CN103516998A - Station caption superposition method for analog video - Google Patents

Abstract

The invention discloses a station caption superposition method for an analog video. A device used in the method comprises a DSP main processor, an A/D chip, a D/A chip, a system control chip CPLD, a serial port RS-232 and corresponding software. A to-be-processed analog video signal firstly enters the A/D chip and undergoes DSP processing after analog-to-digital conversion; if the DSP processor detects that a station caption superstition command is transmitted through the serial port RS-232, a station caption superposition operation is carried out on the collected video and then the video is output, and otherwise, the collected video is not processed at all and is directly output; a station caption undergoing superposition is pre-processed, an image in an RGB format passes an Alpha channel and then is converted to be in a YUVA format, and then superposition operations are carried out in a superposition method; processed data are conveyed to the D/A chip from the DSP processor in a port direct-connection mode, undergo digital-to-analog conversion and then are output. According to the station caption superposition method, hardware circuits and corresponding software are designed, and the station caption superposition operation is carried out on the analog video input in a composite video (CVBS) format. Besides, the device is relatively independent, is easy to control and has good practical value.

Description

A kind of station symbol stacking method towards analog video

Technical field

The invention belongs to technical field of video processing, particularly a kind of station symbol stacking method towards analog video.

Background technology

Station symbol is as a kind of sign, very extensive in broadcast television industry application, in rich and varied TV programme, station symbol not only can identify the copyright of TV programme, and can be to the apparent direction that stresses that expresses content of TV program of spectators, therefore, it is playing the part of extremely important role in actual applications.

Along with the development of video technique, Video processing is widely used in the fields such as reconnaissance and surveillance, safety monitoring and aerial mapping, and particularly various long distance control systems are being brought into play more and more important effect.In complicated video source, the source and the copyright that how to identify intuitively video become a realistic problem that needs solution in application.According to current technology and engineering practice, showing, use for reference the mode in broadcast television industry, with station symbol, solve this problem, is a kind of simple and effective solution route.

Yet different from radio, TV and film industries is varied at the video acquisition video camera of protection and monitor field, class is uneven, can not require these video cameras all to possess station symbol overlaying function.Therefore in order to meet versatility and the diversity of acquisition camera, can to gathers and encode after the digital video station symbol processing that superposes.In this case, first need the video code flow after coding to decode accordingly, and then to decoded video superimpose station symbol, finally recompile again, then does next step transmission or storage.Which type of camera acquisition the stack of station symbol and front end are used irrelevant like this, but shortcoming is to identify from video source, and encoding and decoding processing repeatedly can cause video quality loss in various degree.In order to address this problem, analyze video camera in the market, the output format of the overwhelming majority is all analog video, so for this application characteristic, be necessary to invent a kind of station symbol stacking apparatus towards analog video, this device should possess the feature of independence and high efficiency, can not be subject to the impact of acquisition camera and complete independently station symbol overlaying function, can process in real time again, station symbol picture and original video are combined together.So both from video source leader, know its source and copyright, can reduce video quality loss again as far as possible.

Summary of the invention

The problem solving for needs, the object of the invention is to design a kind of station symbol stacking method towards analog video, the method is controlled simple, practical, by hardware circuit and corresponding software algorithm, realize the station symbol that superposes of the analog video with the input of Analog Composite Video (CVBS) form is processed, with source and the copyright of sign video source, do not lose again the visual quality of video simultaneously.This device is the analog video station symbol stacking apparatus as primary processor by digital signal processor (being designated hereinafter simply as DSP), this device can Wei Yi road analog video the specific station symbol of stack in real time, station symbol and video are combined together, to identify source and the copyright of video.

For realizing above-mentioned goal of the invention, the present invention adopts following technical scheme: a kind of station symbol stacking method towards analog video, realize Dui Yi road analog video stack station symbol and process, the device of the method utilization comprises a slice dsp processor, a slice A/D chip, a slice D/A chip, a slice system control chip CPLD and serial ports RS-232 and corresponding software; First pending analog video signal enters A/D chip, enters DSP and process after analog-to-digital conversion; If dsp processor detects serial ports RS-232, import the order of stack station symbol into, the video collecting is superposeed after station symbol operates and exported, otherwise, the video collecting is left intact and directly output; The station symbol of stack need to carry out preliminary treatment, by scratching the form that converts again YUVA after Alpha passage to, then adopts stacking method to carry out overlap-add operation in the picture of rgb format; Mode by direct port connection is sent to D/A chip by the data after processing from dsp processor carries out exporting digital-to-analogue conversion, and further the concrete steps of the method are as follows:

Step (1), to the preliminary treatment of station symbol picture, after scratching Alpha passage, convert the picture of rgb format to YUVA form;

Step (2), pending analog video signal convert digital signal to through A/D chip, by Video Port port, enter dsp processor;

Step (3), the station symbol overlap-add procedure of carrying out when system detection RS-232 serial ports is input as the order of stack station symbol; Wherein, described stack station symbol is processed, and to the digital video that enters dsp processor, the method for employing is during with the stack of station symbol picture:

Y'(x,y)＝L(x,y)×α+Y(x,y)×(1-α)，

Wherein (x, y) is the position of pixel, Y'(x, y) be the value of stack station symbol rear video pixel, L (x, y) and Y (x, y) they are respectively the values of the value of station symbol picture pixel and the video image vegetarian refreshments of the station symbol that do not superpose, α is stack coefficient:

α＝A/256 （0≤α≤1），

The value of the Alpha passage that wherein A is respective pixel;

Step (4), by the data after processing by Video Port port transmission to D/A chip, after converting analog signal to, export.

Wherein, described dsp processor is the digital signal processor with Video Port port and dma controller.

Wherein, the preliminary treatment of described station symbol picture, first the image in the station symbol picture tri-kinds of Color Channels of RGB being represented is scratched Alpha passage and is processed (for example can adopt Photoshop instrument to complete), convert the picture that tetra-kinds of passages of RGBA represent to, wherein Alpha passage represents the transparency of each pixel in station symbol picture, then tri-kinds of Color Channels of the RGB in RGBA are changed into YUV and represent, keep Alpha passage constant, obtain the storage of YUVA form.

Wherein, described analog video signal is composite video (CVBS) form.

Wherein, described detection RS-232 serial ports input command, when device is in running order, detect in real time from the order of RS-232 serial ports input, when order is for stack is during station symbol, video that will input dsp processor is implemented station symbol overlap-add procedure, when order is not when superposeing station symbol, the video of input dsp processor is left intact, directly by video port mouth, outputs to D/A chip.

Principle of the present invention is:

A kind of station symbol stacking method towards analog video of the present invention, the method operative installations comprises a slice DSP primary processor, a slice A/D chip, a slice D/A chip, a slice system control chip CPLD and serial ports RS-232 and corresponding software; First pending analog video signal enters A/D chip, enters DSP and process after analog-to-digital conversion; If dsp processor detects serial ports RS-232, import the order of stack station symbol into, the video collecting is superposeed after station symbol operates and exported, otherwise, the video collecting is left intact and directly output; The station symbol of stack need to carry out preliminary treatment, by scratching the form that converts again YUVA after Alpha passage to, then adopts stacking method to carry out overlap-add operation in the picture of rgb format; Mode by direct port connection is sent to D/A chip by the data after processing from dsp processor and carries out exporting digital-to-analogue conversion.The present invention processes the analog video stack station symbol with the input of composite video (CVBS) form by design hardware circuit and corresponding software realization, and in addition, this device is relatively independent, and controls simply, has good practical value.

The present invention's advantage is compared with prior art:

1, analog video station symbol stacking apparatus provided by the present invention is by the appropriate design to the preliminary treatment of station symbol picture and video processing circuits, when guaranteeing video quality, for video superimpose station symbol clearly, to identify source and the copyright of video.In addition, simple flow scheme design has very strong practicality.

2, station symbol stacking method provided by the present invention makes full use of the transparence information in Alpha passage presentation video when stack station symbol, using pixel transparency as stack weight, makes transition nature between station symbol edge and former video, combines together.

3, station symbol stacking method processing speed provided by the present invention is fast, and video 120 frames of processing per second that resolution is 720 * 576, meet the requirement of real-time completely, and highly versatile, can be generalized to easily the application of HD video.

Accompanying drawing explanation

Below in conjunction with the drawings and specific embodiments, the present invention is further illustrated.

Fig. 1 is system configuration schematic diagram of the present invention;

Fig. 2 is SAA7115 and DM642 signal connection diagram;

Fig. 3 is DM642 and SAA7129 signal connection diagram;

Fig. 4 is RS-232 serial ports and DM642 telecommunication circuit connection diagram;

Fig. 5 is station symbol picture pretreatment process schematic diagram;

Fig. 6 is video superimpose station symbol handling process schematic diagram.

Embodiment

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention.

A station symbol stacking method for analog video, the device that the method is used is mainly comprised of a slice DSP primary processor, a slice A/D chip, a slice D/A chip, a slice system control chip CPLD and serial ports RS-232 and corresponding software algorithm.It is characterized in that comprising following step:

(1) first pending video data enters into A/D chip by BNC port with composite video (CVBS) form, carries out the analog-to-digital conversion of video on A/D chip, and analog video is changed into digital video;

(2) mode by Video Port direct port connection is sent to the data after processing on DSP primary processor, to carry out video platform mark overlap-add procedure;

(3) video data after above-mentioned DSP master processor processes is sent to D/A chip by Video Port port and carries out digital-to-analogue conversion processing, exports after transferring digital video to analog video with composite video (CVBS) form by BNC port.

Wherein said DSP primary processor is the DSP with Video Port port and dma controller; System control chip is CPLD; Serial ports RS-232, for the order that whether superposes of the reset signal that receives host computer and send and station symbol, then carries out state control by importing DSP primary processor into after system control chip (CPLD) parsing.

In the sheet of described DSP, memory space is divided into a plurality of unit, directly uses memory space Zhong Ge unit in sheet that described video is processed and stored in DSP.

Particularly, in the sheet of described DSP, memory space is at least divided into following Si Ge unit:

Code unit: for depositing code and program running space;

Data storage cell: for depositing the intermediate data of video superimpose station symbol processing procedure;

Collecting unit: collect video data for depositing;

Output unit: for depositing video data for exporting after stack station symbol.

Described video processing procedure in memory space in the sheet of DSP primary processor comprises the steps:

(1 ') judges whether the station symbol that need to superpose, if do not need, by EDMA, acquisition buffer district video data is passed to display buffer and exports; If desired, perform step (2 ');

(2 ') are superimposed with the YUV component of station symbol respectively by the YUV component in the station symbol region that needs in the frame of video in current acquisition buffer district to superpose, and then the video after stack station symbol passed to display buffer by EDMA and export;

The station symbol of wherein said step (2 ') is through pretreated, first the RGB picture as station symbol is saved as to 32 RGBA forms by scratching Alpha passage, and then transfer the figure of RGBA form to yuv format, retain Alpha passage, be stored as YUVA form, as station symbol image data to be superimposed.

The video image relating in the present invention is processed and is comprised analog-to-digital conversion, digital-to-analogue conversion, stingy Alpha passage etc.Be simply described as follows respectively below:

(1) analog-to-digital conversion: Video Decode is become to digital video, be convenient to process.

(2) digital-to-analogue conversion: transfer the digital video after processing to analog video.

(3) Alpha passage: adopt 8 bits to be stored in image file, for representing the additional information of each pixel transparency.For example, RGB color model represents by three color information passages of red, green, blue synthetic, and 8 color depths of each passage, amount to 24, comprised all colour informations, our true color of often saying that Here it is.For realizing the transparent effect of figure, take passage of affix in the processing of graphic file and storage, this passage also adopts 8 bit representations, and this additional passage is used for the information of each pixel transparency in representative of graphics and is just called Alpha passage.

Actual, carry out video station symbol when stack, particularly as relatively independent operating under real-time treatment conditions, first must be when guaranteeing the quality and real-time of loss source video not, also there is station symbol Overlay clearly, the present invention, by the appropriate design to the preliminary treatment of station symbol picture and video processing circuits, has well met above-mentioned requirement.

Example as concrete operations, for implementing a slice TMS320DM642 that DSP primary processor of the present invention is selected TI company, A/D and D/A chip are selected SAA7115 and the SAA7129 of Philip, wherein TMS320DM642 has video port (Video Port, abbreviation VP mouth), built-in dma controller, the ram in slice with 256KB size, processing speed can reach 4800MIPS.

Below, from handling process and station symbol stacking method two aspects of video, be specifically described by reference to the accompanying drawings respectively.

One, Video processing flow process

In view of digital video is than the convenient processing of analog video, therefore guaranteeing, under the prerequisite of video quality, can respective handling will to be carried out after analog video digitlization again.In addition, select as far as possible to control simply convenient and practical Model Design.

The present invention is usingd a slice TMS320DM642 as primary processor, is responsible for video platform target overlap-add operation.Digital video data stream after analog-to-digital conversion (form is YUV4:2:2) first enters DM642; Then check the stack station symbol order whether have serial ports to send, if stack station symbol, the be added to ad-hoc location of video of pretreated station symbol, by the video data EDMA output after processing, otherwise, directly by the video data EDMA output collecting; Finally, after digital-to-analogue conversion, export.Be illustrated in figure 6 video superimpose station symbol handling process schematic diagram.

In the treatment system shown in Fig. 1, concrete data communication design is described as follows:

1. video data enters the mode of DM642: A/D chip adopts the SAA7115 of Philips company, the data communication of and SAA7115 existing with the VP cause for gossip of DM642, and VP mouth is selected the VP0 mouth of DM642.As shown in Figure 2, SAA7115 passes through VP0[0:7 by the data after analog-to-digital conversion to its signal connection layout] output to [2:9] of DM642VP mouth A channel, LLC is connected to VP0CLK0 as synchrodata output clock, and VP0CTL0, as A channel gating signal, draws high.According to IIC agreement regulation, SAA7115 need to have unique hardware address as the addressing address of DM642, and it determines by RTS0 pin, is defaulted as drop-downly, and its hardware address is 0x4A(write address) and 0x4B(read address).

2. the mode that video data is exported: D/A chip adopts the SAA7129 of Philips company, uses the mode output video data of the direct-connected SAA7129 of VP mouth of DM642.Because the collected video of VP0 mouth of DM642 takies, adopt VP1 mouth and the SAA7129 of DM642 to carry out direct-connected.The VP1 of DM642 is configured to display mode, the data after gathering and processing from [2:9] of DM642VP1 mouth A channel by the VP0[0:7 of SAA7129] output to SAA7129 and carry out digital-to-analogue conversion; On DM642, by the external 27M clock of VP1CLK0 (SAA7115 clock), VP1CLK1 is output pin, does not use, and it is unsettled.Its signal connection layout as shown in Figure 3.

3. receive the mode of RS-232 serial port command: self does not have serial ports controller DM642, so expand a serial ports connecting circuit by MAX3221 chip and CPLD in the present invention.Its signal connection layout as shown in Figure 4.Host computer connects RS-232 interface, the order sending is imported in CPLD and is resolved by serial port chip MAX3221, if parsing is the order of stack station symbol, GPIO5 is set to high level, DM642 detects after high level immediately the video the collecting station symbol operation that superposes, otherwise, GPIO5 is set to low level, DM642 does not superpose station symbol to the video collecting and directly exports.

Two, station symbol stacking method

Described stack station symbol, in order to make to reach the effect combining together after station symbol and video superimpose, need to meet following 3 points:

(1) pixel that shows word or figure in station symbol picture shows in opaque mode;

(2) background pixel of station symbol picture shows with transparent mode;

(3) pixel of word or figure and picture background intersection (i.e. the pixel in crossover position) in station symbol picture, according to the difference of its present position and show in translucent mode in various degree.

In view of above-mentioned 3 requirements, first the present invention carries out preliminary treatment by the picture as station symbol, and its handling process schematic diagram as shown in Figure 5.Concrete operation step is as follows:

1. the station symbol picture tri-kinds of Color Channels of RGB being represented is scratched Alpha passage by Photoshop instrument to image wherein and is processed, and converts the picture that tetra-kinds of passages of RGBA represent to, and wherein Alpha passage represents the transparency of each pixel in station symbol picture.

2. for ease of overlap-add procedure, tri-kinds of Color Channels of the RGB in RGBA are carried out to brightness separated with chrominance information, be converted to yuv format and represent, keep Alpha passage constant, obtain the storage of YUVA form.

It is known according to ITU-R BT.601 definition that RGB to step in 2. turns the process of YUV, and when tri-kinds of colors of RGB adopt respectively 8bit to represent, value is 0～255 o'clock, is transformed into YUV can adopts formula as follows by RGB:

$\left\{\begin{array}{c}Y=16+0.257R+0.504G+0.098B\\ \mathrm{Cb}=128-0.148R-0.291G+0.439B\\ \mathrm{Cr}=128+0.439R-0.368G-0.071B\end{array}\right.---\left(1\right)$

By formula (1), can know that transfer process relates to floating number multiplying, in order to reduce computational complexity, improve computational efficiency, the present invention has carried out improving processing to it, first floating number is carried out to fixed point processing by shifting function, in order to reduce loss error, the present invention adopts to move right 14 and realizes fixed point expansion, final result 14 bit recoveries that move to left again, obtain formula as follows:

$\left\{\begin{array}{c}Y=(4211R+8258G+1606B)>>14+16\\ \mathrm{Cb}=(-2425R-4768G+7193B)>>14+128\\ \mathrm{Cr}=(7193R-6324G-1163B)>>14+128\end{array}\right.---\left(2\right)$

Then multiplying is transferred to the realization of tabling look-up, concrete look-up method process is as follows:

First each multiplying all can be assumed to be

F＝XA （3）

In formula (3), X is a binary number that bit wide is 8bit, and A is a binary constant that bit wide is 14bit, and F is product, and when result is not done truncation, the bit wide of F is 22bit.

Formula (3) can be decomposed into:

$\begin{array}{c}F=({\mathrm{<figure-callout\; id="4"\; label="X"\; filenames="HDA0000386850860000011.png"\; state="\{\{state\}\}">X</figure-callout>}}_4\&CenterDot;2^6+{\mathrm{<figure-callout\; id="3"\; label="X"\; filenames="HDA0000386850860000011.png"\; state="\{\{state\}\}">X</figure-callout>}}_3\&CenterDot;2^4+{\mathrm{<figure-callout\; id="2"\; label="X"\; filenames="HDA0000386850860000011.png,HDA0000386850860000012.png"\; state="\{\{state\}\}">X</figure-callout>}}_2\&CenterDot;2^2+X_1)A\\ =X_{4}A\&CenterDot;2^6+X_{3}A\&CenterDot;2^4+X_{2}A\&CenterDot;2^2+X_{1}A\\ =\underset{n=1}{\overset{4}{\mathrm{\&Sigma;}}}{X}_{n}A\&CenterDot;2^{2n-2}\end{array}---\left(4\right)$

X wherein _nfor bit wide is the binary number of 2bit, therefore according to X _nvalue difference can to build look-up table as shown in table 1.

Look-up table in table 1 multiplying

X n(n=1、2、3、4)	X nA·2 2n-2
		00	0
01	A·2 2n-2
		10	2A·2 2n-2
11	3A·2 2n-2

At RGB, turn in YUV process, while carrying out multiplying, according to the numerical value of input, according to formula (4), carry out after resolution process, by the rear addition of look-up table 1.Convert multiplying to add operation like this, greatly reduce computational complexity, improved computational efficiency.

For above-mentioned pretreated station symbol picture, deposit in the memory of apparatus of the present invention, when needs superpose, the video of ad-hoc location and station symbol picture are superposeed, its stacking method is as follows:

Y'(x,y)＝L(x,y)×α+Y(x,y)×(1-α)，

Wherein, Y'(x, y) be the pixel value after stack; (x, y) is the position of pixel; L (x, y) and Y (x, y) are respectively the values of the value of station symbol picture pixel and the video image vegetarian refreshments of the station symbol that do not superpose; α is stack coefficient:

α＝A/256（0≤α≤1），

The value of the Alpha passage that wherein A is respective pixel.

The not detailed disclosed part of the present invention belongs to the known technology of this area.

Above analog video station symbol stacking apparatus provided by the present invention is had been described in detail.For one of ordinary skill in the art, any apparent change of under the prerequisite that does not deviate from connotation of the present invention, it being done, all will form infringement of patent right of the present invention, will bear corresponding legal liabilities.

Claims (5)

1. the station symbol stacking method towards analog video, realize Dui Yi road analog video stack station symbol and process, it is characterized in that: the device of the method utilization comprises a slice dsp processor, a slice A/D chip, a slice D/A chip, a slice system control chip CPLD and serial ports RS-232 and corresponding software; First pending analog video signal enters A/D chip, enters DSP and process after analog-to-digital conversion; If dsp processor detects serial ports RS-232, import the order of stack station symbol into, the video collecting is superposeed after station symbol operates and exported, otherwise, the video collecting is left intact and directly output; The station symbol of stack need to carry out preliminary treatment, by scratching the form that converts again YUVA after Alpha passage to, then adopts stacking method to carry out overlap-add operation in the picture of rgb format; Mode by direct port connection is sent to D/A chip by the data after processing from dsp processor carries out exporting digital-to-analogue conversion, and further the concrete steps of the method are as follows:

Step (1), to the preliminary treatment of station symbol picture, after scratching Alpha passage, convert the picture of rgb format to YUVA form;

Step (2), pending analog video signal convert digital signal to through A/D chip, by Video Port port, enter dsp processor;

Step (3), the station symbol overlap-add procedure of carrying out when system detection RS-232 serial ports is input as the order of stack station symbol; Wherein, described stack station symbol is processed, and to the digital video that enters dsp processor, the method for employing is during with the stack of station symbol picture:

Y'(x,y)＝L(x,y)×α+Y(x,y)×(1-α)，

Wherein (x, y) is the position of pixel, Y'(x, y) be the value of stack station symbol rear video pixel, L (x, y) and Y (x, y) they are respectively the values of the value of station symbol picture pixel and the video image vegetarian refreshments of the station symbol that do not superpose, α is stack coefficient:

α＝A/256 （0≤α≤1），

The value of the Alpha passage that wherein A is respective pixel;

Step (4), by the data after processing by Video Port port transmission to D/A chip, after converting analog signal to, export.

2. a kind of station symbol stacking method towards analog video as claimed in claim 1, is characterized in that: described dsp processor is the digital signal processor with Video Port port and dma controller.

3. a kind of station symbol stacking method towards analog video as claimed in claim 1, it is characterized in that: the preliminary treatment of described station symbol picture, first the image in the station symbol picture tri-kinds of Color Channels of RGB being represented is scratched Alpha passage and is processed, convert the picture that tetra-kinds of passages of RGBA represent to, wherein Alpha passage represents the transparency of each pixel in station symbol picture, then tri-kinds of Color Channels of the RGB in RGBA are changed into YUV and represent, keep Alpha passage constant, obtain the storage of YUVA form.

4. a kind of station symbol stacking method towards analog video as claimed in claim 1, is characterized in that: described analog video signal is composite video (CVBS) form.

5. a kind of station symbol stacking method towards analog video as claimed in claim 1, it is characterized in that: described detection RS-232 serial ports input command, when device is in running order, detect in real time from the order of RS-232 serial ports input, when order is for stack is during station symbol, video that will input dsp processor is implemented station symbol overlap-add procedure, when order is not when superposeing station symbol, the video of input dsp processor is left intact, directly by video port mouth, outputs to D/A chip.

Images