How to generate subtitles for your PeerTube video

Adding subtitles to videos is important for accessibility, but also broader engagement with users that might not have sound turned on.

Unfortunately, many tools available require paid, expensive, proprietary subscriptions. Luckily, Vosk, a "speech recognition toolkit," can automatically generate subtitles for you in SRT format, to be added to your PeerTube videos.

Note: The below procedure is technical and requires command line knowledge. If you are not comfortable working in the command line and your video is on urbanists.video, DM @video@urbanists.social for help to get your subtitles generated. 🙂

Download your video

If you have already uploaded your video to PeerTube, download it. That can be done on the video page. Download the lowest quality version since Vosk just analyzes audio.

If the video opens in browser instead of downloading, simply right click the video and press "Save video as..."

Installation

To install Vosk, you will need pip3. pip3 is bundled with Python 3. Additionally, you will need ffmpeg to extract audio from the video file.

Install dependencies

pip3 and ffmpeg are prerequisites.

For macOS

Install Homebrew, then run:

brew install python3 ffmpeg

For Windows

You can install python 3 via the Microsoft Store. Alternatively, download an install from python.org. Then, download and install ffmpeg.

Install Vosk

Once you have pip3 and ffmpeg, install Vosk:

pip3 install vosk

Optional: Download Vosk model

Download the high quality language model for better transcription quality. For English, vosk-model-en-us-0.42-gigaspeech.

That can be found here: https://alphacephei.com/vosk/models

Extract it into a directory alongside your video file.

Run it

Run vosk-transcriber from the directory with your extracted Vosk model folder and video file:

vosk-transcriber -i MY_VIDEO.mp4 -t srt -o sub_en.srt -m vosk-model-en-us-0.42-gigaspeech

• Replace MY_VIDEO.mp4 with your video filename.
• You can also use a different language by downloading a different model and setting -l, for example, -l fr for French.
• You can omit -m vosk-model-en-us-0.42-gigaspeech if you didn't download the higher quality model

After a short while you will get the subtitles in an SRT file format. 🎉

Upload and cleanup

You can upload this .srt file via your PeerTube video settings. Once uploaded you can edit the raw file to fix any transcription errors. Alternatively, you can use subtitle editing software such as subtitleedit or edit with your text editor of choice.

All done!

That's it! Thanks for taking the time to add subtitles to your video, it really helps. 🥰 Finally, please reach out via Mastodon if you know of a GUI for Vosk that makes this process easier and more accessible!