I turned on captions for my account on YouTube a while ago when testing something, and forgot to turn them off. Then I realised that almost every YouTube video has captions, whether the owner knew about them or not. It also didn’t take long to realise that the quality of captions left a lot to be desired, as they often didn’t (sometimes to comic effect) match the audio.
In 2006, YouTube introduced the ability to upload captions for your video content, and then in 2009 Google brought captioning together with Automatic Speech Recognition (ASR). Together they became YouTube Auto-caps, and made it possible for captions to be automatically created for your video content.
Now activating the captions in the YouTube player causes Auto-caps to kick in and create captions on the fly as the video plays.
Quick recap: captions display the spoken dialogue and important sound effects from your video as on-screen text, synchronised with the original video soundtrack. They make it possible for deaf and hard of hearing people to understand video content with audio and, because they’re text-based captions, they also make your video content easier for search engines to index.
Despite the extraordinary difference Auto-caps have made to the availability of captioned content, from the outset it was clear that even Google’s ASR technology wasn’t perfect. Almost immediately examples of captioning bloopers began to appear, much to the amusement of consumers (if not to the video owners).