All my videos are .mkv with h.264 codec with 4.1 profile and dts and ac3 audio. On my roku3 the video is transcoded to 4.0 profile and the audio is transcoded to aac. This is because roku only supports 4.0 in a .ts file. Does the appletv3 transcode both the audio and video or does it remux the video and transcode the audio?
Check the PMS log - the information is there.
I have no idea what it is currently set to, nor am I sure what the aTV really supports.
I was just checking before I bought one.