Want to design a DVR? For many applications, it is easier and faster to design with a circuit board-level camera system than to design from scratch.
In order to store video images digitally, designers actually have two choices. Either they develop DVR themselves, or they rely on investing in other companies that master the technology. When designing DVR, all aspects of application requirements must be considered. Input signal, data rate, physical storage medium and file management are all important factors.
Disadvantages of independent development of DVR
DVR designers should start by evaluating and analyzing their existing applications. This means evaluating the whole process according to the input signal. In the analog field, the input signal can be S video, composite video or component video. So the first thing to decide is whether it is appropriate to change the signal itself by changing the camera or whether it is appropriate to convert the above signal into digital format. Considering the function, cost and achievable image quality of most commercial analog-to-digital converters (ADC), it is seldom necessary to input signals in digital format.
Note that converting analog signals into digital format is much more complicated than simply selecting ADC. It is easy to underestimate the complexity of decoding analog video into digital components and then using the output of video encoder to form high-quality analog signals. Single-chip analog video decoders and encoders are available from several well-known suppliers. In order to support discrete components, the reference design they provide also indicates the parameter values completely.
However, it should be noted that this formula seems simple, but it provides poor results. Traditional composite video has many characteristics, both good and bad. The common sense that subcarriers, synchronization, brightness and chroma are interdependent belongs to only a few people who are willing to spend time studying the details. They have to spend countless hours witnessing the public problems and work areas in the actual video playback state.
In order to improve image fidelity as much as possible, DVR designers must be familiar with the shortcomings of high-performance device selection when applying reference design to new hardware, and wisely enhance or sometimes give up discrete filters. In the most important layout stage, designers must devote themselves to many details, such as the placement of components, power filtering and the correct use of analog and digital layers close to each other.
Data storage and compression
The next step for DVR designers is to determine the amount of data that needs to be stored. This makes the video compression decision very important. In essence, digital video requires a high data rate, and the higher the image quality, the greater the amount of data required. At present, there are many compression formats available, and each format has its advantages and disadvantages. Which compression technology will directly affect the image quality and storage requirements, so it is very important to know the level of image quality and integrity.
Figure 1: hardware block diagram
Designers must also have a deep understanding of the physical storage medium, location and storage capacity of digital cameras. To put it simply, we must first determine whether the storage medium needs to be a pluggable or hot-pluggable drive, or whether it needs a built-in hard disk, and whether the operating environment needs a solid-state storage medium. Does the data need to be downloaded from the device, and if so, what interface will be used?
The choice of storage media type largely depends on how the designer intends to archive new video images. If flexibility is considered, it is recommended to use a standard 2.5 "laptop hard disk, but for a worse environment, it will be more effective to choose a ready-made high-density flash memory.
File management may be one of the most easily overlooked and misunderstood aspects in video recording. What data format should I choose at first? At present, the most popular-so far, any computer can play QuickTime directly. For pluggable media, the file system in standard PC format that can be conveniently stored on the hard disk has undeniable advantages, especially when files need to be copied for analysis or archiving. Using standard PC file system, you can read video files directly without special software.
You can choose USB 2.0 interface to connect pluggable media. This simple plug-in connection can provide high-speed data reading, and the data rate can be as high as 800 megabytes per second. USB2.0 port is the standard configuration of all the latest PCs and is widely used in mass storage devices. The Windows operating system of these devices directly provides support for USB 2.0.
Figure 2: (above: below the outrider ide; Outrider CF)FFV Outrider products provide two convenient ways to take out and transfer recorded data. The Outrider IDE uses a 2.5-inch, 80gb IDE hard disk for notebook computers, while the Outrider CF uses a small flash card.
Circuit board DVR scheme
An alternative scheme of board-level DVR
In the research and development of DVR system, there are many practical factors to be considered, such as technical support and availability of debugging software. Sometimes it makes more sense to invest money in other successful companies, such as fast-forwarding videos. The following block diagram shows the kernel architecture of Outrider, a board-level product of FFV Company. Obviously, this patent-pending architecture is a successful solution, which can manage and process a large amount of data generated by limiting the use of processors.
Outrider DVR is an ultra-pocket digital camera. Its size is only 4.9 inches x 2.2 inches x .6 inches. Outrider can record video for more than two hours with a commercial small flash card, and the compression ratio is 20: 1, which is convenient for plugging and unplugging transmission or recording materials. Outrider is compatible with NTSC/PAL system, providing composite video, Y/C input/output, and scheduled recording functions, and can record QuickTime files or secure video files that can be played on PC circularly. The camera provides 720 x 486 image pixel resolution and adopts scalable motion JPEG compression format.
FFV's Outrider product provides two convenient ways to take out and transfer recorded data. The Outrider IDE uses 80gb, 2.5-inch laptop IDE hard disk, and the Outrider CF uses a small flash card. The board-level DVR design can meet various challenging application requirements, including portable, vehicle-mounted and remote control applications. The following are three examples of FFV customers using Outrider to meet their unique application requirements.
camcorder
Portable cameras used in cross-country competitions face many challenges. For example, the movement itself has a great vibration, and the camera must work normally under such harsh conditions.
In addition, collisions often occur. The camera should not only be able to withstand the impact, but also provide perfect and uninterrupted video recording in the process.
Ruggedness and performance are the most important factors for racing cars equipped with cameras to capture various sports for off-road broadcasting.
Inertia Unlimited is a supplier of special camera system for Internet TV. When making a helmet camera for Ryan Clark, the driver who participated in the opening ceremony of Jeremy McGrath Invitational Tournament, FFV's Outrider CF DVR was adopted.
Unfortunately, Ryan Clark had an accident in the competition. However, the helmet camera is not only intact, but also provides flawless video without interruption.
Compared with the portable camera with infinite inertia, the Outrider has some other advantages. The weight of the Outrider is less than 1 pound, which is very important because it will not affect the driver at all. It can also record more than two hours of video in QuickTime file format on a flash drive, which can be directly watched on a computer.
Vehicle camera
Inertia Unlimited also used the Outrider CF DVR for their CF solid-state camera, which was used for car-mounted camera shooting in the CORR off-road truck series race in clanton, Wisconsin.
The CF camera with infinite inertia weighs only 0.62 pounds, while its volume is 6 inches x 3 inches x 0.82 inches. The shell is made of electroplated aluminum to adapt to harsh environment, and the video interface is compatible with Sony Handycam. Using the Outrider of FFV, the camera has the video acquisition and playback function of 60 frames per second, and the resolution is greater than 550 lines when the compression ratio is 4: 1.
In this application, hardness is also a key index. In the CORR competition, 26 cameras recorded directly on the racing car in QuickTime format. Two strong G-force impacts were recorded, and these impacts were intact.
Remote monitoring
For many law enforcement applications, manual monitoring is unsafe and impractical. Non-manual systems are usually needed in the fields of monitoring illegal activities, property and building protection and environmental monitoring, as well as intelligence gathering, gang activity records and anti-smuggling.
Because it is necessary to record and display remotely day and night, and designers and manufacturers who want to meet the requirements of law enforcement agencies need to design sophisticated hidden and modular monitoring systems, the second generation hidden deployment system Sentinel G2 is formed. G2 is a pocket-sized independent portable video surveillance system that can be taken care of for several weeks.
G2 system takes photos in an efficient and special way. When the target enters the monitoring area, it wakes up and records, and when the target leaves, it goes into hibernation. In addition, it also sends a notice to law enforcement agencies by wireless, telling them that there are targets in the monitoring area.
G2 chose Outrider IDE DVR because of its excellent video recording function and small size. For non-manual monitoring, the camera must be unobtrusive and can work alone for several weeks in any environment. The size, weight and low power consumption of the uncoiler make the above system possible.
Another important factor of remote monitoring is image quality. Because the video recorded by the monitoring system may have evidence function, the best quality is very important. Outrider adopts motion JPEG technology, which can provide extraordinary image quality in applications such as slow motion, so it can meet the requirements of quick editing, sequential or interactive reproduction. Unlike MPEG technology, which compresses the differences between different frames without preserving every complete frame, Mobile JPEG applies the original JPEG static file compression technology to each individual frame of a video or movie sequence. Through the pixel block matching system that minimizes image degradation, the video compressed by moving JEPG in the camera can be preserved, so users can access every video and every frame. This can provide excellent performance for various applications that need clear images and random access to video materials.
Abstract of this article
Developing digital video storage solutions is a complex, time-consuming and expensive task. A feasible alternative is to use the board-level DVR scheme. For example, FFV's Outrider is a mature technology that can be customized for any application. There is a strong technical guarantee behind FFV's video solution. They have more than 20 years of R&D experience in designing pocket and ultra-reliable products with the best image quality. Extensive technical support can help designers achieve their specific application goals. The company's cameras are suitable for a variety of high-end customers, including broadcasting, military, government agency monitoring, law enforcement agencies and emergency response, as well as challenging applications, including portable, vehicle-mounted and remote monitoring. The DVR of FFV has been integrated into the camera system, which can be used in different environments, such as racing cars, presidential planes, deep-sea cameras, rowing competitions and even space.