Dual Subtitles Maker: Two Languages in One File

How to use the dual subtitles maker

1. Add the main-language file first; its card is labelled "Main language", with a note on where that line will sit in the layout you pick. Then add the other file, labelled "Second language". Any text format the subtitle tools read works, including SRT, VTT, ASS, SBV and TTML. To swap them, remove a file and add it again.
2. Under "Layout", choose "Both languages stacked at the bottom" or "One at the bottom, one at the top (ASS)".
3. For the stacked layout, decide on "Second language in italics" and pick SRT or ASS under "Save as". The top-and-bottom layout always saves ASS.
4. Check the preview panel. In the stacked layout it shows both languages for the first subtitles, without italics; in the top-and-bottom layout it lists the main language only.
5. Press "Combine languages and download". The file is named after the main-language file with "-dual" added.

How the stacked layout pairs lines

Two subtitle files for the same film rarely line up one to one. Translators merge short lines, split long ones and time them slightly differently, so cue 112 in English is seldom cue 112 in Spanish. The tool therefore ignores cue numbers. Each second-language subtitle is attached to the main-language subtitle it overlaps most in time, and the main file supplies all the timing.

Stacked result

one subtitle, 00:02:10,000 --> 00:02:13,400: the English sentence on the first line, "Te dije que no tocaras la radio." on the second

Things that follow from this:

• When two second-language subtitles fall inside one main subtitle, they are joined with a space, as above.
• Each language is flattened to a single line, so a two-line English subtitle becomes one longer line. Players wrap long lines on their own.
• A main subtitle with no overlapping partner is written in the main language only.
• A second-language subtitle that overlaps no main subtitle at all is left out. This happens with translated signs or song lyrics that exist only in the second file. After saving, the status message says how many were left out, so check scenes with on-screen text if the number isn't zero.
• In the stacked layout the main language is written first, so it is the upper of the two lines; in the top-and-bottom layout it sits at the bottom of the screen.

Pairing by overlap works only if both files are timed to the same video. If the second file was made for a release at a different frame rate, the lines drift further apart as the film goes on and start pairing with the wrong partners. Retime that file first with the subtitle frame rate converter, for example from 23.976 to 25 fps, then combine.

Stacked SRT or top-and-bottom ASS

Stacked SRT

plays almost anywhere SRT does, including TVs, VLC and the mydubly subtitle editor; both languages share one block at the bottom

Stacked ASS

the same paired text in an ASS file, with the italic second line written as ASS italic tags so players that render ASS show it slanted

Top and bottom ASS

no pairing at all: each file keeps its own timing and line breaks, the main language uses a bottom-centred style and the second language a top-centred one

The ASS styles are fixed: Arial at 64 in a 1920×1080 script, white text with a black outline, 60 pixels from the edge. To change fonts or sizes, open the file in an ASS editor such as Aegisub. ASS needs a player with a full ASS renderer, such as VLC or mpv; many TVs, phones and web platforms ignore the styling or the whole file. The ASS vs SRT comparison covers where each format works.

Keeping two languages readable

Professional style guides usually limit a subtitle to two lines, and dual subtitles break that rule by design. A few habits help:

• Pick the better-timed file as the main language, since its timing is used for both. Usually that is the file made from the original audio.
• Keep source lines short. Long subtitles become long single lines when stacked, and four lines of text cover a lot of picture.
• If the picture has room at the top, the top-and-bottom layout spreads the text out and lets each language keep its own timing.
• Learners often read one language and glance at the other, so italics or a smaller second line help the eye separate them.

For background on when bilingual subtitles help and how viewers use them, read the dual-language subtitles guide.

Burning both languages into the video

Streaming apps, social platforms and many TVs show only one subtitle track at a time, and some media players can show a second track alongside the first, but only on the device where they run. To make both languages visible everywhere, put them into the picture. Save a stacked SRT, open the video and that SRT in the free subtitle editor, choose a style and render an MP4 with the subtitles burned in. The editor uses one style for the whole video, so the italic marking is dropped and both lines look the same. It doesn't import ASS, so use the stacked SRT. Expect its long-line warning to fire, since each language is one line. Rendering needs Chrome or Edge 94+, Safari 16.4+ or Firefox 130+ on a computer; burning translated subtitles walks through the rest.

If you only have one language

This tool combines two existing files; it does not translate. If you have the video but only one subtitle file, the video translator can produce subtitles in another of its 21 languages from the video's audio. Download that SRT and combine it here with the one you have.

Limits

• Exactly two files. Files over 20 MB are refused; image-based subtitles such as VobSub can't be read.
• Files that are not UTF-8 or UTF-16 are read as Windows-1252, with a note on the card. Fix wrong letters before combining, or they carry into the result.
• To join files from consecutive parts of a film rather than two languages, use merge SRT files.