Added webvtt escape

webvtt.go

@@ -42,7 +42,8 @@ func parseDurationWebVTT(i string) (time.Duration, error) {
 
 // https://tools.ietf.org/html/rfc8216#section-3.5
 // Eg., `X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000` => 10s
-//      `X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:180000` => 2s
+//
+//	`X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:180000` => 2s
 func parseTimestampMapWebVTT(line string) (timeOffset time.Duration, err error) {
 	splits := strings.Split(line, "=")
 	if len(splits) <= 1 {
@@ -112,6 +113,9 @@ func ReadFromWebVTT(i io.Reader) (o *Subtitles, err error) {
 		line = strings.TrimSpace(scanner.Text())
 		lineNum++
 
+		// Unescape line
+		line = unescapeWebVTT(line)
+
 		switch {
 		// Comment
 		case strings.HasPrefix(line, "NOTE "):
@@ -273,6 +277,14 @@ func ReadFromWebVTT(i io.Reader) (o *Subtitles, err error) {
 	return
 }
 
+func escapeWebVTT(i string) string {
+	return strings.ReplaceAll(i, "&", "&amp;")
+}
+
+func unescapeWebVTT(i string) string {
+	return strings.ReplaceAll(i, "&amp;", "&")
+}
+
 // parseTextWebVTT parses the input line to fill the Line
 func parseTextWebVTT(i string) (o Line) {
 	// Create tokenizer
@@ -475,6 +487,9 @@ func (s Subtitles) WriteToWebVTT(o io.Writer) (err error) {
 	// Remove last new line
 	c = c[:len(c)-1]
 
+	// Escape content
+	c = []byte(escapeWebVTT(string(c)))
+
 	// Write
 	if _, err = o.Write(c); err != nil {
 		err = fmt.Errorf("astisub: writing failed: %w", err)

webvtt_test.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/asticode/go-astisub"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestWebVTT(t *testing.T) {
@@ -130,3 +131,26 @@ func TestWebVTTWithTimestampMap(t *testing.T) {
 Evening.
 `, b.String())
 }
+
+func TestWebVTTEscape(t *testing.T) {
+	testData := `WEBVTT
+
+	00:01:00.000 --> 00:02:00.000
+	Sentence with an & in the middle`
+
+	s, err := astisub.ReadFromWebVTT(strings.NewReader(testData))
+	require.NoError(t, err)
+
+	require.Len(t, s.Items, 1)
+	require.Equal(t, "Sentence with an & in the middle", s.Items[0].String())
+
+	b := &bytes.Buffer{}
+	err = s.WriteToWebVTT(b)
+	require.NoError(t, err)
+	require.Equal(t, `WEBVTT
+
+1
+00:01:00.000 --> 00:02:00.000
+Sentence with an & in the middle
+`, b.String())
+}