Just spoke with Apple about the 3rd gen Apple TV 4k and sending pass-through audio to a receiver

[FriedChicken]

AFAIK, this whole discussion and the signal path is off the rails, see above.
Why would anyone choose what is so obviously a less than optimal path for their files?
Beyond that, as to your statement on the "a very clear loss of transparency", if its so clear, so should be the ease
of the presentation of the evidence where the loss of digital info is being corrupted or lost. I'm more than will to
learn here.

No need to go that deep. Atmos carries 5 or 7 base channels, and then the appropriate object-based information for the atmos receiver to decode. My home cinema receiver has the number, location, and distance of all the different speakers and can thus place the sound most accurately. Bitstream PCM is a simple digital encoding of analog audio. It carries no information other than the audio information that the receiver then outputs in a standard way.

It's also way too easy to hear the Apple hate in your posting and to discount the claims due to emotional bias.

I have something like 10 apple devices, my first computer was a mac from the powerPC era, I'm writing this on a macbook right now, and my desktop PC is an iMac. I have an iPhone, an iPad, an iPod, and probably more iDevices I forgot about. I'm not mad because I have a hatred for apple, I'm mad because something that would otherwise be excellent is intentionally neutered for stupid business games being played in the valley against the consumer. This practice has gotten progressively worse over the past two decades and I hate it.

 

[Sal1950]

No need to go that deep. Atmos carries 5 or 7 base channels, and then the appropriate object-based information for the atmos receiver to decode. My home cinema receiver has the number, location, and distance of all the different speakers and can thus place the sound most accurately. Bitstream PCM is a simple digital encoding of analog audio. It carries no information other than the audio information that the receiver then outputs in a standard way.

 

[darkazcura]

AFAIK, this whole discussion and the signal path is off the rails, see above.
Why would anyone choose what is so obviously a less than optimal path for their files?
Beyond that, as to your statement on the "a very clear loss of transparency", if its so clear, so should be the ease
of the presentation of the evidence where the loss of digital info is being corrupted or lost. I'm more than will to
learn here.

It's also way too easy to hear the Apple hate in your posting and to discount the claims due to emotional bias.

I‘ve read a few of your posts, and I don’t totally understand the point you are trying to make. I think you are trying to ask the OP why they aren’t using a computer instead since it is more powerful as if these media players are not a proper way? The OP is completely valid here. This has nothing to do with power. The HDMI ports on all Apple TVs and most media devices have plenty of bandwidth to passthrough audio to the receiver. The receiver is doing the work in this case, not the Apple TV. Unfortunately Apple doesn’t allow this option. The Shield TV (a less powerful option) does offer this option, though, so I would say the OP should get over his Google fears and just buy that device as I have.

I get the frustration, though, as the Apple TV is a far better device than the Shield TV. If Apple allowed audio passthrough, I would never look back.

I would say a computer that uses a ton of power is a very improper way of handling this, and low powered media players like the Apple TV and Shield TV are perfect for this application. I have 3 TVs in my house, two of them are capable of at least 5.1 surround. Why would I want a computer at each TV? The UI would be awful on those computers as well.

 

[Sal1950]

I‘ve read a few of your posts, and I don’t totally understand the point you are trying to make. I think you are trying to ask the OP why they aren’t using a computer instead since it is more powerful as if these media players are not a proper way?

I admit some confusion here. My understanding of what was being said, and I might be completely off-track, is that the OP was complaining of a "bad loss of transparency" when playing back his personal files, say off his computer server network, thru the 4K, and then into the AVR? Putting aside the loss of transparency, why would you path your files in this way to begin with?
Using the Apple 4k box as a streamer IMO probably offers the best shot at high fidelity from those streamer apps available today. It was AFAIK it's not designed to be a network hub.

 

[darkazcura]

I admit some confusion here. My understanding of what was being said, and I might be completely off-track, is that the OP was complaining of a "bad loss of transparency" when playing back his personal files, say off his computer server network, thru the 4K, and then into the AVR? Putting aside the loss of transparency, why would you path your files in this way to begin with?
Using the Apple 4k box as a streamer IMO probably offers the best shot at high fidelity from those streamer apps available today. It was AFAIK it's not designed to be a network hub.

Basically the OP is complaining that the Apple TV doesn’t passthrough audio. There’s no technical reason it can’t because Apple TV uses the latest HDMI spec which has plenty of bandwidth. I agree with the OP, but also it only affects a very niche group of people at the same time. This is basically affecting people who rip UHDs. I can’t get Dolby Atmos via the Apple TV with any of my UHD rips. If Apple flipped the switch to pass through audio, it would do it perfectly fine. If I’m able to stream a lossless 4k video that has bitrates near 100 mbps, there’s no reason it can’t handle the additional bandwidth to just pass through audio. The Shield TV can do it.

But again, it’s for a niche audience.

Just FYI, Infuse is probably one of the best applications I have ever used when it comes to streaming videos from network shares, and it is an Apple TV exclusive app specifically made for this use case.

 

[Sal1950]

Just FYI, Infuse is probably one of the best applications I have ever used when it comes to streaming videos from network shares, and it is an Apple TV exclusive app specifically made for this use case.

I stream all sort of UHD rips /Atmos but then I don't use a network.
They come off my computer over optical HDMI cable to directly to the AVR.
If you absolutely need to go networked I can understand but I personally would
avoid it if possible.

 

[darkazcura]

I stream all sort of UHD rips /Atmos but then I don't use a network.
They come off my computer over optical HDMI cable to directly to the AVR.
If you absolutely need to go networked I can understand but I personally would
avoid it if possible.

IMO, no offense, that’s a bit of an old school mentality, but I get it. HTPCs used to be the thing for sure, but I have 3 TVs in my house and having a HTPC at every TV just isn’t realistic. Luckily only one of those systems does Atmos so I have a Shield TV for that system, and it works perfectly great and better than a HTPC could, imo. I have Apple TVs at my other two TVs.

I have wired connections to all my streamers + nowadays wireless LAN is plenty fast enough to stream 4K UHDs lossless when it was only a dream to get 1080p blu rays streamed wirelessly 10 years ago. We’ve come a long way.

Hell, I’m able to stream 4K UHDs to my iPhones and iPads with no issues at all. Most people go the network route these days. Better energy efficiency, easier to manage localized media, better UIs, etc.

 

[Sal1950]

IMO, no offense, that’s a bit of an old school mentality, but I get it.

No offense, I take it as a compliment. LOL

HTPCs used to be the thing for sure, but I have 3 TVs in my house and having a HTPC at every TV just isn’t realistic. Luckily only one of those systems does Atmos so I have a Shield TV for that system, and it works perfectly great and better than a HTPC could, imo. I have Apple TVs at my other two TVs.

So you stream everything and don't keep any local files?
Just like with music, that works till the day your internet is down.
For audio/video that's important to me, I want the best quality available and
many times that's not whats on the net. Then I have either disc sourced or ripped from on drives.

 

[darkazcura]

No offense, I take it as a compliment. LOL

So you stream everything and don't keep any local files?
Just like with music, that works till the day your internet is down.
For audio/video that's important to me, I want the best quality available and
many times that's not whats on the net. Then I have either disc sourced or ripped from on drives.

Everything is local. It’s on my server sitting in my office. I can still play all my files if my internet goes down because my internet going down doesn’t prevent my LAN network from working. The likely hood of my wireless APs or my router randomly failing are very small. I only need the internet if I want to stream my files outside my home.

I just don’t have my server sitting right at my TV. That’s just unnecessary nowadays because devices like the Apple TV and Shield TV are just better at this stuff nowadays with better UIs, better remotes, better integration with my TV. I have no quality loss over my network. It’s just playing the file over Ethernet or WiFi straight up same as you having your computer connected directly. It also gives me the flexibility to have multiple TVs being able to play my content regardless of where my server is sitting in the house.

I have my UHDs ripped to my hard drive same as you, best quality possible. Files play directly. I just have it connected over Ethernet to allow for a ton of flexibility within my home (and even outside via Plex).

 

[Sal1950]

Everything is local. It’s on my server sitting in my office.

OK, we seem to have a language barrier.
You call yours a "server" and mine a "HTPC".
Same shit, they're both computers storing files,
where ever you chose to locate them.

That’s just unnecessary nowadays because devices like the Apple TV and Shield TV are just better at this stuff nowadays with better UIs, better remotes, better integration with my TV. I have no quality loss over my network. It’s just playing the file over Ethernet or WiFi straight up same as you having your computer connected directly.

Maybe not over your network no. But the Apple & Shield boxes are only capable of delivering highly compressed video, and a lossy form of Atmos. So you either use their lower quality sources, or have ripped and stored your video, immersive music from BluRays on the computer.

"Everything is local."
It's not local if your streaming it from Apple or whoever

You do need to be clearer when you talk about things, the evils in the details.

 

[FriedChicken]

Darkazcura, you're on the money but failed to mention this key point:
Bitstream takes more HDMI bandwidth and more processing power than pass-through.

 

[Tre2023]

Bitstream means a device will passthrough the signal without first decoding it. If playing a lossy Atmos/DD+ stream, bandwidth needs aren't extreme. If decoded first by the source device using Dolby MAT, Apple TV 4K, Amazon Fire Cube, and XBOX Series X/S for example, that lossy signal is converted to and output as LPCM and will increase the bandwidth needed for transmission.

 

[FriedChicken]

Bitstream means a device will passthrough the signal without first decoding it. If playing a lossy Atmos/DD+ stream, bandwidth needs aren't extreme. If decoded first by the source device using Dolby MAT, Apple TV 4K, Amazon Fire Cube, and XBOX Series X/S for example, that lossy signal is converted to and output as LPCM and will increase the bandwidth needed for transmission.

LPCM is bitstream, no?

 

[Hayabusa]

LPCM is bitstream, no?

No, its not a coded bitstream, it are lossless PCM samples

 

[-Matt-]

OK, we seem to have a language barrier.
You call yours a "server" and mine a "HTPC".
Same shit, they're both computers storing files,
where ever you chose to locate them.


Maybe not over your network no. But the Apple & Shield boxes are only capable of delivering highly compressed video, and a lossy form of Atmos. So you either use their lower quality sources, or have ripped and stored your video, immersive music from BluRays on the computer.

"Everything is local."
It's not local if your streaming it from Apple or whoever

You do need to be clearer when you talk about things, the evils in the details.

If the streaming source is Apple (via the internet) then that will provide lossy Atmos - Correct.

However, this thead is about the specific use case when the source is your own full blu-ray rip, saved on a NAS, server or PC on your local network (or it could even be on the hdd in the Apple TV). In this case it is technically possible to stream/play the full lossless Atmos.

Devices like the Nvidia Shield TV, when they play back that blu ray rip allow you to bitstream to the AVR (i.e. to send the Atmos stream direct to the AVR without decoding or any modification). This allows the AVR to correctly identify the stream as lossless Atmos, display this on the front pannel and correctly deliver height channels using the metadata contained in the bitstream.

The problem highlighted in this thread is that the Apple TV could do the same, but Apple won't allow it. They instead insist on decoding the Atmos stream on the Apple TV and converting it to LPCM before sending it to the AVR. (This is probably done as a loophole to avoid having to pay licensing fees to Dolby). Unfortunately (my understanding is) they currently only decode the bed channels and strip the metadata. This means the AVR can't detect or display that it gets an Atmos stream (because it doesn't) and of course height information is lost.

If Apple wanted to correctly decoded the Atmos stream then you'd need to specify the speaker layout on the Apple TV (including heights). Even if they did this I'm still not sure that the AVRs would be able to accept 11.1 LPCM as an input (i.e. for 7.1.4). And if they can, how can you be sure that the channel order has been mapped correctly?

It would be far more preferable if Apple would allow bitstreaming from the Apple TV to the AVR, and just let the AVR do the decoding (which is usually the preferred way of doing it with a blu ray player).

Hope that helps to explain the problem.

By the way, I had the first generation Apple TV and ran Kodi (XBMC) on it many years ago for blu ray rips. We had exactly the same problem getting Apple TV to support 7.1 setups when Dolby TrueHD came out.

 

[Tre2023]

Apple TV 4K supports DD+ input signals and Dolby MAT 2.0. So, Atmos metadata remains intact and can be processed at the receiving end when Atmos/DD+ signals are output as LPCM. It does not support Dolby TrueHD or any flavor of DTS.

Audio Options & Capabilities

Overview Infuse supports up to 7.1 channels of 24-bit 48KHz audio in a wide variety of audio codec formats. Dolby Atmos Infuse supports Dolby Atmos when using E-AC3 audio tracks. To take full advan...

support.firecore.com

 

[-Matt-]

Apple TV 4K supports DD+ input signals and Dolby MAT 2.0. So, Atmos metadata remains intact and can be processed at the receiving end when Atmos/DD+ signals are output as LPCM. It does not support Dolby TrueHD or any flavor of DTS.

Audio Options & Capabilities

Overview Infuse supports up to 7.1 channels of 24-bit 48KHz audio in a wide variety of audio codec formats. Dolby Atmos Infuse supports Dolby Atmos when using E-AC3 audio tracks. To take full advan...

support.firecore.com

Atmos/DD+ implies the lossy version of Atmos.

"Up to 7.1" implies no heights and therefore not Atmos.

DD+ < DD 5.1 (AC3) < Lossy Atmos < TrueHD < Lossless Atmos

 

[Sal1950]

If the streaming source is Apple (via the internet) then that will provide lossy Atmos - Correct.

However, this thead is about the specific use case when the source is your own full blu-ray rip, saved on a NAS, server or PC on your local network (or it could even be on the hdd in the Apple TV). In this case it is technically possible to stream/play the full lossless Atmos.

I do it all, there was nothing left to debate if you read my posts
Cheers

The problem highlighted in this thread is that the Apple TV could do the same, but Apple won't allow it. They instead insist on decoding the Atmos stream on the Apple TV and converting it to LPCM before sending it to the AVR. (This is probably done as a loophole to avoid having to pay licensing fees to Dolby). Unfortunately (my understanding is) they currently only decode the bed channels and strip the metadata. This means the AVR can't detect or display that it gets an Atmos stream (because it doesn't) and of course height information is lost.

Understood but if your streaming bit-perfect data off your server, why would you want to put it thru your A4K box first anywho? That's the part I miss ??? Let the 4K box do what it does best, and your server do what it does best.
JMHO

 

[Tre2023]

Yes, lossy Atmos is Atmos/DD+. It is what every streaming service uses for Dolby Atmos with only Disney+ recently adding IMAX Enhanced Sound by DTS, lossy DTS:X, to the mix. DD(AC3) supports up to 5.1 channels while DD+(EAC3) supports up to 15.1 channels. Streams and discs aren't going to support all of those channels.

Atmos metadata is included in Dolby Atmos tracks. They can be lossy Atmos/DD+ streams or lossless Atmos/Dolby TrueHD on a disc. If the receiving end does not support Dolby Atmos, metadata is not processed.

The Apple TV 4K accepts Atmos metadata over DD+(E-AC3) but cannot accept lossless Dolby TrueHD or DTS HD MA signals. It cannot accept any DTS signals at all.

No stream uses multichannel PCM. There were a few blu-ray discs that contained uncompressed multichannel PCM 5.1 tracks.

The Apple TV 4K can accept uncompressed multichannel PCM signals. So, lossless Dolby and DTS signals have to be re encoded at the source. An Atmos/TrueHD track will be sent to the Apple TV 4K, and output by it, as multichannel PCM 7.1 and any Atmos metadata will be lost.

If the Apple TV 4K is connected to an AVP/AVR supporting Dolby Atmos and is playing a Dolby Atmos stream, the input signal will display as Dolby Atmos or Atmos/PCM on the AVP/AVR regardless of the speaker configuration. An Atmos/DD+ signal stream or Atmos/TrueHD signal from a disc or rip in a bitstream requires a compatible Dolby Atmos speaker configuration. If only a 5.1 configuration with no Dolby Atmos Height Virtualization functionality, Atmos metadata is lost and the input signal displays as DD+ or Dolby TrueHD respectively. Add height virtualization to 5.1 or configure for 5.1.X, or even just 7.1 and Atmos metadata returns and is processed when using bitstream and Atmos/DD+ or Atmos/Dolby TrueHD is again displayed as the input signal.

Because the Apple TV 4K does not support bitstream, it outputs everything as LPCM but retains Atmos metadata via Dolby MAT 2.0, 2.0 and 5.1 signals will display as PCM 2.0 or 5.1 on the receiving end. Dolby Atmos signals from Atmos/DD+ streams will display as Dolby Atmos or Atmos/PCM on AVP/AVRs supporting Dolby Atmos.

Some simply want the ability to bitstream ALL signals in and out of their Apple TV 4K. This is not currently possible using any generation of the Apple TV 4K.

 

[Sal1950]

Because the Apple TV 4K does not support bitstream, it outputs everything as LPCM but retains Atmos metadata via Dolby MAT 2.0, 2.0 and 5.1 signals will display as PCM 2.0 or 5.1 on the receiving end. Dolby Atmos signals from Atmos/DD+ streams will display as Dolby Atmos or Atmos/PCM on AVP/AVRs supporting Dolby Atmos.

Great statement of the abilities of the Apple Music stream and 4k box. It's so complicated it can be
difficult for many to grasp. I first had an early A1842 build but the new A2169 was a big improvement in many ways.
I don't see Apple doing much more on that platform as later builds past the A2169 have been shown to be a downgrade
both in build quality and measurement wise, with the bean counters making more of the decisions.
Of course time will tell, you never know what tomorrow may bring.