Google has introduced automatic captioning across all of YouTube's English-language channels, a move intended to make the site's videos more accessible to the hearing-impaired, opening it up to an audience that includes Britain's nine million deaf or hearing-impaired people.
Automatic captioning should also make YouTube videos more accessible to non-English speakers, while making video content more easily searchable, YouTube said on Thursday.
The auto-captioning uses speech-to-text algorithms found in Google's Voice Search to generate captions that can then be downloaded and corrected by users. The launch of automatic captioning follows a test period when the service was available for a restricted number of educational videos.
Google said the feature could be attractive to viewers, who can request captions for particular videos, as well as to uploaders.
"For content owners, the power of auto-captioning is significant. With just a few quick clicks your videos can be accessed by a whole new global audience," Hiroto Tokusei, a YouTube product manager, said in a blog post.
The company stressed that the speech-to-text feature has a number of limitations, and said content owners need to check the captions are accurate. Only videos with a clearly spoken, English-language audio track can be processed, it said.
Content uploaders can immediately take advantage of auto-captioning, and Google said it is looking to process all past user uploads that meet the feature's technical restrictions. The company has published guides for users and for uploaders on its website.
Viewers can choose to auto-translate English-language captions to other languages, and Google said it is looking to expand auto-captioning to more languages "in the months to come".
Google has pressed ahead with adding new features to YouTube, partly as a way of increasing revenues for the largely advertising-driven site. In December David Eun, Google's vice president of content partnerships, said the company was considering introducing paid subscriptions to view movies and TV shows as a way to attract premium content to the site.
In July, Google said YouTube revenues were increasing steadily and that the site was moving towards profitability in the near future.