Batch Soft Subtitle Muxing Tool

Batch mux SRT, ASS, and other subtitles into MP4 or MKV while preserving the original audio and video codecs

Browser execution mode: Your data is processed in your browser and is not uploaded to the server.

Speed and Stability: Processing speed depends on your device and browser. For large batch work, the desktop version may be more stable.

Loading tool, please wait...

If the online tool fails to load or run, try the desktop tool.https://tools.yikeaigc.com/

Tool Usage

Processing engine not loaded

Videos

Select or drop a video MP4、MKV、MOV、M4V

No video selected

Subtitle Tracks

Select or drop subtitle files SRT, ASS, SSA, VTT; multiple tracks supported

No subtitles selected

Muxing Settings

Output container MP4 subtitles will be encoded as mov_text

Existing Subtitle Tracks Video and audio always use stream copy

Subtitle Text Encoding

Subtitle time offset (sec) Positive delays, negative advances

MKV subtitle encoding

ZIP filename

Keep global and track metadata Keep chapter data Enable Fast Start for MP4 Fix negative timestamps

Packaging and report

Enable DEFLATE compression for ZIP contents Include muxing report in ZIP

Subtitle track metadata

Track language

Track name

Default subtitle track

Detect .default, .forced, and .sdh filename flags Mark all added tracks as forced Mark all added tracks as SDH

Pending0

Subtitle tracks0

Total size0 B

Completed0

Failed/Skipped0

Select video and subtitle files.

Results

Results appear after muxing

Instructions

Usage Instructions

Select a processing mode:
- Single-file muxing: Add one or more subtitle tracks to a video.
- Batch matching and muxing: Select multiple videos and subtitles to automatically create processing tasks based on file names.
Add videos and subtitles: Supported video formats are MP4, MKV, MOV, and M4V. Supported subtitle formats are SRT, ASS, SSA, and VTT. When selecting files in batches, the interface displays the first 20 files; all remaining files are still added to the processing queue.
Review batch matches:
- Smart language suffix matching: Match subtitles such as movie.zh.srt and movie.en.ass with movie.mp4.
- Exact names only: Match videos and subtitles only when their file names without extensions are identical.
- Unmatched videos: Choose to skip them and include them in the report, or continue remuxing them.
Set the output container:
- Match source video: MKV files remain MKV, while other supported videos are output as MP4.
- MP4: Subtitles are converted to mov_text as switchable subtitle tracks.
- MKV: Keep the original subtitle format or convert all subtitles to ASS, SRT, or WebVTT.
Configure subtitle track information: Set the language code, track name, default subtitle, forced subtitle, and subtitles for the deaf and hard of hearing. The .default, .forced, and .sdh tags in file names are also recognized.
Configure muxing options: Set subtitle character encoding, time offset, whether to append or replace existing subtitles, metadata, chapters, Fast Start, negative timestamp correction, and ZIP compression method.
Start muxing: Click “Start Muxing.” The tool copies the original video and audio streams and writes the subtitles to the output file as separate tracks.
Download results: Each result can be downloaded separately. Batch results are saved using the original video names, with numbers automatically appended to duplicate names. You can also download them together using “Download All Results as ZIP.”

Frequently Asked Questions

A: Soft subtitles are stored as separate tracks in the video container and can be enabled, disabled, or switched between languages during playback. Hardcoded subtitles are embedded in the video image and cannot be turned off separately. This tool processes switchable soft subtitles.

A: MP4 works well with text-based subtitles such as SRT, which are converted to mov_text during muxing. MKV supports SRT, ASS, SSA, and other subtitle formats, making it better suited for multilingual subtitles and styled ASS subtitles.

A: MP4 uses mov_text subtitle tracks, which cannot preserve fonts, positioning, or effects commands from ASS files. To preserve ASS styles, select MKV and set the subtitle codec to “Keep original subtitle format.”

A: The subtitle file can have exactly the same name as the video, or a language or track tag can be added after the video name. For example, movie.mp4 can match movie.srt, movie.zh.srt, movie.en.ass, and movie.zh.default.srt.

A: No. The video and audio are not re-encoded. This tool processes video and audio tracks using stream copying and only adds, replaces, or converts subtitle tracks, so it does not alter the original video quality or audio encoding quality.

A: First use “Auto-detect.” If the text is still garbled, manually select UTF-8, GB18030, Big5, Shift-JIS, or UTF-16 based on the subtitle source. Older Chinese subtitles commonly use GBK or Big5 encoding.

A: The first subtitle added can be set as the default, or it can be identified by the .default marker in the file name. Files with .forced in the name can automatically be marked as forced subtitles, while .sdh, .hi, or .cc identifies subtitles for the deaf and hard of hearing.

A: Video muxing requires files to be loaded into the current device’s memory. Process fewer files at a time, close memory-intensive programs, and process large videos in batches. ZIP contents can remain uncompressed to reduce additional processing and memory usage.

A: No. Output files use the original video names by default. If duplicate names are found, a number is added before the extension, such as video.mp4 and video(2).mp4, and all results are added to the ZIP.

Answer: No. Videos, subtitles, muxed output, and ZIP files are read and generated on the current device and are not sent to the server.