Demonstration of encoding SoundData into a packet

VoipEncoder.lua

local ffi = require("ffi")

-- Create a C struct representing the header for our packet
ffi.cdef([[
	typedef struct {
		uint32_t uuid; // user identifier
		uint32_t size; // in bytes
		uint32_t bitrate; // in Hz
		uint16_t bitdepth; // bits per sample
		uint16_t channels; // probably 1 or 2
	} VoipHeader;
]])

local VoipHeader = ffi.typeof("VoipHeader")
local pVoipHeader = ffi.typeof("VoipHeader*")

-- Create a SoundData object to try to transmit
local mySoundData = love.sound.newSoundData(8, 44100, 8, 1)
mySoundData:setSample(0, 0.5)
mySoundData:setSample(7, 0.5)

-- Create a header for this specific SoundData
local packet = ffi.new(VoipHeader, {
	uuid = 1, -- dud UUID, first user
	size = 8, -- 8 bytes of data
	bitrate = 44100, -- 44100 Hz, like we specified above
	channels = 1, -- 1 channel
	bitdepth = 8 -- 8-bit audio
})

-- Encodes a C struct as a string
local function encode(data)
	return ffi.string(ffi.cast("const char*", data), ffi.sizeof(data))
end

-- Turns a string back into a C struct
local function decode(data, pstruct)
	return ffi.cast(pstruct, data)[0]
end

-- Encode our header and payload as a string
local struct = encode(packet)
local encoded = struct .. ffi.string(mySoundData:getPointer(), 8)

-- Decode our encoded packet
local header = decode(encoded, pVoipHeader)
local encodedPayload = encoded:sub(ffi.sizeof(VoipHeader) + 1)
local payload = ffi.new("uint8_t[8]", encoded:sub(ffi.sizeof(VoipHeader)+1))

local newSoundData = love.sound.newSoundData(header.size, header.bitrate, header.bitdepth, header.channels)
ffi.copy(newSoundData:getPointer(), payload, 8)

print(newSoundData:getSample(0)) -- around 0.5