static int find_smallest_bounding_rectangle(AVSubtitle *s) { uint8_t transp_color[256] = { 0 }; int y1, y2, x1, x2, y, w, h, i; uint8_t *bitmap; if (s->num_rects == 0 || s->rects == NULL || s->rects[0]->w <= 0 || s->rects[0]->h <= 0) return 0; for(i = 0; i < s->rects[0]->nb_colors; i++) { if ((((uint32_t*)s->rects[0]->pict.data[1])[i] >> 24) == 0) transp_color[i] = 1; } y1 = 0; while (y1 < s->rects[0]->h && is_transp(s->rects[0]->pict.data[0] + y1 * s->rects[0]->pict.linesize[0], 1, s->rects[0]->w, transp_color)) y1++; if (y1 == s->rects[0]->h) { av_freep(&s->rects[0]->pict.data[0]); s->rects[0]->w = s->rects[0]->h = 0; return 0; } y2 = s->rects[0]->h - 1; while (y2 > 0 && is_transp(s->rects[0]->pict.data[0] + y2 * s->rects[0]->pict.linesize[0], 1, s->rects[0]->w, transp_color)) y2--; x1 = 0; while (x1 < (s->rects[0]->w - 1) && is_transp(s->rects[0]->pict.data[0] + x1, s->rects[0]->pict.linesize[0], s->rects[0]->h, transp_color)) x1++; x2 = s->rects[0]->w - 1; while (x2 > 0 && is_transp(s->rects[0]->pict.data[0] + x2, s->rects[0]->pict.linesize[0], s->rects[0]->h, transp_color)) x2--; w = x2 - x1 + 1; h = y2 - y1 + 1; bitmap = av_malloc(w * h); if (!bitmap) return 1; for(y = 0; y < h; y++) { memcpy(bitmap + w * y, s->rects[0]->pict.data[0] + x1 + (y1 + y) * s->rects[0]->pict.linesize[0], w); } av_freep(&s->rects[0]->pict.data[0]); s->rects[0]->pict.data[0] = bitmap; s->rects[0]->pict.linesize[0] = w; s->rects[0]->w = w; s->rects[0]->h = h; s->rects[0]->x += x1; s->rects[0]->y += y1; return 1; }