VideoCaptureFPS Does not work

[llianc62]

When I set VideoCaptureFPS property it does do changed.

Description

I wanna change the frame rate of reading video.

Steps to Reproduce

here is my code:

package main

import (
    "log"

    "gocv.io/x/gocv"
)

func main() {

    webcam, _ := gocv.OpenVideoCapture("test.mp4")

    webcam.Set(gocv.VideoCaptureFPS, 30)
    log.Printf("video rate: %f", webcam.Get(gocv.VideoCaptureFPS))
}

output:

2021/12/07 21:05:53 video rate: 60.042750

Your Environment

• ubuntu 20.04
• OpenCV version used:
• How did you install OpenCV?
• GoCV version used:
• Go version: go version go1.15.15 linux/amd64
• Did you run the env.sh or env.cmd script before trying to go run or go build? N

[wgjtyu]

after search by google, I have got this: https://stackoverflow.com/questions/52068277/change-frame-rate-in-opencv-3-4-2

[wgjtyu]

this may help us https://github.com/hybridgroup/gocv/blob/release/videoio.go#L379

[jiekechoo]

You should use webca.Grab(webcam.Get(gocv.VideoCaptureFPS) - yourFps) to skip frames before calling webcam.Read()