guess_stream_format 3966 ffserver.c                     stream->fmt = guess_stream_format(NULL, stream->filename, NULL);
guess_stream_format 4011 ffserver.c                         stream->fmt = guess_stream_format(arg, NULL, NULL);
guess_stream_format  754 libavformat/avformat.h AVOutputFormat *guess_stream_format(const char *short_name,