Using DSLR camera as a webcam in Solus

Justin

Step 1: Does your DSLR support live view at all?

alexxtasi

Hi @Justin
it's an "old by now" Canon EOS 550D supporting live view and also comes with Windows software with tethering capabilities.
Also when running gphoto2 --abilities says:

Abilities for camera             : Canon EOS 550D
Serial port support              : no
USB support                      : yes
Capture choices                  :
                                 : Image
                                 : Preview
                                 : Trigger Capture
Configuration support            : yes
Delete selected files on camera  : yes
Delete all files on camera       : no
File preview (thumbnail) support : yes
File upload support              : yes

In the command gphoto2 --summary, full error message is:

*** Error ***              
An error occurred in the io-library ('Could not claim the USB device'): Could not claim interface 0 (Device or resource busy). Make sure no other program (gvfs-gphoto2-volume-monitor) or kernel module (such as sdc2xx, stv680, spca50x) is using the device and you have read/write access to the device.
*** Error (-53: 'Could not claim the USB device') ***

For debugging messages, please use the --debug option.
Debugging messages may help finding a solution to your problem.
If you intend to send any error or debug messages to the gphoto
developer mailing list <gphoto-devel@lists.sourceforge.net>, please run
gphoto2 as follows:

    env LANG=C gphoto2 --debug --debug-logfile=my-logfile.txt --summary

Please make sure there is sufficient quoting around the arguments.

Justin

What does gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0 do?

alexxtasi

it shows this error message:

ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Solus)
  configuration: --prefix=/usr --libdir=/usr/lib64 --disable-debug --disable-stripping --enable-shared --disable-static --enable-avisynth --enable-avresample --enable-gcrypt --enable-gpl --enable-libaom --enable-libass --enable-libbluray --enable-libcaca --enable-libcdio --enable-libdav1d --enable-libdrm --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-libopus --enable-libpulse --enable-libsnappy --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzimg --enable-nonfree --enable-nvdec --enable-nvenc --enable-openal --enable-opengl --enable-openssl --enable-sdl2 --enable-version3
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Capturing preview frames as movie to 'stdout'. Press Ctrl-C to abort.

*** Error ***              
An error occurred in the io-library ('Could not claim the USB device'): Could not claim interface 0 (Device or resource busy). Make sure no other program (gvfs-gphoto2-volume-monitor) or kernel module (such as sdc2xx, stv680, spca50x) is using the device and you have read/write access to the device.
ERROR: Movie capture error... Exiting.
Movie capture finished (0 frames)
pipe:: Invalid data found when processing input

Justin

Two ideas:

Try pkill gvfs-gphoto2-volume-monitor and try again
If that doesn't work try the command with sudo (shouldn't be needed but it does talk about a possible permission issue)

alexxtasi

pkill gvfs-gphoto2-volume-monitor did not work (even with sudo).
But as I search in the web, found this which did the trick !!

To sum up :

before camera is plugged in (usb)

user@test ~ $ ps aux | grep gphoto
user        1073  0.0  0.2 444292  5976 ?        Ssl  01:21   0:00 /usr/lib64/gvfs/gvfs-gphoto2-volume-monitor
user        1598  0.0  0.1 216176  2484 pts/0    S+   01:22   0:00 grep gphoto

right after camera is plugged in

user@test ~ $ ps aux | grep gphoto
user        1073  0.0  0.3 445100  8140 ?        Ssl  01:21   0:00 /usr/lib64/gvfs/gvfs-gphoto2-volume-monitor
user        1674  0.4  0.4 533324  9860 ?        Sl   01:25   0:00 /usr/lib64/gvfs/gvfsd-gphoto2 --spawner :1.4 /org/gtk/gvfs/exec_spaw/1
user        1692  0.0  0.1 216176  2500 pts/0    S+   01:25   0:00 grep gphoto

** running the command
gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0
only succeeds when killing the above two processes:

kill -9 <id / gvfs-gphoto2-volume-monitor>
kill -9 <id / gvfsd-gphoto2>

So...

would it be safe to assume that the correct commands (for current kernel) are:

sudo eopkg install gphoto2 v4l2loopback-current
sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2

what about processes gvfs-gphoto2-volume-monitor and gvfsd-gphoto2 and the need to kill them ??

(i will try the same process on another distro to see ...)
thanks in advance

alexxtasi

The same things happened in ubuntu too.
gvfs-gphoto2-volume-monitor and gvfsd-gphoto2 processes need to be killed by the user in order for gphoto2 to play.

So the two main questions now become:

is this the correct process for Solus to setup dslr as webcam ?

sudo eopkg install gphoto2 v4l2loopback-current
sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2
gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

is the need of killing gvfs-gphoto2-volume-monitor a gnome issue or a Solus issue ?
is there any other solution ?

thanks in advance

Justin

alexxtasi

You're the first to try that I'm aware of
I believe it's a GNOME issue as the process locks the device while it's plugged in
Not that I've seen but I only did brief research on the matter

thechosennone

That is the output I get. That should be what you would have expected right?

I'm happy to provide any info on the system precisely I'm running and so on if there's still a need present for which I could be of assistance.

I hope you find a solution! 🙂

alexxtasi

thechosennone: I use Solus Gnome. Do you run Solus Gnome or another Solus edition ? I am curious if there is no gvfs service running in you system.
... by the way... nice camera 🙂

jeremymolina: My camera is Canon EOS 550D and has no wifi nor bluetooth, so again are you running Solus Gnome ?

Till now I have concluded in the steps to:

install needed software :

sudo eopkg install gphoto2 v4l2loopback-current ffmpeg
# in case of lts kernel I suspect : 
#sudo eopkg install gphoto2 v4l2loopback ffmpeg

create the v4l loopback device (this should be run every time DSLR need to be used) and only after that, /dev/video0 is created :

sudo modprobe v4l2loopback exclusive_caps=1 max_buffers=2

check if gvfs-gphoto2-volume-monitor service is active and stop it ... otherwise the error occurs :

systemctl --user -q is-active gvfs-gphoto2-volume-monitor.service && \
    systemctl --user stop gvfs-gphoto2-volume-monitor.service

only after that, I can capture the camera's video input and fake it's from v4l loopback's device :

gphoto2 --stdout --capture-movie | ffmpeg -i - -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

** Running step 4 before 3 will not solve the problem, because gvfsd-gphoto2 process will be created. This process must also be killed in order for this workaround to succeed.

** As for the stopping of gvfs service and if it's the right way to do it from GNOME's perspective, I have asked there, but it seems an old issue so I 'll give another try asking...

** This is tested in Solus Gnome and also Ubuntu, so I have no clue of non-gnome systems ... I guess there is no gvfs service there ??

Anyway this is all I figured out till now and any suggestion and corrections are welcome.

regards

jeremymolina

In what settings is your camera on? Did you disabled the Bluetooth and/or Wi-Fi connectivity?

I have a Canon Rebel T6 and most of my issues were that you have I needed to disable bluetooth/wi-fi and set the right camera mode. (This is somewhere on the steps for the new driver that Canon released) but it's very well hidden)...

jeremymolina

alexxtasi I'm not using Solus Gnome but I have used the same steps in multiple distros based on Gnome, they all run without no issues. What I have noticed is that must people forget the step 2 and therefore the camera is not mounted in the system as a videoN device.