Particulate recording materials

Information (audio, video, or data) to be recorded magnetically is first encoded into a sequence of time-varying electrical signals which are used to drive a writing head, the magnetic field of which creates, on the moving tape or disk, a spatially varying pattern of magnetization. The reading process uses another head (or the same head) to reconvert this magnetization pattern into time-varying electrical signals that can be amplified and used to drive a loudspeaker, or a TV receiver, or feed data to a computer. Two methods of encoding the information are used; analog and digital. In analog recording, as the adjective suggests, the pattern of magnetization on the recording medium should be a precise analog of the incoming stream of information and the signal obtained on reading should be an exact reproduction of the original. Digital recording involves first converting the information into a sequence of ones and zeros which can then be recorded as a sequence of regions of opposite magnetization. Analog recording has been widely used to store audio and video information while digital recording was used for data recording. This picture is changing and digital recording is now being used increasingly in audio and video recording principally because errors can be corrected dynamically so that the original information can be reconstructed and copied repeatedly and with great fidelity. Whether the recording method used is analog or digital, similar though not identical properties are required of the recording materials and so the distinction between the two methods will not be pursued further.     

数码单反相机拍摄视频的音频解决方案

使用数码单反相机拍摄视频逐渐成为一种流行趋势,但通常拍摄出的视频录音质量较差,这是由单反相机本身在音频方面的设计缺陷造成的。旨在推荐几种能够提高单反相机录音质量的方法,希望为相关领域从业人员提供参考。     

小波变换域雷达视频数据压缩

由于雷达视频信号的带宽问题,在对其进行数字化传输和记录时,必须对雷达视频信号进行压缩。本文提出一种雷达视频信号数据压缩有效算法,该算法主要基于小波变换域压缩编码算法。实际结果表明,该算法性能良好。     

1/2-inch cassette VTR for baseband HDTV signal recording

Technical details are reported for a 1/2-inch cassette videotape recorder (VTR) developed for recording the baseband high-definition TV (HDTV) signal. A recording time of 63 min was achieved by using metal-particle tape and laminated amorphous video heads. The frequency bandwidths used for luminance and chrominance signals were 20 and 7 MHz, respectively. A novel two-channel, three-segment recording method was developed for the purpose. Four-channel digital audio recording with a sampling frequency of 48 kHz and 16-b linear quantization was used. The digital audio signal was recorded on the overlapped area succeeding to the video track by using the same heads used for video recording     

Digital video recording

Through mutual technology transfer between consumer and professional video recorders, the last 20 years has witnessed a rapid evolution from analog to digital recording. Each new digital videotape recorder (VTR) uses different channel coding. This implies that improving the recording density involves the development of new channel-coding schemes together with evolutionary magnetic tapes and heads. As a result, professional digital VTR's offer the best features for video recording. This paper reviews state-of-the-art magnetic recording devices, signal processing techniques for digital recording. It also describes the specifications for home-use digital recorders for current television systems, and discusses disk recording technology in the future     

用于视频监控的便携式数字录像机设计

针对各类视频监控和记录的应用特点和要求,设计并研制了一个基于嵌入式微处理器、专用视频压缩芯片及大容量IDE硬盘或电子盘的便携式数字录像机.讨论了系统结构设计及各功能模块的电路选择,介绍了关键接口电路设计和系统软件设计.系统采用单一直流电源供电,为了方便视频压缩数据的存取,设计了专用的文件系统.测试结果表明,系统性能良好、功能灵活,功耗低、集成度高、独立、便携,非常适合各类视频监控和记录应用.     

Achievements in rotary head magnetic recording

The principal achievements since 1980 in rotary head recording on magnetic tape are outlined. These developments are related to fundamental improvements in recording media, heads, the design of tape transports, and signal processing. The D-1 and D-2 video tape recorders (VTRs), the Hi-Band 8-mm video cassette recorder (VCR), and the rotary digital audio tape (R-DAT) recorders are discussed. The future of rotary head recorders for consumer digital VCRs, professional high-definition TV (HDTV) VTRs, and consumer HDTV VCRs is assessed     

基于DM36X医用高清DVR系统的设计

为适应现代医疗视频设备的便携性需求,设计了一种基于达芬奇视频技术TMD320DM36x的数字视频DVR系统。该系统可外接数字摄像头,或通过A/D转换外接模拟摄像头。系统上集成的视频处理子系统,能对1 280×1 024分辨率每秒30帧的视频图像进行实时视频采集、网络传输和播放,并可通过外接移动硬盘实现大容量视频录像及回放功能,满足了便携式医疗视频设备对高分辨率和大容量视频的存储与播放要求。     

A new video hard disk system for multimedia program production

This paper reports on a new video hard disk system for real-time recording and playing back of high-quality digital video signals, an important component in the production of multimedia programs at broadcasting stations. The paper clarifies some of the problems associated with the recording of high-quality video signals on a conventional hard disk system designed for storing computer data. It describes the requirements of a future video hard disk system. We have developed an experimental high-speed hard disk interface device suitable for transferring video signals. This device can guarantee continuous transfer of video signals with a high bit rate, sending them at 123 Mbps/ch-more than twice as fast as a conventional device. Using this interface, we have developed a video hard disk system capable of real-time recording and playing back of non-compressed video signals (conventional TV)     

Digital video interfacing: a practical solution

Broadcast video technology has begun to shed its analogue history and take on board the benefits of the digital era. Areas such as digital video recording and processing have been addressed. However, the means of conveying digital video information from one device to another have been cumbersome and expensive. The author describes how these problems have been overcome. It describes the limitations of the current method and provides an overview of a new, serial, interface. Details and benefits of the new interface are given and new integrated circuits to implement the interface are also described. Consideration is given to installation, test and measurement     

机载LVDS数字视频信号采集记录技术研究

针对某飞机机载数字平面显示器,以LVDS作为视频信号传输标准,在飞行试验中,对显示器显示的视频画面需要实时采集记录的问题进行了研究分析.介绍了PC104构架的采集器主要设计内容以及实现方法,结合飞行试验对研究结果进行了验证,并对应用情况进行了说明.     

Low cost video scaler and gray scale integrator

A hybrid digital/analog device capable of making high-resolution linear and area measurements from a standard monochromatic video image is described. The device is capable of dynamic as well as static data acquisition when used in conjunction with standard NTSC video recording equipment. Digital output allows for computer interfacing. Linear dimensions are obtained by electronically superimposing two horizontal and two vertical scaling lines on a video monitor. Each linear dimension has an eight-bit resolution and is displayed on the front panel with seven segment LEDs. Eight-bit, digital-to-analog converters are also used to provide analog outputs. A measurement of the temporal deformation pattern of the accessory capsule surrounding a mechanoreceptor (Pacinian corpuscles) in response to vibratory displacements is demonstrated. Area measurements are obtained via a window comparator, a 6 MHz clock, and a 16-bit digital-to-analog converter. Data is only valid within the zone set by the scaling lines, allowing data regions to be isolated from noise, etc. The 16-bit digital signal measuring the area of interest is then converted for analog output. The measurement of the consensual pupillary reflex in response to full-field illumination (Ganzfeld) is given as an example     

Tutorial review of magnetic recording

Most of the technologically important aspects of magnetic recording are reviewed in a nonmathematical manner. After a discussion of recording media and heads, the fundamentals of the media magnetization and writing processes are considered. The factors limiting the bandwidth, distortion, and signal-to-noise ratio of audio, instrumentation, video, and digital recording machines are analyzed. The paper concludes with some predictions on the future of magnetic recording.     

AN H.264/AVC HDTV watermarking algorithm robust to camcorder recording

With the purpose of copyright protection of digital video, this paper proposes an H.264/AVC HDTV watermarking method that is robust to camcorder recording. Because contents in the consecutive frames of a video are almost identical, we embed the copyright information by fine-tuning the luminance relationship of the consecutive frames. To ensure the quality of the video and the robustness of the algorithm, we use an adaptive watermark pattern to reduce the image area to be modified, and we make the embedding strength adaptive according to the improved Watson visual model. When detecting watermarks, to reduce detecting errors caused by recording errors and shot changes, we determine the detecting area adaptively according to the size of the watermarked video and segment the video into shots using the directional empirical mode decomposition method. Experimental results show that the proposed method achieves high video quality and is robust to camcorder recording, transcoding, recoding, and other geometric attacks.     

机载多路数字视频记录仪的设计与实现

视频的压缩记录是现代航空技术中很重要的一个研究内容，通过它可以实时记录飞机的多种直观信息，对飞行指挥和作战训练起到积极的指导作用，本文介绍了一种现代数学图像处理技术实现机载多路数字视频记录的方法，与传统的模拟记录方法相比，该方法具有记录容量大，记录时间长，图像质量高等特点。     

Signal processing for future home-use digital VTR's

The author considers, mainly from the viewpoint of signal processing technologies, the current efforts for future home-use digital videotape recorders (VTRs). Recording technologies for future home-use digital VTRs are reviewed with respect to both current TV and HDTV systems. High-density recording and bit rate reduction are the major technologies needed for digital video recording with small cassettes. Recent experiments show that the technical problems, except those of equipment size and cost, have almost been solved     

基于Hi3515的水平四画面录像机录像功能的实现

简要介绍了海思Hi3515的硬件特性,着重阐述了该录像机录像功能的软件实现。介绍了录像机软件的总体结构;对音频编码、视频编码和AVI封装的实现原理和方法做了细致地分析研究,给出了相关流程图及水平四画面录像的实现方法;将程序放到开发板上进行了测试。测试结果表明,该录像机可以实现四画面的单独录像和组合录像,录像文件可以直接播放,录像质量和效果良好。可以长时间运行,运行稳定性较好,满足项目的要求。     

数字化网络安防系统在银行的应用

讨论银行数字化网络安防系统组成及主要功能。主要涉及监控对象、网络结构、矩阵主机、本地监控、报警、数字录像、远程监控等。     

An error-correction scheme for a helical-scan magnetic data storagesystem

An error-correction scheme for a helical-scan magnetic recording system is presented. The system consists of a commercial VHS video cassette recorder with the front-end electronics adapted for high-speed digital recording. Error statistics have been collected and show a bursty error recording channel both within each track and from track-to-track. The proposed error-correction scheme uses interleaved Reed-Solomon codes. The interleaving function consists of a two-level interleaver performing track interleaving and byte interleaving. An efficient interleaving implementation is presented     

一种提高数字电视节目源利用率的方法

为了充分利用已有的数字电视节目,可以通过录制的方式将其以视频文件的形式保存下来,然后针对每一个视频文件生成相应的索引文件,以方便对指定节目的检索。通过这种方式,不仅可以重复利用已有的节目,而且简化了利用节目的流程。