# VPI Dense Opt Flow example

**URL:** <https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830>\
**Category:** Jetson Xavier NX\
**Tags:** vpi\
**Created:** [April 28, 2022, 10:12am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830 "2022-04-28T10:12:53Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![iklemyshev](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/iklemyshev/32/163605_2.png) [@iklemyshev](https://forums.developer.nvidia.com/u/iklemyshev)\
**Post date:** [April 28, 2022, 10:12am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830/1 "2022-04-28T10:12:53Z")

</div>

Hello!  
I’m trying to run this example on my Xavier NX with JP 4.6.1:  
[https://docs.nvidia.com/vpi/sample\_optflow\_dense.html](https://docs.nvidia.com/vpi/sample_optflow_dense.html)

But I get error: ‘vpi.Image’ object has no attribute ‘rlock\_cpu’. what’s the problem and how to solve it?

---

<div class="post-metadata">

**Author:** ![DaneLLL](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/danelll/32/14043_2.png) [@DaneLLL](https://forums.developer.nvidia.com/u/DaneLLL)\
**Post date:** [April 29, 2022, 2:23am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830/3 "2022-04-29T02:23:50Z")

</div>

Hi,  
We don’t observe the issue. Attach the log for reference:

```auto
nvidia@tegra-ubuntu:/opt/nvidia/vpi1/samples/13-optflow_dense$ sudo ./vpi_sample_13_optflow_dense nvenc ../assets/pedestrians.mp4 high
[sudo] password for nvidia:
NVMEDIA_ARRAY: 53, Version 2.1
NVMEDIA_VPI : 172, Version 2.4
Processing frame 1
Processing frame 2
Processing frame 3
Processing frame 4
Processing frame 5
Processing frame 6
Processing frame 7
...

```

---

<div class="post-metadata">

**Author:** ![iklemyshev](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/iklemyshev/32/163605_2.png) [@iklemyshev](https://forums.developer.nvidia.com/u/iklemyshev)\
**Post date:** [April 29, 2022, 6:23am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830/4 "2022-04-29T06:23:46Z")

</div>

I’m sorry, but there is no ‘samples’ under ‘vpi1’ folder, only vpi\_demo\_stereo & vpi\_demo\_remap.

---

<div class="post-metadata">

**Author:** ![DaneLLL](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/danelll/32/14043_2.png) [@DaneLLL](https://forums.developer.nvidia.com/u/DaneLLL)\
**Post date:** [April 29, 2022, 7:33am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830/5 "2022-04-29T07:33:33Z")

</div>

Hi,  
Do you use Xavier NX emmc and flash the rootfs to the emmc? Seems like the installation is not complete. Probably it is due to insufficient freespace.

---

<div class="post-metadata">

**Author:** ![iklemyshev](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/iklemyshev/32/163605_2.png) [@iklemyshev](https://forums.developer.nvidia.com/u/iklemyshev)\
**Post date:** [April 29, 2022, 8:08am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830/6 "2022-04-29T08:08:49Z")

</div>

Well, guess I’ve got the point. I use microSD and flash it with BalenaEtcher and JetPack4.6.1 image.

---

<div class="post-metadata">

**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\
**Post date:** [May 25, 2022, 2:38am UTC](https://forums.developer.nvidia.com/t/vpi-dense-opt-flow-example/212830/8 "2022-05-25T02:38:22Z")

</div>

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.