From e75a4524bb827991f958a86a6671308bb214ee1a Mon Sep 17 00:00:00 2001
From: Joel Wetzell <git@jwetzell.com>
Date: Sat, 31 Jan 2026 15:54:36 -0600
Subject: [PATCH] add support for timecode packets

---
 artnet.go        |  2 ++
 timecode.go      | 79 ++++++++++++++++++++++++++++++++++++++++++++
 timecode_test.go | 85 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 timecode.go
 create mode 100644 timecode_test.go

diff --git a/artnet.go b/artnet.go
index a7fb4f7..5c3ad9b 100644
--- a/artnet.go
+++ b/artnet.go
@@ -59,6 +59,8 @@ func Decode(bytes []byte) (ArtNetPacket, error) {
 		return NewArtPoll(bytes)
 	case OpDmx:
 		return NewArtDmx(bytes)
+	case OpTimeCode:
+		return NewArtTimeCode(bytes)
 	default:
 		return nil, fmt.Errorf("unhandled opcode: %#x", opCode)
 	}
diff --git a/timecode.go b/timecode.go
new file mode 100644
index 0000000..5e8ca1f
--- /dev/null
+++ b/timecode.go
@@ -0,0 +1,79 @@
+package artnet
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"slices"
+)
+
+type ArtTimeCode struct {
+	ID        []uint8
+	OpCode    uint16
+	ProtVerHi uint8
+	ProtVerLo uint8
+	Filler1   uint8
+	StreamId  uint8
+	Frames    uint8
+	Seconds   uint8
+	Minutes   uint8
+	Hours     uint8
+	Type      uint8
+}
+
+func NewArtTimeCode(data []byte) (*ArtTimeCode, error) {
+	artTimeCode := ArtTimeCode{}
+
+	err := artTimeCode.UnmarshalBinary(data)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &artTimeCode, nil
+}
+
+func (atc *ArtTimeCode) GetOpCode() uint16 {
+	return atc.OpCode
+}
+
+func (atc *ArtTimeCode) GetProtVer() uint16 {
+	return uint16(atc.ProtVerHi)<<8 + uint16(atc.ProtVerLo)
+}
+
+func (atc *ArtTimeCode) GetID() []uint8 {
+	return atc.ID
+}
+
+func (atc *ArtTimeCode) UnmarshalBinary(data []byte) error {
+	fmt.Println(data)
+	if len(data) < 14 {
+		return errors.New("ArtTimeCode packet must be at least 14 bytes long")
+	}
+
+	atc.ID = data[0:8]
+
+	if !slices.Equal(ArtNetID, atc.ID) {
+		return errors.New("ID does not match Art-Net ID")
+	}
+
+	atc.OpCode = binary.LittleEndian.Uint16(data[8:10])
+	atc.ProtVerHi = data[10]
+	atc.ProtVerLo = data[11]
+
+	offset := 12
+	atc.Filler1 = data[offset]
+	atc.StreamId = data[offset+1]
+	atc.Frames = data[offset+2]
+	atc.Seconds = data[offset+3]
+	atc.Minutes = data[offset+4]
+	atc.Hours = data[offset+5]
+	atc.Type = data[offset+6]
+	return nil
+}
+
+func (atc *ArtTimeCode) MarshalBinary() ([]byte, error) {
+	data := []byte(ArtNetID)
+	data = append(data, byte(atc.OpCode), byte(atc.OpCode>>8), atc.ProtVerHi, atc.ProtVerLo, atc.Filler1, atc.StreamId, atc.Frames, atc.Seconds, atc.Minutes, atc.Hours, atc.Type)
+	return data, nil
+}
diff --git a/timecode_test.go b/timecode_test.go
new file mode 100644
index 0000000..7c41bde
--- /dev/null
+++ b/timecode_test.go
@@ -0,0 +1,85 @@
+package artnet_test
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/jwetzell/artnet-go"
+)
+
+func TestGoodArtTimeCode(t *testing.T) {
+	tests := []struct {
+		Data     []byte
+		Expected *artnet.ArtTimeCode
+	}{
+		{
+			Data: []byte{65, 114, 116, 45, 78, 101, 116, 0, 0, 151, 0, 14, 0, 0, 11, 17, 3, 0, 0},
+			Expected: &artnet.ArtTimeCode{
+				ID:        []byte{'A', 'r', 't', '-', 'N', 'e', 't', 0x00},
+				OpCode:    artnet.OpTimeCode,
+				ProtVerHi: 0,
+				ProtVerLo: 14,
+				Filler1:   0,
+				StreamId:  0,
+				Frames:    11,
+				Seconds:   17,
+				Minutes:   3,
+				Hours:     0,
+				Type:      0,
+			},
+		},
+	}
+
+	for _, test := range tests {
+		got, err := artnet.NewArtTimeCode(test.Data)
+
+		if err != nil {
+			t.Fatalf("failed to decode ArtTimeCode: %s", err)
+		}
+
+		if got.OpCode != test.Expected.OpCode {
+			t.Fatalf("ArtTimeCode OpCode does not match got: %d expected: %d", got.OpCode, test.Expected.OpCode)
+		}
+
+		if !slices.Equal(got.ID, test.Expected.ID) {
+			t.Fatalf("ArtTimeCode ID does not match got: %+v expected: %+v", got.ID, test.Expected.ID)
+		}
+
+		if got.Filler1 != test.Expected.Filler1 {
+			t.Fatalf("ArtTimeCode Filler1 does not match got: %d expected: %d", got.Filler1, test.Expected.Filler1)
+		}
+
+		if got.StreamId != test.Expected.StreamId {
+			t.Fatalf("ArtTimeCode StreamId does not match got: %d expected: %d", got.StreamId, test.Expected.StreamId)
+		}
+
+		if got.Frames != test.Expected.Frames {
+			t.Fatalf("ArtTimeCode Frames does not match got: %d expected: %d", got.Frames, test.Expected.Frames)
+		}
+
+		if got.Seconds != test.Expected.Seconds {
+			t.Fatalf("ArtTimeCode Seconds does not match got: %d expected: %d", got.Seconds, test.Expected.Seconds)
+		}
+
+		if got.Minutes != test.Expected.Minutes {
+			t.Fatalf("ArtTimeCode Minutes does not match got: %d expected: %d", got.Minutes, test.Expected.Minutes)
+		}
+
+		if got.Hours != test.Expected.Hours {
+			t.Fatalf("ArtTimeCode Hours does not match got: %d expected: %d", got.Hours, test.Expected.Hours)
+		}
+
+		if got.Type != test.Expected.Type {
+			t.Fatalf("ArtTimeCode Type does not match got: %d expected: %d", got.Type, test.Expected.Type)
+		}
+
+		if got.ProtVerHi != test.Expected.ProtVerHi {
+			t.Fatalf("ArtTimeCode ProtVerHi does not match got: %d expected: %d", got.ProtVerHi, test.Expected.ProtVerHi)
+		}
+
+		if got.ProtVerLo != test.Expected.ProtVerLo {
+			t.Fatalf("ArtTimeCode ProtVerLo does not match got: %d expected: %d", got.ProtVerLo, test.Expected.ProtVerLo)
+		}
+
+	}
+}