Comments on: What is “interoperable TTML”? http://blog.gingertech.net/2012/09/18/what-is-interoperable-ttml/ Silvia's blog Mon, 20 May 2013 17:30:39 +0000 hourly 1 http://wordpress.org/?v=3.1.1 By: John Birch http://blog.gingertech.net/2012/09/18/what-is-interoperable-ttml/comment-page-1/#comment-42214 John Birch Tue, 08 Jan 2013 11:40:52 +0000 http://blog.gingertech.net/?p=1733#comment-42214 EBU-TT is not intended (or promoted) as a format for players to decode (although technically it can be used this way). The primary targeted use of EBU-TT files is for document exchange between broadcasters, distributors etc. and captioneers / subtitlers. It is an authoring / exchange format for subtitles and captions, rather than a presentation format. This is why 'features' like images and scrolling are not present in EBU-TT - scrolling and DVB bitmaps are aspects of the presentation. not the content. EBU-TT is expected to be converted (by a broadcaster or distributor) into SMPTE-TT, SRT, WEB-VTT, line 21 closed captions etc. It is a precursor to the 'distribution' format, but deliberately based on DFXP to take advantage of the framework already established, and to make it easier to perform these anticipated 'publishing' conversions. EBU-TT is not intended (or promoted) as a format for players to decode (although technically it can be used this way). The primary targeted use of EBU-TT files is for document exchange between broadcasters, distributors etc. and captioneers / subtitlers. It is an authoring / exchange format for subtitles and captions, rather than a presentation format. This is why ‘features’ like images and scrolling are not present in EBU-TT – scrolling and DVB bitmaps are aspects of the presentation. not the content.

EBU-TT is expected to be converted (by a broadcaster or distributor) into SMPTE-TT, SRT, WEB-VTT, line 21 closed captions etc. It is a precursor to the ‘distribution’ format, but deliberately based on DFXP to take advantage of the framework already established, and to make it easier to perform these anticipated ‘publishing’ conversions.

]]> By: John Kemp http://blog.gingertech.net/2012/09/18/what-is-interoperable-ttml/comment-page-1/#comment-37509 John Kemp Fri, 21 Sep 2012 13:42:20 +0000 http://blog.gingertech.net/?p=1733#comment-37509 I have just implemented SMPTE TT support for a project I've been working on. In our case, we produce video for online delivery with captions already embedded in the video. Some vendors we work with claim that they cannot themselves extract the captions from the video, or display them as-is from the video, and require us to provide SMPTE TT as well as the actual video. Since this is required for compliance with regulations, I make the simplest possible SMPTE TT file. It contains only timecode and captions, with no layout information. I'd expect that will be one approach,and the other will be to use the SMPTE extension to store the caption blobs from the video without reformatting to produce the XML-formatted data. I have just implemented SMPTE TT support for a project I’ve been working on. In our case, we produce video for online delivery with captions already embedded in the video. Some vendors we work with claim that they cannot themselves extract the captions from the video, or display them as-is from the video, and require us to provide SMPTE TT as well as the actual video. Since this is required for compliance with regulations, I make the simplest possible SMPTE TT file. It contains only timecode and captions, with no layout information. I’d expect that will be one approach,and the other will be to use the SMPTE extension to store the caption blobs from the video without reformatting to produce the XML-formatted data.

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