Google unveiled new technologies that will automatically bring text captions to many videos on the site. This the technology can only insert captions on English language speech. This could broaden the appeal of You Tube videos to millions of people around the world. The company said this would be available by the end of the week.

People who do not speak English, Google giving users the choice to use its automatic translation system to read the captions in 51 languages, this enables the users to use the captioning technology to read subtitles in their native language.

You Tube already has several hundred thousand videos that have closed captions, which typically come from broadcast networks that include them in their programs. But Mr. Harrenstien said the vast majority of clips on You Tube do not have captions and the new Google technology will generate them automatically. You Tube is initially applying the captioning technology only to a few channels, most of them specializing in educational content.

The company plans to gradually expand the number of channels that work with the automatic captioning technology. Mr. Harrenstien said that sometimes the auto-captions are good. Sometimes they are not great, but they are better than nothing if you are hearing impaired or don’t know the language.

Google also introduced a related service that gives anyone who uploads a video to You Tube the option to also upload a text file of the words spoken in the video. Google will turn the text file into captions, automatically matching the spoken words with the files. In addition to helping people who are deaf or do not speak English, the captions will make it easier for anyone to search text inside videos and find specific snippets within a video.