ASS to SMI
Or paste subtitle text
What this conversion changes
3 things are dropped or need a decision
- Styling
all styling except bold and italic (colour, outline, shadow, margins)
- Karaoke
karaoke timing (per-syllable highlighting)
- Format-specific content
content the source format keeps outside its cues (non-cue blocks, header text, per-cue settings, commented-out events) — the target format has no place for it
This list comes from the capability matrix for these two formats, not from the particular file you loaded. A specific file may lose more if it uses features the format allows but the matrix does not model.
This page converts ASS to SMI. Drop a file in — or paste the text — and you get the SMI version back. The conversion runs entirely in your browser, so nothing is uploaded and no account is needed.
These two formats do not store the same things, and the difference is not cosmetic: styling, karaoke and format-specific content have nowhere to go in SMI. The list above comes from what the two formats can each express rather than from your file, so it is the same answer before you load anything.
One file is fine, and so is a whole season: the queue works through them in order and the results come down together as a single ZIP.
Examples
A typical ASS file, converted to SMI
Input
[Script Info]
Title: Example
ScriptType: v4.00+
WrapStyle: 0
[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,20,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,0,0,0,0,100,100,0,0,1,2,2,2,10,10,10,1
Style: Title,Arial,36,&H0000FFFF,&H000000FF,&H00000000,&H00000000,-1,0,0,0,100,100,0,0,1,2,2,2,10,10,10,1
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.00,0:00:04.00,Default,,0,0,0,,Hello there.
Dialogue: 0,0:00:05.00,0:00:08.50,Default,,0,0,0,,{\i1}Italic{\i0} and {\b1}bold{\b0} text.
Dialogue: 0,0:00:09.00,0:00:12.00,Title,,0,0,0,,{\pos(320,240)}Positioned
Dialogue: 0,0:00:13.00,0:00:16.00,Default,,0,0,0,,{\k50}ka{\k30}ra{\k20}o{\k10}ke
Dialogue: 0,0:00:17.00,0:00:20.00,Default,,0,0,0,,Line one\NLine two
Dialogue: 1,0:00:21.00,0:00:24.00,Default,,0,0,0,,{\an7}Top left
Output
<SAMI>
<HEAD>
<STYLE TYPE="text/css">
<!--
P { text-align: center; font-family: Arial, sans-serif; }
-->
</STYLE>
</HEAD>
<BODY>
<SYNC Start=1000>
<P>Hello there.
<SYNC Start=4000>
<P>
<SYNC Start=5000>
<P><i>Italic</i> and <b>bold</b> text.
<SYNC Start=8500>
<P>
<SYNC Start=9000>
<P>Positioned
<SYNC Start=12000>
<P>
<SYNC Start=13000>
<P><c>ka</c><c>ra</c><c>o</c><c>ke</c>
<SYNC Start=16000>
<P>
<SYNC Start=17000>
<P>Line one<br>Line two
<SYNC Start=20000>
<P>
<SYNC Start=21000>
<P>Top left
<SYNC Start=24000>
<P>
</BODY>
</SAMI>
Dropped in this output: styling, karaoke and format-specific content. Everything else matches line for line.
The same conversion on an awkward input
Input
[Script Info]
; 一份真实的脏文件：BOM + CRLF + 认不出的覆写码 + Comment + 坏时间码
Title: Dirty sample
ScriptType: v4.00+
[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,20,&H00FFFFFF,&H000000FF,&H00000000,&H00000000,1,0,0,0,100,100,0,0,1,2,2,2,10,10,10,1
[Fonts]
fontname: Arial
!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Comment: 0,0:00:00.00,0:00:01.00,Default,,0,0,0,,这是一条注释，不该变成字幕
Dialogue: 0,0:00:01.00,0:00:04.00,Default,,0,0,0,,Hello, world
Dialogue: 0,0:00:05.00,0:00:08.00,Default,,0,0,0,,{\fad(300,300)}Unmodelled override
Dialogue: 0,0:00:09.00,0:00:12.00,Default,,0,0,0,,{\an7\pos(320,240)}Both, wrong order
Dialogue: 0,0:00:13.00,0:00:16.5,Default,,0,0,0,,One decimal centisecond
Dialogue: 0,0:00:17.00,0:00:20.00,Default,,0,0,0,,Soft\nbreak
Dialogue: 0,0:00:xx.00,0:00:24.00,Default,,0,0,0,,Broken timecodeOutput
<SAMI>
<HEAD>
<STYLE TYPE="text/css">
<!--
P { text-align: center; font-family: Arial, sans-serif; }
-->
</STYLE>
</HEAD>
<BODY>
<SYNC Start=1000>
<P>Hello, world
<SYNC Start=4000>
<P>
<SYNC Start=5000>
<P>{\fad(300,300)}Unmodelled override
<SYNC Start=8000>
<P>
<SYNC Start=9000>
<P>Both, wrong order
<SYNC Start=12000>
<P>
<SYNC Start=13000>
<P>One decimal centisecond
<SYNC Start=16500>
<P>
<SYNC Start=17000>
<P>Soft<br>break
<SYNC Start=20000>
<P>
</BODY>
</SAMI>
This is the kind of damage real files have — mixed line endings, stray whitespace, fields left empty. Compare it with the tidy example above to see what the parser forgives.
Frequently asked questions
Which styling survives from ASS into SMI?
Emphasis, written into the text as tags: bold, italic, underline and a colour come out as `<b>`, `<i>`, `<u>` and `<font color="…">`, which browsers act on. What the SMI file will not carry is the style table ASS relies on — the font, its size, the outline, the shadow and the margins all go, and the page embedding the subtitles styles them from its own CSS instead.
What happens to karaoke timing from ASS to SMI?
The timing goes; the words stay. Karaoke lives in the `\k`, `\kf` and `\ko` codes an ASS event carries, which mark when each syllable lights up, and SMI has no way to record a moment inside a line — so the marks come off and the syllables arrive as ordinary SMI text.
What happens to ASS's `[Script Info]` block and the rest of the script in SMI?
Only the `Dialogue:` lines become subtitles. The `[Script Info]` block (title included — SMI has nowhere to put one), the style table, any `Comment:` lines and whatever is embedded in `[Fonts]` or `[Graphics]` are all dropped. For an ASS file whose styling was written by hand, this is the loss that shows most.
What does the output look like when ASS becomes SMI?
Like SMI: no cue numbers and no timecode line: every cue is a `<SYNC Start=…>` tag with its text in a `<P>` under it, and — because a SYNC replaces whatever was on screen — a `<P> ` block just after it that puts the screen back to empty. Every ASS cue becomes one SMI cue, in the same order, with the same text.
Are the ASS timings exact in the SMI file?
Yes, to the millisecond — which is as fine as either format goes. ASS writes a moment as `0:00:04.13` and SMI writes the same moment as `Start=4126`; nothing is rounded or shifted between the two, and a cue that was on screen for 2.9 seconds still is.
How does a two-line ASS cue come out in SMI?
As two lines with a `<br>` between them, which is how SAMI writes a hard line break. The pairing survives — the two ASS lines still belong to one subtitle in the SMI output, and a player shows them together.
Do ASS cues keep their order in the SMI output?
Yes, and they are sorted by start time on the way — earliest first, which is how every format here expects them and how players read them. If your ASS file listed its cues out of sequence, the SMI output puts them back in order; that is a change to the file's structure rather than its content, and it is deliberate.
Can I convert the SMI back to ASS?
Yes, and it has its own list: converting SMI to ASS drops precision and format-specific content. That list is different from the one above because the two formats keep different things.
Does the SMI output keep the ASS file's encoding?
No — the output is UTF-8, with Unix line endings and no byte-order mark, whatever the ASS file used. A file that arrives in UTF-16, or in a Windows single-byte encoding, is decoded on the way in (the result panel says so when that happens); what comes out is always the same UTF-8 SMI.