How to Add an SRT to an MP4 with HandBrake

Soft subtitles or burned in?

Soft (selectable) track

The subtitles travel inside the file as text. Players that support them show a subtitle menu; viewers can turn them off. Quality is perfect at any size. Some players, TVs and apps ignore the track.

Burned in

The text is drawn into every frame. It shows everywhere, in every player, chat app and reupload, and can never be turned off or corrected without converting again.

A rule of thumb: soft subtitles for files that people will play in a proper player, burned in for files that go into messaging apps, social feeds, presentations or devices you don't control. Open vs closed captions covers the same choice in broader terms, and embedded vs sidecar subtitles adds a third option: leaving the SRT as a separate file.

Get the SRT right first

HandBrake places each cue exactly where the file says. Make the SRT from the same video you're converting, not from an earlier edit. Open it in a text editor and check names, numbers and line lengths before burning, since burned-in mistakes are permanent. How to edit an SRT file covers safe edits, and if the file shows broken characters such as é, save it as UTF-8 first; subtitles showing strange characters explains why.

Step by step in HandBrake

1. Open HandBrake and choose your video as the source.
2. Pick a preset that suits the destination (a general "Fast 1080p" style preset is a reasonable start) and set the output format to MP4 or MKV in the Summary tab.
3. Go to the Subtitles tab. Use the tracks menu to import a subtitle file and select your .srt. Check the language and the character encoding (UTF-8 for most files).
4. For a selectable track, leave Burn In unticked; tick Default if you want it to appear automatically in players that honour that flag.
5. For burned-in subtitles, tick Burn In. Only one track can be burned in.
6. Choose where to save, then start the encode.

When the encode finishes, open the result in a player and check the start, the middle and the end. If the subtitles are early or late by a constant amount, the import options in recent HandBrake versions let you set an offset; if they drift, the SRT came from a different cut, and syncing subtitles with video explains the fix.

MP4 or MKV for soft subtitles

MP4 stores soft subtitles as a simple text track. It plays on most phones, browsers and editors, but styling is minimal and some players don't show the track at all. MKV stores SRT text as it is (and can also hold styled formats), and players such as VLC and many media servers handle it well, but fewer phones, editors and websites accept MKV. If the file is for a phone or a website, MP4; for a media server or desktop player, MKV is often the smoother choice. The MKV vs MP4 comparison covers the containers in more depth.

Time and quality

HandBrake always re-encodes the video, so a long file takes a while: roughly from a fraction of the video's length to longer than real time, depending on your computer, the preset and the resolution. Re-encoding also loses a little quality compared with the original. To keep losses small, choose a preset at the source resolution and avoid converting the same file repeatedly. If you only need a switchable track and the destination accepts a separate file, skip HandBrake and deliver the SRT next to the original video: no encoding, no quality loss.

Where mydubly fits

mydubly makes the SRT; HandBrake puts it in the file. Upload your final video to the subtitle generator (the video stays on your device; only the audio is sent) and download SRT and VTT files in the spoken language or translated into one of 21 languages, for 1 credit per minute. For a voice version instead of subtitles, the AI dubbing page explains the dubbed MP4 you can download, and you can burn subtitles into that file the same way.

Mistakes and limits

• Burning in a file you haven't proofread. Fix names, numbers and long lines first; you can't fix them afterwards.
• Long lines across the frame. Automatic subtitles arrive one line per cue with no fixed limit; split long cues before burning in. Subtitle segmentation covers good break points.
• Expecting every player to show soft subtitles. Test on the device that matters.
• Expecting styling from SRT. HandBrake renders burned-in SRT with its default look; for custom fonts and positions, use a styled format such as ASS, made in a subtitle editor.
• Re-encoding a file that's already been compressed several times. Start from the best-quality master you have.

Several languages in one file

A soft-subtitle MP4 or MKV can carry more than one subtitle track. Import one SRT per language in the Subtitles tab, set each track's language, and leave Burn In unticked on all of them; players with a subtitle menu then offer every language. Burned-in subtitles are limited to one track, so for several languages you'd make one copy per language. What an SRT file is explains why each language needs its own file, and dual-language subtitles covers the special case of two languages shown together.