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HTPC's (or PC's) cannot decode Atmos surround sound

xrqp

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People are telling me I am wrong what I wrote in this first post, so I added this paragraph, did some text strike outs, and changed the title to say Atmos. I guess I was confused with Atmos vs regular surround. Sorry. The replies below are good though.

HTPC's (or PC's) cannot decode surround sound (like Dolby and DTS) to more than 2 channels. (I was wrong. they can do Dolby up to 8 channels, but not Atmos, and not DTS).
There is no apps or drivers you can add that will do it. They can decode to stereo (2 channel), but not to multichannel (more than 2).

JRiver cannot do it. Dirac and Roon cannot do it.
My guess is the same is true for Macs.


A Shield Pro can NOT decode it.
And Minidsp Flex HT, and SHD can NOT decode it.
My guess is Apple TV cannot decode it.

Some of the confusion comes from
  1. decode vs passthrough.
  2. multichannel that does not need decoding, like a musician creates 5 tracks of PCM - that does not need decoding.

These are interesting links for Atmos with PC:
 
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GXAlan

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ppataki

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PCs can decode Dolby and DTS for like 20 years now (including TrueHD and DTS-HD)....I have always done that eversince
What they cannot decode is the Atmos (and the DTS:X) tracks - they can only 'see' the TrueHD 7.1 core track but not the full 16 or 32 channels
(there are workarounds like the one you linked above but AFAIK a proper real-time solution does not exist yet)
 

GXAlan

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PCs can decode Dolby and DTS for like 20 years now (including TrueHD and DTS-HD)....I have always done that eversince
What they cannot decode is the Atmos (and the DTS:X) tracks - they can only 'see' the TrueHD 7.1 core track but not the full 16 or 32 channels
(there are workarounds like the one you linked above but AFAIK a proper real-time solution does not exist yet)

That's only for 1080p BD's right? My understanding is UHD BD required some sort of integrated Intel graphics which is no longer available in currently produced CPUs?

At least with AppleTV you get DD+ for today's streaming sources.

In any case, I believe the era of the HTPC and PC-based DVR has come and gone... I say this having owned the original ATI All-in-Wonder and having built a HTPC for DVDs built around the original Creative Labs DVD kit and S3 Savage generation chips.
 
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xrqp

xrqp

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PCs can decode Dolby and DTS for like 20 years now (including TrueHD and DTS-HD)
Do you mean they can decode to 2 channel stereo? I modified my original post for that, since they can decode to stereo.
 
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xrqp

xrqp

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ppataki

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A Windows-based PC can decode Dolby Digital, DTS, Dolby TrueHD and DTS-HD up to 7.1
In case of Atmos it will only see the 7.1 core

Here is an example:

1701117517754.png



What you see here is Jriver Media Center 31 playing (in 4K to my OLED TV) Top Gun - Maverick's Atmos track, outputting the core 7.1 TrueHD track
(downmixed to 5.1 then to 4.0 since my system is 4.0)

If you don't need Atmos height channels then a HTPC is an extremely great choice: you can get SOTA sound quality by using for example a Topping DM7 multichannel DAC + your DSP options are also literally limitless (endless number of VST plugins including Dirac Live, etc.)

You can actually get way better sound quality than with any AVR or pre/pros........
 

somebodyelse

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You need to be specific about which codecs you're talking about, and whether using open or closed source software. Decoding and encoding multichannel ac3 has been around in ffmpeg for some years while libdca decodes DTS. These are used by projects like VLC. I'm not sure of the current state but I understand TrueHD and DTS-HD used to be possible using dlls extracted from some closed source players, so presumably those players could do software decode.

Cavern from @VoidX might be worth a look for decoding at least a subset of Atmos to multichannel.
 

Littletycoon

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HTPC's (or PC's) cannot decode surround sound (like Dolby and DTS) to more than 2 channels.
There is no apps or drivers you can add that will do it. They can decode to stereo (2 channel), but not to multichannel (more than 2).

JRiver cannot do it. Dirac and Roon cannot do it.
My guess is the same is true for Macs.

Also, a Shield Pro can NOT decode it.
And Minidsp Flex HT, and SHD can NOT decode it.
My guess is Apple TV cannot decode it.

It took me a long time to figure this out, so I thought I'd share it to save you time if you thought/hoped otherwise. There is a lot of misinformation out there. Some of the confusion comes from
  1. decode vs passthrough. Passthrough is doable, but not decoding.
  2. multichannel that does not need decoding, like a musician creates 5 tracks of PCM - that does not need decoding.

These are confirming and interesting links:
Hoe do you arrive at this conclusion? PC's/pc software can decode Dolby/dts up to 5.1/7.1 into lpcm (for ages already really). Atmos/dts-x etc. they cannot decode. Dolby player software can do Atmos (but i think it is part of a $$$ pro package). Unfortunately you spent a lot of time arriving at wrong conclusions. The reply before mine (on ffmpeg, libdca) is absolutely correct, as well as ppataki's replies.
 
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xrqp

xrqp

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Maybe I am wrong and got mixed up with Atmos vs regular. My apologies to all. Do you have a reference link, like from a manufacturer, that PC can decode Dolby/dts up to 5.1/7.1 into lpcm? The Jriver screen shot looks convincing.
 
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ppataki

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Maybe I am wrong and got mixed up with Atmos vs regular. Do you have a reference link, like from a manufacturer, that PC can decode Dolby/dts up to 5.1/7.1 into lpcm?

I just posted a working example up there

If this is not convincing enough you can google for Jriver Media Center
The 5.1/7.1 decoding capability has been there for ages....it is not something that just recently became available
 
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xrqp

xrqp

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google for Jriver Media Center
I went to Jriver link it said "You will need a receiver that is capable of playing surround sound." I thought that meant an AVR that could decode. Maybe they mean a multi channel amp?
 

ppataki

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I went to Jriver link it said "You will need a receiver that is capable of playing surround sound." I thought that meant an AVR that could decode. Maybe they mean a multi channel amp?

Well, it is not that simple
When you want to use your PC as the source you will have a few options:

Scenario 1: you connect an AVR or a processor to your PC via an HDMI cable
Here you have:
Option 1: use your PC to bitstream (passthrough) the original audio (undecoded) to the AVR so the AVR will do the decoding and the DSP (in this scenario the PC is nothing but a source, really)
Option 2: use your PC to decode the audio stream, do the DSP and send the decoded LPCM signal to the AVR
(there is a hybrid approach as well when decoding is on the PC side and DSP is on the AVR side)

Scenario 2: you connect a multichannel DAC or a DDC to your PC via a USB cable
This is actually when the fun starts! In this case you do all decoding and DSP in your computer and you enjoy the SOTA quality of the multichannel DAC (such as the Topping DM7) which is far superior to any AVR or processor that money can buy
In this scenario you can use fully balanced connections to any multichannel power amp or pairs of stereo amps (I would recommend the Topping PA5 II or the PA7 series - again far superior quality vs any AVR)

The downsides:
- you will have a (steep) learning curve
- you will be limited to 7.1 (actually you can have more than 8 channels (for example 7.4, etc.)) but no height channels
 
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xrqp

xrqp

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When you want to use your PC as the source you will have a few options:
Wow. That is super helpful that you explained it so clearly and completely. JRiver needs you to help them write the help instructions. I will do Scenario 2. I would never go over 5.3. I will begin with 2.2 and future possibility of 3.2. or 3.3. Thanks very much for the help.
 

ppataki

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Wow. That is super helpful that you explained it so clearly and completely. JRiver needs you to help them write the help instructions. I will do Scenario 2. I would never go over 5.3. I will begin with 2.2 and future possibility of 3.2. or 3.3. Thanks very much for the help.
Happy that I could help ;)
 

Tre2023

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Macs can decode Dolby Digital 5.1 and Dolby Digital Plus signals and output them as multichannel PCM. It does not support Dolby MAT like the Apple TV 4K and Dolby Atmos is not available for output over HDMI. Forget about DTS.

When using the Apple Music app on a Mac with an HDMI connection to the receiving end and playing Dolby Atmos tracks with Dolby Atmos output set to "Automatic" or "Always On", the signal will be displayed as Multichannel PCM 7.1B and Atmos metadata will not be sent to the receiving end for processing without support for Dolby MAT.

Microsoft devices require the Dolby Access app for Dolby Atmos and DTS Sound Unbound for DTS:X.


 
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mumford

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not entirely accurate. A PC software can decode full 9.x.6 atmos track, and play it over 16 speakers.


It works great for music. Does not work on moives though.
 

soerenssen

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A Windows-based PC can decode Dolby Digital, DTS, Dolby TrueHD and DTS-HD up to 7.1
In case of Atmos it will only see the 7.1 core

Here is an example:

View attachment 329882


What you see here is Jriver Media Center 31 playing (in 4K to my OLED TV) Top Gun - Maverick's Atmos track, outputting the core 7.1 TrueHD track
(downmixed to 5.1 then to 4.0 since my system is 4.0)

If you don't need Atmos height channels then a HTPC is an extremely great choice: you can get SOTA sound quality by using for example a Topping DM7 multichannel DAC + your DSP options are also literally limitless (endless number of VST plugins including Dirac Live, etc.)

You can actually get way better sound quality than with any AVR or pre/pros........
I also don't need more than 8 channels, Atmos and DTS-X: 2.2 for music and 5.3 for HT, with hi-res music (without Dirac downsampling) being the priority. Honestly, while more work to set it up, it's really tempting to go down this route.
- Is there any way to connect the SPDIF coming from the TV to the HTPC, to somehow get the 5.1 sound of my PS5 and Apple TV 4K (both connected to the TV via HDMI)? Or do I need a Motu Mk5 or Okto DAC8 for the loopback via the DAC?
- Do you have your silent PC build / components described somewhere? (adequate for both Dirac+DLBC and music streaming, TrueHD and DTS HD decoding)
- Do you know by any chance, if multichannel Dirac supports 5.2 or 5.3 configurations? I don't see it listed on their website but maybe there's a workaround, preferably with individual DLBC sub channels.
 

ppataki

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Is there any way to connect the SPDIF coming from the TV to the HTPC, to somehow get the 5.1 sound of my PS5 and Apple TV 4K (both connected to the TV via HDMI)? Or do I need a Motu Mk5 or Okto DAC8 for the loopback via the DAC?

I cannot comment on the AppleTV or Mac in general but under Windows yes, you would need a pro audio device for that, like the MOTU you mentioned
Jriver can open its optical input and apply its DSP on it (note that I have never tried this but theoretically it shall work)

1701285664702.png


Do you have your silent PC build / components described somewhere? (adequate for both Dirac+DLBC and music streaming, TrueHD and DTS HD decoding)

I would recommend visiting www.silentpc.com
If you want 4K HDR passthrough for movies you will need the latest Ryzen 7 with graphics CPU or a dedicated GPU (GTX 1650 min.)

Do you know by any chance, if multichannel Dirac supports 5.2 or 5.3 configurations? I don't see it listed on their website but maybe there's a workaround, preferably with individual DLBC sub channels.

DLBC does support multiple subs, yes
You need to set it up to 5.1 then you can add subsequent individual subs (I think up to 4)
 

ppataki

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@soerenssen @xrqp
Before you guys venture into the (pretty tricky) world of using multiple subs if I may give you one very simple advice:

With just one sub, try the below (I know this is not what you would normally read about how best to place a sub but still.....)

Place it on the X (if you can) - or if you can't then try placing it anywhere on the red line
X is at the same distance from you as your main speakers
If you place it anywhere else on the red line the distance will be different (you can compensate that with delay) but the symmetry will be provided (=equal distance from both your main speakers)

1701288945832.png
 
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