Getting first frame used ffmpeg. Read / Write into stdin /stdout

FirstFrame_ffmpeg.go

func FirstFrame(path string, data []byte) (*bufio.Reader, error) {
	cmd := exec.Command(path,
		"-i", "-", // read from stdin
		"-vframes", fmt.Sprint(1), // frame
		"-s", fmt.Sprintf("%dx%d", 640, 360), // size
		"-q:v", fmt.Sprint(2), // quality
		"-f", "singlejpeg", // jpeg binary
		"-", // read from stdout
	)
	// stdin read
	cmd.Stdin = bytes.NewBuffer(data)

	var buffer bytes.Buffer
	// stdout set buffer
	cmd.Stdout = &buffer

	if cmd.Run() != nil {
		return nil, fmt.Errorf("Cannot run or found ffmpeg file by path: %s", path)
	}

	// reading of stdout
	reader := bufio.NewReader(&buffer)

	return reader, nil
}

It may be. I try many -f options, but correct work only singlejpeg.
Thank you. Your hint is useful.