rtp*: move time decoder into own package

pkg/rtph264/rtph264_test.go

@@ -259,35 +259,6 @@ func TestDecode(t *testing.T) {
 	}
 }
 
-func TestDecodeTimestampOverflow(t *testing.T) {
-	d := NewDecoder()
-	var pts time.Duration
-
-	for _, ts := range []uint32{
-		4294877296,
-		90001,
-		3240090001,
-		565122706,
-	} {
-		pkt := rtp.Packet{
-			Header: rtp.Header{
-				Version:        2,
-				Marker:         true,
-				PayloadType:    96,
-				SequenceNumber: 0x01,
-				Timestamp:      ts,
-				SSRC:           0xba9da416,
-			},
-			Payload: []byte("\x00\x00"),
-		}
-		var err error
-		_, pts, err = d.Decode(&pkt)
-		require.NoError(t, err)
-	}
-
-	require.Equal(t, 15*60*60*time.Second+2*time.Second, pts)
-}
-
 func TestDecodePartOfFragmentedBeforeSingle(t *testing.T) {
 	d := NewDecoder()