Add LFE in stereo downmix

Hi,

I’m using Infuse with an Apple TV 4K connected through an AirPort Express on an analogue stereo system with a subwoofer. I have no possibility to connect the subwoofer to the system other via high impedance inputs. So, with this in mind I have to choose 2.0 as audio output.

My question is does the LFE channel is included in the stereo downmix when 2.0 output is selected? If not, would it be possible to add an option to add it, and the amount of LFE?

Thanks.

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After some tests, I concluded that the LFE channel is not included in the stereo downmix.

Would you please be able to add it in a future release?

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Moving to suggestions for now. Thanks.

Any news on the subject?

Hi,

I would like to have an update on the subject please.

Regards

I would also be interested in this as I also have a 2.0 setup with an active subwoofer.

So when playing multichannel sources via ATV 4K, the LFE signal is excluded from the stereo feed (others, such as center, rear etc are downmixed perfectly). Tested using Dolby’s and DTS’s multichannel test videos. Within ATV’s Audio Options, the “Stereo” setting doesn’t help either.

Looking forward to this!

We’ve looked into this, but the end result was flat and less detailed sound. There’s a slight chance we could tweak things for certain videos, but I don’t believe there is going to be a universally good option here.

FWIW, the mixing algorithms for Dolby/DTS do not include LFE in the 2.0 mix, and it seems like there is a good reason for this.

Also, this would only apply to using Stereo output in Infuse (IE connected to TV speakers, headphones, etc…). Whenever you’re using a receive of some sort, Infuse will be sending multi-channel sound which includes the LFE channel. The sound levels are then adjusted by the AV receiver depending on the DSP mode settings.

One note, deepening on your setup you may try switching the Audio Format option from Auto to Dolby Digital. Doing this will allow for multi-channel audio in some cases (EG passing audio through a TV to an AV receiver).

That said, we have a number of audio processing improvements coming in 6.6. These are mainly aimed at HomePods, but the changes will apply to other devices as well.

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Hi,

Could you review your position on this subject, please? I know it’s a niche use case, but I would really appreciate it.
I suggest that you add this capability in an opt-in manner, not an opt-out.

Best regards

I have a 2 channel setup with a minidsp doing bass management duties to 3 subwoofers. At the moment, I need to manually mux in a custom mixed 2 channel track into every one of my movies as without the LFE channel, I can barely feel even a millimeter of travel with my hand on the subwoofer drivers. It would be appreciated if Infuse could add a slider to adjust LFE mix so I would not need to perform such an arduous task every time I want to add a movie.

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Would be great if Infuse supported this. I am running a 2.1 setup that only supports Stereo PCM and so much of the dynamic range is lost when using Infuse vs an alternate app/device that does allow LFE mixing (MrMC/OSMC).

I know that it is not part of the Dolby/DTS specs to include it and I am sure there is/was a valid reason for it originally, but for those of us running full range speakers or a stereo+sub setup there is no way that it is correct that the LFE track is lost entirely. So having the option to include it in the down-mix at the “source” would be so much easier.

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Hi @James, I really appreciate you took the time to work on this feature and I will be glad to switch to Infuse.

If you need to beta test this feature or have some feedback about it, count me in. You made some very good remarks about less detailed sound, which seems to be a problem with dynamic range.

Have a nice day!

Great that this is back on the roadmap, 7.3.4 is looking to be an awesome update.

Ideally, there should be multiple values to choose from instead of on/off for AVSForum members™ or other people who like the idea of BassEQ but don’t want the tediousness of adjusting miniDSP settings, etc.

Today’s 7.3.4 update adds LFE to the 2.0 stereo downmix on iOS and Apple TV.

Hi! Thanks a lot for this update, it works like a charm.

However, I have to force audio output in the Apple TV settings to Stereo instead of Auto.

Is this normal? Because with the Apple TV app for example, with Auto mode, I have some LFE, I don’t have to force it to Stereo.

Are you just playing audio through TV speakers? If so, forcing stereo should be fine.

The sound is passed via HDMI to my TV, which outputs to my stereo sound card in PCM with its Toslink output.

Apple is not clear about what the Stereo setting is doing, and if it degrades audio quality in any way versus the Auto mode.

It may be related to what the Apple TV detects your TV as being capable of.

It sounds like with Auto enabled the TV may be receiving multi-channel audio and doing the down-mixing on its own.

@james can you confirm that this is a 1x mix? Aka no level adjustment to the LFE channel?

I had the same idea.

In the case of MrMC I am forcing the downmixing to 2.0 in the app directly, so without enabling the LFE option it does not include the LFE channel in the 2.0 downmix.

Apple TV app and Infuse don’t have the option to force downmix in the app, by design I guess to be as simple as possible. However, in the Apple TV app with Auto mode, I have the LFE channel whereas in Infuse I have not. If my TV would do the downmix, I don’t understand why I have the LFE in one app and not in another.

If I switch to Stereo mode, I have a completely different mix on the Apple TV app, which does not include the LFE channel. In Infuse, since 7.3.4 I have now the LFE channel.

So for now, the workaround is to set the Apple TV to Auto for Apple TV app and to Stereo for Infuse.