audiotest

local dfpwm = require("cc.audio.dfpwm")
local speaker = peripheral.find("speaker")

-- Speakers play at 48kHz, so 1.5 seconds is 72k samples. We first fill our buffer
-- with 0s, as there's nothing to echo at the start of the track!
local samples_i, samples_n = 1, 48000 * 1.5
local samples = {}
for i = 1, samples_n do samples[i] = 0 end

local decoder = dfpwm.make_decoder()
for chunk in io.lines("data/example.dfpwm", 16 * 1024) do
    local buffer = decoder(chunk)

    for i = 1, #buffer do
        local original_value = buffer[i]

        -- Replace this sample with its current amplitude plus the amplitude from 1.5 seconds ago.
        -- We scale both to ensure the resulting value is still between -128 and 127.
        buffer[i] = original_value * 0.6 + samples[samples_i] * 0.4

        -- Now store the current sample, and move the "head" of our ring buffer forward one place.
        samples[samples_i] = original_value
        samples_i = samples_i + 1
        if samples_i > samples_n then samples_i = 1 end
    end

    while not speaker.playAudio(buffer) do
        os.pullEvent("speaker_audio_empty")
    end

    -- The audio processing above can be quite slow and preparing the first batch of audio
    -- may timeout the computer. We sleep to avoid this.
    -- There's definitely better ways of handling this - this is just an example!
    sleep(0.05)
end