add-gap.lua

--[[
Copyright (c) 2021 codl

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
]]--

script_name = "Decontiguouize"
script_description = "Keeps the end of cues 500ms away from scene changes and the start of other cues"
script_author = "codl"
script_version = "1.1.0"

filter_description = "Keeps the end of cues 500ms away from the start of other cues"

gap_size = 500

function add_gap(subtitles, i, do_cues, do_scenechanges)
    local changed = false
    local line = subtitles[i]
    if line.class == "dialogue" then
        if do_cues then
            if i < #subtitles then
                for j = i+1, #subtitles do
                    if subtitles[j].class == "dialogue"
                        and line.start_time < subtitles[j].start_time
                        and subtitles[j].start_time - gap_size <= line.end_time then
                        line.end_time = subtitles[j].start_time - gap_size
                        changed = true
                    end
                end
            end
        end
        if do_scenechanges then
            keyframes = aegisub.keyframes()
            if keyframes ~= nil then
                for j = 1, #keyframes do
                    local frametime = aegisub.ms_from_frame(keyframes[j])
                    if frametime >= line.end_time
                        and frametime < line.end_time + gap_size then
                        -- check that the previous scene change is far enough that we
                        -- don't cross it
                        local prev = 0
                        if j > 1 then
                            prev = aegisub.ms_from_frame(keyframes[j-1])
                        end
                        if frametime - gap_size > prev then
                            line.end_time = frametime - gap_size
                            changed = true
                        end
                    end
                end
            end
        end
        if changed then
            subtitles[i] = line
        end
    end
end

function add_gap_filter(subtitles, _)
    for i = 1, #subtitles do
        aegisub.progress.set(i*100/#subtitles)
        add_gap(subtitles, i, true, false)
    end
end

function add_gap_macro(subtitles, selected)
    for i = 1, #selected do
        aegisub.progress.set(i*100/#selected)
        add_gap(subtitles, selected[i], true, true)
    end
end

function add_gap_cues_only_macro(subtitles, selected)
    for i = 1, #selected do
        aegisub.progress.set(i*100/#selected)
        add_gap(subtitles, selected[i], true, false)
    end
end

function add_gap_sc_only_macro(subtitles, selected)
    for i = 1, #selected do
        aegisub.progress.set(i*100/#selected)
        add_gap(subtitles, selected[i], false, true)
    end
end

aegisub.register_filter(script_name, filter_description, 100, add_gap_filter)
aegisub.register_macro(script_name, script_description, add_gap_macro)
aegisub.register_macro(script_name.." (cues only)", script_description, add_gap_cues_only_macro)
aegisub.register_macro(script_name.." (scene changes only)", script_description, add_gap_sc_only_macro)