A composite video signal is a signal in which all the components required to generate a video signal are embedded in a single signal. The three main components that together form a composite signal are as follows:
- The luma signal (or luminance) — contains the intensity (brightness or darkness) information of the video image
- The chroma signal — contains the color information of the video image
- The synchronization signal — controls the scanning of the signal on a display such as the TV screen
The monochrome composite signal is built of two components: luma (or luminance) and synchronization. This signal, which is usually called the Y signal, is shown in Figure 1.
Figure 1. Monochrome Composite Video Signal (Luma Steps from White to Black)
The chroma signal by itself, which is usually called the C signal, is shown in Figure 2.
Figure 2. Color Information Signal for a Color Bar Line (Including the Color Burst)
The composite color video signal, often called the Color Video, Blank, and Sync (CVBS) signal, is the sum of Y and C, is shown in Figure 3.
CVBS = Y + C
Figure 3. Color Composite Video Signal for a Color Bar Line
The two components Y and C can also be distributed separately as two independent signals. These two signals together are called either Y/C or S-video.