This also allows setting the language of different text streams from
the same input. Multiple streams can use the same input stream
using different cc_index values and can each use a different language.
This also will try to pull the language from the input if not
specified.
Change-Id: I7078710b509b7d77dad8cb4299a82f954af7e9e7
Note that this only supports a single page within the DVB-sub stream.
Multiple pages will be merged together. A follow-up will allow
selecting a specific page.
This only supports outputting using TTML or MP4+TTML; you cannot have
DVB-sub output nor can you output it in WebVTT. Since DVB-sub
uses images, it is hard to impossible to do this with WebVTT.
This also only supports interlaced images, not progressive images
nor text.
Closes#832
Change-Id: Id6dbb6393c7b9a05722e61c6bd255bef5e69a7d8
Jacob Trimble