feat(h264parser): EncodeAVCC

codec/h264parser/avcc.go

@@ -13,6 +13,8 @@ func DecodeAVCC(b []byte) ([][]byte, error) {
 		return nil, ErrInvalidAVCC
 	}
 
+	// TODO: AVCC can be 1, 2, 3 or 4 bytes length encoding
+	// At the moment we just force expect it to be 4
 	val4 := pio.U32BE(b)
 	if val4 > uint32(len(b)-4) {
 		return nil, ErrInvalidAVCC
@@ -42,3 +44,17 @@ func DecodeAVCC(b []byte) ([][]byte, error) {
 
 	return nil, ErrInvalidAVCC
 }
+
+func EncodeAVCC(nalus [][]byte) []byte {
+	b := make([]byte, 0)
+
+	for _, nalu := range nalus {
+		// Always encode AVCC with 4 bytes length
+		size := make([]byte, 4)
+		pio.PutU32BE(size, uint32(len(nalu)))
+		b = append(b, size...)
+		b = append(b, nalu...)
+	}
+
+	return b
+}

codec/h264parser/avcc_test.go

@@ -33,9 +33,20 @@ func TestDecodeAVCC(t *testing.T) {
 		t.Errorf("expected 2 NAL unit")
 	}
 	if nal := hex.EncodeToString(nalus[0]); nal != "aabbccaabbccaabb" {
-		t.Errorf("Expected %v", nal)
+		t.Errorf("Unexpected %v", nal)
 	}
 	if nal := hex.EncodeToString(nalus[1]); nal != "aa" {
-		t.Errorf("Expected %v", nal)
+		t.Errorf("Unexpected %v", nal)
+	}
+}
+
+func TestEncodeAVCC(t *testing.T) {
+	nalOne, _ := hex.DecodeString("aabbccaabbccaabb")
+	nalTwo, _ := hex.DecodeString("aa")
+
+	avccFrame := EncodeAVCC([][]byte{nalOne, nalTwo})
+
+	if avccFrameHex := hex.EncodeToString(avccFrame); avccFrameHex != "00000008aabbccaabbccaabb00000001aa" {
+		t.Errorf("Unexpected %v", avccFrameHex)
 	}
 }