[feature] Support ALSA Virtual PCM Devices as Player Outputs

[upfish-sinclare]

Feature Description

Hi Chris,

Firstly, thanks for creating Multi-SendSpin-Player-Container. I was hoping to use it as a replacement for multiple Squeezelite instances on a Raspberry Pi.

Hardware

• Raspberry Pi 5
• Amped 2x Audio HAT (uses the HiFiBerry DAC8x ALSA driver)
• Raspberry Pi OS Lite (Debian Trixie)

The sound card is presented by ALSA as:

snd_rpi_hifiberry_dac8x

Goal

The Amped 2x provides four output channels. Using /etc/asound.conf, I split these into two independent stereo PCM devices:

• bedroom → rear channels (3/4)
• bathroom → front channels (1/2)

using standard ALSA dmix, route and plug plugins.

Running:

aplay -L

returns:

bedroom
    Bedroom Speakers

bathroom
    Bathroom Speakers

Both devices function correctly.

For example:

speaker-test -D bedroom -c 2
speaker-test -D bathroom -c 2

play through the correct speaker pairs.

Likewise, Squeezelite can open bedroom and bathroom independently, allowing two separate players to run simultaneously from the same physical sound card.

Docker Configuration

The container was started with:

devices:
  - /dev/snd:/dev/snd

volumes:
  - /etc/asound.conf:/etc/asound.conf:ro

The container correctly receives both /dev/snd and the custom asound.conf.

Expected Behaviour

Based on the documentation mentioning support for software-defined ALSA devices, I expected the device selector to include the virtual PCM devices:

• bedroom
• bathroom

allowing each SendSpin player to use one stereo pair.

Actual Behaviour

Only the physical hardware device appears:

snd_rpi_hifiberry_dac8x

The ALSA virtual PCM devices are not listed, despite being available through ALSA and visible via aplay -L.

Why this would be useful

Supporting ALSA virtual PCM devices would make it possible to run multiple independent SendSpin players from a single multi-channel sound card.

Let me know if you need any more information. Thankyou!

Use Case

This would benefit users of:

• Amped 2x Audio HATs
• HiFiBerry DAC8x-compatible devices
• Multi-channel USB DACs
• Any ALSA configuration using dmix, route, plug or softvol

without requiring PulseAudio remap sinks or additional audio middleware.

Installation Method

Docker Standalone

Alternatives Considered (optional)

I explored several alternatives before raising this request, including PulseAudio remap sinks, multiple native SendSpin receiver instances, and running separate Raspberry Pis.

While these approaches can work in some environments, they either didn't support my hardware configuration or required additional hardware.

Since ALSA virtual PCM devices already work correctly with applications such as Squeezelite, supporting them directly would provide a simple and hardware-efficient solution for users of multi-channel sound cards.

[Spartan-II-117]

You can create remap sinks in the UI that function like you're looking for, choose settings, create sink.

[upfish-sinclare]

You can create remap sinks in the UI that function like you're looking for, choose settings, create sink.

Yeah I have already tried that, it only enumerates the "snd_rpi_hifiberry_dac8x" as the only available option. Not "Bedroom" or "Bathroom" sinks.

[Spartan-II-117]

When creating a remap sink, choose the hardware device, then the channels and give it whatever custom name you want.

…

On Sun, Jul 5, 2026, 7:11 PM upfish-sinclare ***@***.***> wrote: *upfish-sinclare* left a comment (chrisuthe/Multi-SendSpin-Player-Container#262) <#262 (comment)> You can create remap sinks in the UI that function like you're looking for, choose settings, create sink. Yeah I have already tried that, it only enumerates the "snd_rpi_hifiberry_dac8x" as the only available option. Not "Bedroom" or "Bathroom" sinks. — Reply to this email directly, view it on GitHub <#262?email_source=notifications&email_token=ABFYSQGLIK6SA26AOZNKEDT5DMDFRA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTIOBYHA2TGMBRHEZKM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4888530192>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABFYSQGLDJDGDWXMI5W3DRL5DMDFRAVCNFSNUABFKJSXA33TNF2G64TZHM4TSNBXGYZDEOJZHNEXG43VMU5TIOBRGUYDMMJYGYZ2C5QC> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/ABFYSQC5F5NQK7S6C333BXL5DMDFRA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTIOBYHA2TGMBRHEZKM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/ABFYSQAOGRAWGPXL3NLH5235DMDFRA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTIOBYHA2TGMBRHEZKM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you commented.Message ID: ***@***.*** com>

[chrisuthe]

Thanks for the thorough write-up — and @Spartan-II-117 is pointing you at the right feature, but I think the missing piece is what to select, so let me be concrete.

The add-on can already do what you're describing. It just does the channel splitting at the PulseAudio layer instead of reading your asound.conf.

Your bedroom and bathroom PCMs will never appear in the master-sink list, because PulseAudio enumerates cards through module-udev-detect and opens ALSA hw: devices directly — named PCMs from asound.conf are invisible to it. That's why you only see snd_rpi_hifiberry_dac8x. Selecting the card is correct: it's the equivalent of your hw: device, and the channel mapping is the next step, not a dead end.

What to do instead of the route plugin:

1. Under Sound Cards, confirm the DAC8x profile exposes all four output channels. If it's sitting on a stereo profile, the extra channels aren't visible to PulseAudio at all and nothing downstream can address them. This is the step most likely to be blocking you.
2. Sinks → Create Remap Sink: master = snd_rpi_hifiberry_dac8x, name = Bathroom, 2 channels, mapping front-left/front-right → the card's channels 1/2.
3. Repeat for Bedroom, mapping to channels 3/4.
4. Create a player against each remap sink.

That's the same split your route plugin does, expressed as module-remap-sink, and it gets you the independent simultaneous playback you had from two Squeezelite instances. It also survives restarts and is visible/editable in the UI, which a hand-written asound.conf isn't.

---

On supporting asound.conf PCMs directly, since you asked for it as a feature:

It would mean enumerating user-defined PCMs from aplay -L, adding a flow to load each as a sink via module-alsa-sink device=<pcm>, and suppressing udev detection for the underlying card so the two don't both claim it. The implementation is maybe a couple of days.

The deeper problem is that it would be Docker-standalone only. Under Home Assistant OS, PulseAudio is supervisor-managed and there is no user asound.conf to read — so this would be a headline feature that silently doesn't exist for most of the user base. That's a bad trade when remap sinks already cover the use case on both platforms.

So I'd rather not build it, but I'm leaving this open until you've had a chance to try the remap route. If step 1 turns out to be the blocker — the DAC8x not offering a 4-channel profile — that's a much more targeted bug and I'd want to fix it.