Allow getting frame seek table and setting it on y4m

decoder/y4m/y4m.go

@@ -59,6 +59,12 @@ func NewDecoder(reader io.Reader, settings map[string]any) (*Decoder, error) {
 		return make([]byte, s.frameSize)
 	}
 
+	if t, ok := settings["seek_table"]; ok {
+		if table, ok := t.([]int64); ok {
+			s.frameSeekTable = table
+		}
+	}
+
 	return s, nil
 }
 
@@ -103,6 +109,10 @@ func (s *Decoder) DecodeStream() *frame.Stream {
 	return stream
 }
 
+func (s *Decoder) GetFrameSeekTable() []int64 {
+	return s.frameSeekTable
+}
+
 func (s *Decoder) GetFrame() (parameters map[Parameter][]string, frameObject frame.Frame, err error) {
 	var index int64