What about something like this ?
Code:
ffmpeg -i input.m2ts -vf yadif=deint=interlaced -f rawvideo - | x264 --input-res WxH --fps N -o out.mp4 -
Or, if you have libx264 built in ffmpeg :
Code:
ffmpeg -i input.m2ts -vf yadif=deint=interlaced -vcodec libx264 [..]