audio

PipeWire: output and input volume and mute, device lists, per-app streams and Bluetooth codecs.

list {
    source = mantle.audio:map(function(audio)
        return audio and audio.sinks or {}
    end),
    key = function(sink) return tostring(sink.id) end,
    itemfn = function(sink)
        return button {
            padding = 6,
            background = sink.active and "#45475A" or "#1E1E2E",
            on_click = function() mantle.audio:set_default_sink(sink.id) end,
            children = { text { content = sink.name } },
        }
    end,
}

State

mantle.audio:get() returns AudioState, nil before the first push. A field marked ? may be absent.

mantle.audio’s payload.

AppStream

One app’s playback or recording stream. Streams without a pid are left out.

AudioDevice

One sinks or sources entry.

BluetoothCodecs

One BlueZ audio device’s codec choices, joined to mantle.bluetooth by MAC.

CodecProfile

One entry of BluetoothCodecs::codecs.

Actions

Call each as mantle.audio:<action>(arguments...); ? marks an argument you may omit.

Backend

PipeWire’s native API, on one thread shared with privacy.

The first push waits until PipeWire has reported every object and its volume, so a machine with no audio hardware still gets one push of empty lists. An unreachable PipeWire is logged and audio stays nil. Nothing reconnects: a PipeWire restart freezes audio at its last push until the Supervisor restarts.

How do I…

Change volume on the scroll wheel, mute on middle click

A handler reads with :get(): it needs the value now, not a binding (input).

button {
    on_wheel = function(_, steps)
        local audio = mantle.audio:get()
        if audio == nil or audio.volume == nil then
            return
        end
        mantle.audio:set_volume(math.max(0, math.min(1, audio.volume + steps * 0.05)))
    end,
    on_click = function(_, which)
        if which == "middle" then
            mantle.audio:toggle_mute()
        end
    end,
    children = {
        text {
            content = mantle.audio:map(function(audio)
                if audio == nil or audio.volume == nil then
                    return "--"
                end
                return audio.muted and "muted" or string.format("%d%%", math.floor(audio.volume * 100 + 0.5))
            end),
        },
    },
}

Show an OSD when volume changes

on_change writes named state that a panel binds, and a timer hides the panel again:

local osd_text = state("osd_text", "")
local osd_visible = state("osd_visible", false)
local hide_timer

mantle.audio:on_change(function(audio, previous)
    if previous == nil or audio.volume == nil then
        return -- the first push is learned state, not a change
    end
    if audio.volume == previous.volume and audio.muted == previous.muted then
        return
    end
    osd_text:set(audio.muted and "Muted" or string.format("Volume %d%%", math.floor(audio.volume * 100 + 0.5)))
    osd_visible:set(true)
    if hide_timer then
        hide_timer:cancel()
    end
    hide_timer = timer(2000, function() osd_visible:set(false) end)
end)

local osd = panel {
    id = "osd",
    layer = "Overlay",
    anchor = { bottom = true },
    margin = { bottom = 80 },
    visible = osd_visible,
    padding = 12,
    radius = 12,
    background = "#1E1E2ECC",
    child = text { content = osd_text, font_size = 16 },
}

See also: Volume OSD recipe.

Source: supervisor/src/capabilities/audio/