ffmpeg -i ghosts_s01e15.mkv -c copy ghosts_s01e15.mp4 Use ffmpeg with libx265 for smaller size:
ffmpeg -i ghosts_s01e15.mkv -vf "fps=1/10,scale=160:90,tile=4x4" thumbs.jpg MKV → MP4 without re-encoding: ghosts s01e15 ffmpeg
ffmpeg -i ghosts_s01e15.mkv -ac 2 stereo_version.mp4 Hardcode subs for a social media clip: ffmpeg -i ghosts_s01e15