The utility model content
For above-mentioned deficiency, the utility model provides a kind of wireless audio-video transmission system, and it not only can improve the overall performance of system, and can reduce the plate level and connect the speed restriction that brings.
The technical scheme in the invention for solving the technical problem is: a kind of wireless audio-video transmission system, comprise coded excitation subsystem and receipt decoding subsystem, it is characterized in that, described coded excitation subsystem comprises audio collecting device, video capture device, audio A/D modular converter, the video a/d modular converter, encode processor, digital up converter and radio frequency sending set, the input of described audio A/D modular converter is connected with audio collecting device, output is connected with the input of encode processor, the input of described video a/d modular converter is connected with video capture device, output is connected with the input of encode processor, the output of described encode processor is connected with the input of digital up converter, and the output of described digital up converter is connected with the input of radio frequency sending set; Described receipt decoding subsystem comprises radio demodulating module, decoding processor, audio D/A converter, image display interface circuit, audio-frequence player device and video display apparatus, described radio demodulating module is connected with the input of decoding processor, the output of described decoding processor is connected input with audio D/A converter respectively and is connected with the image display interface circuit, described audio-frequence player device is connected with the output of audio D/A converter, and described video display apparatus is connected with the output of image display interface circuit.
Preferably, described encode processor comprises the audio sample module that is arranged on the fpga chip, H.264 encoder, TS stream packing device and COFDM modulation module, the input of described audio sample module is connected with the output of audio A/D modular converter, output is connected with the input of TS stream packing device, the input of described H.264 encoder is connected with the output of video a/d modular converter, output is connected with the input of TS stream packing device, the input of described COFDM modulation module is connected with the output of TS stream packing device, and output is connected with the input of digital up converter.
Preferably, described decoding processor comprises the TS stream parsing module that is arranged on the fpga chip, the code stream diverter module, Audio recovery module and decoder H.264, the input of described TS stream parsing module is connected with the radio demodulating module, output is connected with the input of code stream diverter module, the output of described code stream diverter module is connected with the input of Audio recovery module and the decoder of being connected respectively, the output of described Audio recovery module is connected with the input of audio D/A converter, and the output of described H.264 decoder is connected with the input of image display interface circuit.
Preferably, described audio collecting device comprises microphone.
Preferably, described video capture device comprises camera.
Preferably, described audio-frequence player device comprises one or more in earphone, loudspeaker and the loud speaker.
Preferably, described video display apparatus comprises LCD display or LED display.
Preferably, described digital up converter adopts the AD9857 chip.
Preferably, described audio A/D modular converter adopts the PCM1808 chip.
Preferably, described video a/d modular converter adopts the SAA7113 chip.
Good effect of the present utility model is, the utility model is by these crucial algorithms such as integrated audio/video encoding/decoding algorithm and wireless-modulated algorithm on fpga chip, especially audio/video coding compression algorithm and wireless-modulated algorithm are integrated in the fpga chip, the problem such as the delay that has solved existing wireless audio-video transmission system is large, image quality is bad has reduced the transmission delay of system greatly; Adopt advanced coding and decoding video algorithm (H.264 algorithm), increased the compression ratio of code stream when improving image quality, reduced the pressure of wireless transmission rate; Adopted outstanding wireless-modulated algorithm COFDM, increased transmission quality and the transmission range of system under mal-condition, had that image quality is good, characteristics such as long transmission distance and system delay are little.
Embodiment
Such as Fig. 1, Fig. 2 and shown in Figure 3, a kind of wireless audio-video transmission of the present utility model system comprises coded excitation subsystem and receipt decoding subsystem.Described coded excitation subsystem comprises audio collecting device, video capture device, audio A/D modular converter, the video a/d modular converter, encode processor, digital up converter and radio frequency sending set, the input of described audio A/D modular converter is connected with audio collecting device, output is connected with the input of encode processor, the input of described video a/d modular converter is connected with video capture device, output is connected with the input of encode processor, the output of described encode processor is connected with the input of digital up converter, and the output of described digital up converter is connected with the input of radio frequency sending set; Described receipt decoding subsystem comprises radio demodulating module, decoding processor, audio D/A converter, image display interface circuit, audio-frequence player device and video display apparatus, described radio demodulating module is connected with the input of decoding processor, the output of described decoding processor is connected input with audio D/A converter respectively and is connected with the image display interface circuit, described audio-frequence player device is connected with the output of audio D/A converter, and described video display apparatus is connected with the output of image display interface circuit.
Described encode processor comprises the audio sample module that is arranged on the fpga chip, H.264 encoder, TS stream packing device and COFDM modulation module, the input of described audio sample module is connected with the output of audio A/D modular converter, output is connected with the input of TS stream packing device, the input of described H.264 encoder is connected with the output of video a/d modular converter, output is connected with the input of TS stream packing device, the input of described COFDM modulation module is connected with the output of TS stream packing device, and output is connected with the input of digital up converter.
Described decoding processor comprises the TS stream parsing module that is arranged on the fpga chip, code stream diverter module, Audio recovery module and decoder H.264, the input of described TS stream parsing module is connected with the radio demodulating module, output is connected with the input of code stream diverter module, the output of described code stream diverter module is connected with the input of Audio recovery module and the decoder of being connected respectively, the output of described Audio recovery module is connected with the input of audio D/A converter, and the output of described H.264 decoder is connected with the input of image display interface circuit.
Described audio collecting device adopts microphone.
Described video capture device is preferred to use camera.
Described audio-frequence player device adopts one or more in earphone, loudspeaker and the loud speaker.
Described video display apparatus adopts LCD display.
Described digital up converter adopts the AD9857 chip.
Described audio A/D modular converter adopts the PCM1808 chip.
Described video a/d modular converter adopts the SAA7113 chip.
The course of work of described coded excitation subsystem is as follows: the original analog audio signal of microphone collection is through forming digital signal after the collection of PCM1808 chip, the audio sample module is extracted buffer memory according to the characteristics of digital signal with voice data, then passes to TS stream packing device; Simultaneously, the signal transition of camera collection becomes composite video signal (CVBS) to pass to the SAA7113 chip of coded excitation subsystem, and the SAA7113 chip becomes the BT656 signal of standard with the CVBS signal transition of input and pass to H.264 encoder to do further processing.H.264 encoder receives the BT656 digital video signal from SAA7113, and the luminance and chrominance information in this signal extracted be transformed into the YUV420 form, and the code stream of YUV420 form further compressed form H.264 code stream and pass to TS stream packetization module.The audio code stream that process gathers and the video codes behind the compression coding fail to be convened for lack of a quorum further packaged, form one by one TS stream packets, and each packet comprises 188 byte.Each packet is divided into again header packet information, supplementary, video/audio/data code stream, padding data.Wherein corresponding different ID number of different code stream is placed in the header packet information for these ID numbers and identifies for receiving terminal TS stream decoder.Further delivering to the COFDM modulation module through the TS stream packets after the packing modulates.The COFDM modulation module is supported the variable channel bandwidth of 1.25MHz, 2MHz, 4MHz and 8MHz, realizes the reasonable utilization of channel width.The COFDM modulation module is modulated the TS stream of input.Signal after the modulation converts radiofrequency signal to through digital up converter, launches through radio frequency sending set again.Digital up converter adopts stable AD9857 chip, and the centre frequency of output signal is 36.166MHz, and the bandwidth of signal determines that by the COFDM modulation module these four kinds of channel widths of 1.25MHz, 2MHz, 4MHz and 8MHz are arranged.
The course of work of described receipt decoding subsystem is as follows: original RF signal is through forming the TS stream of standard after the demodulation of radio demodulating module, these code streams are sent to TS stream parsing module.TS stream parsing module extracts the audio, video data in the TS code stream and control data for subsequent module.Described code stream diverter module decides the flow direction of code stream according to the code stream character after resolving, and voice data is submitted to the Audio recovery module, and video code flow is offered the video decode module.Described Audio recovery module receives and is buffered among the inner FIFO from the voice data of code stream diverter module and with it, then exports to outside audio D/A converter with the data format of I2S, and then drives the audible devices such as earphone, loudspeaker or loud speaker.Described H.264 decoder receives the video code flow from the code stream diverter module, then according to standard H.264 code stream is decoded, thereby recovers video data and be stored in the outside DDR2 memory with the form of YUV420.Described image display interface circuit extracts the video code flow of YUV420 form storage and is converted into the RGB data from the DDR2 memory, and then drives the image that outside LCD display shows the data acquisition end.
Fig. 2 is the schematic diagram of wireless audio-video transmission system bidirectional communication.As shown in Figure 2, the both-way communication scheme of a kind of wireless audio-video transmission system is divided into wireless transmitting system A and wireless transmitting system B, wireless transmitting system A passes through transmission of radio links to wireless transmitting system B with the audio, video data of A side, and the centre frequency of supposing the system A tranmitting frequency is 340MHz; Wireless transmitting system B is made as 340MHz according to exterior arrangement with the receive frequency of radio frequency solution frequency module (Tuner), reception is from the audio-video signal of the A of system, then the Radio Link of feedback information by the B of system passed to the A of system, the centre frequency of supposing the system B tranmitting frequency is 350MHz; Wireless transmitting system A is made as 350MHz according to exterior arrangement frequently with the reception of tuner, and then receives the feedback signal from the B of system.
Fig. 3 is the utility model one concrete structural representation of using.As shown in Figure 3, the utility model adopts the external DC power supply of 12V, and by the control signal of I2C interface reception from external equipment, this external equipment can be that computer also can be special-purpose control daughter board; By the I2C interface tranmitting frequency of radio frequency sending set, the receive frequency of radio frequency solution frequency module (Tuner), the signal bandwidth of COFDM modulation etc. can be set.The wireless audio-video transmission system is by the visual signal around the camera collection, and output signal is composite video signal (CVBS); Audio signal around the wireless audio-video transmission system is transferred to audio collection module on the FPGA plate by microphone; The audio-video signal that gathers is through compression coding, and then packing forms TS stream.Form the analog if signal of 36.166MHz after TS stream process COFDM modulation module, the digital up converter, and then launch by radio frequency sending set, the tranmitting frequency of radio frequency sending set is by peripheral equipment control.The wireless audio-video transmission system finishes reception and the demodulation of radiofrequency signal by rf modulations module (Tuner), and exports to fpga chip with the TS stream of standard.Give Audio recovery module and decoder H.264 after the resolved shunting of TS stream, finally by earphone or sound equipment output sound, by the videl signal of LCD display demonstration transmitting terminal.
The problem such as the delay that the utility model has mainly solved existing wireless audio-video transmission system is large, image quality is bad; Provide a kind of audio/video encoding/decoding algorithm and wireless modulation-demodulation algorithm have been integrated in system scheme on the fpga chip, especially audio/video coding compression algorithm and wireless-modulated algorithm are integrated in the fpga chip delay of having introduced when having avoided adopting the individual chips Integrated Solution; In addition, use advanced coding and decoding video algorithm H.264 and outstanding wireless-modulated algorithm COFDM, the characteristics such as this scheme has that image quality is good, long transmission distance, system delay are little.The utility model has adopted H.264 code decode algorithm, and H.264 the excellent characteristic of code decode algorithm can have higher compression ratio under image quality of the same race, thereby reduces the bandwidth pressure of system; Adopted COFDM wireless modulation-demodulation algorithm, COFDM wireless modulation-demodulation algorithm has extremely strong antijamming capability, availability of frequency spectrum high, help to improve the transmission range of system, utilize fpga chip that audio/video coding compression algorithm and COFDM wireless-modulated algorithm are integrated on the same chip, when improving the entire system performance, reduced the plate level and connected the speed restriction that brings.