diff --git a/pkg/rtpaac/decoder.go b/pkg/rtpaac/decoder.go
index 6d3d2863..064975bc 100644
--- a/pkg/rtpaac/decoder.go
+++ b/pkg/rtpaac/decoder.go
@@ -21,6 +21,10 @@ func NewDecoder(clockRate int) *Decoder {
 	}
 }
 
+func (d *Decoder) decodeTimestamp(ts uint32) time.Duration {
+	return (time.Duration(ts) - time.Duration(d.initialTs)) * time.Second / d.clockRate
+}
+
 // Decode decodes an AU from an RTP/AAC packet.
 func (d *Decoder) Decode(byts []byte) (*AUAndTimestamp, error) {
 	pkt := rtp.Packet{}
@@ -40,6 +44,6 @@ func (d *Decoder) Decode(byts []byte) (*AUAndTimestamp, error) {
 
 	return &AUAndTimestamp{
 		AU:        pkt.Payload[4:],
-		Timestamp: time.Duration(pkt.Timestamp-d.initialTs) * time.Second / d.clockRate,
+		Timestamp: d.decodeTimestamp(pkt.Timestamp),
 	}, nil
 }
diff --git a/pkg/rtph264/decoder.go b/pkg/rtph264/decoder.go
index ac24fab6..0097a668 100644
--- a/pkg/rtph264/decoder.go
+++ b/pkg/rtph264/decoder.go
@@ -50,6 +50,10 @@ func NewDecoder() *Decoder {
 	return &Decoder{}
 }
 
+func (d *Decoder) decodeTimestamp(ts uint32) time.Duration {
+	return (time.Duration(ts) - time.Duration(d.initialTs)) * time.Second / rtpClockRate
+}
+
 // Decode decodes NALUs from RTP/H264 packets.
 // It can return:
 // * no NALUs and ErrMorePacketsNeeded
@@ -82,7 +86,7 @@ func (d *Decoder) Decode(byts []byte) ([]*NALUAndTimestamp, error) {
 			NALUTypeReserved23:
 			return []*NALUAndTimestamp{{
 				NALU:      pkt.Payload,
-				Timestamp: time.Duration(pkt.Timestamp-d.initialTs) * time.Second / rtpClockRate,
+				Timestamp: d.decodeTimestamp(pkt.Timestamp),
 			}}, nil
 
 		case NALUTypeStapA:
@@ -108,7 +112,7 @@ func (d *Decoder) Decode(byts []byte) ([]*NALUAndTimestamp, error) {
 
 				ret = append(ret, &NALUAndTimestamp{
 					NALU:      pkt.Payload[:size],
-					Timestamp: time.Duration(pkt.Timestamp-d.initialTs) * time.Second / rtpClockRate,
+					Timestamp: d.decodeTimestamp(pkt.Timestamp),
 				})
 				pkt.Payload = pkt.Payload[size:]
 			}
@@ -166,7 +170,7 @@ func (d *Decoder) Decode(byts []byte) ([]*NALUAndTimestamp, error) {
 		d.state = decoderStateInitial
 		return []*NALUAndTimestamp{{
 			NALU:      d.fragmentedBuf,
-			Timestamp: time.Duration(pkt.Timestamp-d.initialTs) * time.Second / rtpClockRate,
+			Timestamp: d.decodeTimestamp(pkt.Timestamp),
 		}}, nil
 	}
 }
diff --git a/pkg/rtph264/rtph264_test.go b/pkg/rtph264/rtph264_test.go
index 62e8f0fd..820ecba9 100644
--- a/pkg/rtph264/rtph264_test.go
+++ b/pkg/rtph264/rtph264_test.go
@@ -55,6 +55,25 @@ var cases = []struct {
 			),
 		},
 	},
+	{
+		"negative timestamp",
+		&NALUAndTimestamp{
+			Timestamp: -20 * time.Millisecond,
+			NALU: mergeBytes(
+				[]byte{0x05},
+				bytes.Repeat([]byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}, 8),
+			),
+		},
+		[][]byte{
+			mergeBytes(
+				[]byte{
+					0x80, 0xe0, 0x44, 0xed, 0x88, 0x77, 0x5f, 0x4d,
+					0x9d, 0xbb, 0x78, 0x12, 0x05,
+				},
+				bytes.Repeat([]byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}, 8),
+			),
+		},
+	},
 	{
 		"fragmented",
 		&NALUAndTimestamp{