weebney
Guvcview error: could not start a video stream in the device
Describe the bug webcamize creates a video device which works for VLC and mpv, but guvcview cannot use it, reporting the following error:
Clicking OK just loads another guvcview window and error message dialog. Here's how guvcview sees the device, although no video is shown:
Terminal Output
$ sudo modprobe v4l2loopback
$ pkill -f gphoto2
$ sudo ./webcamize -lDEBUG
webcamize: [DBUG] Using camera: Canon EOS 1300D
webcamize: [DBUG] Initializing V4L2 device: /dev/video3
webcamize: [DBUG] V4L2 device initialized successfully
webcamize: [INFO] Starting webcam `Canon EOS 1300D` on /dev/video3!
webcamize: [DBUG] Found decoder: mjpeg for format: jpeg_pipe
webcamize: [DBUG] Image dimensions: 1056x704
[swscaler @ 0x55c18fd19840] deprecated pixel format used, make sure you did set range correctly
webcamize: [DBUG] V4L2 format set to 1056x704 YUYV
Expected behavior I would like to be able to preview the video using guvcview.
Desktop (please complete the following information):
- Distro and Version:
Debian 13 Trixie - Camera/Device:
Canon EOS Rebel T6 - Webcamize version (from
webcamize -v):2.0.1
gphoto2 Information
- Output from
gphoto2 --summary
Camera summary:
Manufacturer: Canon Inc.
Model: Canon EOS Rebel T6
Version: 3-1.0.2
Serial Number: cc7f932c36d64e4a80212f03641d429f
Vendor Extension ID: 0xb (1.0)
Vendor Extension Description:
Capture Formats: JPEG
Display Formats: Association/Directory, Script, DPOF, MS AVI, MS Wave, JPEG, CRW, Unknown(b103), Unknown(bf02), Defined Type, Unknown(b104), Unknown(b105)
Device Capabilities:
File Download, File Deletion, File Upload
No Image Capture, No Open Capture, Canon EOS Capture, Canon EOS Capture 2
Canon Wifi support
Storage Devices Summary:
store_00020001:
StorageDescription: SD
VolumeLabel:
Storage Type: Removable RAM (memory card)
Filesystemtype: Digital Camera Layout (DCIM)
Access Capability: Read-Write
Maximum Capability: 32009961472 (30527 MB)
Free Space (Bytes): 32002850816 (30520 MB)
Free Space (Images): -1
Device Property Summary:
Property 0xd402:(read only) (type=0xffff) 'Canon EOS Rebel T6'
Property 0xd407:(read only) (type=0x6) 1
Property 0xd406:(readwrite) (type=0xffff) 'Unknown Initiator'
Property 0xd303:(read only) (type=0x2) 1
Battery Level(0x5001):(read only) (type=0x2) Enumeration [100,0,75,0,50] value: 50% (50)
- Output from
gphoto2 --auto-detect
Model Port
----------------------------------------------------------
Canon EOS 1300D usb:003,004
Additional context
$ guvcview -v
Guvcview version 2.2.1
$ sudo apt install libgphoto2-dev libkmod-dev gphoto2 v4l2loopback-dkms
$ make
cc -Wall -Wextra -march=native -mtune=native -O3 -ffast-math -funroll-loops -DUSE_LIBKMOD -I/usr/include/gphoto2 -I/usr/include/x86_64-linux-gnu -o bin/webcamize webcamize.c -lgphoto2 -lgphoto2_port -lm -lavformat -lavcodec -lavutil -lswscale -lkmod
$ lsmod | grep v4l2loopback
v4l2loopback 61440 0
videodev 368640 3 videobuf2_v4l2,v4l2loopback,uvcvideo
$ ./webcamize -s
Webcamize 2.0.1, copyright (c) W. Turner Abney 2025, licensed BSD-2-Clause
Libraries:
libgphoto2: 2.5.31
libavutil: 59.39.100
libavcodec: 61.19.101
libavformat: 61.7.100
libswscale: 8.3.100
$ mpv av://v4l2:/dev/video3
client removed during hook handling
● Video --vid=1 (rawvideo 1056x704 30 fps)
[autoconvert] Converting yuyv422 -> yuv422p
VO: [gpu] 1056x704 yuv422p
V: 00:00:38 / 00:00:38 (99%)
This seems like an issue with guvcview; I'm not familiar with the project, but you put this on their radar and link it here so I can follow.
Also, if there's some kind of debug printout you could get related to the "could not start a video stream with the device" (maybe by running guvcview from the terminal) that explains the error in more detail it would give me more to work with