API changes, most recent first:
+2021-04-27 - xxxxxxxxxx - lavf yyyyyyyyy - avformat.h
+ av_find_best_stream now uses a const AVCodec ** parameter
+ for the returned decoder.
+
2021-04-27 - xxxxxxxxxx - lavc yyyyyyyyy - codec.h
avcodec_find_encoder_by_name(), avcodec_find_encoder(),
avcodec_find_decoder_by_name() and avcodec_find_decoder()