Openvino Multi Python Person demo using NCS2 and Rasberry Pi 4 fails with more than 2 Cameras

[Parth-Sanghvi]

Hey,

I am currently on Raspbian 10 and the Openvino 2019_R3 distribution. I am trying to get the Multi Python Multi Person demo to work and while I have been able to get it to work with up to 2 cameras, adding another camera results in the following errors. I have been able to get the same code working with the NCS1 as well as my standard CPU installation on my local machine, so I dont believe the code is the problem. I am also using 3 identical cameras (If this is helpful)

Error Code:

E: [watchdog] [    484187] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    485187] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    486186] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    487185] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    488184] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    489183] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    490182] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    491182] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    492181] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    493180] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
select timeout
VIDIOC_DQBUF: Resource temporarily unavailable
E: [watchdog] [    494179] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    495178] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    496177] [WatchdogThread] sendPingMessage:121	Failed send ping message: X_LINK_ERROR
E: [watchdog] [    496177] [WatchdogThread] watchdog_routine:315	[0xee57b8] device, not respond, removing from watchdog
select timeout
VIDIOC_DQBUF: Resource temporarily unavailable
VIDIOC_DQBUF: No such device
INFO:root:Demo finished successfully
VIDIOC_REQBUFS: No such device
VIDIOC_REQBUFS: No such device
VIDIOC_REQBUFS: No such device
E: [ncAPI] [    514026] [python3] ncFifoDestroy:3333	Failed to write to fifo before deleting it!
E: [ncAPI] [    524033] [python3] ncDeviceClose:1737	Device didn't appear after reboot

I also occasionally get schedule errors and such and I am not sure why that might be. Especially since the NCS2 is supposed to have better memory bandwidth as well as compute. Any help would be much appreciated!

Some other additional questions I had about the code sample; does this particular  code perform inference in sequence, that is one frame from each camera stream and so on or does it infer on multiple channels simultaneously? 

Thanks!

[Iffa_Intel]

Greetings,

I would recommend you to go with the latest OpenVINO version. Right now latest is 2021.2.

However, please note that the NCS2 is supported from version 2020.3 onwards.

Hence, if you want to use the Movidius stick you need to use an older version of OpenVINO, otherwise, use the latest OpenVINO version with NCS2.

Here is the official documentation:

https://docs.openvinotoolkit.org/latest/openvino_docs_get_started_get_started_raspbian.html

[Parth-Sanghvi · Accepted solution]

So I was able to try the latest distribution, however the demo did not seem to work with more than 2 cameras as well. After a lot of troubleshooting the problems were actually in the way the cameras are connected to a Rasberry Pi. I needed to use a powered USB hub in order to connect multiple cameras to avoid errors. There wasnt enough current passing around

Thanks

[Iffa_Intel]

Greetings,

Intel will no longer monitor this thread since we have provided a solution. If you need any additional information from Intel, please submit a new question. 

Sincerely,

Iffa