What is ffmpeg's default codec?

I haven’t been able to find it. When I’ve converted video with ffmpeg without specifying how to encode the output, ffmpeg uses some default codec. I do not know how to find out what it is. Any ideas?

using ffprobe, I found the default codec. Its is MPEG-2 video. since I was initially encoding from a transport stream, the format is now in mpeg-ts.