Repurposing TV Closed Caption Files for Internet Video Distribution

More than 48 million Americans have hearing loss and rely on closed captions to comprehend TV shows. Others whose native language is not English rely on closed captioning for improved comprehension and fluency.

Telestream Vantage transcoder automates the conversion process from TV captions to SMPTE-complaint Internet captions via watch folders.

To accommodate these groups and others, the U.S. Congress recently passed a new closed captioning law. The new law and FCC rules require broadcasters to caption Internet-distributed video files if the content was broadcast on TV with captions. A March 30, 2014, deadline by the FCC mandates that clips on the Internet must be captioned within 45 days of the programming's television airing.

Repurposing television closed captioning files for the web offers the benefits of obeying the law and reaching a wider audience, but it also presents technical challenges. These challenges can be met more easily when those who must convert TV videos to the Internet have information about the best options.

File Conversion Challenges

Most captioning files for television are created using authoring software designed to work with TV signals in broadcast control rooms, not with Internet protocol (IP) video. As a result, TV caption files may be archived in text file formats that cannot be used with most Internet video players.

Closed caption files for the Internet, on the other hand, can include a variety of different file formats. For example, many developers use timed text markup language, or TTML XML (formerly known as DFXP), for Flash video players. However, Flash video players potentially can support a variety of caption file formats. YouTube's Flash video player supports TTML, for example, but also supports SRT, SCC and WebVTT.

Some Internet caption files are very simple and support only basic features such as timing and line breaks. Other more advanced Internet caption files, such as QuickTime closed caption track WebVTT and SMPTE Timed Text 2052, offer extensive captioning options, including positioning and text animation.

Because of the differences in formats, and also in the content itself, conversion from web to TV can be complicated. In many cases, TV audio or video content may have to be corrected in the following ways prior to Internet deployment:

Segment breaks of five to ten seconds to accommodate commercials may have to be removed.

A video may require separating into parts or combining parts into one video.

Certain music and sounds prohibited by copyright laws from Internet distribution may need to be removed or replaced.

Internet distributors may require original unedited 23.98 fps video without commercials, rather than TV broadcast files at 29.97 fps. As a result, the TV closed caption file created for 29.97 fps will not match the 23.98 fps video timing.

In each case, modifying or deleting elements could desynchronize or delete the captioning data.

Telestream Vantage transcoder automates the conversion process from TV captions to SMPTE-complaint Internet captions via watch folders.

LINK:	http://www.tvtechnology.com/news/0110/repurposing-tv-closed-caption-fi...
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