[FFmpeg-user] MPEG-2 encoding problem

[Jane]

  Hello everyone! I'm encoding video to MPEG-2 using Zeranoe's Windows builds.  The source file is 720p 60fps, progressive. I want to keep high quality and compatibility with DVD standards, so I use:
ffmpeg -hwaccel auto -i "input" -vf scale=ntsc,interlace,fps=fps=29.97 -c:v mpeg2video -q:v 3 -g 15 -mpeg_quant 1 -aspect 16:9 -sc_threshold 40 -bf 2 -intra_vlc 1 -b_stratgey 2 -flags ilme+ildct -maxrate 9M -bufsize 224k -c:a mp2 -b:a 224k "output"
It works all right, but the quality is very low. And I noticed during encoding, qp is floting around 31, what's wrong? After disabled ildct and ilme, the quality is normal. Is the command incorrect?

Due to the lack of information about codec mpeg2 video, I'm not sure about the sc_threshold, b_strategy and the dia_size value. How can i get detailed information?