Using VFW to develop a video capture program in Delphi

Absrtact: Many video-related software (such as video conferencing, videophone, etc.) are developed for video capture technology. Microsoft provides software developers with a VFW SDK dedicated to video capture, which provides a standard interface for video capture in Windows systems and greatly reduces the difficulty of developing programs. As the VFW SDK only VC and VB version, there is no Delphi version, so you need to declare the DLL in the various functions and variables. In this paper, how to use VFW to develop the video capture program in Delphi is introduced in detail, and the program example is given.

1 Introduction

Video capture and real-time processing is one of the most important techniques in image processing system, it is related to the success or failure of the whole system to accurately capture the specified video image and achieve accurate data analysis and processing. The author encountered this situation when developing "highway safety line rolling and pressure detection system". This system mainly studies in the key section of the highway, whether the past motor vehicle is instant rolling yellow safety line. Therefore, one of the main reasons for the rolling stock safety line is that the vehicle overtaking or reversing is violating the rules of the upper and lower lines, which is the most important and direct factor of the traffic accident. The system through real-time shooting, grasping instantaneous image, and through the system analysis and processing to timely and accurate detection of vehicle traffic, so as to drive control equipment to make relevant treatment.

Obviously, the key point of this system is to capture video images in real time. To this end, Microsoft introduced a software package on digital video VFW. It enables applications to get digitized video clips from traditional analog video sources via digital devices. One key idea of VFW is that no dedicated hardware is required to play. In order to solve the problem of large amount of digital video data, it is necessary to compress the data, and VFW introduced the file standard of AVI. The standard does not specify how to capture, compress, and play the video, only specify how the video and audio are stored on the hard disk and alternately store the video frame and match the audio data in the AVI file. But VFW allows programmers to capture, play, and edit video clips by sending messages or setting properties. When a user installs VFW, the installer automatically installs the components needed to configure the video, such as device drivers, video compression programs, and so on. VFW mainly consists of 6 modules. Specifically as shown in table 1.