[FFmpeg-user] 4K Compression using x.265 issues

[Ron Barnes]

All,

For some reason the below command is not working right.  I am unable to compress my movie by an significant amount.
The input movie (MYMOVIE.Mkv) is just over 55GB and the resulting output is just over 53GB.

I thought (and I am probably wrong) that by raising or lowering the -crf value would increase or decrease the size of my output file.  No matter what value I use, be it 18 or 28, the output file size is always the same.

Can anyone determine where I'm going south in order to decrease the files's footprint (size) yet still preserve the movie quality?

I want to take all the audio streams (only audio) and I am converting them to mp3 because I do not have a very good sound system and the actual 7.1 audio stream sounds awful.

ffmpeg -i "MYMOVIE.Mkv" -c:v libx265 -preset medium -map 0 -c:a:0 libmp3lame -b:a:0 128k -c copy -reserve_index_space 1000k -crf 28 -s 3840x2160 -b:v 10M -ac 2 -c:a aac -b:a 128k -metadata title="MYMOVIE" COMPRESSED_MYMOVIE.mkv

Thank you,

-Ron