Fwd: Error Releasing VideoCapture in OpenCV Using GStreamer Pipeline

[Gaspar Ramôa]

Hello Laurent Pinchart,


Thank you for the quick reply!

As I created the issue 3 months ago and got no reply from you I thought 
that you were no longer active or working in this project, and that is 
why I said it was difficult to get you! But I am glad I was able to 
reach you! :-)

I spent the entire afternoon following your suggestion.

So I was successfully able to install the latest version of libcamera 
and the latest version of the rpicam-apps:

/rpicam-apps build: v1.5.3 50958df98d3c 13-11-2024 (16:55:55)
rpicam-apps capabilites: egl:1 qt:1 drm:1 libav:1
libcamera build: v0.3.2+98-75fe515a/

However when trying to run *gst-inspect-1.0 libcamerasrc *the system 
could not find the libcamerasrc. I had to activate some environment 
under /libcamera/build/ with *meson devenv -C build*

After this I was able to start the capture and release it *without any 
errors or warnings*. This is really a great positive step for me!

The frame saved is still weird but I think you probably know what is 
missing here. I know that I still have to use some tunnig-files but the 
horizontal strips I have no idea what they are. I am using *format *= 
BGR and x-raw video on the gstreamer pipeline. Do you have any idea on 
how to convert these to the normal RGB. Like using the *rpicam-still *-o 
test.png gives me this:

And I able getting something like this from the gstreamer pipeline:

Any ideas? Where can I find the documentation of *libcamerasrc *so I can 
have an idea on what I can change/do.


My end goal is to just be able to use the benefits of libcamera 
(changing analog gain, exposure, etc) in JAVA.


Best Regards,

Gaspar Ramôa


On 13/11/2024 14:35, Laurent Pinchart wrote:
> Hello Gaspar,
>
> On Wed, Nov 13, 2024 at 12:51:11PM +0100, Gaspar Ramôa wrote:
>> Dear libcamera community,
>>
>> Thank you for developing such a helpful library.
> I'm glad you find it helpful.
>
>> I am trying to get frames using opencv. I am actually able to get frames via
>> cv2.VideoCapture through GStreamer.
>>
>> However, when I try to release the capture (for ending the program or maybe
>> adjusting raw image size): cap.release()
>> I get the following error:
>>
>> [1:39:52.854669803] [1885] ERROR DeviceEnumerator device_enumerator.cpp:172
>> Removing media device /dev/media4 while still in use
>> [1:39:52.854709759] [1885] ERROR DeviceEnumerator device_enumerator.cpp:172
>> Removing media device /dev/media3 while still in use
>>
>> I've already published an issue on the raspberry Pi libcamera GitHub repo where
>> you can get more detail on my problem:https://github.com/raspberrypi/libcamera
>> /issues/163
>>
>> I found the following commit which apparently did to solve the problem I am
>> having now:https://github.com/raspberrypi/libcamera/commit/
>> fa63d428aef62bacf0a6ad1622a7965b3ff2ba2f
> That commit has been merged a long time ago, before v0.0.1, so I expect
> it is included in the libcamera version you are using. Your problem may
> have the same symptoms but a different root cause.
>
> You mentioned in your bug report that you tried both libcamera v0.0.5
> and v0.3.0+65-6ddd79b5. v0.0.5 is fairly old. v0.3.0 is better, but I
> would still recommend trying the latest master branch to see if the
> issue has been fixed already.
>
> If the issue is still present, can you try running the same GStreamer
> pipeline (likely replacing appsink with some sort of display sink, or
> even fakesink) from gst-launch, and see if the problem exists there too
> ?
>
>> This commit was done by the userhttps://github.com/pinchartl. But I have no
>> way of contacting him to help me fix the problem.
> I'm slightly puzzled by why you had trouble contacting me, given that my
> e-mail address is listed in the commit you mentioned above. Regardless,
> it looks like you found a way :-)
>
>> Any suggestions? Thanks in advance!
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