Denon AVR-S750H Decoding/Upmixing 2 Channel Stereo to Dolby Surround

[mdominic]

Okay, sorry, got lost back there a bit with the atv in the mix, had to reread. I like Treb's post. What are the audio settings possible in the Firestick 4K? Mine is regular Firestick so curious what the difference is (I use the DD+ Automatic setting). I get no forced upmixing, doubt the Firestick is capable.

These are the settings for the firestick 4k. Which also upmixes on the Denon but plays correctly on the Yamaha.

 

[Trebdp83]

Ok, have a look at the format info. 2/0/.0 is a two channel signal.If it were say 7.1, it would display as 3/4/.1 or 3/2/.1 for 5.1. It seems though that it is doing what the Apple TV 4K does and converts a DD+ signal via eARC to PCM and a DD signal is sent via ARC. No matter, now I think what is happening is you are confusing Direct mode with Auto mode when you press the Pure button. Read pages 110 and 111 of your manual carefully. It must be on Direct mode and not Auto or the Denon will play it back in Surround mode even if it is a two channel signal. I'd also be interest to see the input signal when you are playing a Dolby Atmos track via the Apple TV 4K connected directly to the TV. Can you get a pick of that info? Remember that an Atmos track via Apple TV 4K should display signal as Atmos/PCM with no corresponding channel numbers. Other devices should display Atmos/DD+ and a disc player Atmos/DTHD. No Atmos label, no Atmos signal being passed.

 

[mdominic]

Ok, have a look at the format info. 2/0/.0 is a two channel signal.If it were say 7.1, it would display as 3/4/.1 or 3/2/.1 for 5.1. It seems though that it is doing what the Apple TV 4K does and converts a DD+ signal via eARC to PCM and a DD signal is sent via ARC. No matter, now I think what is happening is you are confusing Direct mode with Auto mode when you press the Pure button. Read pages 110 and 111 of your manual carefully. It must be on Direct mode and not Auto or the Denon will play it back in Surround mode even if it is a two channel signal. I'd also be interest to see the input signal when you are playing a Dolby Atmos track via the Apple TV 4K connected directly to the TV. Can you get a pick of that info? Remember that an Atmos track via Apple TV 4K should display signal as Atmos/PCM with no corresponding channel numbers. Other devices should display Atmos/DD+ and a disc player Atmos/DTHD. No Atmos label, no Atmos signal being passed. View attachment 43251View attachment 43252

Those readings were from my TV’s Smart TV Prime Video app not the Apple TV. When I use AUTO with the Apple TV everything is decoded properly. I can confirm from memory that when playing Atmos content it is as you describe and does not show the number of speakers. I am away until Sunday so I can’t take picks.

ANOTHER question. I have been connecting the Apple TV directly to the TV and it shows each format correctly on the display. I decided to try it connecting it to the Denon. When I do this it shows all surround formats other than Atmos as “Multi In.” Stereo shows as stereo. What the heck is Multi In and am I not getting the correct format?

 

[Trebdp83]

I have an Apple TV 4K as well and recognized that pic as another device. Unless you are playing an Atmos track on the Apple TV in its Auto setting, it is sending a PCM signal to the Denon. This is because the Apple TV 4K does not bitstream DD+ and converts it to PCM. That PCM signal can be a two channel signal or a multi channel(5.1 or 7.1) signal. So, the MULTI CHANNEL IN mode becomes selectable because the signal does not have a DD flag on it. Back to the TV. The Prime app was outputting a two channel signal to the Denon. Try streaming some of “Carnival Row.” It has an Atmos track and should output Atmos/DD+ if the TV app actually supports it. It is not enough for a TV, streaming device and AVR to support Atmos and multi channel signals. The content and app used for playback must support them as well. The Apple TV 4K and Nvidia Shield are currently the most well equipped streamers with many apps that support HDR and Atmos tracks. TV apps not so much and disc player apps running behind everybody else. Get home safely and post some more pics at your convenience.

 

[mdominic]

I have an Apple TV 4K as well and recognized that pic as another device. Unless you are playing an Atmos track on the Apple TV in its Auto setting, it is sending a PCM signal to the Denon. This is because the Apple TV 4K does not bitstream DD+ and converts it to PCM. That PCM signal can be a two channel signal or a multi channel(5.1 or 7.1) signal. So, the MULTI CHANNEL IN mode becomes selectable because the signal does not have a DD flag on it. Back to the TV. The Prime app was outputting a two channel signal to the Denon. Try streaming some of “Carnival Row.” It has an Atmos track and should output Atmos/DD+ if the TV app actually supports it. It is not enough for a TV, streaming device and AVR to support Atmos and multi channel signals. The content and app used for playback must support them as well. The Apple TV 4K and Nvidia Shield are currently the most well equipped streamers with many apps that support HDR and Atmos tracks. TV apps not so much and disc player apps running behind everybody else. Get home safely and post some more pics at your convenience.

Thanks. I will do that. So Multi In is just letting the source (Apple TV) do the decoding and it’s still being output the way it is meant to be? I’ve also been trying out the Yamaha TSR-700 (RX-V6A). That decodes all sources perfectly but the sound doesn’t sound as immersive and rich as the Denon.

 

[Trebdp83]

The Apple TV 4K is decoding the signal internally and sending a PCM signal out. The Denon recognizes it as PCM and then enables the MULTI CHANNEL IN mode. The Denon doesn’t dictate anything to any devices. It simply takes what you throw at it from any device and you can select the DSP mode you like for playback. Setting the Denon to DIRECT MODE will result in playback of the signal just as it is. That could be a two channel PCM signal or a 5.1 DD signal. Using the DSP modes in the Denon lets you manipulate that input signal. You can set it to Dolby Surround to expand a two channel PCM signal to use all speakers or take a 5.1 DD signal and contract it by selecting STEREO mode. The kinds of DSP modes you can apply to different input signals can be found in the manual, pages 236-243. Study it well. There will be a test.

 

[mdominic]

The Apple TV 4K is decoding the signal internally and sending a PCM signal out. The Denon recognizes it as PCM and then enables the MULTI CHANNEL IN mode. The Denon doesn’t dictate anything to any devices. It simply takes what you throw at it from any device and you can select the DSP mode you like for playback. Setting the Denon to DIRECT MODE will result in playback of the signal just as it is. That could be a two channel PCM signal or a 5.1 DD signal. Using the DSP modes in the Denon lets you manipulate that input signal. You can set it to Dolby Surround to expand a two channel PCM signal to use all speakers or take a 5.1 DD signal and contract it by selecting STEREO mode. The kinds of DSP modes you can apply to different input signals can be found in the manual, pages 236-243. Study it well. There will be a test.

What would be better audio quality, keeping the Apple TV on “change format” or set it to bitstream so the receiver does the work?

 

[mdominic]

What would be better audio quality, keeping the Apple TV on “change format” or set it to bitstream so the receiver does the work?

I’m not home so I’m not sure the ATV can do that.

 

[Trebdp83]

Well, the Apple TV 4K does not actually bitstream. It decodes the DD+ signal and sends it out as PCM. When you set it to Change Format, it actually converts the signal down to DD 5.1 and sends that out and you lose Atmos altogether. I wish Apple would allow the choice of the Apple TV to bitstream whatever codec is contained in the stream rather than force the conversion to PCM. But, it is what it is.

 

[mdominic]

Well, the Apple TV 4K does not actually bitstream. It decodes the DD+ signal and sends it out as PCM. When you set it to Change Format, it actually converts the signal down to DD 5.1 and sends that out and you lose Atmos altogether. I wish Apple would allow the choice of the Apple TV to bitstream whatever codec is contained in the stream rather than force the conversion to PCM. But, it is what it is.

I think you’re right about bitstream, but the Apple TV 4K has Atmos. There is a specific Atmos setting. And when it goes to the receiver it is the only format that is identified on the display. Rather than just reading “Multi In.”

 

[Trebdp83]

Yes, if Atmos is present, the Dolby indicator on the Denon will light up and it will display Atmos for a Dolby Atmos track as the metadata contains a Dolby Atmos flag even though it is riding on a PCM decoded stream. Changing the format would display Dolby Digital on everything but would downgrade to lossy 5.1 and Atmos metadata would be lost. The PCM stream, which is decoded DD+, carries the Atmos metadata.

 

[Mikeymelons]

I saw this thread is about a year old but was this issue ever resolved? I'm having a very similar issue where stereo audio is being upmixed by my TV's native apps on my Denon S760H whenever I'm set to Pure Auto. Any other setting (for example, selecting stereo discretely) results in all content up to native Atmos being played in stereo. I'm just trying to have everything play in their native format.

 

[Trebdp83]

I saw this thread is about a year old but was this issue ever resolved? I'm having a very similar issue where stereo audio is being upmixed by my TV's native apps on my Denon S760H whenever I'm set to Pure Auto. Any other setting (for example, selecting stereo discretely) results in all content up to native Atmos being played in stereo. I'm just trying to have everything play in their native format.

Can you give an example of the issue? What is it that is being streamed and what is displayed on the Denon's front display in regard to the surround processing? Returned my S760H recently. If I remember, after watching Atmos material, the unit stayed in Dolby Surround mode for any track played after the Atmos track. This resulted in me having to switch to the desired mode for the new track. I'd leave the MUSIC button set to Stereo so I could just tap it when going back to two channel music tracks. With multi channel tracks, I'd tap the MOVIE button repeatedly until the desired mode came up.

 

[Mikeymelons]

Can you give an example of the issue? What is it that is being streamed and what is displayed on the Denon's front display in regard to the surround processing? Returned my S760H recently. If I remember, after watching Atmos material, the unit stayed in Dolby Surround mode for any track played after the Atmos track. This resulted in me having to switch to the desired mode for the new track. I'd leave the MUSIC button set to Stereo so I could just tap it when going back to two channel music tracks. With multi channel tracks, I'd tap the MOVIE button repeatedly until the desired mode came up.

When in AUTO mode, any surround sound source plays in the correct format and is displayed on the front of the receiver (ex. DD+). However, any stereo source gets upmixed to surround and I see DD Surr displayed on the receiver. Its definitely getting upmixed because audio is coming out of the center channel (I have a 3.1 system). If I use one of the mode buttons (MOVIE, MUSIC,GAME) to force a stereo source into stereo mode it will play fine. However, when I go to play a surround sound source, it is stuck in stereo unless I manually switch it to it's native format or back to AUTO. It boggles my mind why I'd have to manual select anything and I can't just play all sources in their native format without upmixing.

 

[Trebdp83]

The manual does a poor job of indicating how it all works. It does state that, in Auto mode, PCM and analog signals would be played in Stereo. But, the issue with the Denon and other makes is that when a DD signal is detected, Surround processing kicks in regardless of the channels in the DD track. TVs set to output Dolby Digital will have an issue with Auto mode because everything coming out of it is some flavor of DD and will trigger the Surround up mixer. If it is a two channel track, one is forced to select Stereo mode. Unfortunately, switching the output of the TV audio to PCM results in everything being down converted and coming out in two channel PCM and multichannel signals are lost. There is just no getting around it unless one chooses Direct mode, BUT, this will rob you of the use of your sub with two channel tracks as bass management is disabled and you will only receive the two channel information in the two front speakers.

For those who do not want to keep tapping a button to change a mode when the channel input changes, the Apple TV 4K is an option. I give Apple a hard time for not having a bitstream option for everything and converting everything to PCM but there is a method to their madness. Apple uses Dolby MAT for Dolby Atmos tracks. The track is converted to multi channel PCM and the metadata stays intact and the track is flagged as Dolby. The Dolby Surround up mixer then configures it for setups of less than 7.1.2. So, in a 3.1 setup, the receiver would display Atmos 3.1. Everything other than Dolby Atmos tracks on the Apple TV 4K will come in as multi channel or two channel PCM. You can turn off Atmos and also convert everything to lossy DD 5.1 but that would be a mistake.

To keep from having to change modes as the signal changes for anybody using an Apple TV 4K, there are a couple of things to do first. While in the Main menu, one should change the sound mode to Stereo. Then, select a multi channel stream that is NOT an Atmos track. Anything labeled 5.1 should do but beware of tracks from Disney+ as many tracks labeled 5.1 are actually Atmos. Once the track is playing, tap the Movie button until MULTI CHANNEL IN is displayed. Stop and leave it there. Now, when you go back to the main menu, it will change the mode back to Stereo mode and any two channel track played will be in Stereo mode as well. Go play an Atmos track and the mode will change automatically to Atmos/PCM and the Dolby light will come on. Since the Dolby light will not come on for anything other than Atmos tracks, the Dolby Surround up mixer will not kick in and screw things up for converted multi channel PCM and two channel PCM tracks and one will retain use of the sub instead of switching to DIRECT mode and losing it on two channel tracks.

These instructions may possibly work for anybody using an XBOX Series X as well as it also uses Dolby MAT like the Apple TV 4K. I don't know of any TV that does so and one will have to deal with the Dolby Surround up mixer for Dolby output or deal with two channel PCM when converting audio using most TVs. Older Samsung TV owners can also select DTS Neo 2:5 output and convert ALL audio to DTS 5.1 and send it out that way. I'm one who likes to play with sound modes and signals constantly but some prefer a "set it and forget it" system. Dolby output of streaming apps can give these folks a headache when Dolby Surround kicks in. I'm gonna' lay this one on Dolby and suggest firmware updates for the up mixer. Maybe they can try and deal with the audio bleed of lousy DD 2.0 tracks as well.

 

[snakeeyes]

I wonder why DTS Neo 2.5 was needed by Samsung. DTS Neo 6 seems very similar.

 

[Trebdp83]

I wonder why DTS Neo 2.5 was needed by Samsung. DTS Neo 6 seems very similar.

DTS Neo 6 is an actual sound mode. Samsung's DTS Neo 2:5 converted Dolby 2.0/5.1 and PCM 2.0 signals to DTS 5.1 audio and a receiver/processor would see the audio as a DTS 5.1 track. The Denon AVR-S760H has some limitations for applicable sound modes based on the signal input. Those limitations were a few of the reasons I returned mine.

 

[Mikeymelons]

The manual does a poor job of indicating how it all works. It does state that, in Auto mode, PCM and analog signals would be played in Stereo. But, the issue with the Denon and other makes is that when a DD signal is detected, Surround processing kicks in regardless of the channels in the DD track. TVs set to output Dolby Digital will have an issue with Auto mode because everything coming out of it is some flavor of DD and will trigger the Surround up mixer. If it is a two channel track, one is forced to select Stereo mode. Unfortunately, switching the output of the TV audio to PCM results in everything being down converted and coming out in two channel PCM and multichannel signals are lost. There is just no getting around it unless one chooses Direct mode, BUT, this will rob you of the use of your sub with two channel tracks as bass management is disabled and you will only receive the two channel information in the two front speakers.

For those who do not want to keep tapping a button to change a mode when the channel input changes, the Apple TV 4K is an option. I give Apple a hard time for not having a bitstream option for everything and converting everything to PCM but there is a method to their madness. Apple uses Dolby MAT for Dolby Atmos tracks. The track is converted to multi channel PCM and the metadata stays intact and the track is flagged as Dolby. The Dolby Surround up mixer then configures it for setups of less than 7.1.2. So, in a 3.1 setup, the receiver would display Atmos 3.1. Everything other than Dolby Atmos tracks on the Apple TV 4K will come in as multi channel or two channel PCM. You can turn off Atmos and also convert everything to lossy DD 5.1 but that would be a mistake.

To keep from having to change modes as the signal changes for anybody using an Apple TV 4K, there are a couple of things to do first. While in the Main menu, one should change the sound mode to Stereo. Then, select a multi channel stream that is NOT an Atmos track. Anything labeled 5.1 should do but beware of tracks from Disney+ as many tracks labeled 5.1 are actually Atmos. Once the track is playing, tap the Movie button until MULTI CHANNEL IN is displayed. Stop and leave it there. Now, when you go back to the main menu, it will change the mode back to Stereo mode and any two channel track played will be in Stereo mode as well. Go play an Atmos track and the mode will change automatically to Atmos/PCM and the Dolby light will come on. Since the Dolby light will not come on for anything other than Atmos tracks, the Dolby Surround up mixer will not kick in and screw things up for converted multi channel PCM and two channel PCM tracks and one will retain use of the sub instead of switching to DIRECT mode and losing it on two channel tracks.

These instructions may possibly work for anybody using an XBOX Series X as well as it also uses Dolby MAT like the Apple TV 4K. I don't know of any TV that does so and one will have to deal with the Dolby Surround up mixer for Dolby output or deal with two channel PCM when converting audio using most TVs. Older Samsung TV owners can also select DTS Neo 2:5 output and convert ALL audio to DTS 5.1 and send it out that way. I'm one who likes to play with sound modes and signals constantly but some prefer a "set it and forget it" system. Dolby output of streaming apps can give these folks a headache when Dolby Surround kicks in. I'm gonna' lay this one on Dolby and suggest firmware updates for the up mixer. Maybe they can try and deal with the audio bleed of lousy DD 2.0 tracks as well.

Thank you so much. I've posted on multiple forums and this has been the most comprehensive explanation I've got so far. Although it doesn't solve the problem I at least understand why it's happening. Would you happen to know if the Nvidia Shield Pro outputs as PCM similar to the Apple TV 4k?

 

[Trebdp83]

The Nvidia Shield bitstreams audio and does not use Dolby MAT like the Apple TV 4K. The Nvidia Shield pro is a hell of a streamer. Coolest looking device with a great remote control. But, one will encounter the Dolby Surround issues with it as well.

 

[Mikeymelons]

The Nvidia Shield bitstreams audio and does not use Dolby MAT like the Apple TV 4K. The Nvidia Shield pro is a hell of a streamer. Coolest looking device with a great remote control. But, one will encounter the Dolby Surround issues with it as well.

Got it. Thanks again!