[ogg-dev] Re: Souffleur subtittle editor (SoC). Need Help with GStreamer

Michael Smith msmith at xiph.org
Wed Jun 21 01:48:46 PDT 2006

On 6/20/06, Daraku <otaky at ukr.net> wrote:
> Hi, All!!!
> I am at last added some GStreamer support to the Souffleur, and I am
> already read this manuals:
>  - http://pygstdocs.berlios.de/
>  -
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/index.html
> But it's steel hard for me to understand (or maybe I something missed)
> how it work. :(

Hi Maxim,

GStreamer's pretty complex, and though the low-level documentation is
pretty complete, it's often quite difficult to understand how to
accomplish some of the higher-level tasks, at least at first. So don't
get too depressed at finding it hard to understand!

> For example: I don't know where to search info on how to load additional
> info on streams (LANGAGE, AUTHOR...). Or how to load streams data
> (Subtitle text). Or how to select some streams in multi streams file
> (one video, and one audio) to play...

I'm not sure how far you've got so far with this stuff. Most of the
information-about-streams stuff comes from "tag messages". You should
be listening to tag messages on your pipeline bus, and you will get
any information about various tags that gstreamer knows. This might
include Author, language info, etc. - of course, if that information
isn't present, gstreamer can't give it to you.

Subtitle information will come on a seperate pad, for playback you
would composite it on to the video. It'll generally have a caps type
of "text/something" for some value of 'something' depending on the
subtitle format in use.

Selecting particular streams depends on what you're doing precisely -
if you're using decodebin, you can just select which ones to use as
they appear, responding to the pad-added signal. If you're using
playbin (which I don't think you will be?), it can do this internally
for you.

I've CCed Edward Hervey - if you have problems specific to gst-python
(rather than general problems understanding how to use gstreamer),
he'll probably be able to help. However, we're also here to help you -
both on the xiph lists, and in the #gstreamer channel if you want to
join us on irc.


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