why volume is different between 714 and 512？

[kaedewang]

why volume is different between 714 and 512？

[VoidXH]

If you only have 2 heights, volume will be reduced by -3 dB to prevent clipping. Some content (like Overwatch) has the top fronts and sides maxed out, and this is what fixes it. For 4 heights, this is not needed, the resulting track can be louder, which is desirable as Atmos tracks don't always have equal gains with the downmix.

[kaedewang]

So about #88 the lastest clipping issue of render 5.1.2front, does it also need to reduce -3 dB volume?
It seems that volume of 5.1.2front is louder than 5.1.2side.
5.1.2front

5.1.2side

[kaedewang]

If you only have 2 heights, volume will be reduced by -3 dB to prevent clipping. Some content (like Overwatch) has the top fronts and sides maxed out, and this is what fixes it. For 4 heights, this is not needed, the resulting track can be louder, which is desirable as Atmos tracks don't always have equal gains with the downmix.

I can understand why to reduce -3 dB volume for surround and height speaker. Maybe two speakers' tracks mix to one.
But I don't know why ch1-ch4 are also reduced, they are same in either 512 or 714.

[VoidXH]

5.1.2 front is not rendered as 5.1.2, it's 5.1.4, but the surrounds and surround heights are mixed together. This is because the renderer by definition can't handle triangles. This rendering method is also used for Dolby Atmos itself. Volume is not decreased in this case, because the heights are not handling the entire plane, just their front counterparts. For 5.1.2 side, volume decrease is required, because it can and will happen that the entire sound output comes from them.

[kaedewang]

the surrounds and surround heights are mixed together
Volume is not decreased in this case

So the surrounds of 5.1.2 front may be clipping???
And I can't find that Dolby supports 5.1.2 front but only 5.1.2 side.

[kaedewang]

I checked Dolby 2016 demo 0034(512 layout) and 0035(514 layout).
The render result is different by DRP and Cavern.

512 by DRP doesn't reduce -3 dB volume.
Left DRP; Right Cavern

LFE by Cavern is lower than DRP.
Left DRP; Right Cavern

[kaedewang]

I also checked 0037(714 layout).
I remember this issue was fixed before. Is it right?
LFE by Cavern is lower than DRP.
Left DRP; Right Cavern

[kaedewang]

So when tuning LFE, which volume should be used?

[VoidXH]

Add 3 dB, and it will be fine.

[ValeZAA]

Fascinating! I found a test sample file that has Transitions and very complicated visual effects including when an object (and yes it does have dynamic objects that are actually flying) multiply so that one object becomes two objects and also it has effect when one object occupies all the speakers to create Super Sound and reverb. Insane. Sounds good with Dolby Access (Atmos Headphones only + Realtek sound chip + GOOD Sony headphones)

https://disk.yandex.ru/i/NcvWSir_uTehfw