Setting Driver Properties
Default Output Size
Figure 52. Default Output Size
The standard DirectShow Properties dialog allows you to select the height and width of captured video (Figure 52). If you click Auto Size, your default video size is sized automatically to your crop settings. The three radio buttons, 1X Crop, 1/2X Crop, and 1/4X Crop, determine whether the output size is scaled down from the crop size.
Example 1: If you are running standard 640 x 480 NTSC video, and the Enable Cropping checkbox is not checked, your crop size is 640 x 480. With Auto Size checked, and the 1X Crop radio button selected, your default size is 640 x 480; with 1/2X Crop, 320 x 240; and with 1/4X Crop, 160 x 120.
Example 2: If you have enabled cropping with size 320 x 240 (one quarter of the full video area), the
default Auto Sizes are as follows: 1X, 320 x 240; 1/2X, 160 x 120; 1/4X, 80 x 60.
If you leave Auto Size unchecked, the default size radio buttons are disabled and the height and width edit boxes are enabled. You can set any default size with the following two restrictions:
∙Since the driver does not upscale video, the default size must be smaller than the crop size. For example, if the crop size is 320 x 240, you cannot set default output size 400 x 300.
∙Sizes are subject to the granularity requirements of the selected video format, as explained in the Granularity section above. For example, if your video format is I420 and you try to set a default width of 360, it gets adjusted down to 352 as soon as you click on another control.
Pin Properties dialog default entry does not appear in the default VFW/DirectShow mapper dialog. Thus, unless a VFW application, like Virtual Dub, specifically allows for custom resolutions, the VFW app is only able to select from the options the VFW/DirectShow mapper lists.
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