diff --git a/client.go b/client.go
index dfc8d1b..d631c24 100644
--- a/client.go
+++ b/client.go
@@ -37,7 +37,7 @@ type ClientOnDecodeErrorFunc func(err error)
 type ClientOnTracksFunc func([]*Track) error
 
 // ClientOnDataAV1Func is the prototype of the function passed to OnDataAV1().
-type ClientOnDataAV1Func func(pts time.Duration, obus [][]byte)
+type ClientOnDataAV1Func func(pts time.Duration, tu [][]byte)
 
 // ClientOnDataVP9Func is the prototype of the function passed to OnDataVP9().
 type ClientOnDataVP9Func func(pts time.Duration, frame []byte)
@@ -73,6 +73,8 @@ type Client struct {
 	//
 	// callbacks (all optional)
 	//
+	// called when tracks are available.
+	OnTracks ClientOnTracksFunc
 	// called before downloading a primary playlist.
 	OnDownloadPrimaryPlaylist ClientOnDownloadPrimaryPlaylistFunc
 	// called before downloading a stream playlist.
@@ -88,7 +90,6 @@ type Client struct {
 
 	ctx         context.Context
 	ctxCancel   func()
-	onTracks    ClientOnTracksFunc
 	onData      map[*Track]interface{}
 	playlistURL *url.URL
 
@@ -101,6 +102,11 @@ func (c *Client) Start() error {
 	if c.HTTPClient == nil {
 		c.HTTPClient = http.DefaultClient
 	}
+	if c.OnTracks == nil {
+		c.OnTracks = func(_ []*Track) error {
+			return nil
+		}
+	}
 	if c.OnDownloadPrimaryPlaylist == nil {
 		c.OnDownloadPrimaryPlaylist = func(_ string) {}
 	}
@@ -140,11 +146,6 @@ func (c *Client) Wait() chan error {
 	return c.outErr
 }
 
-// OnTracks sets a callback that is called when tracks are read.
-func (c *Client) OnTracks(cb ClientOnTracksFunc) {
-	c.onTracks = cb
-}
-
 // OnDataAV1 sets a callback that is called when data from an AV1 track is received.
 func (c *Client) OnDataAV1(forma *Track, cb ClientOnDataAV1Func) {
 	c.onData[forma] = cb
@@ -185,7 +186,7 @@ func (c *Client) runInner() error {
 		c.OnDownloadSegment,
 		c.OnDecodeError,
 		rp,
-		c.onTracks,
+		c.OnTracks,
 		c.onData,
 	)
 	rp.add(dl)
diff --git a/client_processor_fmp4.go b/client_processor_fmp4.go
index 02d52c5..a39af45 100644
--- a/client_processor_fmp4.go
+++ b/client_processor_fmp4.go
@@ -195,18 +195,18 @@ func (p *clientProcessorFMP4) initializeTrackProcs(ctx context.Context, track *f
 
 		switch track.Codec.(type) {
 		case *codecs.AV1:
-			var onDataCasted ClientOnDataAV1Func = func(pts time.Duration, obus [][]byte) {}
+			var onDataCasted ClientOnDataAV1Func = func(pts time.Duration, tu [][]byte) {}
 			if onData != nil {
 				onDataCasted = onData.(ClientOnDataAV1Func)
 			}
 
 			postProcess = func(pts time.Duration, dts time.Duration, sample *fmp4.PartSample) error {
-				obus, err := sample.GetAV1()
+				tu, err := sample.GetAV1()
 				if err != nil {
 					return err
 				}
 
-				onDataCasted(pts, obus)
+				onDataCasted(pts, tu)
 				return nil
 			}
 
diff --git a/client_test.go b/client_test.go
index fd63a95..69f509b 100644
--- a/client_test.go
+++ b/client_test.go
@@ -270,17 +270,6 @@ func TestClientMPEGTS(t *testing.T) {
 				prefix = "https"
 			}
 
-			c := &Client{
-				URI: prefix + "://localhost:5780/stream.m3u8",
-				HTTPClient: &http.Client{
-					Transport: &http.Transport{
-						TLSClientConfig: &tls.Config{
-							InsecureSkipVerify: true,
-						},
-					},
-				},
-			}
-
 			onH264 := func(pts time.Duration, dts time.Duration, au [][]byte) {
 				require.Equal(t, 2*time.Second, pts)
 				require.Equal(t, time.Duration(0), dts)
@@ -292,12 +281,23 @@ func TestClientMPEGTS(t *testing.T) {
 				close(packetRecv)
 			}
 
-			c.OnTracks(func(tracks []*Track) error {
-				require.Equal(t, 1, len(tracks))
-				require.Equal(t, &codecs.H264{}, tracks[0].Codec)
-				c.OnDataH26x(tracks[0], onH264)
-				return nil
-			})
+			var c *Client
+			c = &Client{
+				URI: prefix + "://localhost:5780/stream.m3u8",
+				HTTPClient: &http.Client{
+					Transport: &http.Transport{
+						TLSClientConfig: &tls.Config{
+							InsecureSkipVerify: true,
+						},
+					},
+				},
+				OnTracks: func(tracks []*Track) error {
+					require.Equal(t, 1, len(tracks))
+					require.Equal(t, &codecs.H264{}, tracks[0].Codec)
+					c.OnDataH26x(tracks[0], onH264)
+					return nil
+				},
+			}
 
 			err = c.Start()
 			require.NoError(t, err)
@@ -355,18 +355,18 @@ segment.mp4
 		close(packetRecv)
 	}
 
-	c := &Client{
+	var c *Client
+	c = &Client{
 		URI: "http://localhost:5780/stream.m3u8",
+		OnTracks: func(tracks []*Track) error {
+			require.Equal(t, 1, len(tracks))
+			_, ok := tracks[0].Codec.(*codecs.H264)
+			require.Equal(t, true, ok)
+			c.OnDataH26x(tracks[0], onH264)
+			return nil
+		},
 	}
 
-	c.OnTracks(func(tracks []*Track) error {
-		require.Equal(t, 1, len(tracks))
-		_, ok := tracks[0].Codec.(*codecs.H264)
-		require.Equal(t, true, ok)
-		c.OnDataH26x(tracks[0], onH264)
-		return nil
-	})
-
 	err = c.Start()
 	require.NoError(t, err)
 
@@ -429,10 +429,6 @@ segment1.ts
 	}
 	require.NoError(t, err)
 
-	c.OnTracks(func(tracks []*Track) error {
-		return nil
-	})
-
 	err = c.Start()
 	require.NoError(t, err)
 
diff --git a/examples/client/main.go b/examples/client/main.go
index 6bee66b..543c778 100644
--- a/examples/client/main.go
+++ b/examples/client/main.go
@@ -11,44 +11,45 @@ import (
 // This example shows how to read a HLS stream.
 
 func main() {
-	// setup client.
-	c := gohlslib.Client{
+	// setup client
+	var c *gohlslib.Client
+	c = &gohlslib.Client{
 		URI: "https://myserver/mystream/index.m3u8",
-	}
 
-	// setup a hook that is called when tracks are parsed
-	c.OnTracks(func(tracks []*gohlslib.Track) error {
-		for _, track := range tracks {
-			ttrack := track
-
-			log.Printf("detected track with codec %T\n", track.Codec)
-
-			// setup a hook that is called when data is received
-			switch track.Codec.(type) {
-			case *codecs.AV1:
-				c.OnDataAV1(track, func(pts time.Duration, obus [][]byte) {
-					log.Printf("received data from track %T, pts = %v", ttrack, pts)
-				})
-
-			case *codecs.H264, *codecs.H265:
-				c.OnDataH26x(track, func(pts time.Duration, dts time.Duration, au [][]byte) {
-					log.Printf("received data from track %T, pts = %v", ttrack, pts)
-				})
-
-			case *codecs.MPEG4Audio:
-				c.OnDataMPEG4Audio(track, func(pts time.Duration, aus [][]byte) {
-					log.Printf("received data from track %T, pts = %v", ttrack, pts)
-				})
-
-			case *codecs.Opus:
-				c.OnDataOpus(track, func(pts time.Duration, packets [][]byte) {
-					log.Printf("received data from track %T, pts = %v", ttrack, pts)
-				})
-			}
+		// set a callback that is called when tracks are parsed
+		OnTracks: func(tracks []*gohlslib.Track) error {
+			for _, track := range tracks {
+				ttrack := track
+
+				log.Printf("detected track with codec %T\n", track.Codec)
+
+				// set a callback that is called when data is received
+				switch track.Codec.(type) {
+				case *codecs.AV1:
+					c.OnDataAV1(track, func(pts time.Duration, tu [][]byte) {
+						log.Printf("received data from track %T, pts = %v", ttrack, pts)
+					})
+
+				case *codecs.H264, *codecs.H265:
+					c.OnDataH26x(track, func(pts time.Duration, dts time.Duration, au [][]byte) {
+						log.Printf("received data from track %T, pts = %v", ttrack, pts)
+					})
 
-		}
-		return nil
-	})
+				case *codecs.MPEG4Audio:
+					c.OnDataMPEG4Audio(track, func(pts time.Duration, aus [][]byte) {
+						log.Printf("received data from track %T, pts = %v", ttrack, pts)
+					})
+
+				case *codecs.Opus:
+					c.OnDataOpus(track, func(pts time.Duration, packets [][]byte) {
+						log.Printf("received data from track %T, pts = %v", ttrack, pts)
+					})
+				}
+
+			}
+			return nil
+		},
+	}
 
 	// start reading
 	err := c.Start()
diff --git a/muxer.go b/muxer.go
index 8c6b73b..b96edb6 100644
--- a/muxer.go
+++ b/muxer.go
@@ -194,14 +194,14 @@ func (m *Muxer) Close() {
 	m.segmenter.close()
 }
 
-// WriteAV1 writes an AV1 OBU sequence.
-func (m *Muxer) WriteAV1(ntp time.Time, pts time.Duration, obus [][]byte) error {
+// WriteAV1 writes an AV1 temporal unit.
+func (m *Muxer) WriteAV1(ntp time.Time, pts time.Duration, tu [][]byte) error {
 	codec := m.VideoTrack.Codec.(*codecs.AV1)
 	update := false
 	sequenceHeader := codec.SequenceHeader
 	randomAccess := false
 
-	for _, obu := range obus {
+	for _, obu := range tu {
 		var h av1.OBUHeader
 		err := h.Unmarshal(obu)
 		if err != nil {
@@ -236,7 +236,7 @@ func (m *Muxer) WriteAV1(ntp time.Time, pts time.Duration, obus [][]byte) error
 		forceSwitch = true
 	}
 
-	return m.segmenter.writeAV1(ntp, pts, obus, randomAccess, forceSwitch)
+	return m.segmenter.writeAV1(ntp, pts, tu, randomAccess, forceSwitch)
 }
 
 // WriteVP9 writes a VP9 frame.
diff --git a/muxer_segmenter_fmp4.go b/muxer_segmenter_fmp4.go
index 5888cc3..1cb8ad3 100644
--- a/muxer_segmenter_fmp4.go
+++ b/muxer_segmenter_fmp4.go
@@ -196,7 +196,7 @@ func (m *muxerSegmenterFMP4) adjustPartDuration(sampleDuration time.Duration) {
 func (m *muxerSegmenterFMP4) writeAV1(
 	ntp time.Time,
 	dts time.Duration,
-	obus [][]byte,
+	tu [][]byte,
 	randomAccess bool,
 	forceSwitch bool,
 ) error {
@@ -214,7 +214,7 @@ func (m *muxerSegmenterFMP4) writeAV1(
 
 	ps, err := fmp4.NewPartSampleAV1(
 		randomAccess,
-		obus)
+		tu)
 	if err != nil {
 		return err
 	}