WaveFlow audio visualizer

waveflow.lua

-- WaveFlow audio visualizer
--
-- Usage:
-- - run in background with `bg waveflow`
-- - or run in background on monitor with `bg monitor left waveflow`
-- - then use another program to play audio (e.g. with a DFPWM audio player or MeowSynth)
-- - click to change the colors!
--
-- This program will detect any audio played on speakers via playAudio
-- Unfortunately, in-game it lags everytime a new audio buffer is queued...
-- But it works fine on CraftOS-PC :D

local only_use_speaker = nil -- set to speaker name if you only want to use audio data from a specific speaker

local function downloadFile(filename, url)
    local res = http.get(url)
    if not res then error("Error downloading file from " .. url) end
    local data = res.readAll()
    res.close()
    local file = fs.open(filename, "w")
    if not file then error("Can't write to file " .. filename .. "...") end
    file.write(data)
    file.close()
end

-- BetterBetterBlittle (takes color spaces into account when picking colors)
if not fs.exists("betterbetterblittle.lua") then
    downloadFile("betterbetterblittle.lua",
        "https://raw.githubusercontent.com/Xella37/Pine3D/bf70ce8dfd293c5cfc795183cf1ba8a6d230be73/betterblittle.lua")
end
local betterblittle = require("betterbetterblittle")

local LAST_COLOR = 2 ^ 15
local gradients = {
    {0xf3ee5e, 0xe6ca58, 0xd9a653, 0xcc824e, 0xbf5d48, 0xb14242, 0x9f3b3b, 0x8e3535, 0x7d2f2f, 0x6c2828, 0x5a2222, 0x491c1c, 0x371515, 0x260e0e, 0x140808, 0x040101},
    {0x54d2f3, 0x5eb3e8, 0x6995de, 0x7275d3, 0x7d56c8, 0x813fbc, 0x7439a9, 0x673296, 0x5a2c84, 0x4e2772, 0x41205f, 0x351a4d, 0x28143b, 0x1b0d28, 0x0f0716, 0x020103},
    {0xf45256, 0xec4f6c, 0xe34c82, 0xdc4a98, 0xd448ae, 0xc844b8, 0xb43da5, 0xa13693, 0x8d3082, 0x79296f, 0x66235e, 0x521c4c, 0x3e1539, 0x2b0f28, 0x180816, 0x040103},
    {0x79f256, 0x6de66c, 0x61d983, 0x55cd98, 0x4ac0af, 0x40b2b9, 0x39a0a7, 0x338f95, 0x2c7d82, 0x276c70, 0x205a5e, 0x1a4a4c, 0x14383a, 0x0e2628, 0x071415, 0x010304}
}
local gradientI = 1


-- each sample is an integer between -128 and 127
local samplerate = 48 -- 48 samples per ms (48kHz)

local buffersPlayed = 0
local buffers = {}
local MAX_BUFFERS = 3 -- maximum number of buffers to keep in memory
local bufferI = 0

local newestBufferEndTime = 0 -- in ms, aka nextBufferStartTime

local oldPeripheralCall = peripheral.call
function peripheral.call(name, method, ...)
    if method == "playAudio" then
        if not oldPeripheralCall(name, method, ...) then return false end

        if not only_use_speaker or only_use_speaker == name then
            local newBuffer = ({...})[1]
            local volume = ({...})[2]

            local bufferDuration = #newBuffer / samplerate
            local time = os.epoch("utc")
            if time - newestBufferEndTime > 10 then
                newestBufferEndTime = time + bufferDuration
                buffersPlayed = 0
                buffers = {}
            else
                newestBufferEndTime = newestBufferEndTime + bufferDuration
            end

            buffersPlayed = buffersPlayed + 1

            bufferI = bufferI % MAX_BUFFERS + 1
            buffers[bufferI] = newBuffer
        end

        return true -- success
    else
        return oldPeripheralCall(name, method, ...)
    end
end

local SCREEN_WIDTH, SCREEN_HEIGHT = term.getSize()
local FB_WIDTH, FB_HEIGHT = SCREEN_WIDTH * 2, SCREEN_HEIGHT * 3
local window = window.create(term.current(), 1, 1, SCREEN_WIDTH, SCREEN_HEIGHT)
local frameBuffer = {}

local function setColors()
    local gradient = gradients[gradientI]
    for i = 1, #gradient do
        window.setPaletteColor(2 ^ (i - 1), gradient[i])
    end
end
setColors()

local function userInput()
    while true do
        local event, which, x, y = os.pullEventRaw()
        if event == "mouse_click" then
            gradientI = gradientI % #gradients + 1
            setColors()
        elseif event == "terminate" then
            peripheral.call = oldPeripheralCall
            return
        end
    end
end


local function gameLoop()
    local lastTime = os.epoch("utc")
    local lastI = -1
    local max, min, floor, random = math.max, math.min, math.floor, math.random

    while true do
        local time = os.epoch("utc")
        local dt = time - lastTime

        if dt >= 10 then -- limit to 100 fps
            lastTime = time

            local buffer, sampleIndex = {}, 1
            local sampleOffset = floor((newestBufferEndTime - time) * samplerate)
            if sampleOffset >= 0 then
                buffer = buffers[bufferI] or {}
                sampleIndex = #buffer - sampleOffset
                if sampleIndex < 0 then
                    buffer = buffers[(bufferI - 2) % MAX_BUFFERS + 1] or {}
                    sampleIndex = sampleIndex + #buffer
                end
            end

            local fadeFactor = random() < dt / 20 and 2 or 1
            local fadeFactor2 = random() < dt / 50 and 2 or 1
            for y = 1, FB_HEIGHT do
                local row = frameBuffer[y] or {}
                for x = 1, FB_WIDTH do
                    local color = row[x] or LAST_COLOR
                    row[x] = max(min((color) * (color > 128 and fadeFactor2 or fadeFactor), LAST_COLOR), 2)
                end
                frameBuffer[y] = row
            end

            local scale = 4
            for x = 1, FB_WIDTH do
                local sample = 0
                if sampleOffset >= 0 then
                    sample = buffer[sampleIndex - scale * (x - 1)]
                    if not sample then
                        buffer = buffers[bufferI % MAX_BUFFERS + 1] or {}
                        sample = buffer[sampleIndex + x] or 0
                    end
                end
                local y = floor((sample + 128) / 256 * (FB_HEIGHT - 2) + 1)
                if y > 0 and y < FB_HEIGHT then
                    local row = frameBuffer[y]
                    row[FB_WIDTH - x + 1] = 1
                    frameBuffer[y] = row
                end
            end

            betterblittle.drawBuffer(frameBuffer, window)

            -- window.setTextColor(2)
            -- window.setCursorPos(1, 1)
            -- window.write("" .. sampleOffset .. " " .. sampleIndex)

            window.setVisible(true)
            window.setVisible(false)
        end

        os.queueEvent("gameLoop")
        ---@diagnostic disable-next-line: param-type-mismatch
        os.pullEventRaw("gameLoop")
    end
end

parallel.waitForAny(userInput, gameLoop)