CN101790072A - Method for implementing video conference system by application layer multicast - Google Patents
Method for implementing video conference system by application layer multicast Download PDFInfo
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Abstract
The invention discloses a method for implementing a video conference system by application layer multicast. The system mainly comprises a computer, a video processing module, an audio processing module, a conference management and control module, a sound image synchronous control module and a spines application layer overlay network platform; and after the modules of the system are initialized, the video signal processing and transmission, the audio signal processing and transmission and the sound image synchronous control are sequentially realized, and finally the spines application layer overlay network platform realizes the multicasting. The method can realize system application and data sending and receiving directly through the computer, the application layer multicast technology in the system leads the system to have good network flexibility, meanwhile, the application layer multicast is convenient for implementation and popularization, only an end system needs to be changed, and any modification of a router is unnecessary; and the application layer multicast is convenient for optimizing the specific application, uses different implementation schemes for different applications and is not like the IP multicast which needs to be unified in one model.
Description
Technical field
The present invention relates to a kind of multicast videoconference system implementation method, relate in particular to a kind of video conference system with application layer multicast implementation method.
Background technology
The development of early stage video conferencing system has been experienced from dialing group video conferencing system to ISDN desktop conference system, again the process of the video conferencing system to the LAN.Afterwards on the basis of above technology, grow up gradually based on the multimedia videoconference system of Internet.
Along with the application of IP multicasting technology, use the more video conferencing system that is based on the IP multicast network at present, utilize the IP multicasting technology can make up network with multicast-capable.Multicast allows router once packet to be copied on a plurality of passages, has reduced network bandwidth requirement, effectively saves transmission bandwidth, this for need be between multiple spot the video conference of transport stream medium especially significant.Simultaneously, the IP multicast sends multicast packet according to the multicast tree that Routing Protocol forms the router composition to the group membership, do not need MCU (Multipoint Control Unit, the multiple spot processing unit), realize the video conference function of any multiple spot of video conference terminal by software, saved system cost greatly.
Though IP multicast videoconference systems technology has higher efficient, can guarantee that every link does not have redundant data, owing to needing the support of router and high layer function, the IP multicast is difficult for reasons such as realization, and it is promoted the use of and has been subjected to very big restriction.
Application layer multicast is meant the multicast in the application layer realization of procotol.The difference of it and IP multicast maximum is that the major function of application layer multicast realizes what (being also referred to as End System, also is end system, is different from router) realized on main frame, promptly carry out duplicating and transmitting of data by main frame.Application layer multicast forms a logical network in application layer and utilizes the mode of unicast of route layer to carry out multicast to the group membership.Compare the IP multicast simultaneously, application layer multicast is having outstanding performance aspect network congestion control and the security problems.In this case, the research of video conference system with application layer multicast is important further.
Summary of the invention
The objective of the invention is at the deficiencies in the prior art, a kind of video conference system with application layer multicast implementation method is provided.
The objective of the invention is to be achieved through the following technical solutions: a kind of video conference system with application layer multicast implementation method, video conference system with application layer multicast mainly are made up of computer, video processing module, audio processing modules, conference management and control module, lip synchronization control module and Spines application layer overlay network platform.Described video processing module, audio processing modules, conference management and control module, lip synchronization control module link to each other with computer respectively.Described video processing module, lip synchronization control module link to each other successively with audio processing modules, and link to each other with Spines application layer overlay network platform respectively.Described video conference system with application layer multicast implementation method mainly may further comprise the steps:
(1) each module initialization of system: comprise interconnecting between computer, video processing module, audio processing modules, conference management and control module, lip synchronization control module and the Spines application layer overlay network platform, and the startup of each module and initialization.
(2) vision signal is handled and transmission: Video signal processing mainly realizes function by video processing module with transmission.Concrete steps comprise collection of video signal and broadcast, the compression/de-compression of vision signal, the transmission of vision signal and receive three steps.
(3) Audio Signal Processing and transmission: the processing of audio signal mainly realizes function by audio processing modules with transmission.Concrete steps comprise the collection and the broadcast of audio signal, the compression and decompression of audio signal, the transmission of audio signal and reception.
(4) lip synchronization control: send terminal video flowing and audio stream are separately directly passed to receiving terminal, promptly two kinds of Media Streams do not mix, and walk different network virtual passages respectively; When network was unimpeded, promptly the network bandwidth can guarantee sound, video flowing according to predetermined speed rates, and multi-medium data is not lost substantially, and stationary problem mainly utilizes the timestamp field in sound, video RTP packet header to solve.When network congestion, sound, video flowing can not transmit sound, video information packet loss serious situation by original transmission rate, the message information that transmitted by the control module analysis this moment, according to real-time network condition, the transmission data volume of control multi-medium data realizes synchronously timely and effectively.
(5) Spines application layer overlay network platform realizes that multicast: Spines is divided into two levels: client layer and overlay network node layer.The service that user program will use the Spines overlay network to provide at first is connected to nearest node, sends data by overlay network to other user.When node receives data from user or other nodes, just select suitable routing forwarding data.Through the hop-by-hop transmission, data arrive destination node, according to the port of packet data are submitted to user program again.In Spines application layer overlay network platform, the connection between the node is by consultative management and propagation topology information and multicast information separately, and each node is all being safeguarded the structural information of whole overlay network.
The invention has the beneficial effects as follows, video conference system with application layer multicast of the present invention can directly be used with data by computer implemented system and send reception, and the application layer multicast technology in the native system makes system have good network flexibility, application layer multicast is convenient to realize and promote simultaneously, only need to change end system, and do not need router is carried out any modification; Application layer multicast is convenient to be optimized at application-specific, can use different implementations at different application, must unify in a model and needn't resemble the IP multicast.
Description of drawings
Fig. 1 is system module figure;
Fig. 2 is Directshow integral frame figure;
Fig. 3 is the Audio Processing flow chart;
Fig. 4 is the Spines software architecture diagram.
Embodiment
As shown in Figure 1, video conference system with application layer multicast of the present invention mainly is made up of computer, video processing module, audio processing modules, conference management and control module, lip synchronization control module and Spines application layer overlay network platform.Video processing module, audio processing modules, conference management and control module, lip synchronization control module link to each other with computer respectively; Video processing module, lip synchronization control module link to each other successively with audio processing modules, and link to each other with Spines application layer overlay network platform respectively.
Wherein, the computer realization man-machine interaction, and comprise the operation interface that offers the user.Functions such as video processing module is responsible for the catching of video information, is compressed, decompression and playback.Functions such as audio processing modules is responsible for the catching of audio-frequency information, is compressed, decompression and playback; Conference management and control module are finished the management and the control of whole meeting process.The lip synchronization control module provides the assurance of video flowing transmission quality, by adjusting video information transmission rate, video information also can be transmitted effectively at the network that Bandwidth Dynamic changes.Spines application layer overlay network platform is built the application layer multicast platform, the application layer multicast technical support is provided, and is connected with bottom-layer network.
Computer module is made up of server and client computer.Server consist of a high-performance computer and network interface card.Group of clients becomes common computer, audio amplifier, sound card, network interface card, camera, microphone and client running environment etc.Each equipment effect is as follows:
Server end equipment
High-performance computer: runtime server program;
Network interface card: connect the internet, realize basic network service;
Client device
Common desktop computer;
Network interface card: connect the internet, realize basic network service;
Sound card: microphone is inserted sound card, gather participant's audio frequency media by sound card;
Audio amplifier: play the audio frequency of being asked;
Camera: the video media that is used to catch the participant;
Microphone: be used for the sound input.
The function of video processing module comprises: the collection of video and broadcast, the compression/de-compression of video, the transmission of video and reception.
As shown in Figure 2, system has adopted the Directshow streaming video architecture on the Microsoft windows platform, and it provides the high-quality seizure and the playback of Media Stream.Compare with the common Video ForWindows API video sampling that adopts; The hardware efficiency of Directshow is higher, can use hardware-acceleratedly automatically, saves system resource.Compression to vision signal, system has adopted H.263 standard realization compression, H.263 is one of encoding and decoding of video device of H.323 standard recommendation use, H.263 is present advanced person's network compression algorithm, have medium compression quality, and compression algorithm is simple, compression is quick and compression ratio is high.
In order to adapt to the dynamic change of Internet bandwidth, enhanced system is to the adaptability of network environment, system has done some improvement on compression algorithm: transmitting terminal is periodically analyzed the reception situation of each receiving terminal, obtain the transmission rate of current network, adjust each parameter of compression algorithm with this, thereby obtain best frame per second and quality.The transmission of video is finished by the video communication process.
The design of Video processing is based on the Directshow platform, and FilterGraph has defined in Directshow, so only need design the Filter of oneself, puts into FilterGraph then, allows its control move, and realizes the function that needs.Need two links for video module:
A video acquisition → video compression → video data → multicast sends
B video data → multicast reception → video compression → video playback
Realize that in Directshow a Video Capture previewer probably can be divided into following step:
A creates a FilterGraphManager example, and draws IMediaControl by calling the IGraphBuilder interface, IVideowindow, three interfaces of IMediaEventEx.Application program is provided with the size and the position of video window by calling the Videowindow interface; Call the IMediaControl interface and realize the beginning of video playback and stop by setting control button.
B creates a CaptureGraph example, obtains the ICaptureGraphBuilderZ interface, and the IGraphBuilder interface of FilterGraphManager is associated, initialization FilterGraph.
The system equipment method is enumerated in C utilization, enumerates the video capture device of all uses, and the user can select arbitrary equipment, and the CaptureFilter that it is corresponding joins among the FilterGraph after the initialization.
The CaptureFilter that the D design is used has only a CaptureOutputPin, and FilterGraphManager can insert a Smart Tee Filter automatically PreviewPin is provided, and carries out simultaneously so that be implemented in preview video and store file into.
The groundwork of Network Transmission part is that programming realizes cast communication, and basic step is as follows:
A creates socket
B binding local address and port
C adds multicast group
D is provided with the TTL life cycle
E sends data to multicast address
F receives data from multicast group
The function of audio processing modules comprises: the collection of audio frequency and broadcast, the compression and decompression of audio frequency, the transmission of audio frequency and reception.The Windows Multimedia of Microsoft company is the support that application program has added Voice ﹠ Video, to realize multimedia function.In system, wave collection of functions and ACM (Audio Compression Manager) among the Multimedia Audio have been used when realizing audio collection and compression/decompression, wherein audio compression module adopts G.723.1 CODEC of Microsoft, G.723 is one of audio coding/decoding device of H.323 standard recommendation use; Used the assembly DirectSound of DirectX when realizing audio mixing and playback.The transmission of audio frequency is finished by the voice communication process.
The main flow process of the audio processing modules of system as shown in Figure 3.
Whole module is encapsulated in it in the dll file, below introduces class important in several designs:
1. CWaveIn, it is a class that encapsulates WaveIn api, its main function is to gather corresponding inter-area traffic interarea in the slave unit and data encapsulation is become a self-defining configuration frame.
2. CWaveout corresponding to CWaveIn, also is a class that encapsulates Wavelnapi, and its major function is that the Frame that network is collected is played back in equipment.
3. CSortData, its effect is a management data, adjusts the order of out of order bag.
CUdpsocket inherits in CAsyncsocket, is used for data are sent to server.
CRecsocket also inherits in CAsyncsocket, is used to trigger its OnReceive incident and handles the data of arrival, just data forwarding is gone out if be designated server, for client is then play in the original place.
Each function class that next will design is drawn out in the interface class,
Lip synchronization control is essential key technology and the technological difficulties that solve of all video conferencing systems.According to the characteristics of system, corresponding solution has been proposed.
In this system, send terminal video flowing and audio stream are separately directly passed to receiving terminal, promptly two kinds of Media Streams do not mix, and walk different network virtual passages respectively.Because the video data volume is very big, separately the processing method of sound, video Data Transmission can guarantee the smooth transportation of voice data on the narrower network of bandwidth, and nonsynchronous problem is serious but its shortcoming is an acoustic image.When solving stationary problem, the author uses relative counter measures according to different network conditions.Network operation situation has two kinds of situations: the one, and network is unimpeded, and promptly the network bandwidth can guarantee sound, video flowing according to predetermined speed rates, and multi-medium data is not lost substantially; The 2nd, network congestion, sound, video flowing can not transmit sound, video information packet loss serious situation by original transmission rate.
The previous case, stationary problem mainly utilize the timestamp field in sound, video RTP packet header to solve.The latter analyzes the message information that RTCP transmits by the QoS control module, and according to real-time network condition, the transmission data volume of control multi-medium data realizes synchronously timely and effectively.
System is by the function of software realization conference manager, and conference management is running through the whole process of meeting, comprises initiation, the end of meeting, member's affiliation, defection, authentication and right to speak control, the generation of subject under discussion and management etc.Module has six parts: membership information storehouse, speech processing, process management, information inquiry, registration affiliation, defection management.All participants' action message is organized into database structure and is stored in each participant node, is produced and Dynamic Maintenance by conference manager.The conference management information that conference manager produces is pressed rtcp protocol group bag, in real time passes to all participants by the conference management port in IP Multicast mode by UDP.Whole conference management is consulted to finish by the controller of server end and the controller of client.
As shown in Figure 4, Spines is a disclosed general coverage network system of source code, is set up by the distributed network laboratory of John-John Hopkins University.Spines is divided into two levels: client layer and overlay network node layer.The service that user program will use the Spines overlay network to provide at first will be connected to nearest node, so just can send data to other user by the Spines overlay network.When node receives data from user or other nodes, just select suitable routing forwarding data.Through the hop-by-hop transmission, data arrive destination node, and destination node is submitted to user program to data according to the port of packet.Spines provides reliable transmission and unreliable transmission end to end, and reliable transmission has been used class TCP transmission mode.
As shown in Figure 4, adopting two-layer structure is because Spines is distributed network.Connection between the node is managed by protocol hello, node is propagated topology information and multicast information by State Flood agreement, each node is all being safeguarded the structural information of whole overlay network, and node is also wanted the request and the deal with data of process user, so it is very big that the Spines overlay network can not be expanded, in general can expand to a hundreds of node.Though have only a hundreds of node, each node can be supported 1,000 users nearly.Like this, two-layer structure can well solve the problem of autgmentability.
This system is based on the video conferencing system of Spines overlay network platform, and its Network Transmission relies on the Spines system substantially.The specific implementation step was divided into for two steps, and the one, carry out the design of Network Transmission according to the general ip multi-cast system, the 2nd, the interface with the corresponding interface of Spines system during with the IP multicast is replaced mutually.Be described in detail as follows:
In IP multicast modular design process, the application platform of system is a Windows operating system, use be the WinSock standard.The developing instrument of system is Microsoft Visual C++6.0, it provides MFC class CAsyncSocket class, such has encapsulated Windows Socket API, for the Windows programmer provides an OO Windows Socket abstract, greatly facilitate the programmer and in this OO development environment of C++, use the communication software of WinSock standard exploitation based on TCP/IP.All communication process objects of system all derive from from the CAsyncSocket class, comprising: the video communication process; The voice communication process; Phonotape and videotape transmitting synchronous process; The conference management communication process.
In the ICP/IP protocol group, network layer provides three kinds of IP packet load modes: the one, and 8-IP point-to-point (IP Unicast) mode; The 2nd, broadcast mode (IP Broadcast); The 3rd, multicast mode (IPMulticast).System has adopted the IP multicast mechanism to transmit multi-medium data.System has used the multicast special API of Windows Socket2.0 standard to write the cast communication module.In several communication processs of above-mentioned system, every all is the cast communication process based on UDP, the cast communication process of system comprises: video communication process CVideoSocket (), seven processes such as voice communication process CSoundSocket (), three process CManageSocket, CSpeakCtrlSocket of video communication quality feedback process CVideoFeedBackSocket () and conference manager and CApplySpeakSocket etc. altogether form.Their all CAsyncSocket class successions from the MFC of Microsoft Visual C++6.0.
IP multicast module is the application communication system of ICP/IP protocol, and its network layer and transport layer rely on TCP/IP substantially, is the concrete application of ICP/IP protocol network layer and transport layer.The network layer of system has adopted the IGMP agreement of TCP/IP, and transport layer is mainly used udp protocol.H.323 suggestion is abideed by by this system, and sound, video data transmit with UDP.But high efficiency UDP does not consider reliability, thereby substitute TCP with UDP simply and be not sufficient to make Multimedia Program at the 8-online operation that divides into groups, also need to use some based on the agreement on the UDP, to resetting by the data of UDP transmission and housekeeping operation such as compensation.In system, the Voice ﹠ Video data are abideed by the packing of RTP message format, and design RTP extension header separately, cooperate the packing of finishing these system's characteristics of being fit to, transmit, unpack scheme.In addition, in the design of RTP, provide video transmission quality feedback, provide conference management information, and the participant has used the BYE message to notify other members when withdrawing from meeting with membership information SDES message with the RR message.
Spines overlay network platform is inserted video conferencing system, when specifically inserting, with the function mutual alternative under corresponding port function and the Windows, Spines can be inserted video conferencing system with the Spines_lib library file among the Spines.SPINES port in the Spines_lib library file and the contrast of IP multicast module corresponding interface are as follows:
| The Win_socket function | The Spines_lib function | The function effect |
| ??WSAStartup | ??spines_init | The initialization network connects |
| ??socket | ??spines_socket | Set up port |
| ??closesocket | ??spines_close | Close port |
| ??send | ??spines_send | Send the transmission data |
| ??recv | ??spines_recv | Receive the transmission data |
| ??listen | ??spines_listen | The supervision network port |
| ??accept | ??spines_accept | Affirmation connects |
| ??connect | ??spines_connect | Setting up multicast connects |
In system, realize temperature multi-point monitoring method, mainly may further comprise the steps based on Bluetooth technology:
1) each module initialization of system
Comprise interconnecting between computer, video processing module, audio processing modules, conference management and control module, lip synchronization control module and the Spines application layer overlay network platform, and the startup of each module and initialization.
2) vision signal is handled and transmission
Video signal processing mainly realizes function by video processing module with transmission.Concrete steps comprise collection of video signal and broadcast, the compression/de-compression of vision signal, the transmission of vision signal and receive three steps.
The streaming video technology has been adopted in collection of video signal and broadcast, and it provides the high-quality seizure and the playback of Media Stream.
The compression/de-compression of vision signal has adopted the compression standard realization.This method has been done some improvement on compression algorithm simultaneously: transmitting terminal is periodically analyzed the reception situation of each receiving terminal, obtains the transmission rate of current network, adjusts each parameter of compression algorithm with this, thereby obtains best frame per second and quality.
The transmission of vision signal and reception are realized by following step again: create port; Binding local address and port; Add multicast group; Playback period is set; Send data to multicast address; From multicast group, receive data.
3) Audio Signal Processing and transmission
The processing of audio signal mainly realizes function by audio processing modules with transmission.Concrete steps comprise the collection and the broadcast of audio signal, the compression and decompression of audio signal, the transmission of audio signal and reception.
The collection of audio signal and broadcast realize by the multimedia application program.In system, the compression/de-compression of audio signal has been used coding function collection and audio coding/decoding device; Used player plug-in when realizing audio mixing and playback.The transmission of audio frequency is finished by the voice communication process.
4) lip synchronization control
In the method, send terminal video flowing and audio stream are separately directly passed to receiving terminal, promptly two kinds of Media Streams do not mix, and walk different network virtual passages respectively.Because the video data volume is very big, separately the processing method of sound, video Data Transmission is the smooth transportation that guarantees voice data on the narrower network of bandwidth, and nonsynchronous problem is serious but its shortcoming is an acoustic image.When solving stationary problem, use relative counter measures according to different network conditions.
When network was unimpeded, promptly the network bandwidth can guarantee sound, video flowing according to predetermined speed rates, and multi-medium data is not lost substantially, and stationary problem mainly utilizes the timestamp field in sound, video RTP packet header to solve.When network congestion, sound, video flowing can not transmit sound, video information packet loss serious situation by original transmission rate, the message information that transmitted by the control module analysis this moment, according to real-time network condition, the transmission data volume of control multi-medium data realizes synchronously timely and effectively.
5) Spines application layer overlay network platform is realized multicast
Multicasting technology in this method is realized based on Spines application layer overlay network platform.Spines is divided into two levels: client layer and overlay network node layer.The service that user program will use the Spines overlay network to provide at first is connected to nearest node, sends data by overlay network to other user.When node receives data from user or other nodes, just select suitable routing forwarding data.Through the hop-by-hop transmission, data arrive destination node, according to the port of packet data are submitted to user program again.
In Spines application layer overlay network platform, the connection between the node is by consultative management and propagation topology information and multicast information separately, and each node is all being safeguarded the structural information of whole overlay network.After finishing prior step, the corresponding interface of Spines system can be replaced mutually with original multicast interface and be realized the application layer multicast transmission.
Claims (1)
1. video conference system with application layer multicast implementation method, it is characterized in that video conference system with application layer multicast mainly is made up of computer, video processing module, audio processing modules, conference management and control module, lip synchronization control module and Spines application layer overlay network platform.Described video processing module, audio processing modules, conference management and control module, lip synchronization control module link to each other with computer respectively.Described video processing module, lip synchronization control module link to each other successively with audio processing modules, and link to each other with Spines application layer overlay network platform respectively.Described video conference system with application layer multicast implementation method mainly may further comprise the steps:
(1) each module initialization of system: comprise interconnecting between computer, video processing module, audio processing modules, conference management and control module, lip synchronization control module and the Spines application layer overlay network platform, and the startup of each module and initialization.
(2) vision signal is handled and transmission: Video signal processing mainly realizes function by video processing module with transmission.Concrete steps comprise collection of video signal and broadcast, the compression/de-compression of vision signal, the transmission of vision signal and receive three steps.
(3) Audio Signal Processing and transmission: the processing of audio signal mainly realizes function by audio processing modules with transmission.Concrete steps comprise the collection and the broadcast of audio signal, the compression and decompression of audio signal, the transmission of audio signal and reception.
(4) lip synchronization control: send terminal video flowing and audio stream are separately directly passed to receiving terminal, promptly two kinds of Media Streams do not mix, and walk different network virtual passages respectively; When network was unimpeded, promptly the network bandwidth can guarantee sound, video flowing according to predetermined speed rates, and multi-medium data is not lost substantially, and stationary problem mainly utilizes the timestamp field in sound, video RTP packet header to solve.When network congestion, sound, video flowing can not transmit sound, video information packet loss serious situation by original transmission rate, the message information that transmitted by the control module analysis this moment, according to real-time network condition, the transmission data volume of control multi-medium data realizes synchronously timely and effectively.
(5) Spines application layer overlay network platform realizes that multicast: Spines is divided into two levels: client layer and overlay network node layer.The service that user program will use the Spines overlay network to provide at first is connected to nearest node, sends data by overlay network to other user.When node receives data from user or other nodes, just select suitable routing forwarding data.Through the hop-by-hop transmission, data arrive destination node, according to the port of packet data are submitted to user program again.In Spines application layer overlay network platform, the connection between the node is by consultative management and propagation topology information and multicast information separately, and each node is all being safeguarded the structural information of whole overlay network.
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| CN103517044A (en) * | 2012-06-25 | 2014-01-15 | 鸿富锦精密工业（深圳）有限公司 | Video conference apparatus and lip synchronization method |
| CN103870434A (en) * | 2012-12-14 | 2014-06-18 | 阿瓦亚公司 | Integrating audio and video conferencing capabilities |
| CN103945166A (en) * | 2012-11-01 | 2014-07-23 | 波利康公司 | Method and system for synchronizing audio and video streams in media relay conferencing |
| CN110446003A (en) * | 2019-08-08 | 2019-11-12 | 紫光云技术有限公司 | Video, audio, the method for text are separated in audio/video of mobile phone meeting |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103517044A (en) * | 2012-06-25 | 2014-01-15 | 鸿富锦精密工业（深圳）有限公司 | Video conference apparatus and lip synchronization method |
| CN103517044B (en) * | 2012-06-25 | 2016-12-07 | 鸿富锦精密工业（深圳）有限公司 | Video conference device and the method for lip-sync thereof |
| CN103945166A (en) * | 2012-11-01 | 2014-07-23 | 波利康公司 | Method and system for synchronizing audio and video streams in media relay conferencing |
| CN103945166B (en) * | 2012-11-01 | 2017-05-17 | 波利康公司 | Method and system for synchronizing audio and video streams in media relay conferencing |
| CN103870434A (en) * | 2012-12-14 | 2014-06-18 | 阿瓦亚公司 | Integrating audio and video conferencing capabilities |
| CN110446003A (en) * | 2019-08-08 | 2019-11-12 | 紫光云技术有限公司 | Video, audio, the method for text are separated in audio/video of mobile phone meeting |
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