Corona FPS Benchmark

readme.md

This code will declare global function BenchmarkFPS(). When called it will record frame duration statistics over next 5 seconds after skipping half a second. Duration and skip interval can be overridden if passed as optional parameters (in milliseconds).

Sample output:

Jul 04 12:34:56.789 ------------------------------------------------------------
                    Mean FPS is 62.50 measured in 281 frames
                    with mean frame time 16.00ms, standard deviation of 0.70ms (0.25%)
                    99% of all frames took between 15.89ms and 16.11ms to render
                    ------------------------------------------------------------

mail.lua

-- this code will introduce global function BenchmarkFPS
-- which would print out some statistics collected over 5 seconds
function BenchmarkFPS(duration, skip)
	duration = duration or 5000
	skip = skip or 500
	local function mean( t )
		local sum , count = 0, 0
		for _,v in pairs(t) do
			sum = sum + v
			count = count + 1
		end
		return (sum / count)
	end

	local function std( t )
		local mean, sum, count = mean( t ), 0, 0
		for _,v in pairs(t) do
			local vm = v - mean
			sum = sum + (vm * vm)
			count = count + 1
		end
		return math.sqrt(sum / (count-1))
	end

	local fps = {}
	local prevTime = 0

	function onFrame ( event )
		local t = event.time
		if t < skip then -- skip first second
		elseif t > duration then -- measure fps for 5 seconds
			local n,sigma, x_ = #fps, std(fps), mean(fps)
			local normSigma = 100*sigma/n
			local confRange = 2.57*sigma/math.sqrt( n )
			local confL, confH = x_ - confRange, x_ + confRange
			local res = ""
			.. "------------------------------------------------------------\n"
			..string.format("Mean FPS is %.2f measured in %d frames\n", 1000/x_, n )
			..string.format("with mean frame time %.2fms, standard deviation of %.2fms (%.2f%%)\n", x_, sigma, normSigma)
			..string.format("99%% of all frames took between %.2fms and %.2fms to render\n", confL, confH)
			.. "------------------------------------------------------------"
			print(res)
			Runtime:removeEventListener( "enterFrame", onFrame )
		else
			fps[#fps+1] = t - prevTime
		end
		prevTime = t
	end

	Runtime:addEventListener( "enterFrame", onFrame )
end

-- start benchmark
BenchmarkFPS()