CN112929742A - Ultra-high-speed video stream control method and system based on NI millimeter wave system - Google Patents
Ultra-high-speed video stream control method and system based on NI millimeter wave system Download PDFInfo
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Abstract
The invention discloses a super-high-speed video stream control method and a system based on an NI millimeter wave system, which comprises a network card module, a network card module and a data transmission module, wherein the transmitting end generates and encapsulates video data streams into IP data packets, and pushes the video data streams in a fixed length and transmits the video data streams to the transmitting end; a network card module at a transmitting end buffers and reads received video stream data, and random numbers are filled in the video stream data by using Nlen and len parameters; the network card module at the receiving end receives the high-speed data stream from the baseband processing module, unpacks and repacks the high-speed data stream from the subframe structure into a data packet with a format capable of being recognized by the display and sends the data packet to the display; and a display at the receiving end receives the data packet, and the data packet is unpacked and restored into an original video for playing and displaying. The invention can improve the throughput rate of a wireless communication system, realize the ultra-high-speed data transmission of a millimeter wave frequency band, and is combined with the application scene of the future 5G streaming media.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a super-high-speed video stream control method and system based on an NI millimeter wave system.
Background
To date, there are 4 very mature wireless communication standards around the world, and each generation of systems evolved almost every 10 years from a historical perspective. Taking the united states as an example, the first-generation FM analog communication in 1981, the second-generation digital communication technology in 1992, the 3G technology in 2001, the Long Term Evolution project a in 2011 (LTE-a), and even the 5G which is advancing today (although delayed due to global epidemic), all meet this rule.
With the development of the moore's law in recent ten years, a large number of electronic devices and application scenes are on the way to follow behind the ground, including augmented reality, virtual reality, artificial intelligence, 3D video, intelligent driving, big data analysis, ultra-high definition video transmission and the like. These new devices and new requirements have undoubtedly increased the demand for wireless communication network rates. Key features of future wireless communication technologies necessarily include: high capacity, high spectral efficiency and ultra high throughput at the device level.
Communication protocols, also known as transport protocols, refer to a uniform standard of some kind that allows information to be communicated between two or more communication terminals in any transmission medium, and also generally to a common language for computer communications or network devices. The existence of a communication protocol makes it possible for the system to stably exchange a large amount of information in a short time.
The Internet Communication Protocol (Internet Communication Protocol) is established by the Internet Engineering Task Force (IETF). Among these, the TCP/IP protocol is undoubtedly a huge and far-reaching one of such protocols. Among them, the TCP (Transport Control Protocol) provides a reliable data stream service facing a connection, and the UDP (User Datagram Protocol) provides a simple and unreliable data stream service facing a Datagram.
Since the UDP protocol is an unreliable protocol, it is applied in some applications that can tolerate packet loss, errors and repeated transmissions, such as streaming media, games, etc. The communication technology involved here will be applied to real-time live video streaming, in the form of streaming media, so UDP is certainly a suitable protocol. The TCP protocol should be used in some other reliability critical program applications.
The Real-time Transport Protocol (RTP) is a network Transport Protocol and is located at the application layer of the internet Protocol suite. The RTP protocol specifies a standard packet format for delivering audio and video over the internet, which was originally designed as a multicast protocol but was later used in many unicast applications. The RTP protocol is commonly used in streaming media systems and is the technical basis for the IP telephony industry. The RTP protocol is used together with the RTP control protocol RTCP and it is built on the UDP protocol.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention provides a super-high-speed video stream control method and a super-high-speed video stream control system based on an NI millimeter wave system, which can improve the throughput rate of a wireless communication system, realize super-high-speed data transmission in a millimeter wave frequency band, and are combined with a future 5G streaming media application scene.
The technical scheme is as follows: in order to achieve the above object, the present invention provides a super high speed video stream control method based on NI millimeter wave system, comprising the steps of,
step 1: the data source of the transmitting end generates a preliminary video data stream according to an RTP protocol and encapsulates the preliminary video data stream into an IP data packet of a transmission layer, the video data stream is pushed in a fixed length, and the video data stream is transmitted to a network card module of the transmitting end by using a 10G Ethernet optical fiber route;
step 2: the network card module of the transmitting end buffers the received video stream data, compares the received video stream data with a known MAC header and reads the video stream data based on the deviation sequence number, finishes reading the whole IP data packet according to the data length provided by the UDP header, and fills random numbers in the video stream data by using Nlen and len parameters according to the system clock frequency;
and step 3: the network card module at the receiving end receives the high-speed data stream from the baseband processing module, unpacks the high-speed data stream from the subframe structure, repacks the data stream into a data packet with a format capable of being recognized by the display and sends the data packet to the display;
and 4, step 4: and a display at the receiving end receives the data packet, and the data packet is unpacked and restored into an original video for playing and displaying.
Further, in the present invention: the transmitting end comprises a data source, a network card module, a baseband processing module, a frequency conversion module and a radio frequency transmitting antenna, and the receiving end comprises a radio frequency receiving antenna, a frequency conversion module, a baseband processing module, a network card module and a display.
Further, in the present invention: the method is based on software program control and is written and realized by NI LabVIEW 2015 SP.
Further, in the present invention: the transmitting terminal protects the data packet format from being damaged in the transmission process based on the following steps:
a data source at a transmitting end sends a fixed-length UDP packet, and the fixed-length UDP packet can be sent based on an FFmpeg protocol;
the network card module of the transmitting end sends the complete IP packet into the baseband processing module, and the baseband processing module can find the boundary between the video data and the packet header.
Further, in the present invention: and the data stream is transmitted and controlled based on the FIFO data structure of the NI millimeter wave prototype system.
Further, in the present invention: the buffering of the received video stream data by the network card module of the transmitting terminal further comprises:
based on a 2GB DDR on a 6592R board card as a buffer pool, related configuration and read-write programs are written for driving, a common DDR is configured into a FIFO DDR through address application, data writing/reading operations to the FIFO DDR are completed in the same clock cycle, and meanwhile, the running time of each cycle is controlled through a timer.
Further, in the present invention: said filling random numbers in the video data stream using Nlen and len parameters further comprises:
the len parameter is used for recording the length of the effective number, the Nlen parameter is used for recording the length of each frame in the OFDM symbol, and the two parameters are used for filling random numbers with different lengths into data packets with different lengths through a finite state machine, so that a network card module at a transmitting end is matched with a baseband processing module in data flow rate, a system can normally run under the condition of low video rate,
further, in the present invention: the unpacking of the network card module at the receiving end from the subframe structure further comprises the following steps:
the bit stream obtained from the previous module is used as an input to enter a special sub-VI module to realize unpacking, the sub-VI module determines the beginning of the sub-frame data field by identifying the header structure of each sub-frame, and maintains a sequence number value to identify the sub-frame structure.
Further, in the present invention: the repackaging into a data packet of a format recognizable by the display further comprises:
the repackaging into a data packet of a format recognizable by the display further comprises:
transmitting a P2P protocol passing through a high-speed data stream into a 6592R network card module at a high speed, checking and judging whether IP and UDP headers are correct through a receiving end network card module before repacking, reading specific values of all parameters (SRC _ IP, DST _ IP, SRC _ PORT and DST _ PORT) of the IP headers in received data by the receiving end network card module, comparing the specific values with fixed values set in advance by a device, judging whether the specific values are consistent, if all the specific values are consistent, judging that the specific values are correct, and if not, judging that the specific values are incorrect;
if not, determining as a packet error and ending, if correct, repackaging the video source data into a format that can be accepted by the receiving end display (PC _ RX), which is consistent with the data packet format output from the transmitting end data source (PC _ TX) to the 6592R network card module, as shown in fig. 5, a data packet having an IP header, a UDP header and an ethernet header.
The invention also provides a super-high speed video stream control system based on the NI millimeter wave prototype system, which comprises,
the transmitting terminal comprises a prototype system main control part PXIe-1085, a network card module PXIe-6592, a baseband processing unit PXIe-7902, a digital-to-analog converter PXIe-3610 DAC, an antenna radio frequency module PXIe-7820 and an intermediate frequency module PXIe-3620 LO/IF; the system also comprises a cabinet PXIe-1085 used for providing slots for each module of the transmitting end, and the data source is a computer PC _ TX;
the receiving terminal comprises a prototype system main control part PXIe-1085, a network card module PXIe-6592, a baseband processing unit PXIe-7902, a digital-to-analog converter PXIe-3630 ADC, an antenna radio frequency module PXIe-7820 and an intermediate frequency module PXIe-3620 LO/IF; and the system also comprises a cabinet PXIe-1085 which is used for providing slots for each module at a receiving end, and the data destination video playing device is a computer PC _ RX.
Has the advantages that: compared with the prior art, the invention has the beneficial effects that:
(1) the invention utilizes the radio frequency of the millimeter wave frequency band, realizes the stability of the millimeter wave band wireless transmission system, and the system throughput rate provided by the invention is higher than that of the prior art by virtue of the high-frequency and wide-frequency characteristics of the millimeter wave;
(2) the invention can process the real-time video stream from 400Mbps to the 8K video stream with the rate of 1.5Gbps, and has wide application range;
(3) the system under the method of the invention operates stably and can be expanded to multiple antenna modes.
Drawings
FIG. 1 is a schematic overall flow diagram of the process of the present invention;
FIG. 2 is a diagram illustrating the relationship and data flow of the hardware modules of the present invention;
FIG. 3 is a schematic diagram illustrating a process of unpacking and repacking at a receiving end according to the present invention;
FIG. 4 is a schematic diagram of a field experiment configuration of the present invention;
FIG. 5 is a schematic diagram of the positions of the Nlen and len parameters of the present invention.
Detailed Description
The technical scheme of the invention is further explained in detail by combining the attached drawings:
the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
As shown in fig. 1, which is a schematic overall flow chart of a super-high speed video stream control method based on an NI millimeter wave system according to the present invention, the method includes the following steps,
step 1: a data source of a transmitting end generates a preliminary video data stream and encapsulates the preliminary video data stream into an IP data packet of a transmission layer, the video data stream is pushed in a fixed length, and a 10G Ethernet optical fiber route is used for transmitting the video data stream to a network card module of the transmitting end;
step 2: the network card module of the transmitting end buffers the received video stream data, compares the received video stream data with a known MAC header and reads the video stream data based on the deviation sequence number, finishes reading the whole IP data packet according to the data length provided by the UDP header, and fills random numbers in the video stream data by using Nlen and len parameters according to the system clock frequency;
and step 3: the network card module at the receiving end receives the high-speed data stream from the baseband processing module, unpacks the high-speed data stream from the subframe structure, repacks the data stream into a data packet with a format capable of being recognized by the display and sends the data packet to the display;
and 4, step 4: and a display at the receiving end receives the received data packet, and the data packet is unpacked and restored into an original video for playing and displaying.
The receiving end comprises a radio frequency receiving antenna, a frequency conversion module, a baseband processing module, a network card module and a display. The method is based on software program control and is written and realized by NI LabVIEW 2015 SP.
Referring to fig. 2, a schematic diagram of a transmission relationship between hardware modules at a transmitting end and a receiving end and a data stream is shown, specifically, a baseband processing module is used for performing physical layer related processing specified by an IEEE 802.11ac protocol on data, and the baseband processing module mainly includes the following functions at the transmitting end: time synchronization, IFFT, constellation map modulation mapping, channel coding, scrambling code and the like; the receiving end mainly comprises the following functions: IQ compensation, synchronization, CP removal, FFT, equalization module, demodulation, decoding, descrambling and the like, wherein the action of a receiving end is basically reverse to that of a transmitting end. Wherein, the synchronous judgment uses an autocorrelation calculation method; the FFT/IFFT transform utilizes an integrated IP core provided by Xlinx corporation, and modulates the precision of the result for subsequent calculation; the channel estimation and equalization uses the OCEF field as a lead code, performs channel estimation based on a least squares method, and performs channel equalization by applying zero forcing; the constellation map modulation process comprises two steps, wherein the first step is to adjust the data flow rate in the baseband processing module to be matched with the modulation order, so as to ensure that the normal traffic of the data flow is not congested or idle; the second step is that the bit stream is converted into a complex format containing a real part and an imaginary part through a lookup table relation; the scrambler uses a variable counter to complete counting, and is suitable for burst data flow in the system.
The frequency conversion module and the radio frequency transmitting antenna are only used as auxiliary components, the functions of the frequency conversion module and the radio frequency transmitting antenna are that the transmitting end link and the receiving end link can carry out wireless communication in a millimeter wave frequency band, and control and setting can be carried out only by calling example codes in a software platform.
The data source and the receiving end are both provided with a computer, the sending end of the computer is PC _ TX, the receiving end of the computer is PC _ RX, and the computers are all provided with high-performance display cards, such as GTX 2060 or display cards with better performance, and can process video data, perform some image processing and operation and play and push ultrahigh-speed video stream data.
The network card module is a key link of the whole link capable of transmitting data at high speed in the method, and the function of the network card is realized by using one FPGA hardware board PXIe-6592R
Specifically, the video data stream generated by the transmitting end is in an RTP transmission format, and some header data are easily discarded during synchronization in a wireless transmission environment. If the video data are directly transmitted, the damage of the head data is very easy to cause the damage of the RTP format, so that the subsequent video decoding is influenced, and the visual result comprises that the video of the receiving end is easy to be green screen or mosaic. In the invention, in order to protect the RTP transmission format, a transmitting terminal protects the data packet format from being damaged in the transmission process based on the following steps:
the data source at the transmitting end will first generate a preliminary video data stream according to the RTP protocol of the application layer. The RTP protocol is based on the UDP protocol and relies heavily on the UDP header to guarantee a transmission success rate. Transmitting a fixed length UDP packet that can be transmitted based on an FFmpeg protocol; in this embodiment, the design value of the UDP packet length is fixed 1480 bytes, and the video data stream length is 1472 bytes. 6592R of the receiving end needs to repackage the data received by wireless transmission into UDP packets and IP packets until the packet format required by the MAC layer, considering the symmetry of the receiving end and the transmitting end, the UDP packet of the transmitting end should also be set to 1480 byte length, and the fixed length UDP packet can be pushed by using FFmpeg protocol.
The network card module of the transmitting end sends the complete IP packet into the baseband processing module, and the baseband processing module can find the boundary between the video data and the packet header. Compared with a bare video stream, the IP packet has redundant information of a source IP address, a destination IP address, a source port, a destination port and a UDP length, and the redundant information is known at a transmitting end and a receiving end, so that the boundary between the video data and a packet header can be found smoothly.
Further, the data stream is transmitted and controlled based on the FIFO data structure of the NI millimeter wave prototype system.
Specifically, the buffering the received video stream data by the network card module of the transmitting end further includes:
based on a 2GB DDR on a 6592R board card as a buffer pool, related configuration and read-write programs are written for driving, a common DDR is configured into a FIFO DDR through address application, data writing/reading operations to the FIFO DDR are completed in the same clock cycle, and meanwhile, the running time of each cycle is controlled through a timer.
The maximum size FIFO that can be supported by the current 6592R card is a FIFO with a width of 64 and a bit depth of 260000, while the maximum rate of the MAC layer is up to 10Gbps and the baseband processing speed is 844M symbols/sec. If the QPSK modulation mode is used, the baseband processing rate can reach about 1.7Gbps, in this case, if the burst transmission data stream time exceeds 2ms (260k 64)/(10Gbps-1.7Gbps), FIFO overflow is directly caused, resulting in data loss, and the above buffering operation can solve the problem.
Specifically, because the FPGA works by means of an accurate clock, the speed of baseband processing in the present invention is theoretically fixed at 844M symbols/sec, and in order to process videos in as many situations as possible, both a real-time video stream of 400Mbps and an 8K video stream at a rate of 1.5Gbps should be smoothly operated with a low delay. In order to cope with the situation of low processing data rate, a common method is to fill the idle position without valid data with random numbers. In the present invention, in order to distinguish between a random number and a significant number at a receiving end, a len parameter is used to record the length of the significant number. Referring to the schematic of fig. 5, the locations of the Nlen and len parameters in the packet are shown. Said filling random numbers in the video data stream using Nlen and len parameters further comprises:
the len parameter is used for recording the length of the effective number, the Nlen parameter is used for recording the length of each frame in the OFDM symbol, and the two parameters are used for filling random numbers with different lengths into data packets with different lengths through a finite state machine, so that a network card module at a transmitting end is matched with a baseband processing module in data flow rate, a system can normally run under the condition of low video rate,
the type of the FIFO used for carrying data in the present invention is U32, and the number of the first two U32 of the data field of the FIFO for carrying data is len. len not only serves as a header to provide a data field positioning function for the receiving end, but also provides effective data length information for the receiving end, and the receiving end can take out the effective information by setting the reading length. Meanwhile, as the head is provided with the two lens, the receiving end can judge whether the frame has errors or not by checking whether the two lens are equal, and the len parameter can also play a role in checking codes.
Nlen is the length of each frame in an OFDM symbol. Nlen appears as a FIFO in FPGA implementation, and actually functions as a subframe length table that is updated and maintained in real time. It calculates and maintains Nlen in the HOST program and transfers it to the 6592 network card through the DMA FIFO when the TX enable signal is pulled high. In the 6592R network card, the following steps are also carried out:
1) packing the data, reading Nlen from DMA FIFO, and then pulling up the read video packet enable;
2) reading video stream data in the DDR FIFO, and acquiring the DDR FIFO depth which is recorded as len;
3) len and Nlen-2 are compared in length, Nlen-2 is the frame length after 2-bit check codes are deducted, the sum of the lengths of effective data and filling random numbers is actually the maximum space of a data field in one frame, if len is smaller than Nlen-2, len is filled to the first two positions of the data field, video data are read to the data field, and random numbers are filled in other spaces; otherwise, Nlen-2 is given to len, two positions of the head of the data field are filled, Nlen-2 data are read, and other data are still stored in the DDR;
4) triggering the filling process of the next subframe.
Specifically, the code logic of LabVIEW is stream-based, so most of the time the data is presented in the form of stream, after demodulation by the previous module, the signal has been restored to a simpler bit stream state, and the bit stream will enter the dedicated sub VI module as an input to realize unpacking. The unpacking of the network card module at the receiving end from the subframe structure further comprises the following steps:
the bit stream obtained from the previous module is used as an input to enter a special sub-VI module to realize unpacking, the sub-VI module determines the beginning of the sub-frame data field by identifying the header structure of each sub-frame, and maintains a sequence number value to identify the sub-frame structure.
Furthermore, the main function of the sub VI module is to remove redundant data added by the receiving end, and identify the beginning of the sub-frame data field by identifying the header structure of each sub-frame. The sub-VI module maintains a sequence number value to identify the sub-frame structure, for example, when the sequence number value is 0 and 1, the current U32 data should be two equal len parameters, indicating the number of valid data contained in the current sub-frame. When the sub VI module verifies that the two len parameters are equal and confirms that the next module allows data to be input, the len length data is read from the sequence number value of 2, and the data is complete valid data. Secondly, the network card module repacks the video data. The FPGA card 6592 of the network card module provides an optical fiber interface for a transfer link connecting the millimeter wave system platform and the external device in the system, and supports high-rate data transmission. The blur of non-real-time video, such as recorded video, during transmission is usually related to two factors, namely data damage and loss during transmission, and failure of unpacking and reading data due to design defects. In a relatively stable indoor environment, the reason for the occurrence of ambiguity in transmission is generally the second. For example, the edge of the RTP packet carrying video data is damaged, which results in that the video decoding program at the receiving end cannot decode correctly, and at the transmitting end, the above problem is usually solved by an increased redundancy length method of retaining an IP header and a UDP header. Because the information of the IP and the UDP are known at the receiving end, a checking step is added in the link to determine that the IP and the UDP headers are correct, otherwise, the packet error is judged. The source data is then repackaged into a format that is acceptable to PC _ RX, and is consistent with the packet format coming out from PC _ TX at the transmitting end, as shown in fig. 3.
Specifically, the repackaging into a data packet whose format can be recognized by the display further includes:
high-speed data flow is transmitted into a 6592R network card module at high speed through a P2P protocol of a chassis backboard, whether IP and UDP headers are correct is judged through checking steps before repackaging, if not, mispackaging is judged to be not carried out, if correct, source data are repackaged into a format which can be accepted by a PC-RX, and the format of a data packet which is output from the PC-TX corresponding to a transmitting terminal is consistent,
the invention also provides a super-high speed video stream control system based on the NI millimeter wave prototype system, which enables the method to be realized based on the system, the system comprises,
the system comprises a prototype system main control part PXIe-1085, a baseband processing unit PXIe-7902, a network card module PXIe-6592R, a digital-to-analog converter PXIe-3610 DAC, an analog-to-digital converter PXIe-3630 ADC and an intermediate frequency module PXIe-3620 LO/IF.
To verify the beneficial effects of the present invention, the following experiments were performed: fig. 4 shows a test site of the present invention, the upper half of which is a transmitting end portion and the lower half of which is a receiving end portion. The fisheye curved surface effect of the video picture is a picture formed by splicing 6-mesh cameras at a data source by a PC (personal computer). Because the data volume of the camera in real-time shooting is unstable, the ultrahigh-speed transmission characteristic of the system is difficult to embody, the invention uses the existing oversized video and pushes the oversized video into the system at the speed of 1.5 Gbps. The system uses a QPSK modulation mode to carry out on-site verification, and the experimental result is as follows: clear and non-scattered constellation maps can be seen on a human-computer interaction interface of a receiving end, the error rate is within 0.1%, and a video picture of the transmitting end can be restored on a screen of the receiving end with low delay, and the delay is about 3-4 seconds. The test proves the stability of the invention in practical application and the capability of the invention for transmitting the media stream data with ultrahigh speed and large data volume, can well meet the requirement of high-speed transmission in the 5G standard, and can adapt to various application scenes.
Example 2
The invention also provides a super-high speed video stream control system based on the NI millimeter wave system, and the method of the embodiment can be realized based on the system, and specifically comprises,
the transmitting terminal comprises a prototype system main control part PXIe-1085, a network card module PXIe-6592, a baseband processing unit PXIe-7902, a digital-to-analog converter PXIe-3610 DAC, an antenna radio frequency module PXIe-7820 and an intermediate frequency module PXIe-3620 LO/IF; the system also comprises a cabinet PXIe-1085 used for providing slots for each module of the transmitting end, and the data source is a computer PC _ TX;
the receiving terminal comprises a prototype system main control part PXIe-1085, a network card module PXIe-6592, a baseband processing unit PXIe-7902, a digital-to-analog converter PXIe-3630 ADC, an antenna radio frequency module PXIe-7820 and an intermediate frequency module PXIe-3620 LO/IF; and the system also comprises a cabinet PXIe-1085 which is used for providing slots for each module at a receiving end, and the data destination video playing device is a computer PC _ RX.
It should be noted that the above-mentioned examples only represent some embodiments of the present invention, and the description thereof should not be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various modifications can be made without departing from the spirit of the present invention, and these modifications should fall within the scope of the present invention.
Claims (10)
1. A superspeed video stream control method based on an NI millimeter wave system is characterized in that: comprises the following steps of (a) carrying out,
step 1: the data source of the transmitting end generates a preliminary video data stream according to an RTP protocol and encapsulates the preliminary video data stream into an IP data packet of a transmission layer, the video data stream is pushed in a fixed length, and the video data stream is transmitted to a network card module of the transmitting end by using a 10G Ethernet optical fiber route;
step 2: the network card module of the transmitting end buffers the received video stream data, compares the received video stream data with a known MAC header and reads the video stream data based on the deviation sequence number, finishes reading the whole IP data packet according to the data length provided by the UDP header, and fills random numbers in the video stream data by using Nlen and len parameters according to the system clock frequency;
and step 3: the network card module at the receiving end receives the high-speed data stream from the baseband processing module, unpacks the high-speed data stream from the subframe structure, repacks the data stream into a data packet with a format capable of being recognized by the display and sends the data packet to the display;
and 4, step 4: and a display at the receiving end receives the data packet, and the data packet is unpacked and restored into an original video for playing and displaying.
2. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 1, wherein: the transmitting end comprises a data source, a network card module, a baseband processing module, a frequency conversion module and a radio frequency transmitting antenna, and the receiving end comprises a radio frequency receiving antenna, a frequency conversion module, a baseband processing module, a network card module and a display.
3. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 2, wherein: the method is based on software program control and is written and realized by NI LabVIEW 2015 SP.
4. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 3, wherein: the transmitting terminal protects the data packet format from being damaged in the transmission process based on the following steps:
a data source at a transmitting end sends a fixed-length UDP packet, and the fixed-length UDP packet can be sent based on an FFmpeg protocol;
the network card module of the transmitting end sends the complete IP packet into the baseband processing module, and the baseband processing module can find the boundary between the video data and the packet header.
5. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 4, wherein: and the data stream is transmitted and controlled based on the FIFO data structure of the NI millimeter wave prototype system.
6. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 5, wherein: the buffering of the received video stream data by the network card module of the transmitting terminal further comprises:
based on a 2GB DDR on a 6592R board card as a buffer pool, related configuration and read-write programs are written for driving, a common DDR is configured into a FIFO DDR through address application, data writing/reading operations to the FIFO DDR are completed in the same clock cycle, and meanwhile, the running time of each cycle is controlled through a timer.
7. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 6, wherein: said filling random numbers in the video data stream using Nlen and len parameters further comprises:
the len parameter is used for recording the length of the effective number, the Nlen parameter is used for recording the length of each frame in the OFDM symbol, and the two parameters are used for filling random numbers with different lengths into data packets with different lengths through a finite state machine, so that a network card module at a transmitting end is matched with a baseband processing module in data flow rate, a system can normally run under the condition of low video rate,
8. the ultra-high speed video stream control method based on the NI millimeter wave system according to claim 7, wherein: the unpacking of the network card module at the receiving end from the subframe structure further comprises the following steps.
The bit stream from the baseband processing module will be used as an input to enter a dedicated sub-VI module to perform unpacking, the sub-VI module determines the beginning of the sub-frame data field by identifying the header structure of each sub-frame, and will maintain a sequence number value to identify the sub-frame structure.
9. The ultra-high speed video stream control method based on the NI millimeter wave system according to claim 8, wherein: the repackaging into a data packet of a format recognizable by the display further comprises:
transmitting a P2P protocol passing through a high-speed data stream into a 6592R network card module at a high speed, checking and judging whether IP and UDP headers are correct through a receiving end network card module before repacking, reading specific values of all parameters (SRC _ IP, DST _ IP, SRC _ PORT and DST _ PORT) of the IP headers in received data by the receiving end network card module, comparing the specific values with fixed values set in advance by a device, judging whether the specific values are consistent, if all the specific values are consistent, judging that the specific values are correct, and if not, judging that the specific values are incorrect;
if not, determining as a packet error and ending, if correct, repackaging the video source data into a format that can be accepted by the receiving end display (PC _ RX), which is consistent with the data packet format output from the transmitting end data source (PC _ TX) to the 6592R network card module, as shown in fig. 5, a data packet having an IP header, a UDP header and an ethernet header.
10. A superspeed video stream control system based on an NI millimeter wave system is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
the transmitting terminal comprises a prototype system main control part PXIe-1085, a network card module PXIe-6592, a baseband processing unit PXIe-7902, a digital-to-analog converter PXIe-3610 DAC, an antenna radio frequency module PXIe-7820 and an intermediate frequency module PXIe-3620 LO/IF; the system also comprises a cabinet PXIe-1085 used for providing slots for each module of the transmitting end, and the data source is a computer PC _ TX;
the receiving terminal comprises a prototype system main control part PXIe-1085, a network card module PXIe-6592, a baseband processing unit PXIe-7902, a digital-to-analog converter PXIe-3630 ADC, an antenna radio frequency module PXIe-7820 and an intermediate frequency module PXIe-3620 LO/IF; and the system also comprises a cabinet PXIe-1085 which is used for providing slots for each module at a receiving end, and the data destination video playing device is a computer PC _ RX.
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