hls->size = new_start_pos - hls->start_pos;
ret = hls_append_segment(hls, hls->duration, hls->start_pos, hls->size);
hls->start_pos = new_start_pos;
hls->size = new_start_pos - hls->start_pos;
ret = hls_append_segment(hls, hls->duration, hls->start_pos, hls->size);
hls->start_pos = new_start_pos;