Friday, June 12, 2009

Closed Captions and Subtitles

This is Neil Hunt, Chief Product Officer at Netflix. We've had some inquiries about why Netflix doesn't yet provide closed captioning or subtitles for streaming movies and TV episodes. Captioning is in our development plans but is about a year away.

You might be asking how it could be so hard, since we already subtitle foreign language streams with English subtitles. These subtitles are "burned in" to the video stream at the time of encoding - they are so-called "open captions" that cannot be turned on and off by the viewer. The majority of viewers would object to English captions on English content, so we have to figure out how to let individual viewers turn them on and off.

Encoding a separate stream for each title is not an option - it takes us about 500 processor-months to make one encode through the entire library, and for this we would have to re-encode four different formats. Duplicating the encoded streams is prohibitive in space too.

So we are working on optionally delivering the SAMI file (Synchronized Accessible Media Interchange), or similar, to the client, and having it render the text and then overlay it on the video at playback time. Unfortunately, the tools for rendering SAMI files in Silverlight, or in CE (Consumer Electronics) devices, are weak or non-existent, and there is some technology development required.

I would expect to deliver subtitles or captions to Silverlight clients sometime in 2010, and roll the same technology out to each CE device as we are able to migrate the technology, and work with the CE manufacturer to deliver firmware updates for each player.