Data exists 24 frames at the beginning of the coding latency, namely
Ret=avcodec_encode_video2 (c, & amp; PKT, NULL, & amp; Got_output);
Call after 25 times, got_output don't to 0,

If instead the h264 encoding, call the following statement, delay no longer exists,
Av_opt_set (c - & gt; Priv_data, "preset", "ultrafast", 0);//the new statement, set to coding delay
Av_opt_set (c - & gt; Priv_data, "most cerebral sci-film", "zerolatency", 0);//real-time encoding key to see this sentence, the above that there is no

But vp9 format code, av_opt_set call fails,

How to modify the vp9 coding excuse me? Ask everybody to give directions,