if (!ost->frame_rate.num)
ost->frame_rate = ist->framerate;
- ost->st->avg_frame_rate = ost->frame_rate;
+
+ if (ost->frame_rate.num)
+ ost->st->avg_frame_rate = ost->frame_rate;
+ else
+ ost->st->avg_frame_rate = ist->st->avg_frame_rate;
ret = avformat_transfer_internal_stream_timing_info(of->ctx->oformat, ost->st, ist->st, copy_tb);
if (ret < 0)