Convert TXT to SUB Online

How to Convert TXT to SUB Online

1. Upload Your TXT File: Drag and drop the .txt file or click "Add Files" to pick it from disk. You can also paste the transcript text directly into the editor. Batch is supported — queue multiple text files and convert them in one pass. Files never leave your browser session.
2. Confirm SUB as the Target Format: SUB is already selected as the output. XConvert writes the SubViewer 2.0 variant of .sub — time-based cues with HH:MM:SS.cc start/end stamps and an [INFORMATION] header — not the legacy MicroDVD frame-numbered variant that drifts when the video FPS changes.
3. Review the Cue Mapping (Optional): XConvert reads timestamps already present in your TXT (formats like 00:00:12,500 --> 00:00:15,000, [00:01:23], or MM:SS Speaker: lines) and pairs each line with start/end cues. If your TXT has no timestamps, the parser assigns default cue durations so you can fine-tune timing afterward in Aegisub or Subtitle Edit.
4. Convert and Download: Click Convert. Everything runs in your browser session — no upload to a server, no sign-up, no watermark. Output is a clean SubViewer-format .sub ready for VLC, MPC-HC, KMPlayer, or DVD-authoring tools.

Why Convert TXT to SUB?

Plain .txt is how most transcripts land on disk — exported from a transcription service, copy-pasted from a Word doc, dictated into a notes app, or downloaded as a YouTube auto-caption file. A raw text file has no timing structure, so it can't be loaded as a sidecar subtitle by a media player. Converting to SUB (SubViewer) wraps each line in proper cue timestamps and gives you a file that players will display alongside the video. Common reasons people make this switch:

• VLC, MPC-HC, KMPlayer playback — Older and lightweight media players auto-load .sub from the video folder. VLC supports SubViewer and MicroDVD; MPC-HC and KMPlayer ship with strong SubViewer compatibility, which is why XConvert writes the SubViewer flavor.
• DVD and Blu-ray authoring — DVDStyler, ConvertXtoDVD, and similar burning tools accept SubViewer .sub as a soft-subtitle source. WebVTT and many TTML variants aren't recognised by older disc-authoring chains.
• Hand-off to subtitle editors — Aegisub, Subtitle Edit, and Subtitle Workshop open .sub natively. Translators and proofreaders often prefer the cleaner SubViewer structure when working from a raw transcript.
• Legacy set-top boxes and smart TVs — Pre-2018 smart TVs and many DLNA media servers still expect .srt or .sub next to the video file on a USB drive. WebVTT support is inconsistent on hardware that old.
• Archival of a transcript with timing — Once a transcript has cue timestamps, it stops being a wall of text and becomes a navigable artefact. SubViewer 2.0 has been frozen for years, which makes it a stable long-term archive format for captions paired with video.
• Stripping doc-format noise — Pasting from Word or Google Docs into TXT often carries smart quotes, page-break markers, and stray whitespace. The conversion normalises encoding to UTF-8 and drops anything that isn't a caption line, so the resulting .sub is clean.

If you'd rather end up with the most universally supported subtitle format, SRT is generally a safer pick than SUB — same time-based cue model, broader player support. Use Audio Cutter or Video Cutter first if you need to trim the source media to match your transcript before authoring subtitles.

TXT vs SUB — Format Comparison

Property	TXT	SUB (SubViewer 2.0)
Type	Plain text	Subtitle file with timed cues
Timing model	None (free-form text)	Time-based (HH:MM:SS.cc, centiseconds)
FPS dependent?	N/A	No (SubViewer is time-based; MicroDVD .sub IS frame-based)
Header / metadata	None	[INFORMATION] block with [TITLE], [AUTHOR], [FONT]
Styling	None	Basic <b>, <i>, <u> only
Line breaks	Native newlines	[br] inside a cue (SubViewer v2 addition)
Player support	Text editors only	VLC, MPC-HC, KMPlayer, PotPlayer, Kodi (desktop players)
Typical use	Transcripts, drafts, notes	Sidecar subtitles for desktop playback, DVD authoring

Two Flavors of .sub — Know Which One You Need

The .sub extension is shared by two unrelated formats. XConvert writes the SubViewer flavor by default because it survives frame-rate changes; here's how to tell them apart:

Flavor	Timing	First-line marker	Behavior at 23.976 vs 25 fps
SubViewer 2.0	00:01:23.45,00:01:25.12 (centiseconds)	[INFORMATION] header	Identical — FPS-independent
MicroDVD	{1000}{1200}Text (frame numbers)	{1}{1}23.976 or similar fps marker	Drifts — must be re-converted for new fps

If your downstream player or workflow specifically requires MicroDVD frame-stamped .sub (rare in 2026 — mostly very old DivX-era hardware), convert to SRT first and run a separate frame-stamping pass. For everything else — VLC, MPC-HC, DVD-authoring, smart-TV USB playback — SubViewer is the right .sub.

Frequently Asked Questions

My TXT file has no timestamps — will the SUB file still play?

Yes, but every cue will use the parser's default duration (one cue per line, fixed gap between cues), which almost certainly won't match your video. The result is playable as a captions file, but the timing is a starting point, not a finished subtitle. Open the .sub in Aegisub or Subtitle Edit and use their audio-waveform timing tools to drag each cue to the right position — much faster than typing timestamps by hand.

What timestamp formats does the parser recognise in the source TXT?

The common ones: SRT-style 00:00:12,500 --> 00:00:15,000, bracketed [00:01:23] or [01:23.45], transcription-style 00:01:23 Speaker: text, and YouTube-style MM:SS at the start of a line. If your file has a non-standard timestamp pattern (e.g., (at 1:23)), strip or normalise it in a text editor first — anything not recognised as a cue boundary gets folded into the previous caption's text.

Will the .sub file work with my Samsung / LG smart TV via USB?

Usually yes for SubViewer .sub, but smart TV subtitle support varies by year and model. As a rule of thumb: if your TV plays .srt from a USB stick, it almost certainly accepts SubViewer .sub too. If you see "subtitle format not supported," the safest fallback is SRT — broadest device support of any sidecar subtitle format. Make sure the subtitle file's base name matches the video file (e.g., Movie.mkv and Movie.sub in the same folder).

Why doesn't VLC load my converted .sub?

VLC reads both SubViewer and MicroDVD .sub and picks one parser based on the first line: [INFORMATION] triggers the SubViewer parser, {1}{1}... triggers MicroDVD. XConvert's output opens with [INFORMATION], so VLC reads it as SubViewer. If VLC still ignores the file, check (a) filename matches the video, (b) the file is in the same folder, and (c) "Subtitle Track" under Video isn't set to "Disable." VLC's auto-load behaviour is filename-based, not content-based.

Is SubViewer frame-rate dependent like MicroDVD?

No — that's the most common mix-up because both use .sub. SubViewer uses real timestamps (HH:MM:SS.cc), so it plays at the right time regardless of whether the video is 23.976, 24, 25, 29.97, or 60 fps. MicroDVD uses frame numbers {start}{end} and DOES drift if the video frame rate changes. XConvert writes the SubViewer flavor specifically to sidestep that whole class of sync bug.

What encoding does the SUB file use?

UTF-8 by default, which handles every language including CJK, Arabic, Cyrillic, Hebrew, and emoji. Some very old players (early-2000s DivX boxes, some hardware DVD players) expect ANSI / Windows-1252 and may show mojibake on UTF-8 files. In that case, open the resulting .sub in a text editor that lets you re-save as Windows-1252 or ISO-8859-1. Modern players — VLC, MPC-HC, PotPlayer, Kodi, Plex — all read UTF-8 SubViewer correctly.

Can I batch-convert a whole season of transcripts at once?

Yes. Drop the entire folder of .txt files into the queue and they all process in parallel in your browser. There's no per-file or quantity cap because nothing leaves your machine. Output filenames mirror the input (e.g., S01E01.en.txt → S01E01.en.sub) so they auto-pair with the matching video files in players that do filename-based subtitle loading.

How do I add basic styling like italics?

SubViewer supports <b>, <i>, and <u> inline tags. If you put those into the source TXT around the words you want emphasised (e.g., <i>whispered</i>), they pass through into the SUB file and most players will honour them. SubViewer doesn't carry colours, fonts, sizes, or positioning — for full styling control, the right format is ASS/SSA, not SUB.

Will line breaks in my TXT survive?

A blank line in the source TXT is treated as a cue separator, not as a line break inside a cue. To force a line break inside a single caption (so the words wrap onto two display lines), use [br] between the words in your TXT — that's SubViewer 2.0's documented line-break marker, and XConvert preserves it.