There are too many variables. Some manufactures may have their own terminology that may use the same abbreviations. Buyer beware.
Television is an old technology, and the industry is so desperate to evolve in to new technology.
Back when tubes ruled the day instead of transistors it was hard to make an electronic circuit "work fast".
They came up with some pretty good "tricks" to overcome the limitations of the technology at the time.
They devised a system that would make a picture by scanning the odd number of lines, and then come back, and "fill in the picture" by scanning the even number of lines.
A scan is called a field. In other words it creates two fields to create one frame.
60 fields is the same as 30 frames.
The afterglow of the phosphor of CRTs, in combination with the persistence of vision results in two fields being perceived as a continuous image which allows the viewing of full horizontal detail with half the bandwidth that would be required for a full progressive scan while maintaining the necessary CRT refresh rate to prevent flicker.
Only CRTs can display interlaced video directly – other display technologies require some form of deinterlacing.
There is no way to measure record quality. What you see is what you get.
Guarding a residence, and guarding a diamond store are completely different situations.
How much are you willing to spend? This will be the first way to measure the record quality that you will receive.
There are some devices that sacrifice the FPS in order to give you higher quality in record video. This is a fair trade off except where timing is of the essence such as in license plate capture. Low FPS may miss the timing of the plate at the crucial point that would be optimum for recording as the plate passes by the camera.
For a hospital that wants to catch facial shots of people in an area can have high record quality, and low FPS. The snap shot effect will not create too much of a problem. Very low FPS may create a situation where you might miss a face due to the turning of the face, or a change in the travel path of the person being reviewed.
You have to look at what you want your surveillance system to do then you need to select the proper DVR.
Residential systems are not "high threat" situations unless you have antiquities, a million dollars cash under the mattress, or jewelry that you need to protect.
Inexpensive DVRs can be used. Now it become the lens selection that can make, or break a good system. Most "kits" come with wide angle lenses. Wide angle lenses suffer from distance distortion. At about 20 things in the video will appear farther away then in reality. Faces become smaller in the video, and you have less pixals to create the face.
The more you need facial recognition the more you need the video to look like the 6 O'Clock news with only head, and shoulders in the video frame.
Select the right lens, and poor record quality may not be as much of a factor in having a decent system.
Several years ago it was expensive buying a hard drive for you DVR. Hard drive size that you decided on would be based on what you could afford at the time.
Prices of hard drives have come down in cost in recent years. If you are making a decision on what size hard drive to buy for your DVR then here are some pointers. There are too many DVR manufactures, designs, recording formats, and there are environmental factors such as how the cameras are mounted. Inside camera will not have as much activity if you are using motion detection to record compared to cameras that are facing a busy street where cars will constantly trigger motion detection on your DVR.
Since there are too many variables lets use a representation of numbers to at least explain what to look for.
Let use a number of 5GB a day per DVR channel based on 30 Frames Per Second NTSC.
A for channel DVR will use 20GB of information per day. If you buy an 80GB hard drive then divide it by 20GB. This will give you a rough idea of how long your recorded history will fill the hard drive.
80GB / 20GB will give you roughly about 4 days of history.
If you need 7 days of recording then 7 X 20 = 140GB will be used. You will need a hard drive that is larger then 140GB.
A 250GB hard drive / 20 = 12.5 days of recording.
A 500GB hard drive / 20 = 25 days of recording.
This is not fact as this is only a representation of numbers. Your actual usage will be based on Compression used, Frames Per Second used, and the quality setting in the DVR menu for video recording, and whether you use 24/7 recording, or you use motion detection recording.
This should at least get you fairly close to an idea of what you should look for in hard drive decisions.
CONEXTANT
http://www.conexant.com/products/entry.jsp?id=145 (Taiwan)
Conexant designs, develops and sells semiconductor system solutions that connect personal access products such as set-top boxes, residential gateways, PCs and game consoles to voice, video and data processing services over broadband and dial-up connections. Key semiconductor products include digital subscriber line (DSL) and cable modem solutions, fiber optic system-on-chips, broadcast video encoders and decoders, digital set-top box components and systems solutions.
THIS IS THE MOST WIDELY USED VIDEO DECODER ON THE DVR CARD MARKET.
FUSION 878A http://www.conexant.com/products/entry.jsp?id=409
VIDEO DECODERS
http://www.conexant.com/products/entry.jsp?id=202
WHAT IS A PCI DECODER?
http://www.conexant.com/servlets/DownloadServlet/PBR-200097-001.pdf?docid=98&revid=1
BLOCK DIAGRAMS, CHIP PIN OUTS, FUNCTIONAL DISCRIPTION, FIFO DATA INTERFACE, ELECTRICAL INTERFACES,
PCI BUS INTERFACE INFO, IO PORT, REGISTER DEFINITIONS, VIDEO TIMING CONTROL REGISTERS, AND MORE!
http://www.conexant.com/servlets/DownloadServlet/DSH-200115-001.pdf?docid=116&revid=1
HINT
HINT (PLXTECH) (Taiwan)
http://www.plxtech.com/
HB1 PCI to PCI Bridge
Chip Number: HB1/1-SE/HB6
Chip Description: Universal PCI-to-PCI Bridge (non-transparent mode)
Notes: now called PCI 6140/52/6254
PCI / PCI X BRIDGES
http://www.plxtech.com/products/fastlane/
PCI 6140 TECHNICAL DOCUMENTATION
http://www.plxtech.com/products/fastlane/pci6140.asp#techdocs
PICTURES OF HINT CHIPS
http://www.plasma-online.de/index.html?content=http%3A//www.plasma-online.de/english/identify/picture/hint.html
NXP
WWW.NXP.COM (Korea)
http://www.nxp.com/profile/
NXP is a top 10 semiconductor company founded by Philips more than 50 years ago. Headquartered in Europe, the company has 37,000 employees working in more than 20 countries and posted sales of USD 6.3 billion in 2007.
NXP creates semiconductors, system solutions and software that deliver better sensory experiences in mobile phones, personal media players, TVs, set-top boxes, identification applications, cars and a wide range of other electronic devices.
VIDEO DECODERS
http://www.nxp.com/#/homepage/cb=[t=p,p=/50804/50823/31571]|pp=[t=pfp,i=31571]
PCI / PCIe MULTIMEDIA INTERFACES
http://www.nxp.com/#/homepage/cb=[t=p,p=/50804/55466]|pp=[t=pfp,i=55466]
THIS CHIP IS WIDELY USED BY GENERIC ASIAN OEM DVR CARDS.
SAA7146A PHILLIPS CHIP SET
http://www.nxp.com/#/pip/pip=[pip=SAA7146A_2]|pp=[t=pip,i=SAA7146A_2]
WHITE PAPER PDF (INFORMATION OVERLOAD)!
http://avmaster.bnx.homelinux.net/datasheets/saa7146.pdf
SAA7146A PHILLIPS MANUALS (WINDOWS 95, WINDOWS 3.1)
http://www.dize.de/manuals/rel103.pdf
USED IN ICREALTIME FLEX SERIES DVRS
PHILIPS TRIMEDIA VIDEO PROCESSOR
http://en.wikipedia.org/wiki/TriMedia
THE TRIMEDIA TM-1 PCI VLIW MEDIA PROCESSOR PDF
http://www.hotchips.org/archives/hc8/3_Tue/HC8.S6/HC8.6.1.pdf
PAPER TM3270 MEDIA PROCESSOR PDF
http://ce.et.tudelft.nl/publicationfiles/1228_587_thesis_JAN_WILLEM.pdf
MOTION ESTIMATION PERFORMANCE OF THE TM3270 PROCESSOR PDF
http://ce.et.tudelft.nl/publicationfiles/982_587_sac2005_v6.pdf#search=%22tm3270%22
TRIMEDIA USER GROUP (YAHOO)
http://tech.groups.yahoo.com/group/trimedia/
USED IN ICREALTIME PRO SERIES DVRS
BLACKFIN ONLINE LEARNING AND DEVELOPMENT (USED IN ICREALTIME PRO SERIES DVRS)
http://www.analog.com/processors/learning/index.html
BLACKFIN ONLINE LEARNING AND DEVELOPMENT (USED IN ICREALTIME PRO SERIES DVRS)
http://www.analog.com/en/embedded-processing-dsp/blackfin/content/index.html
BLACK FIN CORE PROCESSOR
http://www.analog.com/en/embedded-processing-dsp/blackfin/content/blackfin_core_basics/fca.html
BLACKFIN PROCESSOR ARCHITECTURE OVERVIEW
http://www.analog.com/en/embedded-processing-dsp/blackfin/content/blackfin_architecture/fca.html
BLACKFIN PROCESSOR HIGHLIGHT PDF'S
http://www.analog.com/en/embedded-processing-dsp/blackfin/processors/product-highlights/resources/index.html
DATA SHEETS
http://www.analog.com/en/embedded-processing-dsp/blackfin/processors/data-sheets/resources/index.html
Workshops
http://www.analog.com/processors/blackfin/training/workshops/index.html
University Program Frequently Asked Questions
http://www.analog.com/processors/universityProgram/universityfaq.html
AVERLOGIC
http://www.averlogic.com/about_aver1.htm
Founded in 1996, AverLogic Technologies is a fabless semiconductor company with headquarters in Taipei, Taiwan. Specialized in high-performance application specific memory and video processing circuits, the Company has design centers in San Jose, California USA, Hsinchu, Taiwan and ShenZhen City, PRC.
AVERLOGIC Video Decoder and ADC ICs, including: AL240, AL242, AL243, AL244, AL875
http://glyn.com/data/glyn/media/doc/AVERLOGIC_product_overview.pdf
AL240 Video Decoder Description
The AL240 is silicon efficient, cost effective high video quality NTSC/PAL SECAM video decoder with high quality Y/C separation process. The AL240 decodes NTSC/PAL/SECAM composite video or S-video and convert it into YCbCr 4:2:2, 8-bit digital video output. Employing adaptive filter technology, the AL240 is able to provide a clear Y/C separated signals while maintaining excellent frequency response. The result is sharp, high detail video that eliminates unwanted dot crawl and false color effects. Fully programmable video characteristic controls, such as hue, contrast, brightness, saturation, are supported. The AL240 decoder incorporates an advanced vertical blanking interval (VBI) data processor to do data slicing, parsing and decoding teletext, closed caption, and other formats. Two wires of hardware channel switching inputs allow decoder to do an instant alternation of analog CVBS inputs from one to the other. Up to 4 serial bus addresses can be selected via two configuration pins that allow multiple AL240 chips on the design without extra logic.
Mentor Graphics Embedded Systems
http://www.mentor.com/products/embedded_software/
Operating System
http://www.mentor.com/products/embedded_software/nucleus_rtos/index.cfm
TEXAS INTRUMENTS
Streaming Media
http://focus.ti.com/docs/solution/folders/print/202.html
Video Compression and Data Flow for Video Surveillance Texas Instruments White Paper
http://focus.ti.com/lit/wp/spry104/spry104.pdf
DaVinci Technology Overview
http://focus.ti.com/lit/ml/sprb189b/sprb189b.pdf
Driving IPTV Growth:
The Challenges and Perspectives
http://focus.ti.com/lit/wp/sphy004/sphy004.pdf
TMS320DM355 TEXAS INSTRUMENTS DaVinci Processor DM355
http://www.ti.com/corp/docs/landing/davinci/dm355.html
LIST OF BLOCK DIAGRAM LIBRARY
http://www.ti.com/sc/docs/psheets/diagrams/index.htm
DVR BLOCK DIAGRAM (With IP)
http://focus.ti.com/docs/solution/folders/print/207.html
SECURITY END EQUIPMENT SOLUTIONS
http://focus.ti.com/apps/docs/appcategory.tsp?appId=246
DIGITAL VIDEO RECORDER
http://focus.ti.com/docs/solution/folders/print/268.html
CAMERA: SURVEILLANCE ANALOG
http://focus.ti.com/docs/solution/folders/print/408.html
WHITE PAPERS EXCELLANT READING!!
http://focus.ti.com/apps/docs/whitepaper.tsp?appId=246
Audio www.ti.com/audio
Automotive www.ti.com/automotive
Broadband www.ti.com/broadband
Clocks and Timers www.ti.com/clocks
Digital Control www.ti.com/digitalcontrol
Medical www.ti.com/medical
Military www.ti.com/military
Optical Networking www.ti.com/opticalnetwork
Security www.ti.com/security
RFID www.ti-rfid.com
Telephony www.ti.com/telephony
RF/IF and ZigBee® Solutions www.ti.com/lprf
Video & Imaging www.ti.com/video
Wireless www.ti.com/wireless
DVR JAVA APPLICATION
AVTECH AND CPCAM VIEWER FOR MAC, SOLARIS, LINUX, WINDOWS USERS!
CLICK HERE!
http://www.shixin-cn.com/en/js.asp
THE BASIC CLASSIFICATION OF THE DVR
DVR due hundred schools of thought contend in the early stages of development, a wide range of stakeholders for the industry rather "confusing" feeling, after a period of time after the changes, the classification of various types, about the forming. According to the Taiwan Industrial Technology Research Institute Photoelectric Industrial Research Institute "Optoelectronic Industry Analysis" report, the DVR broadly divided into all three categories:
1. Type Digital STB
STB refer to the Set-top Box (generally translated into: digital satellite receiver, set-top boxes, Internet-TV, video-on-demand box, and so on, because translation differences, and therefore collectively referred to in this to the STB). Digital STB types of DVR functions in the nature of the signal reception integrated platform to provide digital video function and receive digital broadcasting and interactive applications based signals, the option to receive digital wireless terrestrial transmission (Digital Terrestrial), digital cable television distribution (Digital Cable), digital satellite transmission (Digital Satellite), and other different types of communication signals.
2. PC-based types
PC-based DVR types of its application platform for the general PC, portable computers, and so on. The installation of a PC video capture card or film, using software image compression and image editing function implementation, the system more unstable.
3. Single (Standalone) type
The DVR is a single-CPU and RAM to use to develop the design, using proprietary software program, research and development costs are relatively high. Using hardware compression, quality and stability, there will be no freeze up problems, and the images are stored in speed, resolution and image quality, both larger improvements. This type of products provide only purely functional digital video recorders, such as other broadcasting without additional signal reception, on the Internet, and other functions. As used in the field of security surveillance products are mostly above Category 2 and 3 category, this article will only do these two types of. PC-based and stand-alone type of system types merits of the dispute, so far still unable to draw a conclusion. Although the current PC-based DVR accounted for the majority of the market, but it has been observed, the two types of products will have a market segmentation each. 1995 is the development of the area into DVR Japan Ikegami company and its overseas manager Yasuhiko Saito pointed out: "DVR market will be two different directions towards development, on the one hand, as RTOS (Real time Operation System, real-time operating system) in the reliability of the operation is expected to be greatly the development; but on the other hand, stressed that the DVR could networking products, the Windows operating system because it is simple and will become a mainstream. "
DVR technology is still in development, one of which is the key technology operating system and imaging compression technology.
1. Operating system
1. Windows interface for operation
With regard to the PC as the main structure of the DVR, the use of the Windows platform with its simple, universal application of the characteristics of various operating systems and ranked list of the top. South Korea 3 R Group CEO Chang Sung - Ik said: "At present the majority of DVR and related products manufacturers use Windows-based operating system; Especially in the United States such a big market, users in order to facilitate future maintenance, and more inclined to use Windows-based DVR products. " Korea Digital Logic overseas marketing manager Jonathan Kim also said: "We believe that the Windows operating system is the most suitable for DVR family of products. Because Windows is a generic operating system, therefore a higher support, regardless of any local support can be most Windows-related products. "
In addition, Windows software upgrades, also stronger than other operating systems. In recent years, the IT industry is closely related with the Security Industry, when digital technology in the IT industry into the 10,000 kilometers At the same time, related technology development which is bound to affect the security industry. The reason why Windows will be loved by many vendors, is because it has a great scalability. Manufacturers that since DVR systems can not stay long-term at fixed levels, the upgrade of systems development is bound to become a key point. If cost considerations and eliminating the old, once users have a system for both higher requirements or legacy systems exposed some flaws, most of the customers less likely to buy a new system to replace, so that products on the escalation of a prime solution.
Although vendors, system stability depends on the user's actual operation, however, the Windows operating system itself is unstable, so that users still considerable doubt. Some manufacturers have said that if the use of only simple monitoring system, Windows 98 system fairly stable; But if the Windows platform running other procedures, system instability, or even crashed on the inevitable.
2. Linux interface for operation
IT industry in Windows and the Linux operating platform also spread to the fierce competition Security industries. Linux can be used for the operating environment will allow many users at the same time within the mainframe computer at the same time the use of the resources. Linux provides a complete people (Multiuser), multi-tasking (Multitasking) and multi-trip (Multiprocessing) environment, can be downloaded on the network to use. Because of its original code (Source Code) is open to the public, it can be developed, modified, so Linux users need not have to trouble the lack of applications, and has accelerated the pace of research and development, and the system itself and most of the application is free, allows developers to save large sums of R & D expenditures. In addition, lower demand for Linux hardware, users can save hardware costs more input, then reduce overall product cost. With the prevalence of Internet, the global use of the Linux people more and more, and attract numerous inputs improved core developers, the application software and hardware peripheral driver ranks so that the function and integrity of Linux growing to become parties to focus attention.
In addition, Linux is based on the network environment the operating system with a comprehensive network function, users can even Linux on the Internet singly, may also set up local area network (LAN); Linux can also set up various Server to provide Internet and Intranet in the mail, FTP, Web ... services. In such a trend, Linux DVR manufacturers eager to become the operating system. Some vendors even indicated that Linux more suitable than Windows applications on the DVR. South Korea Eastern Info-Com companies overseas markets that the Ministry of Associate Hyoksang Kwon, said: "As more Windows unstable, and the high prices, in contrast, Linux seems to be the most development potential of the mainstream operating system."
In fact, now under "Linux as a DVR will be superior to the Windows operating system" still too early to draw such a conclusion. According to other manufacturers respond in Linux compatibility there are still some problems, such as printer support, such as Internet connectivity, such as Windows do not. In addition, already accustomed to using Windows applications users, will be the beginning of the operations are not suited Linux; While Linux can read Windows files, but Linux still unable to read files on Windows systems shortcomings, coupled with the subsequent rise of the Linux operating system, so in the current peacekeeping staff is not very adequate for the circumstances, the use of many manufacturers choose to use Linux systems will also have some psychological barriers.
3. The operation interface to RTOS
For single - or PC-based DVR is, RTOS (Real Time Operation System) is the best operating system, currently available in the market this type of supplier mainly to South Korea and Japan. Many South Korean manufacturers such as 3 R, Korea Computer Technologies, Kodicom, Artinix feel that single-DVR with high economic efficiency, high stability and Security Controller and the existing high compatibility, and other features, it rolled out the first time, have a single type of DVR. For Japanese manufacturers, will be committed to the development of single-DVR is mainly based on considerations of image clarity, the majority of PC-based DVR image quality are not as single-DVR.
However, the current single-DVR is the greatest challenge facing the networking functions. All in networking today, a growing number of Internet users, Korea Digital Logic's Jonathan Kim that said: "When we talk about single-DVR, the networks often omitted swap part of the remote control. But DVR systems and network convergence if not, to be honest, it not a DVR system. " Most western manufacturers also have the same viewpoints, such as the United States, Germany, Britain and other Nordic countries, has been the network will function as digital CCTV products is the key. British Dedicated Micros chief executive Mike Fawcett illustrate: "Britain's chemical industry, manufacturers have adopted the function of the network DVR equipment, in addition to substantial savings in manpower costs, but also can be anywhere monitored the staff and production line status, thus saving many costs." Can networking features allow users through LAN / WAN, Internet and other network remotely monitor. This characteristic has been forecast to become the mainstream of the future CCTV market. To enable products with networking capabilities, single-DVR manufacturers into "price vs. Functional "dilemma. Korea Korea Computer Technology Corporation general manager Y. H. Min pointed out: "To allow DVR with networking capabilities, we must add standalone DVR certain type chip. Therefore, we must increase the amount of investment and cost, price competition in the increasingly severe circumstances, the cost increase to our considerable disadvantage. "
2. Compression Technology
At this stage DVR used by the compression technology to JPEG, MPEG1, MPEG2 - based. Strictly speaking, these compression technologies may not be able to fully meet the demand for a long time video.
1. JPEG
JPEG compression multiples of 20 to 80 times, for the static picture compression, resolution no choice. Previous JPEG compression technology is directly deal with the entire picture, so we have to wait until the completion of the entire compressed file transfers only started to extract video sources and picture, and the means to cause such a high resolution picture transmission to be time-consuming tens or even for a few minutes. The new generation of JPEG is gradually taken-layer technology, the first transmission Document Analysis low, and then supplemented send details of the information so that the picture quality improvement. The time required for this method although the same manner as with the original, but because it can first see the screen, so users will feel better this way.
2. MPEG1 and MPEG2
While MPEG1, MPEG2 in mobile imaging under the circumstances of having little compressed multiples approximately 100 times (General VCD, DVD about 35 times), from VCD, DVD specifications, MPEG1 the resolution of 320 x 240 (or less), MPEG2 is usually 720 x 480. MPEG1, MPEG2 is a transmission-in action partial picture.
3. MPEG4
As for the compressed multiples of 450 times (static images up to 800 times), the resolution can be imported from 320 x 240 to 1280 x 1024 MPEG4, it is designed for mobile communications equipment (such as mobile phones) in the Internet real-time transmission of audio / video signals and the latest development of MPEG standards. MPEG4 and MPEG compared to the previous version, the biggest difference is MPEG4 use of "layers" (layer), the images can be intelligent choices differ, the individual editors in the compressed images to map documents capacity substantially reduced, and speed up the audio / video transmission. Some people think that MPEG4 the emergence of the DVR manufacturers, is undoubtedly a blessing, but also some manufacturers that MPEG4 specifications Although set, but the actual application of the DVR technology has not yet matured, at this stage, both in software and hardware have to be to achieve a breakthrough (details of the "technical articles - MPEG4 pressure DVR technology in the reduction of the article ").
For what compression DVR products more applicable to the views of the views of manufacturers were very different. South Korea 3 R's IK Chang Sung-specific: "Generally speaking, compression technology uses two methods, one is intraframe, the other is Interframe. Interframe imaging can distinguish between each piece of the difference, and only transmit images of different parts of H.263 and MPEG is the representative of this format . The animation Intraframe way put a decomposed into a number of fixed images of a piece of a transmission to this end Wavelet and Motion JPEG mode representatives. from the transmission efficiency considerations, Interframe in performance is far superior to Intraframe; but, Interframe technical changes in the smaller screen circumstances, can not provide much wrong definition. " However, the security products must take into account the user image-quality problems, and in this connection MPEG and JPEG to Wavelet more favorably. Digital Logic's Jonathan Kim, said: "We recognize the MPEG4 video compression comparison outstanding, but there are MPEG series of images of interference and distortion of the picture distortion. If users want to buy a large amount of storage DVR, he can consider MPEG compression format; But if users want to have good quality, it should consider other means of compression; As for the good in one way, depending on customer needs. " Eastern Info-com companies Hyoksang: "image clarity, and image compression rate of the CPU and other related hardware is inversely proportional to the load, as MPEG4 with high compression ratio, the resulting image is not clear, the Security Industry to achieve the standards required for the image, a lot of room for improvement. " DM company's executive president Mike Fawcett further pointed out: "For static images, whether using JPEG or MPEG compression mode compression mode, the transmission speed is the same. However, if the object is the state of sports show, MPEG format will not immediately react transmission, it is because MPEG the slower speed transmission format, or in monitoring the scene prone to interference. " In his view, both in JPEG image compression technology in the quality or speed, is more suitable for Security industries. He said: "I think the quality JPEG better, more competitive, but also more secure." Along with the constant development of DVR technology, the storage capacity is expanding, and the quality requirements of users will inevitably rise higher and higher. British Visionfactory chairman David Beanland said: "Although the JPEG image format and Wavelet uses larger storage space, but this kind of compression technology in the DVR industry is still mainstream. Undoubtedly, the DVR storage capacity will be gradually expanded storage capacity of 200 GB above DVR will be the slowest in 2 three years later appeared in the market. Once the capacity problem is solved, users will be to focus on image quality, and MPEG compression technology approach will be eliminated. " Beanland also questioned MPEG compression technology can record images as reliable evidence in court, the current market in Europe and the United States also is open to question. Philips is working in the company, with 14 experienced Alan Everid think that the DVR products, Wavelet compression is the best way. Wavelet remove the main reason lies in the high-frequency components of the image (high frequency components), retaining only single-frame image signal. This feature is particularly applicable to the frequent changes in the screen occasions, such as time-of-use multi-screen display. However, although the Security Industry Wavelet Image request, but in consideration of whether interconnection factors, readers should pay attention to the Wavelet existing IT networks is not generally supported by the format, so the use of the network will be limited.
http://scorpiontheater.com/contactus.aspx