gstreamer 1.20: v4l2bufferpool spams "newly allocated buffer is not free"

[Nicolas Dufresne]

Le ven. 24 juin 2022, 14 h 14, Michiel Konstapel <michiel at aanmelder.nl> a
écrit :

> Hi Nicolas,
> On 24-06-2022 19:50, Nicolas Dufresne via gstreamer-devel wrote:
>
> Hi,
>
>
> gstv4l2bufferpool.c:478:gst_v4l2_buffer_pool_alloc_buffer:<v4l2src0:pool0:src>
>>
>> newly allocated buffer 1 is not free
>>
>> Despite the warnings, the pipeline appears to work, but I would prefer
>> it to not spam warnings continuously :) Any ideas? This is on Ubuntu
>> 20.04, on different PCs and with different cameras.
>>
>
> Do you have any information about the driver?
>
> It's a very common Logitech C920 webcam (but I've seen the same message
> with a Z-Cam M3 camera). I think that uses a generic UVC driver? Anything I
> can run to get you more info?
>
I'm asking as I cannot reproduce, and from the look of it, the trace
implies is will leak data. Which Kernel? Have you tested with your own
GStreamer build (main branch)?


Something interesting perhaps:
>
> v4l2-ctl -d /dev/video2 --list-formats
> ioctl: VIDIOC_ENUM_FMT
>     Index       : 0
>     Type        : Video Capture
>     Pixel Format: 'YUYV'
>     Name        : YUYV 4:2:2
>
>     Index       : 1
>     Type        : Video Capture
>     Pixel Format: 'MJPG' (compressed)
>     Name        : Motion-JPEG
>
> If I use the YUYV mode, I *don't* get the warning:
>
> GST_DEBUG=3 gst-launch-1.0 v4l2src device=/dev/video2 ! video/x-raw !
> videoconvert ! autovideosink
>
> reports no warnings (but the framerate is awful, of course).
>
> HTH,
> Michiel
>
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