func (s *Stream) Seek(offset int64, whence int) (int64, error) {
	if s.resampling != nil {
		return s.resampling.Seek(offset, whence)
	}
	return s.orig.Seek(offset, whence)
}
func (s *Stream) Seek(offset int64, whence int) (int64, error) {
	if s.resampling != nil {
		return s.resampling.Seek(offset, whence)
	}
	return s.orig.Seek(offset, whence)
}
// Seek is implementation of io.Seeker's Seek.