mouse-detective

frame-extraction.go

func extractFrames(done <-chan struct{}, filename string) (<-chan frame, <-chan error) {
    framec := make(chan frame)
    errc := make(chan error, 1)

    go func() {
        defer close(framec)

        video, err := gocv.VideoCaptureFile(filename)
        if err != nil {
            errc <- err
            return
        }
        frameMat := gocv.NewMat()

        errc <- func() error {
            n := 1
            for {
                if !video.Read(&frameMat) {
                    return &endOfFile{n}
                }
                buf, err := gocv.IMEncode(gocv.JPEGFileExt, frameMat)
                if err != nil {
                    return err
                }
                select {
                case framec <- frame{n, buf}:
                case <-done:
                    return errors.New("Frame extraction canceled")
                }
                n++
            }
        }()
    }()
    return framec, errc
}