diff --git a/utils.go b/utils.go
index c8423f2..90def84 100644
--- a/utils.go
+++ b/utils.go
@@ -214,3 +214,44 @@ func getDevicesWindows() ([]string, error) {
 	devices := parseDevices(builder.String())
 	return devices, nil
 }
+
+// Error representing a strings.Builder failure in the buildSelectExpression func.
+var errExpressionBuilder = fmt.Errorf("vidio: failed to write tokens to the frame select expresion")
+
+// Helper function used to generate a "-vf select" expression that specifies which video frames should be exported.
+func buildSelectExpression(n ...int) (string, error) {
+	sb := strings.Builder{}
+	if _, err := sb.WriteString("select='"); err != nil {
+		return "", errExpressionBuilder
+	}
+
+	for index, frame := range n {
+		if index != 0 {
+			if _, err := sb.WriteRune('+'); err != nil {
+				return "", errExpressionBuilder
+			}
+		}
+
+		if _, err := sb.WriteString("eq(n\\,"); err != nil {
+
+			return "", errExpressionBuilder
+		}
+
+		if _, err := sb.WriteString(strconv.Itoa(frame)); err != nil {
+
+			return "", errExpressionBuilder
+		}
+
+		if _, err := sb.WriteRune(')'); err != nil {
+
+			return "", errExpressionBuilder
+		}
+	}
+
+	if _, err := sb.WriteRune('\''); err != nil {
+
+		return "", errExpressionBuilder
+	}
+
+	return sb.String(), nil
+}
diff --git a/video.go b/video.go
index 504013b..c377d7c 100644
--- a/video.go
+++ b/video.go
@@ -6,7 +6,6 @@ import (
 	"os"
 	"os/exec"
 	"os/signal"
-	"strconv"
 	"strings"
 	"syscall"
 )
@@ -405,44 +404,3 @@ func (video *Video) cleanup() {
 		os.Exit(1)
 	}()
 }
-
-// Error representing a strings.Builder failure in the buildSelectExpression func.
-var errExpressionBuilder = fmt.Errorf("vidio: failed to write tokens to the frame select expresion")
-
-// Helper function used to generate a "-vf select" expression that specifies which video frames should be exported.
-func buildSelectExpression(n ...int) (string, error) {
-	sb := strings.Builder{}
-	if _, err := sb.WriteString("select='"); err != nil {
-		return "", errExpressionBuilder
-	}
-
-	for index, frame := range n {
-		if index != 0 {
-			if _, err := sb.WriteRune('+'); err != nil {
-				return "", errExpressionBuilder
-			}
-		}
-
-		if _, err := sb.WriteString("eq(n\\,"); err != nil {
-
-			return "", errExpressionBuilder
-		}
-
-		if _, err := sb.WriteString(strconv.Itoa(frame)); err != nil {
-
-			return "", errExpressionBuilder
-		}
-
-		if _, err := sb.WriteRune(')'); err != nil {
-
-			return "", errExpressionBuilder
-		}
-	}
-
-	if _, err := sb.WriteRune('\''); err != nil {
-
-		return "", errExpressionBuilder
-	}
-
-	return sb.String(), nil
-}