Finish AV1 Implementation

1. Rewrite the AV1 Payloader according to the spec.
2. AV1 bitstream reader.
3. Tries to optimize the use of the W field as much as possible to
    reduce the size of the packet.
4. Added tests around edge cases.

codecs/av1_depacketizer.go

@@ -35,10 +35,10 @@ func (d *AV1Depacketizer) Unmarshal(payload []byte) (buff []byte, err error) {
 	}
 
 	// |Z|Y| W |N|-|-|-|
-	obuZ := (0b10000000 & payload[0]) != 0     // Z
-	obuY := (0b01000000 & payload[0]) != 0     // Y
-	obuCount := (0b00110000 & payload[0]) >> 4 // W
-	obuN := (0b00001000 & payload[0]) != 0     // N
+	obuZ := (av1ZMask & payload[0]) != 0     // Z
+	obuY := (av1YMask & payload[0]) != 0     // Y
+	obuCount := (av1WMask & payload[0]) >> 4 // W
+	obuN := (av1NMask & payload[0]) != 0     // N
 	d.Z = obuZ
 	d.Y = obuY
 	d.N = obuN
@@ -120,10 +120,7 @@ func (d *AV1Depacketizer) Unmarshal(payload []byte) (buff []byte, err error) {
 		}
 
 		if len(obuBuffer) == 0 {
-			return nil, fmt.Errorf(
-				"%w: OBU size %d is 0",
-				errShortPacket, lengthField,
-			)
+			continue
 		}
 
 		obuHeader, err := obu.ParseOBUHeader(obuBuffer)

codecs/av1_depacketizer_test.go

@@ -39,12 +39,6 @@ func TestAV1Depacketizerr_invalidPackets(t *testing.T) {
 	if !errors.Is(err, errShortPacket) {
 		t.Fatalf("Unexpected error: %v", err)
 	}
-
-	_, err = depacketizer.Unmarshal([]byte{0x00})
-	if !errors.Is(err, errShortPacket) {
-		t.Fatalf("Unexpected error: %v", err)
-	}
-
 	_, err = depacketizer.Unmarshal([]byte{0b11000000, 0xFF})
 	if !errors.Is(err, obu.ErrFailedToReadLEB128) {
 		t.Fatalf("Unexpected error: %v", err)
@@ -55,7 +49,7 @@ func TestAV1Depacketizerr_invalidPackets(t *testing.T) {
 		t.Fatalf("Unexpected error: %v", err)
 	}
 
-	_, err = depacketizer.Unmarshal(append([]byte{0b00000000}, obu.WriteToLeb128(0)...))
+	_, err = depacketizer.Unmarshal(append([]byte{0b00000000}, obu.WriteToLeb128(0x01)...))
 	if !errors.Is(err, errShortPacket) {
 		t.Fatalf("Unexpected error: %v", err)
 	}
@@ -95,6 +89,29 @@ func TestAV1Depacketizerr_singleOBU(t *testing.T) {
 	}
 }
 
+func TestAV1Depacketizerr_singleOBUWithPadding(t *testing.T) {
+	payload := []byte{0x01, 0x02, 0x03}
+	obuData, expectedOBU := createAV1OBU(4, payload)
+
+	packet := make([]byte, 0)
+
+	packet = append(packet, []byte{0b00000000}...)
+	packet = append(packet, obu.WriteToLeb128(uint(len(obuData)))...)
+	packet = append(packet, obuData...)
+	// padding
+	packet = append(packet, []byte{0x00, 0x00, 0x00}...)
+
+	d := AV1Depacketizer{}
+	obu, err := d.Unmarshal(packet)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+
+	if !bytes.Equal(obu, expectedOBU) {
+		t.Fatalf("OBU data mismatch, expected %v, got %v", expectedOBU, obu)
+	}
+}
+
 // AV1 OBUs shouldn't include the obu_size_field when packetized in RTP,
 // but we still support it since it's encountered in the wild (Including pion old clients).
 func TestAV1Depacketizerr_withOBUSize(t *testing.T) {