Why does fps onscreen of video very different from fps printed when using -show_stats or -real_input_fps with face detection models? Openvino on FPGA vs CPU: face-detection-adas-001 vs face-detection-retail-0004

[SGrif4]

Hardware/Software Used

Intel® Distribution of OpenVINO™ Toolkit 2018 R5

Intel® Vision Accelerator Design with Intel® Arria® 10 FPGA (IEI's Mustang-F100-A10)

What I did: Run the face detection model, both while having the video play and show fps on the screen, and without showing the video (using -no_show) and printing fps numbers with either -real_input_fps or -show_stats.

QUESTION: Showing FPS on screen (by omitting no_show flag) doesn’t always give same number as –real_input_fps (retail-0004) and –show_stats (adas-0001). Can vary by 50-100 fps. Is there a reason for this? What does each FPS value (from the flags, higher vs. printed on the video while inference is running, lower) indicate?

Notes / Appendix:

Multiple Videos Processed at Once – Face Detection

Used face-detection-adas-0001

ieisw@ieisw-SER0:~/inference_engine_samples/intel64/Release$

Command:

./multi-channel-demo -m $mFDA32 -i ~/FPGA_POV1/brooklyntest.mp4 ~/FPGA_POV1/brooklyntest.mp4 ~/FPGA_POV1/brooklyntest.mp4 ~/FPGA_POV1/brooklyntest.mp4 ~/FPGA_POV1/brooklyntest.mp4 -nc 0 -no_show -show_stats -d HETERO:FPGA,CPU

Omit -no_show to see real time face detection, used -show_stats to get FPS measurements.

This multi-channel demo supports 25 video files and/or 16 camera streams (still need to test streams).

Multiple Videos Processed at Once – Face Detection

Using face-detection-retail-0004

Using this flag:

-real_input_fps             Disable input frames caching, for maximum throughput pipeline

Got FPS for both FPGA in hetero mode and CPU

Command:

./multi-channel-demo -m /opt/intel/computer_vision_sdk/deployment_tools/intel_models/face-detection-retail-0004/FP32/face-detection-retail-0004.xml -i ~/FPGA_POV1/brooklyntest.mp4 -nc 0 –real_input_fps -d HETERO:FPGA,CPU –no_show  

[JohnT_Intel]

Hi,

QUESTION: Showing FPS on screen (by omitting no_show flag) doesn’t always give same number as –real_input_fps (retail-0004) and –show_stats (adas-0001). Can vary by 50-100 fps. Is there a reason for this? What does each FPS value (from the flags, higher vs. printed on the video while inference is running, lower) indicate?

There will be variation due to the CPU will be performing the post processing to show the image in your display which will cause it to have a lower fps compare to not showing the image. The FPS will varies depending on how many detection has been detected and whether if other task need to be performed on the CPU.