VideExp.lua

--[[
@title video exposure control
by fudgey 2010/08/23

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

This script uses several event procedures (native function calls) which supposedly are
portable across many camera models, but may not exist or may fail to work on others
or the way to register them on a570 may cause problems. In addition, even on the
author's a570 100e this script causes frequent crashes.

You have been warned, try at your own risk!

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 sv step (unknown unit)
@default d 128

The script uses certain camera functions to set exposure values. Tv and Av 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. On a570 it looks like camera
limits are at or near CHDK override limits, not the usual Canon UI limits.

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:
- find a way to get working start value for ISO (currently just gives 0 which is not right)
- 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

-- 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 is tied to ISO speed rating S by equation sv96 = 96 * 2*log2(S/3.125)
-- but the sv96 used in this script is not really sv96. I don't know what it is,
-- possibly a 10-bit PGA amp gain control setting ranging from 0 to 1024 for ISO100 to ISO800 (or 1600, but that's a software mode)
-- that's a 3 Ev range, so a step size of 128 crudely approximates 1/3 stop change
sv96_min=0
sv96_max=2000

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

-- this is required for event procedures SetAE_ShutterSpeed, MoveIrisToAv, SetCDSGain
if (call_event_proc("InitializeAdjustmentFunction") == -1) then
    error("InitializeAdjustmentFunction failed")
end

-- returns 0 if no ND present, 1 if ND present and real diaphragm NOT present, 2 if both ND & diaphragm present.
nd=get_nd_present()
if nd==1 then
  iris=false
else
  iris=true
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
    -- adjust tv
    ret=call_event_proc("SetAE_ShutterSpeed",tv96)
    -- Canon's function seems to return sane values, let's use them as limits:
    if OVERRIDE ~= 1 then
      tv96=ret
    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 iris==true then
        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
        -- adjust iris
        ret=call_event_proc("MoveIrisToAv",av96)
        -- Canon's function seems to return sane values, let's use them as limits:
        if OVERRIDE ~= 1 then
          av96=ret
        end
        -- change menu text to show new value
        curmenu[curitem].name=function() return(tostring(string.format("%s %d", "Av", av96))) end
    end
end

function sv_adj(incr)
    if incr==increase then
        sv96=sv96-SVSTEP
    else
        sv96=sv96+SVSTEP
    end
    -- range limit
    if sv96<sv96_min then
        sv96=sv96_min
    elseif sv96>sv96_max then
        sv96=sv96_max
    end
    -- 0 to 1024 vale range to ISO 100--800 or 1600 range (I think)
    ret=call_event_proc("SetCDSGain",sv96)
    --print("SetCDSGain="..ret)
    --this one appears to return 0 always
    --sleep(500)
    curmenu[curitem].name=function() return(tostring(string.format("%s %d", "Sv", sv96))) end
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("Sv "..sv96,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()