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fix: use secondary delay for secondary subtitles #182

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Merged
tatsumoto-ren merged 2 commits into from
Sep 4, 2026
Merged

fix: use secondary delay for secondary subtitles #182

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53189af
fix: use secondary delay for secondary subtitles
kuator Sep 2, 2026
9123050
refactor
tatsumoto-ren Sep 4, 2026
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33 changes: 32 additions & 1 deletion mpvacious/subtitles/subtitle.lua
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,15 @@ function Subtitle:from_text(text, start_time, end_time)
return self:new { ['text'] = text, ['start'] = start_time, ['end'] = end_time }
end

--- Return the selected subtitle track's delay relative to the audio track.
--- mp_api defaults to mp; tests may provide an mp-compatible stub.
local function subtitle_delay(is_secondary, mp_api)
mp_api = mp_api or mp
local delay_property = is_secondary and 'secondary-sub-delay' or 'sub-delay'
return mp_api.get_property_native(delay_property) - mp_api.get_property_native('audio-delay')
end

--- Return the currently displayed primary or secondary subtitle with mpv delays applied.
function Subtitle:now(secondary)
local prefix = secondary and "secondary-" or ""
local this = self:new {
Expand All @@ -38,7 +47,7 @@ function Subtitle:now(secondary)
['is_secondary'] = (secondary and true or false),
}
if this:is_valid() then
return this:delay(mp.get_property_native("sub-delay") - mp.get_property_native("audio-delay"))
return this:delay(subtitle_delay(secondary))
else
return nil
end
Expand Down Expand Up @@ -143,12 +152,34 @@ local function test_expand_end_time()
h.assert_equals(expanded['end'], 3)
end

local function make_mp_stub_for_tests()
local delays = { ['sub-delay'] = 10, ['secondary-sub-delay'] = 3, ['audio-delay'] = 1 }
local function get_property_native(name)
return delays[name]
end
return { get_property_native = get_property_native }
end

local function test_subtitle_delay()
local mp_stub = make_mp_stub_for_tests()
local cases = {
{ is_secondary = false, expected_start = 10, expected_end = 11 },
{ is_secondary = true, expected_start = 3, expected_end = 4 },
}
for _, case in ipairs(cases) do
local shifted = sub("Line", 1, 2):delay(subtitle_delay(case.is_secondary, mp_stub))
h.assert_equals(shifted['start'], case.expected_start)
h.assert_equals(shifted['end'], case.expected_end)
end
end

function Subtitle.run_tests()
test_is_same_event()
test_eq_uses_same_event()
test_time_overlap()
test_can_expand_with()
test_expand_end_time()
test_subtitle_delay()
end

return Subtitle