Detect Cuts.lua

--[[
    Detect Cuts.lua
    Jamie Hardt 16 Dec 2020
]]

ScriptExtKey = "COM_SQUAD51ENTERPRISES_DETECTCUTS"
FFmpegPathKey = "FFMPEG_PATH"
LastThresholdKey = "LAST_THRESHOLD"


function Get_FFMpeg_Path ()

    local function test_ffmpeg (test_path)
        return os.execute(test_path .. " -t 1.0 -f lavfi -i 'color=black' -filter:v 'scdet=t=3.0' -f null /dev/null") -- on my system os.execute returns a boolean
    end

    local path = nil
    if reaper.HasExtState(ScriptExtKey, FFmpegPathKey) then
        path = reaper.GetExtState(ScriptExtKey, FFmpegPathKey)
    else
        local retval = reaper.MB("FFMpeg is required for this action, find the path to your FFmpeg executable now or click Cancel.","Detect Cuts",1)
        if retval == 1 then
            retval, path = reaper.GetUserFileNameForRead("/usr/local/bin/", "Find FFMpeg executable", "")
            if retval then
                reaper.SetExtState(ScriptExtKey,FFmpegPathKey,path, true)
                return Get_FFMpeg_Path() -- tail call
            end
        else
            return nil
        end
    end

    if test_ffmpeg (path) then
        return path
    else
        reaper.MB("Working FFMpeg could not be found at " .. path .. ".", "Detect Cuts Error",0)
        reaper.DeleteExtState(ScriptExtKey, FFmpegPathKey, true)
        return Get_FFMpeg_Path() -- tail call
    end
end


local ffmpeg_path = Get_FFMpeg_Path() 
if ffmpeg_path == nil then return else ffmpeg_path = ffmpeg_path .. " -hide_banner" end

function Iterate_cuts ( file_path, detection_threshold, start_offset, length )
    local args = " "

    if start_offset ~= nil then
        args = args .. "-ss " .. string.format("%f", start_offset) .. " "
    end

    if length ~= nil then
        args = args .. "-t " .. string.format("%f", length) .. " "
    end

    args = args .. "-i \"" .. file_path .. "\" -filter:v 'scdet=t=" ..
        string.format("%f",detection_threshold) .. ":s=1,metadata=print:file=-' -f null - 2>/dev/null"

    local ffmpeg_read = io.popen(ffmpeg_path .. args, "r")
    local line = nil
    return function ()
        while true do
            line = ffmpeg_read:read("*l")
            if line == nil then break end
            local pts_time = line:match("pts_time:(%d+)%.")
            if pts_time ~= nil then
                local time = tonumber(pts_time)
                local time_parts = line:match("pts_time:%d+%.(%d+)")
                if time_parts ~= nil then
                    time = tonumber(pts_time .. "." .. time_parts)
                end
                return time, line
            end 
        end
    end


end

local count = reaper.CountSelectedMediaItems(0)

if count > 1 then
    reaper.MB("Please select one object. Cut detection only works on single media files.", "Cut Detection",0)
    return
elseif count == 0 then
    reaper.MB("Please select a video media object.", "Cut Detection",0)
    return
end

local selected = reaper.GetSelectedMediaItem(0,0)

local selected_take = reaper.GetTake(selected, 0)
local source = reaper.GetMediaItemTake_Source(selected_take)

local filename = reaper.GetMediaSourceFileName(source, "")
local source_type = reaper.GetMediaSourceType(source, "")

if source_type ~= "VIDEO" then 
    reaper.MB("Please select a video media object.", "Cut Detection",0)
    return
end 


local default_threshold = 5.0
if reaper.HasExtState(ScriptExtKey, LastThresholdKey) then
    default_threshold = tonumber(reaper.GetExtState(ScriptExtKey, LastThresholdKey))
end

local result, rvals = reaper.GetUserInputs("Cut Detection with ffmpeg",1,"Detection Threshold",tostring(default_threshold))
if result then
    local position = reaper.GetMediaItemInfo_Value(selected, "D_POSITION")
    local length = reaper.GetMediaItemInfo_Value(selected, "D_LENGTH")
    local start_offset = reaper.GetMediaItemTakeInfo_Value(selected_take, "D_STARTOFFS")
    local this_threshold = tonumber(rvals)
    reaper.SetExtState(ScriptExtKey, LastThresholdKey, tostring(this_threshold), true)

    local n = 1
    for time, line in Iterate_cuts(filename, this_threshold, start_offset, length) do
        -- reaper.SetEditCurPos(time+position, false, false)
        -- reaper.Main_OnCommandEx(40012,0,0)
        -- SPLIT: 40012
        reaper.AddProjectMarker(0, false, time + position, 0., "Cut: " .. line, n)
        n = n + 1
    end
end