[gst-devel] is it possible dynamically change framerate in a running pipeline?

[John Buckley]

Tim-Philipp Müller-2 wrote:
> 
> On Sat, 2010-01-09 at 21:23 +0100, Farkas Levente wrote:
> 
> Hi,
> 
>> is it possible dynamically change a running pipeline's framerate while 
>> it's in RUNNING state?
> 
> Yes.
> 
>> or should we've to set to READY, set the 
>> framerate and set back to RUNNING?
> 
> No.
> 
>> since if've to change it to READY 
>> then we loose a few frame during the state transmission which wouldn't 
>> be useful in case of using a grabber card.
>> or gstreamer not able to change the capabilities in an already 
>> negotiated pipeline?
> 
> It depends a bit on the elements involved, but there's no problem in
> principle with changing the framerate on the fly. The framerate field in
> the caps is at best indicative, what matters more are timestamps on
> buffers (and the initial newsegment event). Some elements (e.g.
> theoraenc) will not react well if you change the input framerate, but
> most elements won't really care and just process things based on the
> timestamps.
> 
> Cheers
>  -Tim
> 
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> 

Do you know of any example code of changing these parameters on the fly?
I would like to apply this approach to videocrop, videoscale & the image
size...

-John Buckley


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