mpv.io audio channels levelmenter

showvolumes.lua

local mp = require 'mp'
local msg = require 'mp.msg'

function setup_volume_meter()
    local tracks = mp.get_property_native("track-list")
    if not tracks then
        msg.warn("No track list found.")
        return
    end

    local input_labels = {}
    local input_count = 0
    local has_video = false

    for _, track in ipairs(tracks) do
        if track.type == "audio" then
            input_count = input_count + 1
            local label = string.format("[aid%d]", track.id)
            table.insert(input_labels, label)
        elseif track.type == "video" then
            has_video = true
        end
    end

    if input_count == 0 then
        msg.warn("No audio tracks found.")
        return
    end

    local filter_graph

    if input_count == 1 then
        if has_video then
            filter_graph = "[aid1]asplit[ao][as];[as]showvolume=r=29.97:h=70:w=300[vvol];[vid1]format=pix_fmts=yuv420p[vf];[vf][vvol]overlay[vo]"
        else
            filter_graph = "[aid1]asplit[ao][as];[as]showvolume=r=29.97:h=480:w=640[vo]"
        end
    else
        local merged_inputs = table.concat(input_labels, "")
        if has_video then
            filter_graph = string.format(
                "%samerge=inputs=%d,asplit[ao][as];[as]showvolume=r=29.97:h=70:w=300[vvol];[vid1]format=pix_fmts=yuv420p[vf];[vf][vvol]overlay[vo]",
                merged_inputs, input_count
            )
        else
            filter_graph = string.format(
                "%samerge=inputs=%d,asplit[ao][as];[as]showvolume=r=29.97:h=480:w=640[vo]",
                merged_inputs, input_count
            )
        end
    end

    mp.set_property("lavfi-complex", filter_graph)
    msg.info("Applied lavfi-complex: " .. filter_graph)
end

mp.register_event("file-loaded", setup_volume_meter)