On Sun, Mar 13, 2011 at 11:31 PM, Joe
<address@hidden> wrote:
Hi everyone!
On Sunday 06 March 2011 09:21:05 Martin Lambers wrote:
> On 06/03/11 00:39, Joe wrote:
> > I was looking how to implement subtitles support and found support for
> > subtitles (.srt) decoding only in git version of ffmpeg (srt decoding
> > appears to be missing even in latest gentoo unstable version
> > 0.6_p25767). Am I missing something? Or is it better to us some other
> > subtitle decoding library? And what about subtitles rendering library,
> > don't you have some hint?
>
> I did not yet look into subtitles in detail, but I think we can stick to
> what FFmpeg provides. Version 0.6.1 seems to have support for subtitles,
> but I don't know about .srt files (what are those? where are they
> used?). FFplay apparently handles subtitless, and we could take a look
> how it is done there.
SRT subtitles are located in separate file and I think they are the most common
subtitle format (at least in my area every subtitles are in srt format).
FFmpeg gained support for srt decoding on December 2010, so it is now only in
git version.
> Some subtitle formats are stored in text form, while others are stored
> in a fixed bitmap form. I don't know how FFmpeg handles these two, but
> bitmaps could be put into a texture and overlayed onto the
> color-corrected video texture, and text could be rendered with an OpenGL
> font rendering library. I'd rather not use Qt's built-in text rendering
> for this, so that we can make subtitles work also with Equalizer. FTGL
> seems to be widely used:
> <http://sourceforge.net/apps/mediawiki/ftgl/index.php?title=Main_Page>.
Thanks for the tip! I used FTGL to implement basic subtitles support ("--with-
ftgl" configure param). Please see the attached patch (it is one big patch, but
I have finer grained history in my repository). So far I've implemented support
for srt files and subtitles embedded in video files in form of plain text
(tested on Matroska). Subtitles in image form will hopefully follow.
I draw directly into framebuffer, because I'm not so skilled in opengl so I did
not managed to put text directly into left/right textures and also was unable
to set proper color. I think it would be much better to have it in textures to
be able to set "depth" of subtitles. It would be great if you find the time to
correct it. (I think FTTextureFont or FTBufferFont will have to be used). Font
rendering starts at line 905 in video_output.cpp.
The patch is just RFC and I plan to clean it into mergeable state so comment
please!
Bye,
Joe.