How to set framerate with OpenCV camera capture

Question

How can I set the capture framerate, using OpenCV in Python? Here's my code, but the resulting framerate is less than the requested 30fps. Also, quality of video very bad.

import cv
cv.NamedWindow ('CamShiftDemo', 1)
device = -1
cap = cv.CaptureFromCAM(device)
size = (640,480)
cv.SetCaptureProperty(cap, cv.CV_CAP_PROP_FPS,30)
cv.SetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_WIDTH, size[0])
cv.SetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_HEIGHT, size[1])
while True:
    frame = cv.QueryFrame(cap)
    cv.ShowImage('CamShiftDemo', frame)
    cv.WaitKey(10)

Answer 1

You are limited by the hardware, namely:

1. your camera's capture capabilities, and
2. your computer's system resources.

If either of these cannot handle the requested capture parameters (in your case 640x480 resolution at 30fps), you're out of luck. Parameters you give to OpenCV are merely suggestions -- it tries to match them as best it can.

What model camera are you using? I would first look at the model specs to see if they advertise the parameters you desire.