Merge pull request #8 from jwplayer/feature/SSAI-217-EXT-X-INDEPENDEN…

…T-SEGMENTS Add independent segments for MediaPlaylist
jwplayer · Aug 14, 2023 · c08fb32 · c08fb32
2 parents 10d72f3 + 067bfef
commit c08fb32
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Showing 6 changed files with 200 additions and 24 deletions.
diff --git a/reader.go b/reader.go
@@ -581,6 +581,8 @@ func decodeLineOfMediaPlaylist(p *MediaPlaylist, wv *WV, state *decodingState, l
 	case line == "#EXT-X-ENDLIST":
 		state.listType = MEDIA
 		p.Closed = true
+	case line == "#EXT-X-INDEPENDENT-SEGMENTS":
+		p.SetIndependentSegments(true)
 	case strings.HasPrefix(line, "#EXT-X-VERSION:"):
 		state.listType = MEDIA
 		if _, err = fmt.Sscanf(line, "#EXT-X-VERSION:%d", &p.ver); strict && err != nil {

diff --git a/reader_test.go b/reader_test.go
@@ -1132,3 +1132,75 @@ func BenchmarkDecodeMediaPlaylist(b *testing.B) {
 		}
 	}
 }
+
+func TestDecodeMediaPlaylistWithIndependentSegments(t *testing.T) {
+	f, err := os.Open("sample-playlists/media-playlist-with-independent-segments.m3u8")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p, listType, err := DecodeFrom(bufio.NewReader(f), true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	pp := p.(*MediaPlaylist)
+	CheckType(t, pp)
+	if listType != MEDIA {
+		t.Error("Sample not recognized as media playlist.")
+	}
+	err = pp.DecodeFrom(bufio.NewReader(f), false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !pp.IndependentSegments() {
+		t.Error("Expected independent segments to be true")
+	}
+}
+
+func TestDecodeMediaPlaylistWithoutIndependentSegments(t *testing.T) {
+	f, err := os.Open("sample-playlists/media-playlist-with-gap.m3u8")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p, listType, err := DecodeFrom(bufio.NewReader(f), true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	pp := p.(*MediaPlaylist)
+	CheckType(t, pp)
+	if listType != MEDIA {
+		t.Error("Sample not recognized as media playlist.")
+	}
+	err = pp.DecodeFrom(bufio.NewReader(f), false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if pp.IndependentSegments() {
+		t.Error("Expected independentsegments to be false")
+	}
+}
+
+func TestWriteMediaPlaylistWithoutIndependentSegments(t *testing.T) {
+	f, err := os.Open("sample-playlists/media-playlist-with-gap.m3u8")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p, listType, err := DecodeFrom(bufio.NewReader(f), true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	pp := p.(*MediaPlaylist)
+	CheckType(t, pp)
+	if listType != MEDIA {
+		t.Error("Sample not recognized as media playlist.")
+	}
+	err = pp.DecodeFrom(bufio.NewReader(f), false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if pp.IndependentSegments() {
+		t.Error("Expected independentsegments to be false")
+	}
+}
diff --git a/sample-playlists/media-playlist-with-independent-segments.m3u8 b/sample-playlists/media-playlist-with-independent-segments.m3u8
@@ -0,0 +1,26 @@
+#EXTM3U
+#EXT-X-VERSION:4
+#EXT-X-TARGETDURATION:10
+#EXT-X-MEDIA-SEQUENCE:0
+#EXT-X-INDEPENDENT-SEGMENTS
+
+#EXTINF:10.000,
+0.ts
+#EXTINF:10.000,
+1.ts
+#EXTINF:10.000,
+2.ts
+#EXTINF:10.000,
+3.ts
+#EXTINF:10.000,
+4.ts
+#EXTINF:10.000,
+5.ts
+#EXTINF:10.000,
+6.ts
+#EXTINF:10.000,
+7.ts
+#EXTINF:10.000,
+8.ts
+#EXTINF:10.000,
+9.ts
diff --git a/structure.go b/structure.go
@@ -106,30 +106,31 @@ const (
 //	#EXTINF:7.975,
 //	https://priv.example.com/fileSequence2682.ts
 type MediaPlaylist struct {
-	TargetDuration   float64
-	SeqNo            uint64 // EXT-X-MEDIA-SEQUENCE
-	Segments         []*MediaSegment
-	Args             string // optional arguments placed after URIs (URI?Args)
-	Iframe           bool   // EXT-X-I-FRAMES-ONLY
-	Closed           bool   // is this VOD (closed) or Live (sliding) playlist?
-	MediaType        MediaType
-	DiscontinuitySeq uint64 // EXT-X-DISCONTINUITY-SEQUENCE
-	StartTime        float64
-	StartTimePrecise bool
-	durationAsInt    bool // output durations as integers of floats?
-	keyformat        int
-	winsize          uint // max number of segments displayed in an encoded playlist; need set to zero for VOD playlists
-	capacity         uint // total capacity of slice used for the playlist
-	head             uint // head of FIFO, we add segments to head
-	tail             uint // tail of FIFO, we remove segments from tail
-	count            uint // number of segments added to the playlist
-	buf              bytes.Buffer
-	ver              uint8
-	Key              *Key // EXT-X-KEY is optional encryption key displayed before any segments (default key for the playlist)
-	Map              *Map // EXT-X-MAP is optional tag specifies how to obtain the Media Initialization Section (default map for the playlist)
-	WV               *WV  // Widevine related tags outside of M3U8 specs
-	Custom           map[string]CustomTag
-	customDecoders   []CustomDecoder
+	TargetDuration      float64
+	SeqNo               uint64 // EXT-X-MEDIA-SEQUENCE
+	Segments            []*MediaSegment
+	Args                string // optional arguments placed after URIs (URI?Args)
+	Iframe              bool   // EXT-X-I-FRAMES-ONLY
+	Closed              bool   // is this VOD (closed) or Live (sliding) playlist?
+	MediaType           MediaType
+	DiscontinuitySeq    uint64 // EXT-X-DISCONTINUITY-SEQUENCE
+	StartTime           float64
+	StartTimePrecise    bool
+	durationAsInt       bool // output durations as integers of floats?
+	keyformat           int
+	winsize             uint // max number of segments displayed in an encoded playlist; need set to zero for VOD playlists
+	capacity            uint // total capacity of slice used for the playlist
+	head                uint // head of FIFO, we add segments to head
+	tail                uint // tail of FIFO, we remove segments from tail
+	count               uint // number of segments added to the playlist
+	buf                 bytes.Buffer
+	ver                 uint8
+	independentSegments bool
+	Key                 *Key // EXT-X-KEY is optional encryption key displayed before any segments (default key for the playlist)
+	Map                 *Map // EXT-X-MAP is optional tag specifies how to obtain the Media Initialization Section (default map for the playlist)
+	WV                  *WV  // Widevine related tags outside of M3U8 specs
+	Custom              map[string]CustomTag
+	customDecoders      []CustomDecoder
 }
 
 // MasterPlaylist structure represents a master playlist which

diff --git a/writer.go b/writer.go
@@ -405,6 +405,18 @@ func (p *MediaPlaylist) ResetCache() {
 	p.buf.Reset()
 }
 
+// IndependentSegments returns true if all media samples in a segment can be
+// decoded without information from other segments.
+func (p *MediaPlaylist) IndependentSegments() bool {
+	return p.independentSegments
+}
+
+// SetIndependentSegments sets whether all media samples in a segment can be
+// decoded without information from other segments.
+func (p *MediaPlaylist) SetIndependentSegments(b bool) {
+	p.independentSegments = b
+}
+
 // Encode generates output in M3U8 format. Marshal `winsize` elements
 // from bottom of the `segments` queue.
 func (p *MediaPlaylist) Encode() *bytes.Buffer {
@@ -416,6 +428,10 @@ func (p *MediaPlaylist) Encode() *bytes.Buffer {
 	p.buf.WriteString(strver(p.ver))
 	p.buf.WriteRune('\n')
 
+	if p.IndependentSegments() {
+		p.buf.WriteString("#EXT-X-INDEPENDENT-SEGMENTS\n")
+	}
+
 	// Write any custom master tags
 	if p.Custom != nil {
 		for _, v := range p.Custom {

diff --git a/writer_test.go b/writer_test.go
@@ -1223,3 +1223,62 @@ func BenchmarkEncodeMediaPlaylist(b *testing.B) {
 		_ = p.Encode() // disregard output
 	}
 }
+
+func TestMediaPlaylistIndependentSegments(t *testing.T) {
+	p, _ := NewMediaPlaylist(3, 5)
+	for i := 0; i < 5; i++ {
+		p.Append(fmt.Sprintf("test%d.ts", i), 5.0, "")
+	}
+	if p.IndependentSegments() {
+		t.Errorf("Expected independent segments to be false by default")
+	}
+	p.SetIndependentSegments(true)
+	if !p.IndependentSegments() {
+		t.Errorf("Expected independent segments to be true")
+	}
+	if !strings.Contains(p.Encode().String(), "#EXT-X-INDEPENDENT-SEGMENTS") {
+		t.Error("Expected playlist to contain EXT-X-INDEPENDENT-SEGMENTS tag")
+	}
+	fmt.Print(p)
+	// Output:
+	// #EXTM3U
+	// #EXT-X-VERSION:3
+	// #EXT-X-INDEPENDENT-SEGMENTS
+	// #EXT-X-MEDIA-SEQUENCE:0
+	// #EXT-X-TARGETDURATION:5
+	// #EXTINF:5.000,
+	// test0.ts
+	// #EXTINF:5.000,
+	// test1.ts
+	// #EXTINF:5.000,
+	// test2.ts
+}
+
+func TestMediaPlaylistWithoutIndependentSegments(t *testing.T) {
+	p, _ := NewMediaPlaylist(3, 5)
+	for i := 0; i < 5; i++ {
+		p.Append(fmt.Sprintf("test%d.ts", i), 5.0, "")
+	}
+	if p.IndependentSegments() != false {
+		t.Errorf("Expected independent segments to be false by default")
+	}
+	p.SetIndependentSegments(false)
+	if p.IndependentSegments() {
+		t.Errorf("Expected independent segments to be false")
+	}
+	if strings.Contains(p.Encode().String(), "#EXT-X-INDEPENDENT-SEGMENTS") {
+		t.Error("Expected playlist shouldn't contain EXT-X-INDEPENDENT-SEGMENTS tag")
+	}
+	fmt.Print(p)
+	// Output:
+	// #EXTM3U
+	// #EXT-X-VERSION:3
+	// #EXT-X-MEDIA-SEQUENCE:0
+	// #EXT-X-TARGETDURATION:5
+	// #EXTINF:5.000,
+	// test0.ts
+	// #EXTINF:5.000,
+	// test1.ts
+	// #EXTINF:5.000,
+	// test2.ts
+}