Fwd: [gst-devel] newbie questions

Edward Hervey bilboed at gmail.com
Tue May 24 10:45:31 CEST 2005

Forgot to forward the mail to the mailing list

---------- Forwarded message ----------
From: Edward Hervey <bilboed at gmail.com>
Date: May 24, 2005 4:01 PM
Subject: Re: [gst-devel] newbie questions
To: Akos Maroy <darkeye at tyrell.hu>


On 5/24/05, Akos Maroy <darkeye at tyrell.hu> wrote:
> Hi,
> I'm new to gstreamer, and I have a few questions, which I'm sure you'll
> find very basic, but I couldn't myself find the answer for.
> - difference / converting between audio/x-raw-int and audio/x-raw-float
> I see that some audio related plugins use x-raw-int, some use
> x-raw-float as the raw audio format. is there a plugin that would
> convert between these two formats?
> for example, vorbisdec has a 'src' pad in x-raw-float format, but for
> osssink (or volenv) only support x-raw-int
> - how to write a play offset plugin?
> I'd need the following functionality: for an input, I'd either need to
> play only a portion, or I'd need to add extra silence before or after
> the input.
> for example, say I have a 60 second audio input, I need to play it as
> follows:
>     - only play from the 5th second up to the 45th second,
>       making it a 40 second input
>          +--------- 60 second input -----------------+
>             +---- 5th to 45th second ---------+
>     - start playing only 11seconds later, and after the 60secs, have
>       a 5second silence afterwards, making it a 76second input
>            +--------- 60 second input -----------------+
>   +-11sec-++--------- 60 second input -----------------++-5sec-+
> I wonder how this could be achieved with a plugin (or if there's already
> a plugin that achieves this functionality). why I'm wondering is that
> the chains channel data through the whole chain, but here a plugin
> making the above functionality available whould need to act to some
> extent without receiving input on its sink.

  You might want to have a look at the Gnonlin library, based above
GStreamer, which is aimed at creating audio/video non-linear editors,
but which also fits your need.

  With your given example you use 3 GnlSource : 2 with the silence
source in it (silence1 and silence2), and one with your real source in
it (mysource).
 Set silence1 properties as follow :
    start=0, stop=11*GST_SECOND
 Set silence2 properties as follow :
 Set mysource properties as follow :

 Add those gnlsource to a Gnlcomposition, and add that composition to
a GnlTimeline. You can now use that timeline as a source that
automatically switches to the good source depending on where you want
to seek.

 GNonLin's API details it a bit further, but that should get you starting.

 Gnonlin website : http://gnonlin.sf.net/


> Akos
> -------------------------------------------------------
> This SF.Net email is sponsored by Oracle Space Sweepstakes
> Want to be the first software developer in space?
> Enter now for the Oracle Space Sweepstakes!
> http://ads.osdn.com/?ad_id=7412&alloc_id=16344&op=click
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel

More information about the gstreamer-devel mailing list