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?
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.
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.