Embedding subtitles in mediasite player

I recently wrote about our extracting video and audio from recordings produced Sonic Foundry Mediasite recorders.

We want to embed the subtitles I produced (and uploaded to youtube here) in the standalone mediasite player (screenshot below). 

The standalone mediasite player is really interesting because all of the timecode for slides are automatically detected, and there is built in support for closed caption display (i.e. no need for overlays like universalsubtitles.org)

I started off by scanning the standalone mediasite player javascript and HTML sourcecode to find configuration options for captions or subtitles. I found a promising lead in the standalone-manifest.js file (among many other matches, Sonic Foundry have very strong support for captioning and accessibility).

$ grep -Ri 'caption' *

I then dropped in the  edited this to point to our SRT file in the Content directory. The mediasite player directory structure looks like this:

$ find . -d 1 -type d

This didn't work properly (the CC icon appears in the interface, but no closed captions are overlaid). I dug a little deeper and found that there is support for the Microsoft SAMI subtitling format.

$ grep -Ri 'SAMI' *
Players/Scripts/SamiDropDownArea.js: this.IsClosedCaptioningVisible = false;

I was thinking maybe the silverlight-based mediasite player might detect SAMI subtitle streams in the "video.wmv" inside the content folder, so I asked ffmpeg to blend the subtitle stream with the existing video:

ffmpeg -i video.wmv -i subtitles.srt -acodec copy -vcodec copy -scodec srt output.wmv

... but that didn't work.

Could not write header for output file #0 (incorrect codec parameters ?)

I found some really useful information on the microsoft SAMI (or SMI) subtitling and captioning format and I found some vintage windows media encoding tools from 1999 (Space... 1999!) which claimed to be able to embed subtitles in a windows media format.

... but that didn't work either.

I also found a really interesting homemade tool for converting between SRT and SAMI (or SMI)

Unfortunately none of these approaches (coupled with corresponding changes to the standalone-manifest.js file) have persuaded the standalone mediasite player to display subtitles. ;o(

My next port of call is the sonic foundry technical support, and/or user group community.

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