DSLR webcam and pipewire"">DSLR webcam and pipewire

Berend De Schouwer

tl;dr

It used to be possible to use a DSLR as a webcam, or in OBS, on Linux, and with the move to pipewire this broke.

Here’s the code to make it work again:

gst-launch-1.0 \
     clockselect \
     v4l2src \
     device=/dev/video0 \
     ! queue ! videoconvert \
     ! pipewiresink mode=provide stream-properties="properties,media.class=Video/Source,media.role=Camera" \
     client-name=DSLR

background

On Linux, you can use your DSLR as a webcam, and have any application use it. What you need is: * gphoto2 * ffmpeg * v4l2loopback (kernel module)

The recipe can be slightly different based on camera functionality like frame rate and resolution, but it basically follows

gphoto2 --set-config liveviewsize=2 \
        --stdout --capture-movie \
        | ffmpeg -i - \
                 -re \
                 -vcodec rawvideo \
                 -pix_fmt yuv420p \
                 -threads 2 \
                 -f v4l2 /dev/video0

Most DSLRs are supported.

With the move to pipewire, another step is needed. This blog post describes that step.

You may need to change:

liveviewsize=2

Different cameras will have different options

-re

-re should make ffmpeg match the native framerate, which may save CPU cycles

clock bug

The output of the gst command should have an advancing clock. If the clock remains stuck on 00:00:00, you will need to add clockselect to the gst-launch command at the top.

This is related to Pipewire Regressin 4389

when

Right now, December 2024. Firefox, OBS and Chrome are moving to pipewire. The move has happened in some distributions, and is in the process in others.

firefox

Look in about:config for media.webrtc.camera.allow-pipewire

chrome

Look in chrome://flags for Pipewire Camera Support

who

pipewire aims to improve the handling of audio and video on Linux, and it’s pretty good at that.

You’ll need version 1.2.6 or later for this to work. Look for libpw-v4l2.so.

what

A DSLR camera, attached via USB, that you used to use using gphoto2 and v4l2loopback

where

wpctl status

Look for a section like:

Video
 ├─ Devices:
 │      56. ...
 │  
 ├─ Sinks:
 │  
 ├─ Sources:
 │  *   64. USB2.0 FHD UVC WebCam (V4L2)       
 │      93. DSLR

You want your DSLR to show up under Sources.

You can then get more information using pw-cli info 93

why

Update to pipewire. It really is better.

how

After running gphoto2 the way you normally do, run the command at the top. You can name your DSLR something else if you like.

Test it using wpctl status and pw-cli info