Caption support (#2462)

Co-authored-by: WithoutPants <53250216+WithoutPants@users.noreply.github.com>

vendor/github.com/asticode/go-astikit/time.go

@@ -0,0 +1,58 @@
+package astikit
+
+import (
+	"context"
+	"strconv"
+	"time"
+)
+
+var now = func() time.Time { return time.Now() }
+
+// Sleep is a cancellable sleep
+func Sleep(ctx context.Context, d time.Duration) (err error) {
+	for {
+		select {
+		case <-time.After(d):
+			return
+		case <-ctx.Done():
+			err = ctx.Err()
+			return
+		}
+	}
+}
+
+// Timestamp represents a timestamp you can marshal and umarshal
+type Timestamp struct {
+	time.Time
+}
+
+// NewTimestamp creates a new timestamp
+func NewTimestamp(t time.Time) *Timestamp {
+	return &Timestamp{Time: t}
+}
+
+// UnmarshalJSON implements the JSONUnmarshaler interface
+func (t *Timestamp) UnmarshalJSON(text []byte) error {
+	return t.UnmarshalText(text)
+}
+
+// UnmarshalText implements the TextUnmarshaler interface
+func (t *Timestamp) UnmarshalText(text []byte) (err error) {
+	var i int
+	if i, err = strconv.Atoi(string(text)); err != nil {
+		return
+	}
+	t.Time = time.Unix(int64(i), 0)
+	return
+}
+
+// MarshalJSON implements the JSONMarshaler interface
+func (t Timestamp) MarshalJSON() ([]byte, error) {
+	return t.MarshalText()
+}
+
+// MarshalText implements the TextMarshaler interface
+func (t Timestamp) MarshalText() (text []byte, err error) {
+	text = []byte(strconv.Itoa(int(t.UTC().Unix())))
+	return
+}