CN101873505B - Method and system for synchronously transmitting audio/video signal - Google Patents
Method and system for synchronously transmitting audio/video signal Download PDFInfo
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- CN101873505B CN101873505B CN2010101839788A CN201010183978A CN101873505B CN 101873505 B CN101873505 B CN 101873505B CN 2010101839788 A CN2010101839788 A CN 2010101839788A CN 201010183978 A CN201010183978 A CN 201010183978A CN 101873505 B CN101873505 B CN 101873505B
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Abstract
The invention provides a method and a system for synchronously transmitting an audio/video signal, which can truly realize the compounding and synchronous output of the audio/video signal. The system comprises a low pass filter, a signal modulator, a signal superposition device and a video amplification buffer. The method comprises the following steps of: performing low pass filtering processing on an initially acquired audio signal by using the low pass filter and then modulating the processed audio signal and a sinusoidal carrier signal in the signal modulator; performing superposition on the modulated signal and a composite synchronizing signal in a CCD video output signal in the signal superposition device; performing video amplification buffer on the superposed signal by using the video amplification buffer to obtain an audio/video composite signal; and separating the audio/video composite signal. The method and the system can truly realize the audio/video composite output and better realize the synchronization of the video signal and the audio signal.
Description
Technical field
The present invention relates to the electronic monitoring technical field, relate in particular to a kind of modulation, stack of audio signal and the method and system that transmits synchronously with vision signal.
Background technology
At present, in most video camera and television system, analog video or analogue audio frequency are separated transmission, export such as S terminal AV, CVBS (Composite Video Broadcast Signal or Composite Video Blanking and Sync, the CVBS signal is called in composite video broadcast singal or composite video blanking and synchronous in the following text.) signal etc. is and separates output.It all is independently to carry out that the process such as collection, processing of the collection, processing, transmission etc. of simulated audio signal and analog video signal is arranged in the prior art.In the audio and video equipment of main flow, employing transfers to a video/audio encoding and decoding chip with the vision signal of gathering and audio signal respectively as the autonomous channel and carries out the AD conversion, through a series of data structure algorithm, according to digital signal standards such as ITU656, convert digital signal to and give CPU processing.The collection of this kind audio signal, processing and transmission are independently carried out, and need independently audio frequency, video channel respectively, have taken extra transmission channel, and also needing increases extra audio frequency processing circuit, causes waste.The employing modulation and demodulation principles is also arranged in the prior art, the audio signal of the processing such as filtering of gathering is modulated on the carrier signal of a certain frequency, and then be superimposed on the synchronizing signal of CVBS, by delay circuit realize with vision signal synchronously after, transmit again.Adopt this scheme to realize, to the demodulation of the inner increase of needs such as present analog monitor audio frequency with circuit such as separate; Audio modulation signal can cause interference to synchronizing signal etc., and the CVBS signal is impacted; In the CVBS signal, can increase the sound carrier synchronizing signal.
Summary of the invention
Technical problem to be solved by this invention is, a kind of method and system that can really realize the audio-video signal synchronous transmission of the compound and synchronous output of audio frequency and video is provided.
For solving the problems of the technologies described above, the invention provides a kind of method of audio-video signal synchronous transmission, comprise step:
S101 carries out low-pass filtering treatment with audio signal;
S102, the sinusoidal carrier of selection characteristic frequency;
S103 modulates the carrier signal of selecting among the audio signal handled through described step S101 and the step S102;
S104 will separate after will superposeing through the composite synchronizing signal that audio signal after the step S103 modulation and CCD video are exported again;
S105 superposes the composite synchronizing signal and the audio signal of separating again, amplifies buffering through video and obtains the audio frequency and video composite signal, more compound audio-video signal is separated.
Described sinusoidal carrier among the step S102 can produce or produce by sinusoidal oscillation circuit via oscillator.
Can be after the audio signal modulation of step S103, the audio signal of step S104 increases by a controllable delay step before being superimposed to composite synchronizing signal, the synchronous transmission of control audio frequency and video.
The present invention also comprises a kind of system of audio-video signal synchronous transmission, this system comprises low pass filter, signal modulator, a signal superposition device and a video amplify buffer, the audio signal of obtaining is at first modulated in signal modulator with a sinusoidal carrier signal after low pass filtered is handled, composite synchronizing signal in a signal after the modulation and the CCD video output signals superposes in signal superposition device, signal after the stack amplifies buffer through video and amplifies buffering, amplify buffering through video and obtain the audio frequency and video composite signal, compound audio-video signal separates again.
Compared with prior art, the present invention has following beneficial effect: can really realize the compound output of audio frequency and video, can realize the synchronous of vision signal and audio signal preferably.
Description of drawings
Fig. 1 is an embodiment of the invention method flow diagram;
Fig. 2 is an embodiment of the invention system construction drawing;
Fig. 3 is embodiment of the invention sync separator circuit figure.
Embodiment
The present invention adopts modulation and demodulation principles, the audio signal of the processing such as filtering of gathering is modulated on the carrier signal of a certain characteristic frequency, and then be superimposed to CVBS signal (Composite VideoBroadcast Signal or Composite Video Blanking and Sync, the CVBS signal is called in composite video broadcast singal or composite video blanking and synchronous in the following text.) synchronizing signal on, by delay circuit realize with vision signal synchronously after, transmit again.This method need not increase extra audio frequency processing circuit, and the outer transmission channel of occupying volume does not realize the synchronous of audio frequency and video easily.
Be illustrated in figure 1 as the flow chart of the method for a kind of audio-video signal synchronous transmission of the embodiment of the invention, process step is as follows:
S101 carries out Filtering Processing with audio signal.
By low pass filter, get rid of undesirable high-frequency signal in the audio signal, obtain filtered audio signal.
S102, the sinusoidal carrier of selection characteristic frequency.
According to the frequency interlace principle, after the stack of the composite synchronizing signal in audio modulation signal and the CVBS signal, show on the spectrogram that audio modulation signal can separate with composite synchronizing signal, there are not stack and intersection mutually, the size of the carrier frequency of this moment is optimal selection, if the carrier frequency of this moment is w, carrier wave can be a sine wave of oscillator generation, and then the size of carrier wave is sin (wt).Carry out the modulation of audio signal with this carrier wave, can make synchronizing signal undistorted, do not have influence on vision signal, the phenomenon of avoiding crosstalking takes place.This carrier wave can also can produce by sinusoidal oscillation circuit for a sine wave of oscillator generation.
S103 carries out the audio signal modulation.
The frequency range of audio signal is roughly 10hz-20khz, and according to principles of modulation and demodulation, establishing audio signal is f (t), and the size of carrier wave is sin (wt), and wherein w is described particular carrier wave frequency, and then the expression formula of audio signal modulation can be designated as
f(t)*sin(wt) (1)
In looking voice receiver, increase the audio sync wave detector, according to the characteristics of synchronous detector, to having the modulated signal component of 90 degree phase differences not have detection output with demodulation subcarrier (1); And only detection output being arranged for the modulated signal component of demodulation subcarrier (1) homophase, the signal of output is proportional to the modulation signal that this component reflects, so the audio signal expression formula after the detection can be designated as
f(t)*sin(wt)*sin(wt) (2)
For above-mentioned carrier signal process synchronous detector in looking voice receiver, audio signal and composite synchronizing signal are separated; Through a low pass filter filtering, the purpose of filtering is that audio signal is separated with carrier signal then, obtains that original audio signal.As for decaying on the amplitude, can compensate by circuit gain fully.
S104, audio signal (2) after the modulation is superimposed on the composite synchronizing signal of CCD video output, and form complete CVBS (Composite Video Broadcast Signal or Composite Video Blanking and Sync with other signal, composite video broadcast singal or composite video blanking and synchronous) signal, separate this composite synchronizing signal again.
To be superimposed to the composite synchronizing signal of CCD video output in the audio signal after the above-mentioned steps S103 modulation, this composite synchronizing signal is formed complete CVBS signal with other signals (as luminance signal, carrier chrominance signal etc.).
Wherein, the effect of synchronizing signal is for the synchronous needs of sending and receiving, adds a lock-out pulse at transmitting terminal whenever having scanned delegation, adds field system chronizing impulse whenever having scanned one, transmit during the field flyback of being expert at respectively, therefore just in the transmission of CVBS signal, play auxiliary effect.
For guaranteeing better synchronous effect, can be after the audio signal modulation, being superimposed to synchronizing signal increases suitable controlled delay circuit before, controls the synchronous of audio frequency and video.
Externally adopt synchronizing separator circuit that the composite synchronizing signal in the CVBS signal is separated in the circuit, composite synchronizing signal split circuit of the present invention as shown in Figure 3.
S105, with the composite synchronizing signal of separating and audio signal through overcoupling, by principle of stacking, can be on composite synchronizing signal with the audio signal clamper, amplify buffer through necessary video again and can obtain the audio frequency and video composite signal, more compound audio-video signal is separated.
The embodiment of the invention adopts modulation and demodulation principles, the audio signal of the processing such as filtering of gathering is modulated on the carrier signal of a certain characteristic frequency, and then be superimposed on the synchronizing signal of CVBS, by delay circuit realize with vision signal synchronously after, transmit again.This method need not increase extra audio frequency processing circuit, and the outer transmission channel of occupying volume does not realize the synchronous of audio frequency and video easily.
Be illustrated in figure 2 as the system construction drawing of the method for a kind of audio-video signal synchronous transmission of the embodiment of the invention.
This system comprises that low pass filter, signal modulator, signal superposition device and a video amplify buffer.This system comprises initial audio signal input, sinusoidal carrier input signal and CCD video output signals, and the CCD video output signals comprises composite synchronizing signal, forms the CVBS signal with other signals such as carrier chrominance signal, luminance signal etc.
At first, audio signal inputs to low pass filter, and low pass filter is used for the audio signal of input is passed through low-pass filtering treatment, removes undesirable high-frequency signal in the audio signal, obtains filtered audio signal.
Input carrier signal again, this carrier signal is modulated through signal modulator with the audio signal through low-pass filtering.This carrier signal is a sinusoidal carrier signal, can perhaps produce by sinusoidal oscillation circuit for a sine wave of oscillator generation.According to the frequency interlace principle, after audio modulation signal and synchronizing signal stack, show on the spectrogram that audio modulation signal can separate, not have stack and intersection mutually with synchronizing signal, the size of the carrier frequency of this moment is optimal selection, if the carrier frequency of this moment is w, then the size of carrier wave is sin (wt).Carry out the modulation of audio signal with this carrier wave, can make synchronizing signal undistorted, do not have influence on vision signal, the phenomenon of avoiding crosstalking takes place.
Signal modulator is used for audio signal after the low-pass filtering and carrier signal are modulated, the audio signal after obtaining modulating.The modulation system that this signal modulator adopts is the quadrature amplitude balance modulation system.
The frequency range of audio signal is roughly 10hz-20khz, and according to principles of modulation and demodulation, establishing audio signal is f (t), and the size of carrier wave is sin (wt), and wherein w is described particular carrier wave frequency, and then the expression formula of audio signal modulation can be designated as
f(t)*sin(wt) (1)
In looking voice receiver, increase the audio sync wave detector, according to the characteristics of synchronous detector, to having the modulated signal component of 90 degree phase differences not have detection output with demodulation subcarrier (1); And only detection output being arranged for the modulated signal component of demodulation subcarrier (1) homophase, the signal of output is proportional to the modulation signal that this component reflects, so this time audio signal expression formula of output can be designated as
f(t)*sin(wt)*sin(wt) (2)
For above-mentioned carrier signal process synchronous detector in looking voice receiver, audio signal and composite synchronizing signal are separated; Through a low pass filter filtering, the purpose of filtering is that audio signal is separated with carrier signal then, obtains that original audio signal.As for decaying on the amplitude, can compensate by circuit gain fully.
Audio signal after the modulation is superimposed on the composite synchronizing signal of ccd output signal, form complete CVBS signal with other signals, suitable controlled delay circuit can be increased, to guarantee the stationary problem of audio frequency and video better before being superimposed to the synchronizing signal of CVBS.The effect of composite synchronizing signal is for the synchronous needs of sending and receiving, add a lock-out pulse at transmitting terminal whenever having scanned delegation, add field system chronizing impulse whenever having scanned one, transmit during the field flyback of being expert at respectively, therefore just in the transmission of CVBS signal, play auxiliary effect.By a synchronous split circuit (detailed aftermentioned sees also Fig. 3) synchronizing signal in the CVBS signal is separated again.
The composite synchronizing signal of separating is superposeed by a signal superposition device and audio signal through overcoupling, can audio signal is clamped on composite synchronizing signal.This signal superposition device is one can realize the circuit arrangement of signal overlaying function.This composite synchronizing signal is amplified buffer by a video again, vision signal is amplified, thereby the audio frequency and video that obtain meeting demand meets signal, can audio-video signal be separated then again.
Fig. 3 is a sync separator circuit of the present invention, comprises transistor V, capacitor C 1 and resistance R 1, resistance R C.The operation principle of this circuit is: the base stage of transistor V is 0 biasing, and when no signal, transistor V ends, and collector potential is-E.When synchronizing signal arrives, transistor V saturation conduction, collector potential rises to the saturated tube voltage drop Uces of transistor V, in transistor V conduction period, capacitor C is charged to the peak level of synchronizing signal rapidly through the emitter junction forward resistance of signal source internal resistance R1 and transistor V, and the right side current potential of capacitor C is near 0V.Synchronizing signal was after the past, and capacitor C discharges slowly through high value R2.At active line period, the change in voltage on the capacitor C is very little, and the reverse bias of transistor formed V, and it is ended.So in the base stage of transistor V, the sync signal level in the composite video signal is near the fixed value of 0V.And by the collector electrode output level of transistor V by-E positive polarity composite synchronizing pulse to Uces.
The embodiment of the invention adopts modulation and demodulation principles, the audio signal of the processing such as filtering of gathering is modulated on the carrier signal of a certain characteristic frequency, and then be superimposed on the synchronizing signal of CVBS, by delay circuit realize with vision signal synchronously after, transmit again.This method need not increase extra audio frequency processing circuit, and the outer transmission channel of occupying volume does not realize the synchronous of audio frequency and video easily.
The above only is preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of being done within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.
Claims (4)
1. the method for an audio-video signal synchronous transmission is characterized in that, comprises step:
S101 carries out low-pass filtering treatment with audio signal;
S102, the sinusoidal carrier of selection characteristic frequency;
S103 modulates the carrier signal of selecting among the audio signal handled through described step S101 and the step S102;
S104 will separate after will superposeing through the composite synchronizing signal that audio signal after the step S103 modulation and CCD video are exported again;
S105 superposes the composite synchronizing signal and the audio signal of separating again, amplifies buffering through video and obtains the audio frequency and video composite signal, more compound audio-video signal is separated.
2. the method for audio-video signal synchronous transmission as claimed in claim 1 is characterized in that, the described sinusoidal carrier among the step S102 can produce or produce by sinusoidal oscillation circuit via oscillator.
3. the method for audio-video signal synchronous transmission as claimed in claim 1 or 2, it is characterized in that, can be after the audio signal modulation of step S103, the audio signal of step S104 increases by a controllable delay step before being superimposed to composite synchronizing signal, the synchronous transmission of control audio frequency and video.
4. the system of an audio-video signal synchronous transmission, it is characterized in that, this system comprises low pass filter, signal modulator, signal superposition device, a composite synchronizing signal split circuit and a video amplify buffer, the audio signal of obtaining is at first modulated in signal modulator with a sinusoidal carrier signal after low pass filtered is handled, composite synchronizing signal in a signal after the modulation and the CCD video output signals superposes in signal superposition device, composite synchronizing signal in the signal after the composite synchronizing signal split circuit will superpose is separated, signal superposition device is with the composite synchronizing signal of separating and audio signal stack through overcoupling, signal after the stack amplifies buffer through video and amplifies buffering, amplify buffering through video and obtain the audio frequency and video composite signal, compound audio-video signal separates again.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010101839788A CN101873505B (en) | 2010-05-17 | 2010-05-17 | Method and system for synchronously transmitting audio/video signal |
| HK11103284.6A HK1149399A1 (en) | 2010-05-17 | 2011-03-31 | Method and system for synchronously transmitting audio/video signal |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010101839788A CN101873505B (en) | 2010-05-17 | 2010-05-17 | Method and system for synchronously transmitting audio/video signal |
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| Publication Number | Publication Date |
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| CN101873505A CN101873505A (en) | 2010-10-27 |
| CN101873505B true CN101873505B (en) | 2011-11-09 |
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| CN2010101839788A Expired - Fee Related CN101873505B (en) | 2010-05-17 | 2010-05-17 | Method and system for synchronously transmitting audio/video signal |
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| HK (1) | HK1149399A1 (en) |
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| CN103685903B (en) * | 2012-09-13 | 2016-12-21 | 北京同步科技有限公司 | Video camera attitude data transmitting device and transmission method thereof |
| CN111131917B (en) * | 2019-12-26 | 2021-12-28 | 国微集团(深圳)有限公司 | Real-time audio frequency spectrum synchronization method and playing device |
| CN112423074B (en) * | 2020-11-11 | 2022-09-16 | 广州华多网络科技有限公司 | Audio and video synchronization processing method and device, electronic equipment and storage medium |
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| CN2161035Y (en) * | 1992-11-27 | 1994-04-06 | 茅金声 | Multifunctional video frequency switching controller |
| CN2500055Y (en) * | 2000-03-15 | 2002-07-10 | 李荣欣 | Micro liquid crystal colour television |
| TWI282691B (en) * | 2001-03-23 | 2007-06-11 | Matsushita Electric Ind Co Ltd | Data-transmission method, data-transmission device, data-reception method and data reception device |
| CN1832565B (en) * | 2005-12-15 | 2010-05-05 | 康佳集团股份有限公司 | Built-in audio signal transmission circuit and method |
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| CN101873505A (en) | 2010-10-27 |
| HK1149399A1 (en) | 2011-09-30 |
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