[gst-devel] dynamic change element's parameter

[Chandler Li]

I have read the mail Nicola and Stefan given, and that really inspired
me a lot.
Thank you!
In the first, I try to replace some elements and encounter some
problem, the following I will show my target first.
Because I want to stream webcam frame on the internet,
and dynamically change the frame size without stopping the pipeline.

According to my experience, if the v4l2src element opens webcam
device, it only captures one size at one time.
if I want to change the size of webcam, I need to restart it.
So I try another architecture of gstreamer,

    v4l2src  ->  capsfilter1  ->  videoscale -> capsfilter2  ->
ffmpegcolorspace ->   .... (to internet)

videoscale links two filters, the first filter (capsfilter1)
negotiates with v4l2src in a static frame size,
I want to change the size I assigned in the second filter (capsfilter2) ,

BUT I get an error message after I change the capsfilter2 to the new filter,

    videoscale can't link to new capsfilter,

I don't know what's happened? does anyone know that?
Thank you!

Best regards,
Chandler Lee.

2010/9/14 Stefan Kost <ensonic at hora-obscura.de>:
> Am 12.09.2010 09:01, schrieb Chandler Li:
>> Hi all,
>>     I'm new to use gstreamer,
>>     and I have a problem don't know how to solve for a long time,
>>
>>     Is there possible to dynamic change the parameter in elements or pads?
>
> gobject parameters -> g_object_set or use GstController
>
>
>>
>>     For example,
>>     In a playing state streaming,
>>     could I dynamic change the size of video without stop the streaming?
>
> yes you can. if you resize the video window for xvimagesink the video adjusts if
> it can. So if you run gst-launch videotestsrc ! xvimagesink, the videotest is
> sending videoframes in the native resolution instead of xvimagesink scaling them.
>
> Stefan
>
>>
>>     hopes that's not a stupid question,
>>     and very hopefully for your reply,
>>     Thank you
>>
>>     Chandler Lee
>>
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>