VideExp.lua

--[[
@title video exposure control
by fudgey 2010/08/22

Requires CHDK built with native call support
Thanks to ewavr (method) and reyalp (lua things, eventprocs)

This script uses hard coded firmware function entry points which will only
work on this specific camera + firmware version.

If 1, camera will reset to autoexposure when script ends:
@param a set auto exp on exit?
@default a 1

How large adjust steps to use. 32 is 1/3 stop, 96 is full stop:
@param b tv96 step (96=full stop)
@default b 32
@param c av96 step (96=full stop)
@default c 32
param d sv96 step (96=full stop)
default d 32

The script uses certain camera functions to set exposure values. These functions
appear to return whatever value they actually set. If this argument is zero,
the camera return value is used as the current exposure value shown on the console
and as the seed value for the next adjustment. Thus the camera may will limit
the adjustment range. If you feel brave and optimistic, set this to '1' to see if
you can go further than the camera wants to let you go. There are built-in limits
in the script too, you may need to relax them too to do this:
@param e override cam limits
@default e 0
--]]


--[[
todo:
- ISO control
- show Av in 1/f
- show Tv in milliseconds or fractional or divisor from video frame rate
- ND filter control (ExpCtrlTool.ND or whatever CHDK uses?). I can't do this since I don't have a suitable camera.
--]]

TVSTEP=b
AVSTEP=c
--SVSTEP=d
OVERRIDE=e

--**************************************************************************
-- configure camera model and sub here once entry points have been changed
--**************************************************************************
bi=get_buildinfo()
print("platform: ",bi.platform," ",bi.platsub)
if bi.platform~="a570" then
  error("wrong camera model")
elseif bi.platsub~="100e" then
  error("wrong firmware version")
end

-- don't run in play mode
rec,vid,mode=get_mode()
print("rec:",rec,"vid:",vid)
sleep(1000)
if rec~=true then
  error("Not in rec mode.")
end

--**************************************************************************
-- configure limiting values here
--**************************************************************************
-- tv96 is tied to exposure time in seconds by equation tv = 2^-(tv96/96)
tv96_min=5*96 -- 448 crashes a570, this one seems stable (1/30 s is slightly slower than 30 fps but this works in 60 fps mode too)

-- av96 is tied to aperture number N in f/N by equation av96 = 96 * 2*log2(N)
av96_min=2*96
--av96_min=get_prop(prop.MIN_AV) -- returns 0 for my cam, which sounds dangerous (literally). Also, require "propcase" hangs during video record.
av96_max=8*96 -- (f/16)
--sv96_min=4*96
--sv96_max=9*96

if (type(call_event_proc) ~= "function" ) then
    error("your CHDK does not support native calls")
end

-- this is required for event procedure AllocateMemory
if (call_event_proc("SystemEventInit") == -1) then
    error("SystemEventInit failed")
end

-- this is required for event procedures ExpCtrlTool.*
if (call_event_proc("Capture.Create") == -1) then
    error("Capture.Create failed")
end

-- to make lua happy
tv96=get_tv96()
av96=get_av96()
--sv96=get_sv96()

decrease=0
increase=1

-- 1/3 stop Tv adjustment
-- too slow tv crashes the cam.
function tv_adj(incr)
    if incr==increase then
        tv96=tv96-TVSTEP
    else
        tv96=tv96+TVSTEP
    end
    -- prevent tv from going slower than safe minumum or higher than signed short can go
    if tv96<tv96_min then
        tv96=tv96_min
    elseif tv96>32767 then
        tv96=32767
    end
    -- Sets exposure by calling an eventproc which takes a pointer to a 16-bit signed short as argument.
    -- We need to allocate a word of memory and poke our value there before calling:
    buf=call_event_proc("AllocateMemory",4)
    if buf > 0 then
        poke(buf,tv96)
--**************************************************************************
-- configure entry point here or switch to event proc if you can
--**************************************************************************
        ret=call_func_ptr(0xffe0b70c,buf) --SetAE_ShutterSpeed(&tv)
        --ret=call_event_proc("SetAE_ShutterSpeed",buf)
--**************************************************************************
        -- Canon's function seems to return sane values, let's use them as limits:
        if OVERRIDE ~= 1 then
          tv96=ret
        end
        call_event_proc("FreeMemory",buf)
    else
        error("AllocateMemory failed")
    end
    -- change menu text to show new value
    curmenu[curitem].name=function() return(tostring(string.format("%s %d", "Tv", tv96))) end
end

-- 1/3 stop Av adjustment
function av_adj(incr)
    if incr==increase then
        av96=av96-AVSTEP
    else
        av96=av96+AVSTEP
    end
    -- prevent tv from going slower than safe minumum or higher than signed short can go
    if av96<av96_min then
        av96=av96_min
    elseif av96>av96_max then
        av96=av96_max
    end
    -- Sets exposure by calling an eventproc which takes a pointer to a 16-bit signed short as argument.
    -- We need to allocate a word of memory and poke our value there before calling:
    buf=call_event_proc("AllocateMemory",4)
    if buf > 0 then
        poke(buf,av96)
--**************************************************************************
-- configure entry point here or switch to event proc if you can
--**************************************************************************
        ret=call_func_ptr(0xffe05ba4,buf) --MoveIrisToAv(&tv)
        --ret=call_event_proc("MoveIrisToAv",buf)
--**************************************************************************
        -- Canon's function seems to return sane values, let's use them as limits:
        if OVERRIDE ~= 1 then
          av96=ret
        end
        call_event_proc("FreeMemory",buf)
    else
        error("AllocateMemory failed")
    end
    -- change menu text to show new value
    curmenu[curitem].name=function() return(tostring(string.format("%s %d", "Av", av96))) end
end

function sv_adj(incr)
  -- TODO
  -- maybe using call_event_proc("SetAE_CdsGainValue", ...)
end

-- go to manual exposure mode
function manualexp()
    ret=call_event_proc("ExpCtrlTool.StopConti")
    if ret==-1 then
      error("ExpCtrlTool.StopConti failed")
    end
end

-- go to auto exposure mode
function autoexp()
    call_event_proc("ExpCtrlTool.StartConti")
    if ret==-1 then
      error("ExpCtrlTool.StartConti failed")
    end
end

function menuitem(name,item)
    t={item = item}
    if type(name) ~= "function" then
        t.name = function()
            return(tostring(name))
        end
    else
        t.name = name
    end
    return t
end

mainmenu={
    menuitem("Tv "..tv96,tv_adj),
    menuitem("Av "..av96,av_adj),
    --menuitem("ISO",sv_adj),
}

function domenu()
    curmenu=mainmenu
    curitem=1
    while true do
        cls()
        print("U/D:pick |    quit:MENU")
        print("L/R:adj  | autoexp:SET ")
        if curitem > 1  then
            print(string.format("|%s",curmenu[curitem-1].name()))
        else
            print("-----------------------")
        end
        print(string.format(">%s",curmenu[curitem].name()))
        if curmenu[curitem+1] then
            print(string.format("|%s",curmenu[curitem+1].name()))
        else
            print("-----------------------")
        end
        wait_click(5000)
        if is_pressed("down") then
            if curmenu[curitem+1] then
                curitem = curitem + 1
            end
        elseif is_pressed("up") then
            if curitem > 1 then
                curitem = curitem - 1
            end
        elseif is_pressed("left") then
            if type(curmenu[curitem].item) == "function" then
                curmenu[curitem].item(increase)
            end
        elseif is_pressed("right") then
            if type(curmenu[curitem].item) == "function" then
                curmenu[curitem].item(decrease)
            end
        elseif is_pressed("set") then
            print("auto exposure, wait...")
            autoexp()
            sleep(1000)
            -- update values in menu
            tv96=get_tv96()
            mainmenu[1].name=function() return(tostring(string.format("%s %d", "Tv", tv96))) end
            av96=get_av96()
            mainmenu[2].name=function() return(tostring(string.format("%s %d", "Av", av96))) end
            --sv96=get_sv96()
            --mainmenu[3].name=function() return(tostring(string.format("%s %d", "Sv", sv96))) end
            manualexp()
        elseif is_pressed("menu") then
            break
        end
    end
end

function restore()
  if a==1 then
    print("enabling autoexposure")
    autoexp()
  end
end

manualexp()

-- startup values
tv96=get_tv96()
av96=get_av96()
--sv96=get_sv96()

domenu()
restore()