PROCESSOR-SDK-J784S4: Is graph pipelining required for CSI capture node?

Jakub Olesinski

Tool/software:

Hi TI experts,

I'm experimenting with CSI sensor and wanted to have a single-shot capture app and seek some explanation of the capture API.

The sample code in vx_app_single_cam uses graph pipelining API and tivxGraphParameterEnqueueReadyRef to schedule the graph:

Is pipelining a requirement of tivxCaptureNode?
How can the graph of tivxCaptureNode - tivxVpacVissNode be scheduled with vxScheduleGraph to grab a single frame?

Thanks!

over 1 year ago

+1 Nikhil Dasan over 1 year ago

TI__Guru* 87581 points

Hi,

Jakub Olesinski said:
Is pipelining a requirement of tivxCaptureNode?

In the framework, the process callback of the capture node starts executing after it receives 3 frames. (either enqueue 3 buffers in pipelining or call vxScheduleGraph three times)

So you can remove the graph parameter part from the single cam and call vxProcessGraph instead to execute the application in non-pipeline mode.

Regards,

Nikhil

0 Jakub Olesinski over 1 year ago in reply to Nikhil Dasan

Prodigy 40 points

Thanks for answer! Just for complete understanding, why is it 3 frames? When I call graph schedule only once, I get an old frame (from previous process call, when it was correctly scheduled) - but no errors

+1 Nikhil Dasan over 1 year ago in reply to Jakub Olesinski

TI__Guru* 87581 points

As the capture node is a source node, we have kept 3 frames as a buffer to start to node in order to keep the real time capturing and not let the later video processing slow this capture.

This can be seen in the macro TIVX_CAPTURE_MIN_PIPEUP_BUFS in ${PSDKRA}/video_io/kernels/video_io/include/tivx_kernel_capture.h in the latest SDK

0 Jakub Olesinski over 1 year ago in reply to Nikhil Dasan

Prodigy 40 points

Ok, thanks!

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PROCESSOR-SDK-J784S4: Is graph pipelining required for CSI capture node?