streaming

commit 8b9dabb3f7e20b95c9d353d7cdc8deed50330b9f
parent df15482535093988ec1b4514e5fc9e0f12c4de49
Author: Oliver Lowe <o@olowe.co>
Date:   Fri, 17 May 2024 17:28:49 +1000

m3u8: implement EXT-X-DATETIME tag encoding

For testing out our scte35 package.

Diffstat:
M
m3u8/segment.go
 | 
1
+
M
m3u8/write.go
 | 
43
+++++++++++++++++++++++++++++++++++++++++++
M
m3u8/write_test.go
 | 
21
+++++++++++++++++++++

3 files changed, 65 insertions(+), 0 deletions(-)
diff --git a/m3u8/segment.go b/m3u8/segment.go
@@ -19,6 +19,7 @@ const (
 	tagGap             = "#EXT-X-GAP"
 	tagBitrate         = "#EXT-X-BITRATE"
 	tagPart            = "#EXT-X-PART"
+	tagDateRange       = "#EXT-X-DATERANGE"
 )
 
 // parseSegment returns the next segment from items and the leading
diff --git a/m3u8/write.go b/m3u8/write.go
@@ -1,8 +1,10 @@
 package m3u8
 
 import (
+	"encoding/hex"
 	"fmt"
 	"io"
+	"strings"
 	"time"
 )
 
@@ -12,6 +14,14 @@ func Encode(w io.Writer, p *Playlist) error {
 	fmt.Fprintf(w, "%s:%s\n", tagPlaylistType, p.Type)
 	fmt.Fprintf(w, "%s:%d\n", tagTargetDuration, p.TargetDuration/time.Second)
 	for _, seg := range p.Segments {
+		if seg.Discontinuity {
+			fmt.Fprintln(w, tagDiscontinuity)
+		}
+		if seg.DateRange != nil {
+			if err := writeDateRange(w, seg.DateRange); err != nil {
+				return fmt.Errorf("write date range: %w", err)
+			}
+		}
 		us := seg.Duration / time.Microsecond
 		// we do .03f for the same precision as test-streams.mux.dev.
 		fmt.Fprintf(w, "%s:%.03f\n", tagSegmentDuration, float32(us)/1e6)
@@ -22,3 +32,36 @@ func Encode(w io.Writer, p *Playlist) error {
 	}
 	return nil
 }
+
+func writeDateRange(w io.Writer, dr *DateRange) error {
+	fmt.Fprint(w, tagDateRange+":")
+	var attrs []string
+	if dr.ID != "" {
+		attrs = append(attrs, fmt.Sprintf("ID=%q", dr.ID))
+	}
+	if dr.Class != "" {
+		attrs = append(attrs, fmt.Sprintf("CLASS=%q", dr.Class))
+	}
+	if !dr.Start.IsZero() {
+		attrs = append(attrs, fmt.Sprintf("START-DATE=%q", dr.Start.Format(time.RFC3339)))
+	}
+	if !dr.End.IsZero() {
+		attrs = append(attrs, fmt.Sprintf("END-DATE=%q", dr.End.Format(time.RFC3339)))
+	}
+	// TODO(otl): dr.Duration, dr.Planned. Differentiate zero value and user-set zero.
+	// TODO(otl): dr.Custom.
+	// TODO(otl): dr.CueCommand, when to write this versuse cuein, cueout.
+	if dr.CueIn != nil {
+		attrs = append(attrs, fmt.Sprintf("SCTE35-IN=0x%s", hex.EncodeToString(dr.CueIn)))
+	}
+	if dr.CueOut != nil {
+		attrs = append(attrs, fmt.Sprintf("SCTE35-OUT=0x%s", hex.EncodeToString(dr.CueOut)))
+	}
+	if dr.EndOnNext {
+		attrs = append(attrs, "END-ON-NEXT:YES")
+	}
+	if _, err := fmt.Fprintln(w, strings.Join(attrs, ",")); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/m3u8/write_test.go b/m3u8/write_test.go
@@ -3,6 +3,7 @@ package m3u8
 import (
 	"bufio"
 	"bytes"
+	"encoding/base64"
 	"testing"
 	"time"
 )
@@ -32,3 +33,23 @@ func TestEncodeSegDuration(t *testing.T) {
 		t.Errorf("no matching segment duration %s", want)
 	}
 }
+
+func TestDateRange(t *testing.T) {
+	// splice insert from SCTE 35 section 14.2
+	out, err := base64.StdEncoding.DecodeString("/DAvAAAAAAAA///wFAVIAACPf+/+c2nALv4AUsz1AAAAAAAKAAhDVUVJAAABNWLbowo=")
+	if err != nil {
+		t.Fatal(err)
+	}
+	dr := DateRange{
+		ID:     "break",
+		CueOut: out,
+	}
+	buf := &bytes.Buffer{}
+	if err := writeDateRange(buf, &dr); err != nil {
+		t.Fatalf("write date range: %v", err)
+	}
+	want := `#EXT-X-DATERANGE:ID="break",SCTE35-OUT=0xfc302f000000000000fffff014054800008f7feffe7369c02efe0052ccf500000000000a0008435545490000013562dba30a` + "\n"
+	if buf.String() != want {
+		t.Errorf("encode %v: got %s, want %s", dr, buf.String(), want)
+	}
+}