Images into video streams (Matt Clark)

Marianna Smidth Buschle msb at
Thu Mar 10 07:47:58 UTC 2022


You have a non-negotiated error, that means you have problems with the CAPS.
So you need to investigate that.

Try running with: GST_DEBUG=*:3,GST_CAPS:5
In order to get more information about the CAPS available and trying to 
be negotiated.

Also, I vaguely recall some cases where you might need to specify the 
CAPS in the input and output of the compositor to get it to work properly.

Best Regards


On 08.03.2022 22.32, gstreamer-devel-request at wrote:
> (Sorry if this duplicates, I thought I had fully signed up for the mailing
> list before trying to send this the first, but it seems it didn't
> go through. So now that I know I'm on the mailing list I hope this wont
> mess anything up.)
> *Context:* I'm making a server that composites various sources of media
> into a video stream(like a 2x2 grid from different sources for instance)
> and supports multiple streams at the same time (including being able to
> update those pipelines dynamically with web calls in the future). One
> source is an image(image/png) that gets generated upon request by a
> separate microservice. I was trying to use an Appsrc to pull the image and
> then push it into a PngDec --> ImageFreeze and then link that to the
> composite element with the sink properties for which part of the grid it
> should show on.
> I've got it pulling the image and pushing that buffer, but I'm getting the
> error below, and I'm not sure exactly what's causing it.
> *Questions:*
> 1. What do you think is happening and what's the best way to resolve it?
> 2. Is there a better way for me to do this?
> 3. Knowing that I plan to have multiple streams pulling from multiple
> sources and want to update them live, any pointers?
> *Error:*
> should have image
> should have image in pipeline: Ok
> Error from
>> Some("/GstPipeline:pipeline_6be3b6be-0767-49db-a2b1-26708950261b/GstAppSrc:vsource0_top_left"):
>> Internal data stream error. (Some("../libs/gst/base/gstbasesrc.c(3127):
>> gst_base_src_loop ():
>> /GstPipeline:pipeline_6be3b6be-0767-49db-a2b1-26708950261b/GstAppSrc:vsource0_top_left:\nstreaming
>> stopped, reason not-negotiated (-4)"))
Best regards / Med venlig hilsen
“Marianna Smidth Buschle”
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