[antony23]

Hi, 
i'm investigating about buying or not ATV 4k, i read the review but i have some questions.

Audio
- Didn't understand in the first post, DD+ is decoded to PCM? or bitstreammed? or downmixed 5.1? 
- EAC3/Atmos is bitstreammed or decoded to PCM?
- What happens with True-hd/Atmos and DTS-X content? Downmixed to True-hd and DTS-HD MA or what?

All audio with the ATV 4K can be decoded into multichannel (2.0 / 5.1 / 7.1) LPCM, and in 99.9% of cases it will be lossless decoding for no loss in audio quality. For >48kHz FLAC or the other rare Bluray audio > 48kHz, audio will be resampled and output at 48kHz.

EAC3/DD+ with Atmos is decoded to LPCM and output as Dolby Atmos in Dolby MAT 2.0:
https://www.dolby.com/uploadedFiles/wwwd...ations.pdf

Bluray quality lossless TrueHD/Atmos and DTS:X will lose the height audio components, with the TrueHD and DTS-HD parts of that audio being losslessly decoded into LPCM.

The other option is selecting in tvOS settings - everything be remixed into highly compatible 2.0 or 5.1 AC3/DD for use with older audio receivers or pass thru a TV and out again via HDMI/SPDIF ARC. That works well for legacy AC3/DD only audio receiver compatibility.

So summing up, all the majority of ATV 4K users are really losing is Bluray quality lossless Atmos or DTS:X height audio.

Video: 
- i read you speak about YADIF2x for software deinterlacing and Lanczos3 for software upscaling. Ok, i'm really confused here, these are software decoders... what about HW decoders? Why use SW decoders instead of HW decoders? They are worst then software generally, or simply ATV 4k HW decoders are bad?

The ARM based CPU package the ATV 4K is using is the most powerful currently available on any ARM based media player on the market.
MrMC can CPU software decode mpeg2 and h264 interlaced content and do Full Motion -YADIF2x - deinterlacing of such content.

I'm not sure why MrMC CPU / YADIF2x software deinterlacing was chosen to be honest, maybe the PowerVR GPU does not do HW deinterlacing that well ?
(excluding Hi10P Anime which is also CPU SW decoded) ) ATV 4K has no problems HW decoding everything else.

CPU based Lanczsos3 upscaling really is not needed because the ATV 4K's - PowerVR GPU does great upscaling of non 4K content already, with no limitations.

Lately, it seems is not mentioned in the first post that ATV 4k does not have Correct MaxCLL/FALL HDR Infoframe data output in mrmc and other apps.

Thanks

Now this gets a bit complicated because it seems 4K HDR TV's all do Tone Mapping differently, especially if Dynamic Tone Mapping functionality is enabled in 4K HDR TV settings.

If you had a HDR10 auto Tone Mapping Projector - I would say yes correct passthru of MaxCLL/FALL metadata is really important.

But for modern 4K HDR TV's, well you really have to do your own research about what Tone mapping techniques each Brand uses. Some even ignore MaxCLL/FALL metadata and do their own dynamic frame by frame analysis.
See this https://forum.kodi.tv/showthread.php?pid...pid2897271 for a more info.

W. 

Hi @wrxtasy, thanks a lot for the answer.

So summing up, all the majority of ATV 4K users are really losing is Bluray quality lossless Atmos or DTS:X height audio.

It loses height audio, or it loses full extended metadata? That is, shoudn't it sound as standard trueHd/DTS-x signal without object metadata?

CPU based Lanczsos3 upscaling really is not needed because the ATV 4K's - PowerVR GPU does great upscaling of non 4K content already, with no limitations.

So, it is possible sw deinterlacing and then hw upscaling? I wrongly thinked all stuff should be handled full sw or ful hw.

Thanks again!