Added display matrix

display_matrix.go

@@ -0,0 +1,30 @@
+package astiav
+
+//#cgo pkg-config: libavutil
+//#include <libavutil/display.h>
+import "C"
+import (
+	"encoding/binary"
+	"fmt"
+	"unsafe"
+)
+
+type DisplayMatrix [9]uint32
+
+func NewDisplayMatrixFromBytes(b []byte) (m DisplayMatrix, err error) {
+	// Check length
+	if len(b) < 36 {
+		err = fmt.Errorf("astiav: invalid length %d < 36", len(b))
+		return
+	}
+
+	// Loop
+	for idx := 0; idx < 9; idx++ {
+		m[idx] = binary.BigEndian.Uint32(b[idx*4 : (idx+1)*4])
+	}
+	return
+}
+
+func (m DisplayMatrix) Rotation() float64 {
+	return float64(C.av_display_rotation_get((*C.int32_t)(unsafe.Pointer(&m[0]))))
+}

display_matrix_test.go

@@ -0,0 +1,16 @@
+package astiav
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDisplayMatrix(t *testing.T) {
+	_, err := NewDisplayMatrixFromBytes([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})
+	require.Error(t, err)
+	dm, err := NewDisplayMatrixFromBytes([]byte{0, 0, 0, 0, 0, 0, 255, 255, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 64})
+	require.NoError(t, err)
+	require.Equal(t, DisplayMatrix{0x0, 0xffff, 0x0, 0x100, 0x0, 0x0, 0x0, 0x0, 0x40}, dm)
+	require.Equal(t, float64(-90), dm.Rotation())
+}