Problem with using gst-launch (with avidemux and videoconvert)

[Tim-Philipp Müller]

On Tue, 2013-10-01 at 13:21 +0100, Ian Davidson wrote:

> I noticed that you recommended camerabin 'not using gst-launch' but I 
> tried it anyway to see what happened.  I noticed that I got what I 
> assume to be a 'viewfinder' - which is good.  I also noticed that I did 
> not get any still pictures - presumably that is why you said I should 
> use an application.
> 
> I assume that I need to send a signal to camerabin to tell it when to 
> take the picture (a shutter release) - but looking at the output from 
> gst-inspect I did not notice how I should do that.

Yes, the {start-stop}-capture signal I presume (and somewhere a mode to
set the capture mode and other things.

You can't emit signals via gst-launch. However, you can use
gst_parse_launch() to easily create a pipeline from a gst-launch string
in a C/python/whatnot application and then use that to do things.


> I noticed that there is a property 'video-filter' which says what is 
> going to  handle the picture - I assume that I need to create a pipeline 
> which includes 1) camerabin and 2) pngenc (for example) and 3) 
> filesink.  I will then need to link pngenc to filesink, but presumably 
> camerabin will link itself once it knows what it should link to?

No, camerabin is a stand-alone top-level pipeline by itself. It will
create all these things for you as requested based on its configuration
(there's an example/test program for it in gst-plugins-bad/tests
somewhere I think).

These -filter properties are just so you can insert additional effects
if you like (like 'cheese' does for example).

Cheers
 -Tim

> Ian
> 
> On 30/09/2013 15:08, Tim-Philipp Müller wrote:
> > On Mon, 2013-09-30 at 14:10 +0100, Ian Davidson wrote:
> >
> > Hi Ian,
> >
> >> This example is purely a test - what I really want to do is to take
> >> snapshots using a live camera, but on this machine I do not have a
> >> camera.  I think that pngenc might be useful to make my snapshots.
> > Use camerabin from an application or script (not gst-launch), it handles
> > snapshotting and video recording for you.
> >
> >
> >
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