// Clip returns a filter that extracts a clip between begin and begin + duration (in seconds, starting at 0)
// Il will try to include a key frame at the beginning, and keeps the same chunks as the origin media
func Clip(m *mp4.MP4, begin, duration time.Duration) (ClipInterface, error) {
end := begin + duration
if begin < 0 {
return nil, ErrClipOutside
}
if begin > m.Duration() {
return nil, ErrClipOutside
}
if end > m.Duration() {
end = m.Duration()
}
if end < 0 {
return nil, ErrClipOutside
}
return &clipFilter{
m: m,
end: end,
begin: begin,
}, nil
}
// EncodeFiltered encodes a media to a writer, filtering the media using the specified filter
func EncodeFiltered(w io.Writer, m *mp4.MP4, f Filter) error {
err := m.Ftyp.Encode(w)
if err != nil {
return err
}
err = f.FilterMoov(m.Moov)
if err != nil {
return err
}
err = m.Moov.Encode(w)
if err != nil {
return err
}
for _, b := range m.Boxes() {
if b.Type() != "ftyp" && b.Type() != "moov" && b.Type() != "mdat" {
err = b.Encode(w)
if err != nil {
return err
}
}
}
return f.FilterMdat(w, m.Mdat)
}
