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Subtitle Burn-In Composer

Burn reviewed plain subtitle cues into a local video and save a captioned WebM.

Files stay on your device No sign-up Free to use
How this works

The tool runs in this browser. Your file or text is not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

Privacy details

Drop your file here

or choose one from your device

One browser-decodable MP4/MOV or WebM, one video track and at most one audio track. Total selected media up to 256 MiB; video up to 60 minutes and 8.3 megapixels.

    Plain SRT or WebVTT, up to 200 cues. Formatting and position settings require the explicit discard option.

    How to use Subtitle Burn-In Composer

    1. Choose a supported video and paste reviewed plain SRT or WebVTT cues.
    2. Choose the source start, output length, caption position, color and size.
    3. Render with the tab visible, then watch each caption before saving the WebM.

    Example: Subtitle Burn-In Composer

    Burn one cue into a silent clip.

    You add
    Source: two-second silent video, 640 × 360. SRT: 1 00:00:00,500 --> 00:00:01,500 Hello. Start: 0; duration: 2; font size: 24; color: #ffffff; position: Bottom; discard formatting: off.
    You get
    The WebM shows Hello. during the cue interval near the bottom of the frame and retains zero audio tracks. Its report states the measured recording duration.

    Options

    Source start and output seconds
    Choose the input segment here. Cue timestamps still refer to the original source timeline.
    Caption size, color and position
    Font size is measured in output pixels. Top or bottom places the whole block; it must fit inside the bounded frame.

    Supported inputs and limits

    Selected files256 MiB total
    Supported duration120 source seconds
    Local MP4/MOV-family or WebM input, up to 256 MiB and 60 minutes, with frames up to 4K and one video track. Record a selected interval up to 10 minutes as WebM, within 128 MiB and 1080p. Keep the page visible during real-time recording. Up to 200 subtitle cues; overlapping cues, more than four rendered lines or text that cannot fit the frame are refused. Unsupported styling requires explicit discard permission. Burned text cannot be switched off in a player. Native codec support, frame timing and audio capture vary; no MP4 export or metadata preservation.

    Where your input is processed

    This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

    Cue times belong to the source timeline

    The source-start control selects a segment of the input video. Subtitle times still refer to that input timeline; they are not automatically retimed from zero. Preview cues at both ends of the segment and check that the entered text belongs to the selected recording.

    Plain captions keep a small editing scope

    The renderer supports its own font-size, color and top/bottom placement controls. Subtitle styling and position settings are not a full layout language here. When you permit their removal, review the loss report and the rendered text; do not assume an original styled subtitle looks identical.

    Questions about Subtitle Burn-In Composer

    Can viewers turn these captions off?

    No. They are drawn into the recorded video frames. Keep a separate subtitle file when a switchable track is needed.

    Do cue times restart when source start changes?

    No. Subtitle times refer to the source video timeline. Check the cues against your selected source segment.

    Is my input uploaded?

    Nothing is uploaded.

    Project manager: Tony Hines · Content updated 4 October 2026 · Report a problem

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