Different FOV with different capture API's

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1

Hi everyone,

I’m curious to know why this is. An image captured from the same webcam but with different API’s gives two different results. The top part of the image is with ‘apiPreference’ left at its default of ‘0’.

The lower part of the image is with it set to CAP_DSHOW.

Capture
Capture640×960 99 KB

Is someone able to tell me why that is? Both images have the same resolution. Is the default API just not using the full sensor? I’d like to use DSHOW because of it’s field of view but it just a so much slower than the default.

2

usually, it’s a matter of some service program by the manufacturer.

when you ask for 0, you specifically are getting MSMF.

both system APIs might have different “persistent” settings as to the zoom factor of the camera.

one might be set to take a 640x480 crop of the sensor, while the other is set to take the entire sensor and downsample it.

3

Yeah that makes sense. Do you think it is something I can change in code by setting a few properties?