Video recorder.lua

local sim = require 'sim-1'
local simUI
local simSubprocess

function sysCall_info()
    return {autoStart = false, menu = 'Exporters\nVideo recorder...'}
end

function sysCall_init()
    simUI = require 'simUI'
    capturing = false
    numCapturedFrames = 0
    outputDir = sim.getStringParam(sim.stringparam_importexportdir)
    ui = simUI.create [[<ui title="Video Recorder" closeable="true" on-close="onUiClose">
        <group flat="true" layout="hbox" content-margins="0,0,0,0">
            <label text="Output dir:" />
            <edit id="${editOutputBaseDir}" value="${outputDir}" />
            <button id="${btnBrowseOutputDir}" text="Browse..." on-click="browse" />
        </group>
        <checkbox id="${chkMakeVideo}" text="Convert image sequence to video" on-change="updateUi" />
        <group enabled="false" id="${grpVideoEncoderOptions}" flat="true" layout="vbox" content-margins="0,0,0,0">
            <group flat="true" layout="hbox" content-margins="0,0,0,0">
                <label text="Frames per second:" />
                <edit id="${editFPS}" value="20" />
            </group>
            <group flat="true" layout="hbox" content-margins="0,0,0,0">
                <label text="Bitrate: (kbps)" />
                <edit id="${editBitrate}" value="1800" />
            </group>
        </group>
        <group flat="true" layout="hbox" content-margins="0,0,0,0">
            <button id="${btnStartCapture}" text="Start capture" on-click="startCapture" />
            <button id="${btnStopCapture}" text="Stop capture" on-click="stopCapture" enabled="false" />
        </group>
    </ui>]]
end

function sysCall_cleanup()
end

function sysCall_addOnScriptSuspend()
    return {cmd = 'cleanup'}
end

function sysCall_afterSimulation()
end

function sysCall_beforeInstanceSwitch()
end

function sysCall_sensing()
    if capturing then capture() end
end

function sysCall_nonSimulation()
    if leaveNow then return {cmd = 'cleanup'} end

    if capturing then capture() end
end

function onUiClose()
    leaveNow = true
end

function browse()
    local fileNames = simUI.fileDialog(
                  simUI.filedialog_type.folder, 'Select output directory', outputDir, '', '', '',
                  true
              )
    if #fileNames == 0 then return end
    outputDir = fileNames[1]
    updateUi()
end

function startCapture()
    if capturing then return end
    capturing = true
    filePrefix = string.format('%d', os.time())
    numCapturedFrames = 0
    updateUi()
end

function stopCapture()
    if not capturing then return end
    capturing = false
    if numCapturedFrames > 0 then
        if simUI.getCheckboxValue(ui, chkMakeVideo) > 0 then
            local fps = tonumber(simUI.getEditValue(ui, editFPS))
            local br = tonumber(simUI.getEditValue(ui, editBitrate))
            local inf = string.format('%s/%s_%s.png', outputDir, filePrefix, '%08d')
            local outf = string.format('%s/%s.mp4', outputDir, filePrefix)
            local args = {
                '-r', tostring(fps), '-i', inf, '-c:v', 'libx264', '-b:v', br .. 'k', outf,
            }
            sim.addLog(sim.verbosity_scriptinfos, 'Running: ffmpeg ' .. table.join(args, ' '))
            simSubprocess = simSubprocess or require 'simSubprocess'
            local exitCode, output = simSubprocess.exec(
                                         'ffmpeg', args, '',
                                         {useSearchPath = true, openNewConsole = false}
                                     )
            if exitCode ~= 0 then
                simUI.msgBox(
                    simUI.msgbox_type.critical, simUI.msgbox_buttons.ok, 'Error',
                    'Failed to execute ffmpeg:\n\n' .. output
                )
            else
                sim.addLog(sim.verbosity_scriptinfos, output)
            end
        end
    end
    updateUi()
end

function updateUi()
    simUI.setEnabled(ui, btnStartCapture, not capturing)
    simUI.setEnabled(ui, btnStopCapture, capturing)
    simUI.setEditValue(ui, editOutputBaseDir, outputDir)
    simUI.setEnabled(ui, grpVideoEncoderOptions, simUI.getCheckboxValue(ui, chkMakeVideo) > 0)
end

function capture()
    local img, res = auxFunc('fetchframe', -1) -- sim.getScaledImage('\xff\x00\xff',{1,1},{1024,768},0)
    local fileName = string.format('%s/%s_%08d.jpg', outputDir, filePrefix, numCapturedFrames)
    numCapturedFrames = numCapturedFrames + 1
    sim.saveImage(img, res, 0, fileName, -1)
end