIP stack): Example 1: Advanced Definition and Extension of System Memory Data Structures In the SIP media bridging bridge of this system, in order to achieve accurate determination of high and low pitch and efficient differentiation of core channels, a unique extension is made to the underlying mapping structure: a real-time transient energy logical variable, such as the cur_energy field, is introduced into the core bridging data structure to store the absolute value of sound pressure calculated periodically (every N milliseconds) by the underlying DSP decoding module; at the same time, special logical pointer identifiers are introduced (peer_channel is the identifier of the called device, and chan_vsrc is the identifier of the currently unique legal source).

[0030] Example 2: Implementation of typical call processing flow for three or more parties Assume that there is one called device as the presentation end in the system, and two SIP terminals, namely the first SIP terminal and the second SIP terminal.

[0031] (1) The first SIP terminal initiates a video call to the called device through the SIP application. The media gateway constructs a bidirectional path bridge and establishes RTP stream transmission. After the gateway identifies the relevant service attributes, it binds the logical channel where the called device is located as the controlled terminal identifier. At this time, the first SIP terminal is the only access party in the system, and the gateway binds its channel as the unique video source variable. The first SIP terminal can normally send and receive the audio track and video of the called device.

[0032] (2) The second SIP terminal then joins the conference / bridging pool via the end-side interface. The uplink media stream sent by the called device will be broadcast to the first and second SIP terminals in a one-to-many manner in the media queue. However, the system intercepts the default mixing and distribution logic on the data request paths sent by the first and second SIP terminals to the called device.

[0033] (3) Environment Determination - Single Point of Talk (First SIP Terminal Speaking): Because the first SIP terminal is in the current active video source marking state, only the audio (PCM stream or compressed stream) and key video frames of the first SIP terminal are output to the called device through a specific unidirectional dedicated channel. The media data flowing to the second SIP terminal is directly discarded by the routing engine.

[0034] (4) Environmental Judgment - Noise Ignore (Slight Abnormal Sounds from the Second SIP Terminal): When a very slight abnormal sound or keyboard tapping occurs in the environment of the second SIP terminal, the system extracts its voice feature energy value (and finds that it has not reached the preset energy threshold). Since the threshold is not exceeded, the routing engine does not respond to this action, and the system still maintains the unidirectional flow injection from the first SIP terminal to the called device, without generating frequent switching or flashing of the called device's interface.

[0035] (5) Environmental Judgment - Preemptive Handover (Clear Communication with the Second SIP Terminal): When a person using the second SIP terminal initiates a continuous clear conversation, and the DSP detects that the instantaneous energy reaches and exceeds the set high threshold, the gateway's source controller actively changes the routing rights, transferring the active pointer from the first SIP terminal to the second SIP terminal, and pushes a video frame forced refresh update packet (I-frame request) to the target device. The main display area of ​​the called device then seamlessly transitions to display the second SIP terminal's screen, accompanied only by the second SIP terminal's independent audio routing, while suspending uplink transmission in the direction of the first SIP terminal.

[0036] (6) Environmental Judgment - Abnormal Recovery (Network Disconnection Backup): If the second SIP terminal loses network access due to a network blind spot during communication (SIP heartbeat timeout or abnormal connection termination), the system's anti-drop hook will capture the release event. While recovering the data, the system immediately checks the available backup nodes in the communication pool that conform to the SDP video negotiation protocol, relocates the communication source handle and redirects it to the surviving first SIP terminal, so that the called device automatically switches back to the perspective of the preceding node in a very short time, ensuring uninterrupted service.

[0037] Based on the same inventive concept, this application also provides an apparatus corresponding to the method in Embodiment 1, as detailed in Embodiment 2. Example 2

[0038] This embodiment provides a multi-channel call audio / video forwarding device based on voice energy detection, such as... Figure 5 As shown, it includes: The bridging tagging module is used to establish a media bridge in response to a SIP call request, identify the called device in the bridge and tag its session channel, and set the video forwarding mode of the bridging gateway to single-source mode. The audio / video stream recognition module is used to determine whether the current data frame originates from the called device when it receives an audio / video data frame from a SIP terminal. If so, it executes the copy-and-multicast process; otherwise, it executes the energy detection and source switching process. The multicast copy module is used to directly multicast and copy the audio and video data frames of the called device and send them to other SIP terminals in the bridging environment. The energy detection and source switching module is used to extract the current absolute value of voice energy of the SIP terminal channel. If it is greater than the preset energy threshold and the channel is not the current active source channel, the channel is marked as an active source channel; if it is less than the preset energy threshold, the current active source channel marking remains unchanged. The selective routing module is used to execute a selective routing policy based on the current active source channel label, so that the audio and video of the active source channel are sent only to the called device.

[0039] Preferably, the energy detection and source switching module is further configured to automatically trigger a traversal of the remaining SIP terminal session channels when the current active source channel is hung up or leaves the current bridge; after skipping the channels in the suspended state and the called device, select one from the online SIP terminal channels that support video format attributes in the current media capability negotiation as a new active source channel and execute the selective routing module.

[0040] Preferably, in the selective routing module, the selective routing strategy specifically includes: Video strategy: Only extract video frames from active source channels and forward them separately to the called device; Audio strategy: Only extract audio frames from the active source channel and forward them separately to the called device; Bypass Mixing: In bridged polling, once the target receiver is detected as a tagged called device, the underlying media system completely skips the regular audio decoding, mixing, re-encoding, collection, and distribution process for the corresponding channel.

[0041] Specifically, the session channel of the called device is marked as a peer_channel pointer, and the active source channel is marked as a chan_vsrc pointer.

[0042] Since the apparatus described in Embodiment 2 of the present invention is an apparatus used to implement the method of Embodiment 1 of the present invention, those skilled in the art can understand the specific structure and variations of the apparatus based on the method described in Embodiment 1 of the present invention, and therefore will not be described again here. All apparatuses used in the method of Embodiment 1 of the present invention fall within the scope of protection of the present invention.

[0043] The technical solutions provided in the embodiments of the present invention have at least the following technical effects: 1. By selectively forwarding audio and video media streams in multi-call scenarios, only the currently active SIP terminal is allowed to output audio and video to the called device, while blocking audio communication between other SIP terminals. This effectively avoids crosstalk, noise interference, and privacy leaks caused by traditional multi-party mixing methods, and significantly improves the privacy and call quality during communication.

[0044] 2. By introducing a DSP-based voice energy detection mechanism and combining it with a preset energy threshold to determine the speaking status of each SIP terminal, the active source is switched only when a valid human voice is detected. This effectively suppresses false triggers caused by non-target sounds such as ambient noise and slight abnormal noises, avoids frequent switching and flickering of the screen on the called device, and improves the stability of audio and video interaction and viewing experience.

[0045] 3. By bypassing the regular mixing, decoding, re-encoding, and full media distribution processes directly at the bridging layer through the media gateway, targeted forwarding is only performed on the target active source, thereby significantly reducing the processing burden on the server-side DSP and CPU, reducing system resource consumption and deployment costs, and improving the overall carrying capacity in multi-concurrency scenarios.

[0046] 4. When the current active source channel goes offline, is disconnected, or exits abnormally, a new active source can be automatically selected from the remaining online SIP terminals with video capabilities, and a media update can be triggered to realize the automatic sequential switching of audio and video on the called device, avoiding black screen, mute, or service interruption, thereby improving the continuity, reliability, and fault tolerance of system operation.

[0047] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0048] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0049] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0050] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0051] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for multi-channel call audio and video forwarding based on speech energy detection, characterized in that, include: Bridging marking process: In response to a SIP call request, a media bridge is established, the called device in the bridge is identified and its session channel is marked, and the video forwarding mode of the bridging gateway is set to single-source mode. Audio and video stream identification process: When an audio and video data frame is received from a SIP terminal, it is determined whether the current data frame comes from the called device. If so, the copy multicast process is executed. If not, then perform the energy detection and source switching procedure: Multicast copy process: The audio and video data frames of the called device are directly multicast copied and sent to other SIP terminals in the bridging environment; Energy detection and source switching process: Extract the absolute value of the current voice energy of the SIP terminal channel. If it is greater than the preset energy threshold and the channel is not the current active source channel, then mark the channel as an active source channel. If the energy level is less than the preset energy threshold, the current active source channel label remains unchanged. Selective routing process: Based on the current active source channel label, a selective routing policy is executed so that the audio and video of the active source channel are sent only to the called device.

2. The method according to claim 1, characterized in that, The energy detection and source switching process is also used to automatically trigger the traversal of the remaining SIP terminal session channels when the current active source channel is hung up or leaves the current bridge; after skipping the channels in the suspended state and the called device, one of the online SIP terminal channels that support video format attributes in the current media capability negotiation is selected as the new active source channel, and then a media update request is sent.

3. The method according to claim 1, characterized in that: In the selective routing process, the selective routing strategy specifically includes: Video strategy: Only extract video frames from active source channels and forward them separately to the called device; Audio strategy: Only extract audio frames from the active source channel and forward them separately to the called device; Bypass Mixing: In bridged polling, once the target receiver is detected as a tagged called device, the underlying media system completely skips the regular audio decoding, mixing, re-encoding, collection, and distribution process for the corresponding channel.

4. The method according to claim 1, characterized in that: The session channel of the called device is marked as a peer_channel pointer, and the active source channel is marked as a chan_vsrc pointer.

5. A multi-channel call audio / video forwarding device based on voice energy detection, characterized in that, include: The bridging tagging module is used to establish a media bridge in response to a SIP call request, identify the called device in the bridge and tag its session channel, and set the video forwarding mode of the bridging gateway to single-source mode. The audio and video stream recognition module is used to determine whether the current data frame comes from the called device when it receives an audio and video data frame from the SIP terminal. If so, it executes the copy multicast process. If not, then perform the energy detection and source switching procedure: The multicast copy module is used to directly multicast and copy the audio and video data frames of the called device and send them to other SIP terminals in the bridging environment. The energy detection and source switching module is used to extract the current absolute value of voice energy of the SIP terminal channel. If it is greater than the preset energy threshold and the channel is not the current active source channel, then the channel is marked as an active source channel. If the energy level is less than the preset energy threshold, the current active source channel label remains unchanged. The selective routing module is used to execute a selective routing policy based on the current active source channel label, so that the audio and video of the active source channel are sent only to the called device.

6. The apparatus according to claim 5, characterized in that, The energy detection and source switching module is also used to automatically trigger the traversal of the remaining SIP terminal session channels when the current active source channel is hung up or leaves the current bridge; after skipping the channels in the suspended state and the called device, it selects one from the online SIP terminal channels that support video format attributes in the current media capability negotiation as the new active source channel, and then sends a media update request.

7. The apparatus according to claim 5, characterized in that: The selective routing module includes the following selective routing strategies: Video strategy: Only extract video frames from active source channels and forward them separately to the called device; Audio strategy: Only extract audio frames from the active source channel and forward them separately to the called device; Bypass Mixing: In bridged polling, once the target receiver is detected as a tagged called device, the underlying media system completely skips the regular audio decoding, mixing, re-encoding, collection, and distribution process for the corresponding channel.

8. The apparatus according to claim 5, characterized in that: The session channel of the called device is marked as a peer_channel pointer, and the active source channel is marked as a chan_vsrc pointer.

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