[vlc-devel] Re: [PATCH] MKV USF subtitles support

Bernie Purcell b.purcell at adbglobal.com
Mon Mar 12 23:58:56 CET 2007

I don't really have many test-streams which are practical to upload 
(several GB each). I have just created a small one and uploaded it though: 
usf_subtitles_demo.mkv. I've also uploaded the USF file that was used to 
create it (my Muxing with mmg.exe in MkvToolnix). You don't need the USF 
file to play the stream, but it shows the sort of syntax that ends up 
getting encoded into the mkv file.

Hope this helps


Derk-Jan Hartman <hartman at videolan.org> 
Sent by: vlc-devel-bounce at videolan.org
13/03/2007 08:05 AM
Please respond to
vlc-devel at videolan.org

vlc-devel at videolan.org
Bernie Purcell <b.purcell at adbglobal.com>
[vlc-devel] Re: [PATCH] MKV USF subtitles support

On 12-mrt-2007, at 0:53, Bernie Purcell wrote:
> Got a bit tired of not having Matroska USF support. :-)
> The patch below adds the following:
> * Decodes USF streams muxed within the Matroska container format. 
> USF was created especially for the Matroska container.
> * Adds additional routines to the Freetype module's text rendering 
> engine to support subtitles whose font, style, size and colour is 
> allowed to change partway through the subtitle, ie. HTML version of 
> the subtitle. Sytles now supported are bold and italics (supported 
> by fontconfig) and underline which is manually calculated. This 
> code has only tested on the linux version.
> * Code added to subpictures to choose HTML rendering over Text 
> rendering if rendering module supports HTML and if a HTML version 
> of the subtitle exists.
> * Additional fields added to subpicture_region_t filter_t to permit 
> the additional information to be carried without interfering with 
> the existing plain text version of the subtitle.
> * Code added to configure.ac to detect presence of fontconfig - 
> which is required by the new rendering functions. Absence of 
> fontconfig causes the plain text rendering code to be used.
> At present only USF is rendered using the new rendering functions. 
> This minimises its impact on existing modules. It is, however, not 
> difficult to extend part of this functionality to SSA subtitles, 
> for example, in order to more greatly support the style information.

VERY nice work. Thank you so much.
It still needs a bit of review before it goes in, because it's a lot 
of new code, but it looks good so far.
One thing, if you have same examples, could you please upload them to 
ftp://streams.videolan.org/incoming ?

Again, thank you very much for tackling two of our biggest subtitle 


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