libcamerasrc and formats?

[Nicolas Dufresne]

Hi,

Le vendredi 17 mars 2023 à 10:21 +0100, Florian Echtler a écrit :
> Thank you - turns out it's rather hard to build libcamera on the target device, 
> which is a Raspberry Pi Zero. I'll test with another Raspi ASAP.
> 

Meson based projects aren't too hard to cross compile, there is a concises
instruction how to set this up a toolchain for RPi OS:

https://deardevices.com/2019/04/18/how-to-crosscompile-raspi/

I would have hoped for already made docker image. I never tried this. An
alternative I've used (though I have a Pi4 now with 8G of RAM), is to use qemu
to chroot into the SD card rootfs and just build using emulation.

regards,
Nicolas

> 
> Best, Florian
> 
> On 15.03.23 19:13, Nicolas Dufresne wrote:
> > Hi,
> > 
> > Le mercredi 15 mars 2023 à 17:24 +0100, Florian Echtler via gstreamer-devel a
> > écrit :
> > > Hello everyone,
> > > 
> > > I'm experimenting with a Raspberry Pi camera and would like to process the
> > > frames with OpenCV. Apparently, the "modern" way of doing so is through
> > > libcamera, and for OpenCV, this means using a GStreamer pipeline with libcamerasrc.
> > > 
> > > For efficiency reasons, I'd like to get a grayscale image directly from the
> > > camera to avoid unneeded conversions; so I used the following pipeline:
> > > 
> > > libcamerasrc !
> > > video/x-raw,width=(int)640,height=(int)480,framerate=(fraction)30/1,format=GRAY
> > > ! appsink
> > > 
> > > "GRAY" is listed as a supported format for the camera in the Video4Linux device,
> > > but I don't get a working pipeline when I try that. If I leave out the format
> > > parameter, then I'm getting NV12 (or I can pick something generic like RGB). How
> > > can I see which formats I can actually get out of libcamerasrc and the sensor?
> > 
> > Any chance you can give this patch a try ? I'll post it to the libcamera project
> > if you can confirm its working. Note that libcamerasrc is entirely developed as
> > part of libcamera project.
> > 
> > ---
> > commit abf017f5c0f547ceaa863e658f22af9f547a863d (HEAD -> logger-crash)
> > Author: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> > Date:   Wed Mar 15 14:10:08 2023 -0400
> > 
> >      gstreamer: Map R8 pixel format
> >      
> >      This enables monochrome 8bit to be supported in libcamerasrc.
> >      
> >      Signed-off-by: Nicolas Dufresne <nicolas.dufresne at collabora.com>
> > 
> > diff --git a/src/gstreamer/gstlibcamera-utils.cpp b/src/gstreamer/gstlibcamera-
> > utils.cpp
> > index 750ec351..f1e34b60 100644
> > --- a/src/gstreamer/gstlibcamera-utils.cpp
> > +++ b/src/gstreamer/gstlibcamera-utils.cpp
> > @@ -26,6 +26,9 @@ static struct {
> >          { GST_VIDEO_FORMAT_ENCODED, formats::SGRBG8 },
> >          { GST_VIDEO_FORMAT_ENCODED, formats::SRGGB8 },
> >   
> > +       /* Monochrome */
> > +       { GST_VIDEO_FORMAT_GRAY8, formats::R8 },
> > +
> >          /* RGB16 */
> >          { GST_VIDEO_FORMAT_RGB16, formats::RGB565 },
> >   
> > 
> > 
> > 
> 
> -- 
> SENT FROM MY DEC VT50 TERMINAL
>