I get an mp4 file of the same size of the original m2ts file (camcorder file), With H.264 profile 18000k.

My doubt is: is it best quality m2ts or mp4 ????

To get the same quality of original recording should I choose an higher profile with bigger file size result ???

Bye bye

18000k H.264 is very high quality, roughly the same as high as your MPEG-2 m2ts.