# Auto Captions in the Concat Video Editor

> Concat transcribes speech on your own computer with Whisper and places timed caption titles on the timeline, but you have to download a model first and CPU transcription is slow.

URL: https://concatvideoeditor.com/features/auto-captions
Updated: 2026-10-18
Source: Concat Video Editor Guide, an independent guide. Not the official Concat website.

Concat makes auto captions with Whisper, the open-source speech recognition model, running through whisper.cpp on your own computer. You pick a model, point it at the voice on your timeline and it adds one caption title per spoken phrase, cut to the timing of the words. Nothing gets uploaded and the Concat app adds no watermark.

![Captions dialog in the Concat video editor with Use voice from timeline switched on and the Base (English) model selected](/images/feat-captions.webp)

## How do you add auto captions in the Concat video editor?

1. Open **Settings**, go to **Transcriber** and download a model. For English speech, **Base (English)** is a good place to start.
2. Put the clip with the voice on the timeline.
3. Click the **T** button on the timeline toolbar to open **Captions**, then switch on **Use voice from timeline**.
4. Check that the **Audio** field shows the right clip, then set **Model** to the one you downloaded.
5. Choose a **Placement** (Bottom, Centre or Top) and a **Size** (Small, Medium or Large).
6. Click **Generate captions**.

Each phrase lands as its own title clip on the first track lane with free space. If Whisper mishears a word, you fix it the same way you would edit any other title.

## Which Whisper model should you download?

Start with Base unless your computer is slow or your audio is hard to make out. The Concat video editor offers three model sizes. Each one comes in an English version and a multilingual version.

| Model | Download size | Versions | Trade-off |
|---|---|---|---|
| Tiny | 78 MB | English, Multilingual | Fastest, rough on names and punctuation |
| Base | 148 MB | English, Multilingual | The middle ground most people want |
| Small | 488 MB | English, Multilingual | Better wording, noticeably slower |

The Transcriber page shows how many models you have installed and how much disk space they use. It also labels the whole list "Runs locally", so once a model is on disk you can caption without a connection.

![Transcriber settings in Concat listing Whisper Tiny, Base and Small models from 78 MB to 488 MB](/images/feat-transcriber-models.webp)

## How long does it take to add subtitles to a video?

Expect transcription to take a few times longer than the audio itself on a plain CPU. In our test of the Concat video editor 0.2.7 on Linux, Base (English) needed about 20 seconds to transcribe a 7 second voiceover. That machine used software rendering with no GPU help, so a newer laptop should do better. Tiny will also be faster if you can live with rougher text.

The finished 32 second 1080p project with captions then exported in about 40 seconds on the same machine.

![A 16:9 frame with white auto captions at the bottom, generated by Whisper in Concat](/images/ba-captions-after.webp)

## How does this compare with CapCut captions?

The biggest difference is where the work happens. In Concat the speech never leaves your disk and there is no account, credit or plan involved. If you are weighing Concat against CapCut for short clips, keep in mind that free CapCut exports top out at 1080p and Pro assets can add a watermark. The Concat video editor has neither catch. You can also read the code yourself on the Concat GitHub page.

## What are the limits?

- **Speed depends on your hardware.** At the rate we measured, a long recording will keep a plain CPU busy for a good while.
- **Accuracy follows the model.** Tiny gets names wrong often. Small writes better text but runs a few times slower.
- **Only three sizes.** Small is the largest model offered in 0.2.7.
- **You need the download first.** Plan for 78 MB to 488 MB per model.
- **It is beta software.** The Concat video editor is still marked beta, so read through the captions once before you export.

## Videos

### Video: Before and after: auto captions in Concat

Raw footage on the left and the same moment exported from the Concat video editor with auto captions on the right. (6 seconds, https://concatvideoeditor.com/videos/loop-captions.mp4)

### Video: Auto captions in the Concat video editor

Screen recording of Concat 0.2.7: generate a voiceover from a typed script, caption the clip from that voice with Whisper, then open the caption to restyle it. (23 seconds, https://concatvideoeditor.com/videos/demo-auto-captions.mp4)

Steps shown:
1. Type a script and generate a voiceover
2. Generate captions from that voice
3. Click a caption to edit and restyle it

## Questions people ask

### Are auto captions in Concat free?

Yes. The captions feature and the Whisper models cost nothing and need no account. The export carries no watermark either.

### Does Concat upload my audio to make captions?

No. Whisper runs through whisper.cpp on your own machine and the Transcriber settings page marks every model as running locally. After the model download you can caption offline.

### Can Concat caption speech that is not in English?

Yes. Tiny, Base and Small each come in a multilingual version next to the English one. Pick the multilingual build in Settings > Transcriber if your speaker uses another language.

### Does Concat burn captions into the video?

Yes. Captions in Concat are title clips on the timeline, so they are rendered into the picture when you export. We did not see a separate subtitle file option such as SRT on the 0.2.7 export screen.