HWB-DVR digital video video recorder designed - Technology

Summary: This text has introduced the whole design philosophy of HWB-DVR digital video video recorder, has described the composition of its software and hardware, arrange to embedded CPU among them / operating principle to decode IC make in detail proving. Keyword: Digital VTR (DVR) ; MPEG-2; MPEG-4; PS; TS

It is that the family based on MPEG-1, MPEG-2/DVB, MPEG-4 standard should deal with and store the platform to sum up HWB-DVR digital video video recorder with the multimedia, can carry on the code video of MPEG-1, MPEG-2 or MPEG-4 form and return to simulation and digital television signal, it is the digitized household electrical appliance incorporating set-box and video recorder into an organic whole. This text explains its mentality of designing on hardware and software two respects.

Hardware design can find out DVR system is mainly made up of two major function parts by Fig. 1: Arrange / decode some and CPU part. It is to convert the simulation sound / video signal input to the data flow of MPEG-1, MPEG-2 or MPEG-4 form to compile / decode the partial function, can store the data flow, can convert it to simulation sound / video output again too. It is HT2010 to arrange / decode the partial key chip. It is in it sound / video system digital signal compile /demoder,last MPEG-1, arrange / decode MPEG-2 and MPEG-4 that three kinds of forms, and can carry on the conversion between three kinds of forms while arranged / decoded. HT2010 has codes and decodes the double function, can carry on code and decode procedure of the data flow at the same time. HT2010 can arrange / decode the data flow TS of MPEG form flows or PS flows. The processing procedure of the video signal is shown as in Fig. 2. It can be the following two forms to compile / decode the partial input video signal: ? Composite TV signal (CVBS) ? Separate the television signal (S-Video) Output it as CVBS signal, the system can expand S-Video I/O. The simulation video signal passing video ADC input, decode the analog video signal into a video data flow of ITU-656 form, the data flow of this video can be converted to the data flow of MPEG-1, MPEG-2 or MPEG-4 form after HT2010 chip is encoded, input the data flow of this kind of form into the hard disk and store, finish the storage function of DVR. MPEG data flow after the code that the hard disk stores is after HT2010 decode, run to the video DAC in video data which outputs ITU-656 form, output CVBS signal and S-Video signal after conversion. Couple the television signal to television through the video lead-out terminal of DVR, finish the broadcasting function of DVR. If carried on the above-mentioned two pieces of course at the same time, finished the simultaneous recording-playing function of DVR. The processing proc edure of the voice signal is similar to video processing procedure: The voice signal input is converted to the numberical voice signal through the audio frequency ADC, and then encode MPEG form through HT2010. The voice signal of MPEG form is converted to the audio frequency of simulation and exported through the audio frequency DAC. DVR supports the sound / synchronisation acquisition of the video, deals with. HT2010 has offered the interface of standard PCI, can carry on data interchange through PCI bus and CPU. The main control chip adopts embedded x86 CPU, its integrated 32-bit microcomputer PCI bus control unit, support polytype outside memory interface, 2 USB1.1 control devices, 10/100Mbps adaptation Ethernet controller, serial port communication control device, and visit a large amount of peripheral module such as storage control unit, clock generator, power supervisor, interrupt control unit and common I/O port directly. CPU carries on data transmission through I2C i nterface and other chips of the system, sends the order. The data flow after arranging / decoding through HT2010 carries on data interchange through the PCI total wired and CPU, can send the data to the hard disk and store through CPU. Peripheral interface offered through CPU, DVR can be connected with many kinds of apparatuses, users can obtain program information stored in the hard disk by peripheral interfaces such as USB interface, serial interface,etc.. Users can also connect with camera through the peripheral interface, in this way the program that the camera is recorded and produced is stored through DVR, also can broadcast through DVR. Users can also connect with computer through the common I/O port, can also connect with Internet network through interface of Ethernet, realize remote control. Reserve the interface and is used in the system expansion in the future in this DVR system.

The design software overall design DVR system software of system software is designed according to the modularization, functionalization, expansibility principle, 4 layers of architecture used wholly are shown as in Fig. 3. The relation between every module and hardware is shown as in Fig. 4. PCI driver program key CPU and compiling / using the communication of PCI bus while decoding IC, PCI driver program realizes and compiles / decodes the nuclear data communication and control in IC and operating system. PCI driver program optimization of design concerns the degree of dependence of running systematically. PCI driver program designs by way of module, it is easy to load and debug. The design of PCI driver program is divided into two pieces of course: 1. The module loads the course. The operating system loads the driver program through operating the insmod command, the driver program finishes the initialisation and systematic allocation of resources of the apparatus throug h a series of course. Call assigned resource control equipment normal operation of utility program. 2. The apparatus unloads the course. The operating system unloads the driver program through transferring the rmmod command. The driver program releases the system resource, removes the systematic control on hardware. The workflow is shown as in Fig. 5. Mainly realize the following contents in PCI driver program: static intcard_open(struct inode *, struct file *) ; static intcard_close(struct inode *, struct file *) ; static intcard_ioctl(struct inode *, struct file *, u_int, u_long) ; static voidcard_isr(int, void *, struct pt_regs *) ; Among them, card_open realizes that turns on PCI apparatus, increases and visits to count, does the preparation for the R/W device. Card_close realizes the function of shutting off the apparatus, release and visit to count, and mark the equipment state the mark as the inactive state. Card_ioctl realizes the basic control of PCI apparatus, main ly includes reading the apparatus, writing the apparatus, arrangement apparatus job parameter. Card_isr realize the intersection of PCI and interrupt processing of apparatus, data transmission finish and data initiate, stop, combine the intersection of call and function this ready for receiving. Because the interrupted call is very fast, transferring efficiency to expect very much of this function. Data transmission in user space and kernel space adopt iobuffer mechanism, use map_user_kiobuf to map user's space memory to the space of kernel, realize the sharing of the data in user space and kernel space is visited, this method has avoided the duplication in user space and kernel space of data, thus the speed that the improvement system runs.

Technical appraisement that project of " video recorder of the digital video " based on this conceptual design of concluding the speech has already organize been through Technology Office of State Broadcasting Film & TV Head Bureau. Because the HWB-DVR digital video video is mechanically controlled to help, the memory capacity can be very large and working stably and reliably, so the application of the digital VTR is quite extensive. First of all, the digital VTR can substitute the function of the traditional simulation video recorder in an all-round way, in traditional TV programming, record and produce, store to imitating the program, and can carry on the program search fast conveniently; In addition can also receive the digital television program that the digital television system conveyed, carry on program record and produce depending upon need, and can according to different to adopt different digital compression ways to the intersection of program and qualitative req uirement. Digital VTR can used in broadcasting the intersection of TV and forward end, can the masses of consumer used too. In control project while being civil, such as in the closed circuit television equipment, the digital VTR can be regarded as the central supervisory equipment, the vision storing every lens and coming is encoded, and convey the signal to the distal control centre depending upon need. In addition, the digital VTR can be regarded as the program tools of VCD, DVD, can make VCD, DVD CD program respectively while taking the recording interface equipment with digital VTR.

Bibliographical reference 1 Wang XueLong Write. Embedded Linux systematic design and application. The publishing house of Tsing-Hua University, 20012 Michbael Barr writes greatly the will and translates. C/C ++ embedded system programming. China Electric Power Publishing House, 20013 Lee faces blue and green and writes. PC and one-chip computer data communication technology. Beihang University publishing house, 20004 MPEG expert panel. ISO; 14496 IEC DIS, 19995 Alessandro Rubini, Jonathan Corbet it writes Wei to be to translate. Linux apparatus drives the programming. China Electric Power Publishing House, 2002