外文翻譯---電視信號-文庫吧資料
2025-05-22 09:02本頁面
【正文】 called frames , A video engineer would say that each frame contains 525 lines, the television jargon for what programmers call rows. This number is a little deceptive because only 480 to 486 of these lines contain video information。 the remaining 39to 45 lines are reserved for sync pulses to keep the television’s circuits synchronized with the video signal. Standard television uses an interlaced format to reduce flicker in the displayed image. This means that all the odd lines of each frame are transmitted first, followed by the even lines. The group of odd lines is called the odd field, and the group of even lines is called the even field. Since each frame consists of two fields, the video signal transmits 60 fields per second. Each field starts with a plex series of vertical sync pulses lasting milliseconds. This is followed by either the even or odd lines of video. Each line lasts for microseconds, including a microsecond horizontal sync pulse, separating one line from the next. Within each line, the analog voltage corresponds to the gray scale of the image, with brighter values being in the direction away from the sync pulses. This place the sync beyond the black range. In video jargon, the sync pulses are said to be blacker than black.. The hardware used for analogtodigital conversion of video signals is called a frame grabber. This is usually in the form of an electronics card that plugs into a puter, and connects to a camera through a coaxial cable. Upon mand from software, the frame grabber waits for the beginning of the next frame, as indicated by the vertical sync pulses. During the following t
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