Free online MP4 to SRT converter

Source format: MP4

MP4 is a widely used video container format that can store video, audio, subtitles, and metadata in one file. It is commonly used by content creators, streaming platforms, mobile devices, cameras, and video editors because it offers broad compatibility and efficient compression. In an MP4 file, subtitle tracks may be embedded as timed text, but many MP4 files contain no subtitle data at all; they only contain the video and audio streams.

Target format: SRT

SRT is a simple subtitle text format used for captions and subtitles. It stores subtitle entries as numbered blocks with start and end timestamps plus the subtitle text. SRT is popular because it is lightweight, easy to edit, and supported by most media players, video editors, and subtitle tools. It is ideal for creating separate subtitle files that can be loaded alongside a video.

How to convert mp4 to srt

The right method depends on what your MP4 contains:

1. If the MP4 already has an embedded subtitle track, you can extract it to SRT with a subtitle tool such as FFmpeg or Subtitle Edit.
2. If the MP4 has no subtitles, you cannot directly convert video to SRT without first creating subtitles through transcription or OCR. In that case, use speech-to-text software or subtitle editing software to generate the captions.

Using FFmpeg to extract an existing subtitle track:

1. Check the streams in the file with ffmpeg -i input.mp4.
2. If a subtitle stream is present, extract it with ffmpeg -i input.mp4 -map 0:s:0 subtitles.srt.
3. Open the resulting subtitles.srt in a text editor or subtitle editor to verify timing and text.

This works best when the subtitle stream is already text-based. If the subtitles are image-based, they cannot be converted directly to SRT and must be OCR-processed first.

Using Subtitle Edit for extraction or creation:

1. Open the MP4 in Subtitle Edit.
2. If the file contains embedded subtitles, use the import option to extract them, or open the subtitle track if Subtitle Edit detects it.
3. If there are no subtitles, use the program’s speech recognition or Whisper-based tools to generate captions from the audio.
4. Review and correct the subtitles, then export them with File → Save as and choose SRT.

Using speech recognition for MP4 files without subtitles:

If your MP4 only contains spoken audio, the process is really transcription, not file conversion. Tools based on Whisper or other speech-to-text engines can create subtitle text with timestamps, which you can then save as .srt. Accuracy depends on audio quality, background noise, accents, and language support, so manual correction is often needed.

Notes on quality and limitations

MP4 to SRT is not always a true format conversion. If the MP4 contains an embedded subtitle track, the process is usually a straightforward extraction. If it does not, the conversion requires transcription of the spoken audio, which may introduce errors and usually needs manual correction.

Some embedded subtitle tracks in MP4 are stored as bitmap subtitles or in formats that do not convert cleanly to plain-text SRT. In those cases, OCR or manual retyping may be necessary. Also, SRT supports only basic subtitle text and timing; it does not preserve advanced styling, positioning, or rich formatting from more complex subtitle formats.

For best results, review the output in a subtitle editor and test it in your media player to confirm timing, line breaks, and character encoding.

You can also convert the file on 101convert.com for free, without installing any software, when the MP4 already contains speech that can be transcribed.