i.MX ProcessorsのトピックRe: imx8mp simultaneous video access

imx8mp simultaneous video access

malik_cisse — Fri, 18 Feb 2022 12:03:01 GMT

Hi,

Video does show up correctly on /dev/video0 node and I can access it normally. However I want to access video in different process.

Doing that a resource conflict occurs saying one cannot open /dev/video0 twice.

There is a tool called "v4l2loopback" that seemed promising but this did not help much in the end.

Any idea how this can be achieved?

BR, MC

joanxie — Wed, 23 Feb 2022 08:37:58 GMT

"However I want to access video in different process."

> what do you mean?

could you give me detailed information of your operation

malik_cisse — Wed, 23 Feb 2022 09:09:54 GMT

In my application, I preview camera on an LCD screen.

Upon request, I capture single snapshot images or stream a video over network.

In order to capture single snapshot images or stream a video over network I need to stop camera preview on LCD screen first.

I would like to continue to preview camera on an LCD screen while doing snapshot or streaming.

This is not possible in my current QT application.

BR, MC

joanxie — Thu, 24 Feb 2022 02:25:55 GMT

how do you stop the camera? if you don't release the camera totally, should show the error that you couldn't open it twice

malik_cisse — Thu, 24 Feb 2022 08:57:14 GMT

>>if you don't release the camera totally, should show the error that you couldn't open it twice

yes, this is why I need to unload (really stop) the camera in QT before I can do snapshots.

However the whole process takes way too long and display is not showing camera preview during this time.

This is the reason, why I try to find a way to access to images in 2 different threads.

joanxie — Thu, 10 Mar 2022 07:37:45 GMT

yes, you couldn't access one device in the same time