Audio & Video · Local processing

Video Subtitle Burner

Put readable captions directly into your video. Open SRT or VTT subtitles, adjust timing and styling, and preview the active captions before exporting.

Local file processingMP4 & WebMPreview before download

1. Open your video

One file up to 150 MiB. Select up to 2 minutes of output; up to 1080p landscape or portrait. The local engine loads about 31 MiB on first use.

No file loaded.

Choose a file or try the example.

2. Prepare the captions

Video formatDownload filename

Your captions

Subtitle text · original video timing

No captions loaded.

Timing offset (seconds)Caption size (output px)Vertical margin (output px)Outline thickness (px)Caption positionText colorOutline color

Plain text only. Formatting tags and VTT placement are not interpreted. Uses the existing Liberation Sans font (Latin, Greek and Cyrillic); other scripts may show missing glyphs. Captions become permanent pixels. No automatic transcription.

Choose a time range

Start (seconds)End (seconds)

Output size & compression

Output width (px)Output height (px)Keep cropped aspect ratioFit within output frameOutput frames per secondCompression level · lower = sharperApproximate target size (MiB) · 0 = quality modeRemove audio

Quality mode uses CRF. Target size calculates a bitrate, including an allowance for audio and overhead; it cannot guarantee an exact size. Exports re-encode and may be larger than an efficient original.

Crop, rotate & flip

Drag across the source frame to crop, or enter exact pixels. Crop is applied before rotation. The preview shows the planned output.

Crop X (source px)Crop Y (source px)Crop width (source px)Crop height (source px)Rotate clockwiseFlip horizontallyFlip vertically

Audio finishing · speed, fades & volume

Audio sample rateOutput channelsLossy audio bitrateSpeed · pitch preservedAudio fade in (seconds)Audio fade out (seconds)

Volume change (dB)NormalizationPeak normalization target (dBFS)Protect against new excessive peaksGently compress loud passages

Peak normalization measures the selected audio first, with a maximum boost of 30 dB. Loudness modes are one-pass targets. Extra gain is applied afterward; protection can reduce it. Already clipped detail cannot be restored.

Hiss reduction (dB)Estimated noise floor (dBFS)Electrical hum removalCut low rumble below (Hz)Cut high frequencies above (Hz) · 0 = off

For steady hiss and hum. Strong settings can damage speech and music. Compare the original and result; this does not separate speakers or remove every kind of noise.

Keep or restore your settings

Settings do not contain your file. Reopen the same source before restoring them.

Load a file to see the export plan.

3. Preview & compare

Original file

Choose a video to preview its framing

Planned frame & caption preview

Processing runs on your device. No account or processing upload is needed. Keep the tab open while working. Browser memory and source codecs can limit which files succeed; a short test clip helps you check the result.

Using Video Subtitle Burner

Put readable captions directly into your video. Open SRT or VTT subtitles, adjust timing and styling, and preview the active captions before exporting.

Choose one local file, drop it into the upload area, or try the built-in example. Review the source and file information.
Start with a quick preset. Adjust the main controls, then open Extra controls for trimming, quality and other finishing changes.
Process the selection, compare the original and result, then download. Save the report if you want to keep a record of settings.

Example

Try the moving-color example. Keep seconds 1–4, select a sharing preset and compare the measured file size.
Use a short clip first to check framing, audio and caption timing.

Questions & answers

Are my files uploaded for processing?

No. Conversion runs in this browser using the locally hosted FFmpeg engine. Media is not automatically saved. Public pages include advertising and site services described in the privacy policy.

Which input files work?

Common unencrypted MP3, WAV, FLAC, AAC/M4A, Ogg, MP4, MOV and WebM files can be processed by the local engine. Browser source previews support fewer codecs. Protected media, unusual codecs and damaged files may fail; output errors are shown instead of a download.

Why does conversion take time?

The local engine loads about 31 MiB on first use. Processing uses your device and can take longer than the selected clip, especially for high-resolution video. Keep the tab open. Cancel releases the engine and preserves your loaded file.

Are quality, tags and tracks preserved?

These tools re-encode the selected media. Lossy formats change quality. Exports remove source metadata and use the first audio track and, for video, the first video track. Other tracks, chapters and soft subtitles are not carried over. Keep your original.

What can I save?

Download the processed file and an optional settings/report JSON. Reports include your chosen settings and measured file sizes, not the source media. Nothing is saved automatically.

Are captions permanent?

Yes. Burned captions become pixels in the video and cannot be switched off. Keep your original video and SRT/VTT file. This tool does not generate subtitles from speech.

Which subtitle styling works?

Plain cue text, line breaks, size, color, outline, alignment and a vertical margin. HTML/VTT positioning, inline formatting and word-level karaoke are not interpreted. Text is burned with a locally hosted Liberation Sans font; some scripts require fonts not included here.

How is timing applied?

Subtitle times belong to the original video. Apply a global offset, then trimming and speed move those times to the exported clip. Overlapping cues are retained. A cue list and preview show what will appear.