Apple TV 4 reduces dynamic range?

In the MacRumors forum there’s a debate going on about allegedly “poor dynamic range” in Apple TV 4:

There is also a thread in the Apple Support Communities addressing this issue:

To make a long story short, the allegation is that Apple TV in a way processes the audio stream instead of allowing it to pass through to the receiver untouched. This in turn causes the dynamic range to suffer.

As the discussion is quite technical, I don’t understand all of it, nor can I verify the statements. What worries me, though, is that this may affect Infuse as well.

If there’s something about Apple TV itself which reduces the dynamic range, regardless of Infuse, does it matter what audio format infuse supports? Like everyone else here, I want of course the best possible sound quality.

In the Apple Support Community thread a contributor claims to have contacted Apple about the issue. He says Apple engineering got back with him and said that the issue has been submitted for a fix, but it will have to wait until a software update.

Any thoughts on this subject?

Really interesting! Hope you’ll get an answer…

Excellent question! Depending on how your Apple TV is configured, the answer ranges from ‘maybe’ to ‘definitely not’.

With Infuse’s Dolby/DTS passthrough options disabled, Infuse will downmix all audio to 2ch stereo. It’s then handed off to the inner workings of the Apple TV and we have no control over what happens. While it’s possible the Apple TV may be modifying the audio at this point, it likely doesn’t matter much since Infuse has already downmixed a 5.1 (or 7.1) audio track to 2.0, which inherently results in some degradation due to the reduced number of discrete audio channels.

With the passthrough settings enabled, Infuse will pass the raw and unchanged Dolby/DTS audio track to your receiver. In earlier versions of Infuse there were cases where the Apple TV attempted to modify these audio tracks (by injecting menu sounds when using the Playback Menu while a video was playing). The result of this was bits of static in place of a where a normal menu sound would be heard. The workaround included in 4.0.1 avoids this by pausing video playback while the Playback Menu is active, when the passthrough options are enabled.

With all that said, there are of course a number of additions we’re working on to improve compatibly with some receiver models, as well as adding extra passthrough options, all of which we plan to have available in an upcoming version.

Hope this helps!

That is all fine, James, however…
The missing feature to pass through DTS and Dolby 5.1 still is there and your fine app is more or less unusable as it is for now.
I just checked Plex a couple of minutes ago and it pass DTS perfectly without any problems. There IS a problem with Infuse that HAS to be addressed NOW!

Please stick to the topic of the thread. There’s a sticky thread on the passthrough-issues, where you can go nuts…

Hey, hey, hey…
It was James who was talking about capability issues, and I was just putting my two cents!
This forum is turning into a place where NO complaints are allowed… Why???

Complaints are fine, but you’re not exactly adding anything new to the discussion, you’re just hijacking a thread to complain some more and in the process making it harder to discuss other things.

I’m pretty sure Firecore are working intensely on the passthrough issues…

This is not adding anything into the fact that James had not being posting in the thread that addresses the issue about passing audio directly for a long time.
It seems however that my posting caused some attention after all.
But when are we going to see some work and a sincere effort to provide us with pass through audio???

Thanx a lot for your quick response, James. This was clarifying and sounds reassuring. Also great to hear that you’re working on extra passthrough options. Keep up the good work!

Congratulations. Because your the only one who got plex to passthrough the dts audio stream on the atv4. All others have to deal with plex transcoding it to ac3 5.1.

I tend to agree with you and that was the reason I switched from Plex to Infuse in mid January. However yesterday I installed Plex Server again on my Windows 10 PC and I downloaded a couple of demo files to test with. From Plex Windows server to atv4 it works (according to the display on my Denon) and the sound impression from just listening. If I install Plex server on my NAS, it transcode and the output is surely not DTS.
I am not sure, but it looks as if Plex pass through DTS to the atv4 and from the Plex app on atv4 it is passed on to my Denon - or maybe my old ears are not able to classify ac3 5.1 from DTS?
No matter what, Plex “surround sound” (ac3 5.1) plays from atv4 and that is NOT the case with Infuse - it just gives me static noise :frowning:

Plex on Apple TV 4 definitely does not support DTS passthrough – it will always transcode to AC3. To know that this is the case, you’d want to look for some kind of indicator on your receiver, either in the on-screen display or an actual light-up icon on the front panel (depending on your particular receiver). Trying to tell just by listening is obviously going to be error-prone.

It’s unfortunate that Infuse seems to have problems with your particular model/brand of receiver. The DTS passthrough feature does seem to work well for many others. (It works for me.)

New user of Infuse PRO, but I definitely have poor dynamics in for example Dolby True HD movies. I have done all the correct settings according to support thread Audio Options (tvOS) – Firecore

I have compared the exact same movie file through PC connected to surround system with ATV4 with Infuse PRO 5.5 and it is a big difference!!! Less bass, poor dynamics and the sound sounds compressed.
Not funny at all!
Am I missing something? Any ideas anyone!
I am an audiophile with a good surround system, maybe it makes it easier to hear the difference…

Appreciate help!

One difference that can come into play is the special handing some receivers have in place for certain audio formats. For example, one of the Yamaha receivers we have here increases the center channel volume by 3dB for Dolby streams, but not for others. This can cause a disparity in the actual sound you end up hearing when doing side-by-side comparisons using various devices.

Of course, you may also check to ensure the ‘Reduce Loud Sounds’ option remains disabled in Settings > Video and Audio as this will definitely impact Infuse’s dynamic range.

Thanks for fast response James!
I have disabled the setting “Reduce Loud Sounds” so I am very confused regarding this issue.
I have not noticed any higher level on for example center channel.
I will test again later, but if I don’t solve this I need to look on another solution. Stick with PC :frowning:

One thing to try (just for fun) would be to switch the Audio Output option in Infuse from Auto to Passthrough. This will allow you to bitstream the 16-bit AC3/E-AC3/DTS audio tracks to compare volume levels.

I agree completely. HD audio sounds considerably better on the Shield TV than it does on ATV 4. Even the centre channel audio sounds noticeably “compressed” on ATV4. I am hoping that the new ATV will “sound” better. I had hoped that ATV would let the audio passthrough similar to the Shield and displayed on the receiver as DTS-HDMA or True HD or Atmos instead of LPCM. I know everyone has said that there should be no difference but there is. It may have something to do with how it’s handled within the hardware. I know it’s not my receiver as it’s a brand new Denon AVR-X7200WA. I’ll be getting the new ATV regardless since the 4K video on the Shield is poor. It would be nice if there was one device that got everything right - 4K video, HD audio passthrough, frame rate!