Interprocess communication with shmsink

[Benjamin Rapaport]

I am trying to run a gstreamer pipeline via the command line tool in a subprocess of my main application, where I will read back the output image buffers from my main process. This process does not link in the gstreamer libraries. 

In order to quickly transfer the image buffers between the processes, I would like to use an shmsink in my pipeline (as stdout with fdsink has been far too slow). Does anyone have any pointers to how to read that back out properly when using shmsink? My application is written in c++.

Thanks

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[Martin Vachovski]

Hi Benjamin,

A suggestion (not sure if it will fit with what you need exactly):

You could create a pipeline within your app's process (in a different thread)

with the 

gst_pipeline_new() API

https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPipeline.html#gst-pipeline-new​

which can be used with the same pipeline syntax- i.e. you can call something like:

GstElement *pPipeline = gst_pipeline_new("autovideosrc ! videoconvert ! ... ! appsink");

That way you can avoid the IPC communication all together, and it will be easier (and maybe faster)

to obtain your image buffers in real time using the

appsink

element

Cheers

Martin

---

From: gstreamer-devel <[hidden email]> on behalf of Benjamin Rapaport <[hidden email]>
Sent: Friday, September 14, 2018 6:28 PM
To: [hidden email]
Subject: Interprocess communication with shmsink

 

I am trying to run a gstreamer pipeline via the command line tool in a subprocess of my main application, where I will read back the output image buffers from my main process. This process does not link in the gstreamer libraries. 

In order to quickly transfer the image buffers between the processes, I would like to use an shmsink in my pipeline (as stdout with fdsink has been far too slow). Does anyone have any pointers to how to read that back out properly when using shmsink? My application is written in c++.

Thanks

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[Olivier Crête-3]

Hi,

The shmpipe.[ch] API is designed exactly for that. You can copy shmpipe.[ch] and shmalloc.[ch] into your code (notice how these specific files have a very liberal license). And use the API defined (and documented) in shmpipe.h to receive.

Olivier

On Fri, 2018-09-14 at 13:28 -0400, Benjamin Rapaport wrote:

I am trying to run a gstreamer pipeline via the command line tool in a subprocess of my main application, where I will read back the output image buffers from my main process. This process does not link in the gstreamer libraries. 

In order to quickly transfer the image buffers between the processes, I would like to use an shmsink in my pipeline (as stdout with fdsink has been far too slow). Does anyone have any pointers to how to read that back out properly when using shmsink? My application is written in c++.

Thanks

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-- 
Olivier Crête
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