[gst-devel] few newbie questions....

Martin Soto soto at informatik.uni-kl.de
Thu Feb 23 04:17:05 CET 2006

On Thu, 2006-02-23 at 05:24 +0000, srikanth wrote:
> 1) how are these subtitles fonts are supported i mean where this font file are
> stored in a dvd for example Arial font or to be specific if we want to store a
> chinese(traditional) font to look up convert the unicode, is there anyinfo
> regarding in ifo file  (((i am a new bie to gstreamer and dvd if i have gone
> wrong in the concept itself anywhere please correct it)))

DVD subtitles are just raster graphics that get composited on top of the
video. This means: there are no fonts at all in a DVD. The fonts are in
the DVD authoring application, and are rendered to a bitmap graphic
before being stored in the subtitle (subpicture) stream. I think the
reason they did that was precisely to avoid requiring an international
set of fonts in every DVD player, or, as you suggest, having to
distribute the fonts in the DVD.

> 2)and also want to know as in transport stream the  language_code will be used
> as search key to identify the PES- packets which carries the subtitle streams
> with viewer's selected language, via PMT then send to decode for presentation.
> but how does this process work in program stream in dvd

I'm not sure I understand your question completely. In a DVD, subpicture
streams are just numbered. The IFO files in the DVD contain information
that let the player select a particular stream based on user input and
on the area of the DVD currently being played.  IFO files also contain
information about the language used for every subpicture stream, that
you could use to help select an appropriate stream. Depending on your
application, this information may or may not be useful.

M. S.

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