- pos = (t >> 1) + ppos[0]*2 - ppos[1];
- av_add_index_entry(s->streams[0], pos, i << seekd, 0, 0, AVINDEX_KEYFRAME);
+ pos = (t >> 1) + (uint64_t)ppos[0]*2 - ppos[1];
+ av_add_index_entry(s->streams[0], pos, (int64_t)i << seekd, 0, 0, AVINDEX_KEYFRAME);