truehd is the HD audio that is included on many 4k blurays.
another is dts-hd-ma.
they are both different brands high bitrate lossless surround audio.
so if you intend to rip and play 4k bluray disks, the apple tv will not pass through the hd audio.
so, if any of that hd audio is important to you, you should understand that it does not work with apple tv 4k.
you may find some other 4k info @ Plex, 4k, transcoding, and you
