repochecker/videos: Also check video ratio

repochecker/videos/video.go

@@ -25,6 +25,28 @@ type VideoInfo struct {
 	} `json:"streams"`
 }
 
+func gcd(a, b int) int {
+	var bgcd func(a, b, res int) int
+
+	bgcd = func(a, b, res int) int {
+		switch {
+		case a == b:
+			return res * a
+		case a%2 == 0 && b%2 == 0:
+			return bgcd(a/2, b/2, 2*res)
+		case a%2 == 0:
+			return bgcd(a/2, b, res)
+		case b%2 == 0:
+			return bgcd(a, b/2, res)
+		case a > b:
+			return bgcd(a-b, b, res)
+		default:
+			return bgcd(a, b-a, res)
+		}
+	}
+	return bgcd(a, b, 1)
+}
+
 func checkResolutionVideo(e *fic.Exercice, exceptions *sync.CheckExceptions) (errs []error) {
 	i, ok := sync.GlobalImporter.(sync.LocalImporter)
 	if !ok {
@@ -66,6 +88,12 @@ func checkResolutionVideo(e *fic.Exercice, exceptions *sync.CheckExceptions) (er
 				errs = append(errs, fmt.Errorf("video track is too wide: %dx%d (maximum allowed: 1920x1080)", s.Width, s.Height))
 			}
 
+			ratio := s.Width * 10 / s.Height
+			if ratio < 13 || ratio > 19 && !exceptions.HasException(":size:strange_ratio") {
+				m := gcd(s.Width, s.Height)
+				errs = append(errs, fmt.Errorf("video track has a strange ratio: %d:%d. Is this really expected?", s.Width/m, s.Height/m))
+			}
+
 			if s.CodecName != "h264" {
 				errs = append(errs, fmt.Errorf("video codec has to be H264 (currently: %s)", s.CodecLongName))
 			}