Is there a way to remove lead-in time without affecting karaoke timings?

[pizzaisdavid]

I am making subtitles with the karaoke effect.

Here is an example:

Sometimes I want to experiment with the amount of lead time for a line.

Here I added an exaggerated amount of time (using the C hotkey.)

Then committing, turning off karaoke mode, and dragging the red line back to near where it started results the rest of the timings being squished. See here:

And here is a comparison for easy viewing:

In my mind, the karaoke timings would be tied to the audio timing and not relative to the start of a line. -- As shifting a line does not change when an dialogue is said. I understand the ASS format may specify it that way, but the program could do something cool to avoid this problem.

Does anyone have any ideas or work-around?

---

Here is the files used: unexpected_behaviour.txt https://pixabay.com/sound-effects/welcomestranger-34421/

[arch1t3cht]

The easiest way to do this from within Aegisub is probably to use Subtitle > Split by Karaoke, delete the first line, and then Join the lines as karaoke again. Alternatively, this could easily be done with an automation script, though I don't know off-hand if there already exists a script for that somewhere.

[pizzaisdavid]

Thanks for the insights. It has pushed me towards making my first Lua script.

While figuring out how to precede, so far, I think I found some easy manual steps which achieve the goal:

1. In the user interface, ensure the Time/Frame radio input is set to Time.
2. Select the line you want to modify.
3. Decide on the amount of lead-in time we want to remove (in centiseconds.)
4. Add that amount to the Start Time input.
5. Subtract that amount from the first non-zero k tag.

I always use a whole number of centiseconds because I am not sure how to handle the rounding for the k tag.

[pizzaisdavid]

Here's what I came up with, it seems to work well for my usecase:

--[[

ORIGINAL:
{
  "start_time": 1360, (1360 milliseconds / 136 centiseconds)
  "end_time": 2590,
  "text": "{\\k10}{\\k43}Hey,{\\k8} {\\k26}Ihr{\\k5} {\\k21}da.{\\k10}",
  ...
}

SHIFTED VIA THE AUTOMATION (THE GOAL):
{
  "start_time": 1370, <== added 10
  "end_time": 2590,
  "text": "{\\k9}{\\k43}Hey,{\\k8} {\\k26}Ihr{\\k5} {\\k21}da.{\\k10}"
  ...          ^== subtracted 1
}

]]

script_name='Remove lead-in without affecting karaoke'
script_description='works best when you set it to a hotkey'
script_author='pizzaisdavid'
script_version='1.0'

function macro_function(
  subtitles,
  selected_line_indices,
  active
)
  for _, selected_line_index in ipairs(selected_line_indices) do
    local line = subtitles[selected_line_index]

    line.start_time = line.start_time + 10
    line.text=line.text:gsub(
      '\\k(%d+)',
      function(duration)
        duration = tonumber(duration)
        duration = duration - 1
        new_tag = string.format('\\k%d', duration)
        return new_tag
      end,
      1
    )

    subtitles[selected_line_index] = line
  end
  return selected
end

aegisub.register_macro(
  script_name,
  script_description,
  macro_function
)

Filename is: remove-lead-in-without-affecting-karaoke Then copying it into the autoload folder and setting a free hot key. I did CTRL-SHIFT-. as it contains the > on my keyboard.