[FAQ] TDA4VH-Q1: How to create openvx graph with a node that needs data from the next node

Hi,

Openvx doesn't allow this cyclic data flow. But using graph parameters application can control the buffers and make this usecase possible.

Note: This breaks the pipelining between NODE_B and NODE_C.

The following demo is created to demonstrate this usecase.

app_graph_feedback_loop.zip

Extract this zip file and copy the folder into $(psdkra)/vision_apps/apps/basic_demos/

Build the sdk and copy the files to sd_card

cd $(psdkra)/sdk_builder
make vision_apps
# insert the sd card
make linux_fs_install_sd

cd /opt/vision_apps
./vx_app_graph_feedback_loop.out

The demo will have the following flow and will prints the input and output values when the node is executed.

Intr_img parameter of both NODE_B and NODE_C is made as graph parameter and a separate task is created to handle the enqueue/dequeue which swaps the buffers between parameters so that output of NODE_C is given as input of NODE_B. The feedback input will be used by NODE_B from the next execution of graph.

This demo is just for reference to create a openvx graph with the feedback loop represented in the flow diagram.

Regards,
Gokul