# Only extract Eng language.
ffmpeg -i "input.mkv" -map 0:v -map 0:a:m:language:eng? -map 0:s:m:language:eng? -map 0:d? -map 0:t? -c:v libx265 -crf 23 -c:a copy -threads 12 -bufsize 4M "out.mkv"
 
# Set language to Eng for Audio when language of audio is not defined for English.
ffmpeg -i "input.mkv" -map 0:v -map 0:a:m:language:eng? -map 0:a -metadata:s:a:0 language=eng -map 0:s:m:language:eng? -map 0:d? -map 0:t? -c:v libx265 -crf 23 -c:a copy -threads 12 -bufsize 4M "out1.mkv"

h264

h265

5.1 Audio

Batch encode all files in folder

Set Language

Get the ffmpeg encoders available