Show-me webcam: An open source, trustable and high quality webcam

This firmware transforms your Raspberry Pi into a high quality webcam. It works reliably, boots quickly, and gets out of your way.

Show-me webcam is proudly powered by peterbay’s uvc-gadget.

What you need

• Raspberry Pi Zero with or without Wifi
• Raspberry Pi Zero Camera Adapter/Ribbon (The one that comes with the camera may not fit)
• Raspberry Pi Camera or Raspberry Pi High-Quality Camera
• A compatible lens if you use the HQ Camera sensor
• Micro SD card (at least 64MB)
• A case or mounting plate (optional)

What works and what doesn’t

• The camera is known to work on Linux, Windows 10 and Mac OS
• The camera is known to work with Zoom, Teams, Skype, Jitsi, Firefox and Chrome
• Here’s a compatibility matrix as far as we could test. Let us know if you had the chance to test other variants:

Raspberry Pi \ Camera version
v1 5MP
v2 8MP
High Quality 12MP

Pi Zero v1.3 (without Wifi)
✓
✓
✓

Pi Zero W (with Wifi)
✓
✓
✓

Pi 4+

✓
✓

Instructions

• Follow the Cytron tutorial.
• Smile & Enjoy!

Stable releases

We release new versions of this firmware regularly at the release tab:
https://github.com/showmewebcam/showmewebcam/releases

LED indicator

After booting, the built-in LED will blink three times quickly to show you it’s ready.

When the camera is in use the LED will be lit. In addition,
GPIO 21 pin is set to HIGH, so an
external LED or another payload can be triggered with this pin to indicate that
the camera is in use.

Debugging

For debugging, a 115200 baud serial interface is provided as a ttyACM device:

• Use screen, minicom, picocom or the included smwc-expect script to connect to it
• Use username: root, password root

Also, there is a serial interface on the 40-pin header: https://pinout.xyz/pinout/uart

Linux example:

$ ls -l /dev/ttyACM*
crw-rw---- 1 root dialout 166, 0 sep 25 14:03 /dev/ttyACM0
$ sudo screen /dev/ttyACM0 115200

Mac OS example:

$ ls -l /dev/tty.*
crw-rw-rw-  1 root  wheel    9,  18 Dec  7 13:14 /dev/tty.usbmodem13103
$ screen /dev/tty.usbmodem13103 115200

If the terminal is blank try pressing enter to see the login prompt. To exit
the session, use Ctrl-A \ (screen) or Ctrl-A X (minicom & picocom).

Warning: This serial debug interface is automatically enabled and is controlled
by the file called enable-serial-debug in the /boot folder. This is a potential
security issue. For now, you should strongly consider disabling this feature by
removing the file after you have finished customizing the webcam.

My camera doesn’t show up on my host computer! What to do?

From version 1.80, on Linux, you can see what happens by watching dmesg
before you plug in the webcam:

$ sudo dmesg -w

If you only see the ttyACM device show up, but not the webcam, it’s likely you
have not plugged in the camera cable correctly, or the camera cable has gone bad.

If you see nothing, maybe your USB cable is bad, or you have plugged in the cable
to the wrong port.

Customizing camera settings

Automatic

Log in to the debug interface and execute:

/usr/bin/camera-ctl

This tool will allow you to show and tweak all available camera parameters.
Additionally it will save your settings to /boot/camera.txt if you choose to
do so. This will handle remounting /boot automatically.

Manual

Overriding camera settings temporarily

Log in to the debug interface. Then list all tweakable parameters:

/usr/bin/v4l2-ctl -L 
|
 less

Then you can apply parameters on the fly, e.g.

/usr/bin/v4l2-ctl -c auto_exposure_bias=15
/usr/bin/v4l2-ctl -c contrast=3

Overriding camera settings permanently

Mount the SD card on your computer, edit a file called camera.txt in
/boot and put all parameters you want overridden, e.g:

# Tweak the auto exposure bias
auto_exposure_bias=15
# Tweak the contrast
contrast=3

You can edit camera.txt on-target by remounting /boot read-write:

mount -o remount,rw /boot

Overriding the controls available to the host computer

Since version 1.80 we try to expose as many controls as possible via the UVC
standard, which are then translated back to the controls that are available
on your specific camera module. Some host operating systems may be confused
by controls that are advertised via USB, but don’t turn out to work, due to
not being available for your specific camera module.

You can therefore customize the controls advertised to the computer via the
USB device descriptor. Warning: This is an advanced user feature only.
You should probably consult the UVC controls bitmap documentation on GitHub.

You can add the parameters to cmdline.txt on the boot volume as follows:

usb_f_uvc.camera_terminal_controls=0,0,0 usb_f_uvc.processing_unit_controls=0,0

The above example disables all controls and should thus be safe.
The parameters directly correspond to the bmControls bitfields in the descriptor.
Please, again, read the documentation linked above.

An example for enabling all the available controls for the 8 Mpixel (v2) camera for the Raspberry Pi 4B is given below:

usb_f_uvc.camera_terminal_controls=10,0,0 usb_f_uvc.processing_unit_controls=219,4

Configure available camera resolutions and streaming format

The camera advertises the available resolutions and streaming formats to the
connected host PC. Usually the best suitable resolution is chosen. The available
resolutions can be reduced to enforce a specific setting.

By default the camera uses the Motion JPEG codec to stream the video signal.
For the host PC it offers several video resolutions up to 1080p HD video to
choose from.

These settings can be overwritten by copying the file video_formats.txt into
the /boot folder and editing it.

cp /etc/video_formats.txt /boot

In this file one line corresponds to one video resolution and streaming format.
Until now, only mjpeg and uncompressed video are supported. If you want to make
certain resolutions unavailable, comment them out by prepending a # to that
line or removing them altogether.

Please note that you have to reboot your piwebcam (power cycle it) for changes to take effect.

Development & building

Clone or download this repository. Then inside it:

• Clone the repository with submodules:
  • git clone --recurse-submodules https://github.com/showmewebcam/showmewebcam.git
• Run build command:
  • ./build-showmewebcam.sh raspberrypi0w to build Raspberry Pi Zero W (with Wifi) image.
  • ./build-showmewebcam.sh raspberrypi0 to build Raspberry Pi Zero (without Wifi) image.
  • ./build-showmewebcam.sh raspberrypi4 to build Raspberry Pi 4 image.
• The resulting image sdcard.img will be in the output/$BOARDNAME/images folder
• If you add a camera.txt file to the root of this repository, the contents will be automatically added to /boot/camera.txt

Note: If you want to use external Buildroot directory you need to set the Buildroot path manually, e.g. BUILDROOT_DIR=../buildroot ./build-showmewebcam.sh raspberrypi0

Credits

• David Hunt: http://www.davidhunt.ie/raspberry-pi-zero-with-pi-camera-as-usb-webcam/
• Petr Vavřín: uvc-gadget
• Buildroot
• ARM fever: https://armphibian.wordpress.com/2019/10/01/how-to-build-raspberry-pi-zero-w-buildroot-image/
• The repository icon is attributed to the GNOME project