[gst-devel] Data Probing or Identity Element?

Nick Haddad nhaddad at mathworks.com
Thu Jan 31 21:13:04 CET 2008

I am writing an application to read video frame data from any video  
file that gstreamer supports and save it in memory.   To do this I  
need to extract the image data from a video from a playing pipeline.   
The gstreamer manual is a little unclear on the "best" way to do this  
so I thought I would ask the group.  The data probing page in the  
manual says the following:

	"If you just want to inspect buffers as they pass through the  
pipeline, you don't even need to set up pad 		probes. You could also  
just insert an identity element into the pipeline and connect to its  
	"handoff" signal."

On the very next page in the manual, the topic "Manually adding or  
removing data from/to a pipeline" reads as follows:

	"Those who're paying close attention, will notice that the purpose of  
identity is almost identical to that of 		probes. Indeed, this is  
true. Probes allow for the same purpose, and a bunch more, and with  
less overhead 	plus dynamic removing/adding of handlers, but apart  
from those, probes and identity have the same 			purpose, just in a  
completely different implementation type."

This leaves me a little confused as to which method is better for  
getting data out of pipeline.

Which method is the better method?

Thanks for any advice you can offer,

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