[libcamera-devel] How to activate AGC control in libcamera, or set the GAIN/EXPOSURE parameter by v4l2 command.

[Laurent Pinchart]

Hi Kieran,

On Mon, Nov 23, 2020 at 10:26:18AM +0000, Kieran Bingham wrote:
> On 23/11/2020 10:19, Laurent Pinchart wrote:
> > On Sun, Nov 22, 2020 at 03:10:59PM +0000, David Plowman wrote:
> >> Hello Nomura-san
> >>
> >> Yes, I have had some similar errors in recent weeks, I'm not too sure
> >> why. There seems to be a new Python package required ("ply") and
> >> sometimes I've found myself having to delete the build directory under
> >> libcamera entirely and start over. Anyway, I've double-checked that
> >> the following instructions work, starting from a clean Raspberry Pi OS
> >> installation.
> >>
> >> First update the Pi's software as usual:
> >>
> >> sudo apt update
> >> sudo apt upgrade
> >> sudo rpi-update
> >>
> >> and then reboot it. Next install all the prerequisites for libcamera:
> >>
> >> sudo apt install libboost-dev
> >> sudo apt install libgnutls28-dev openssl libtiff5-dev
> >> sudo apt install meson
> >> sudo apt install qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5
> >> sudo pip3 install pyyaml ply
> > 
> > You can also install the native python3-yaml and python3-ply packages.
> > In the not too distant future we'll also require python3-jinja2.
> 
> In that past I started looking at / thinking about a
> 'bootstrap-dependencies.sh' script to live in utils.
> 
> Something that would allow:
> 
> ./utils/bootstrap.sh [qcam] [raspberrypi] [gstreamer] [hotplug]
> [documentation] [tracing]
> 
> or something like that to be able to pick / install packages required.
> 
> Is this worth posting? Or does anyone want to implement it?
> 
> (my local script is not yet anything 'exotic' beyond apt install xxxx..)
> 
> Or any other thoughts?

I think it's a good idea, it certainly improves user experience. I
wonder if we shouldn't event make it simpler by installing all
dependencies by default (or even as the only option), but maybe that's a
bit harsh ?

Ideally we should support multiple distributions too :-) It shouldn't be
too difficult, there seems to be a "systemd standard" (I know...)
https://www.freedesktop.org/software/systemd/man/os-release.html.
Another option could be https://linux.die.net/man/1/lsb_release, but I'm
not sure if that's installed by default by most distributions (it isn't
on Gentoo).

> >> Note the new "ply" Python package. Finally download and build libcamera:
> >>
> >> git clone git://linuxtv.org/libcamera.git
> >> cd libcamera
> >> meson build
> >> ninja -C build
> >>
> >> That all seemed to work for me. You may have read that we're (very
> >> soon, I hope!) introducing libcamera-based versions of our
> >> raspistill/raspivid applications and once those are available I'll be
> >> doing an update to all our related documentation.

-- 
Regards,

Laurent Pinchart