I have an .mp4 video file which contains a High Level 3.1 "avc1.64001f" video and a Low-Complexity AAC "mp4a.40.2" audio.
How can I convert the Low-Complexity AAC to "HE-AAC" audiocodec by using the "libfdk_aac" FFmpeg encoder and keep/get the best possible quality? I just want to copy the "avc1.64001f" video into the target file.