之前对着几种视频格式认识不是很清晰，所以看数据手册的时候，看的也是稀里糊涂的。
因为项目中需要用到cvbs做视频输入，在元器件选型上，看到tw2867的数据手册上,有这么一句话：
The TW2867 includes four high quality NTSC/ PAL/SECAM video decoders that convert analog composite video signal to digital component YCbC r data for security application。
我硬是看了好几次，还去专门查了下，composite video是不是就是cvbs信号？
结果在维基百科上面看到：
Composite video (one channel) is an analog video transmission (without audio) that carries standard definition video typically at 480i or 576i resolution. Video information is encoded on onechannel, unlike the slightly higher-quality S-video (two channels) and the even higher-quality component video (three or more channels).
Composite video is usually in standard formats such as NTSC, PAL, and SECAM and is often designated by the CVBS initialism, for color, video, blanking, and sync, or simply as video.
来自：https://en.wikipedia.org/wiki/Composite_video
然后再接着就看到了下面这篇文章，实在是太有用了，转了，分享给大家。
还是老外说的实在，图文并茂的，不明白都不行：(此文出自：http://blog.csdn.net/lanmanck/article/details/8946971)
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[Tech : video ] Content 2004 by Lyberty; last updated March 30, 2005
 S-Video (Separated-Video) is better than a composite video connection.
But note that the bandwidth of S-video (also written as "S Video") is the same as that of composite video. The real benefit of an S-video connection is that it can reduce dot crawl, hanging dots, and crawling edges that appear on the vertical and horizontal edges (respectively) of some colored objects in the picture. [more]
S VIDEO, originally known as "Y/C Separated video", is one of the higher quality ways to transmit the television signal from a peripheral device (DVD player, PlayStation 2, whatever) to a television. The way S-Video works is that it basically separates the color information (Chrominance) from the brightness (Luminance). By doing this, it reduces things like color bleeding and dot crawl and greatly increases the general clarity and sharpness of the picture. The reason that this is so is that televisions are designed to display separate Luminance (Y) and Chrominance (C) signals.
S-Video connector pin-out:
Recommendation: The increase in picture quality that you'll get in platform games (like the PS2) when you move from composite (yellow-plug) to S-Video is very noticeable and is well worth spending the extra money to buy the optional cable.
 Component (not composite) Video [aka Analog Component Video; Y - Pb - Pr; red-green-blue]:
Uses a three jack cluster of wires with the ends color coded green, blue, and red. (does not include audio cable).
Y-Pb-Pr, or what we nowadays refer to as component video or color difference video, was invented to simplify video electronics and reduce the overall bandwidth requirements for transmitting video compared with RGB. In practice it provides one luminance signal with full horizontal resolution and two color signals with reduced horizontal resolution.
Y = Luminance, Pb = Chrominance 1, Pr = Chrominance 2
From your DVD player or HDTV set top box to your TV, it is analog, thus its full name "analog component video".
Also referred to as Y, R-Y, B-Y or color difference video. Some DVD players label the green, blue, and red jacks Y, Cb, Cr .
 Composite Video [RCA or BNC] (aka "yellow-plug" video)
The old "AV" standard connector. The common RCA connector is color-coded Yellow for Composite video.
The term "yellow-plug video" is recommended to help cut down on confusion between "composite" and "component" (which sound alike).
SUMMARY:
The four types of standard video connections described in the following table give you four levels of video quality. Optimize your viewing experience by using the best connection available for your connected component. For example, if your DVD player supports a component video connection, connect the DVD player to your Plasma TV using component video instead of composite video or S-Video.
| Quality |
Cable and Connector |
Connection Description |
| Best |
 |
Component - The video signal is split into three signals, two color and one black and white, giving you the best picture. Use component video to take advantage of the superior picture found in such signal sources as HDTV and progressive DVD. |
| Better |
 |
S-Video - The video signal is split into two signals, giving you an even better quality picture. For example, text displayed on-screen using this connection is noticeably sharper than composite or coaxial (RF). |
| Good |
 |
Composite ("yellow plug") - The video signal is carried through a single "pin". This connection type is the one that is most commonly found on video devices (as of 2004/2005). |
| Basic |
 |
Coaxial (RF) - The video and audio signals are both carried in one cable. Used for antenna and cable signals.
(The other three connection types only handle video, requiring separate connections for sound.) |
But what about those red and white connectors?
 Audio Inputs
Stereo Analog Audio connections use red and White color coded "RCA" connections. These support mono or stereo analog audio.
Building a home theatre: Get a 27" or bigger TV with a component video input.
The only feature you should shop for when buying this TV is a component input (in addition to composite and s-video). This input is about 1/2 an inch in diameter with about five pins in the center.
Component video comes in different non-interchangeable formats (scan rate formats) for regular TV or HDTV, for example:
>>>>>>>>>>>>> Interlaced or 480i from a standard NTSC DVD player : : 480i = NTSC interlaced video = 640x480 pixels = 480 displayed horizontal lines of resolution
>>>>>>>>>>>>> 480p from a progressive scan NTSC DVD player : : 480p = NTSC progressive scan = 640x480 pixels = 480 displayed horizontal lines of resolution
>>>>>>>>>>>>> 720p (HDTV) :: 720 displayed horizontal lines of resolution
>>>>>>>>>>>>> 1080i (HDTV) :: 1080 displayed horizontal lines of resolution
Note: Typically, standard TVs and HDTVs support only a 60Hz refresh rate.
Component or s-video? ( vs.)
S-Video: separates chrominance and luminance
Component: further separates chrominance into two signals
This is why component is better. Makes a big difference even on an analog tv when using a dvd player.
Recomendation: Use high quality cables. Gold plated, double shielded, and made for video only.
Note: If your DVD player does not have a progressive scan (480p) button then the signal will be 480i.
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其他知识可参考：http://www.lyberty.com/encyc/articles/svideo.html