ffmpeg -f v4l2 -list_formats all -i /dev/video1 -> L. of Formats & Err

PeerK · 2025-03-18 01:26:48

Hi all,

I am trying to re-setup obs with Droidcam as webcam and a virtual camera for sending the obs video stream to the usual conference-systems.

Unfortunately, I receive an error in obs, when I try to start the virtual cam.

1. Popup: "Failed to start the output. Please check the lag file for details. Note: If you are using the NVENC or AMD encoders, make sure your device drivers are up to date)
2. obs-STDOUT: "error: Failed to start streaming on '/dev/video1' (Das Argument ist ungültig) warning: Failed to start virtual camera"

$ v4l2-ctl --list-devices
'P30' (platform:v4l2loopback-000):
        /dev/video0

'VirtualCam' (platform:v4l2loopback-001):
        /dev/video1

But when I try to look for the formats accepted, I receive an error:

ffmpeg -f v4l2 -list_formats all -i /dev/video1
ffmpeg version n7.1 Copyright (c) 2000-2024 the FFmpeg developers
  built with gcc 14.2.1 (GCC) 20250207
  configuration: --prefix=/usr ...
  libavutil      59. 39.100 / 59. 39.100
  libavcodec     61. 19.100 / 61. 19.100
  libavformat    61.  7.100 / 61.  7.100
  libavdevice    61.  3.100 / 61.  3.100
  libavfilter    10.  4.100 / 10.  4.100
  libswscale      8.  3.100 /  8.  3.100
  libswresample   5.  3.100 /  5.  3.100
  libpostproc    58.  3.100 / 58.  3.100
[video4linux2,v4l2 @ 0x618602493800] Raw       :        bgr0 : 32-bit BGRA/X 8-8-8-8 : {2-8192, 1}x{1-8192, 1}
.. (lot of formats) ..
[video4linux2,v4l2 @ 0x618602493800] Compressed: Unsupported :                 HEVC : {2-8192, 1}x{1-8192, 1}
[in#0 @ 0x618602493540] Error opening input: Immediate exit requested
Error opening input file /dev/video1.

I assume, that the Error opening input: Immediate exit requested indicates a configuration problem. But I have no idea, where to start.

For completeness:
/etc/modprobe.d/v4l2loopback_options.conf

options v4l2loopback devices=2 max_buffers=4 video_nr=0,1 card_label='P30','VirtualCam' exclusive_caps=1,0

Does anyone have an idea, where to start to fix the problem?

Kind regards,
Peer

Last edited by PeerK (2025-03-18 01:27:38)

seth · 2025-03-18 08:00:37

I don't think that the error is relevant, there's no actual input on the virtual cam at this point

.. (lot of formats) ..

should™ be the desired information, no?

The OBS problem is likely https://github.com/obsproject/obs-studio/pull/11906

PeerK · 2025-04-25 09:56:06

seth wrote:

I don't think that the error is relevant, there's no actual input on the virtual cam at this point
.. (lot of formats) ..
should™ be the desired information, no?
The OBS problem is likely https://github.com/obsproject/obs-studio/pull/11906

Thank you! I saw this too an hoped, that a new version of v4l2loopback would fix it. But it did not.

Since I don't want to necropost and continue here: https://bbs.archlinux.org/viewtopic.php?pid=2238603.

Solved (was an obs issue) / workaround -> https://bbs.archlinux.org/viewtopic.php … 3#p2238613

Last edited by PeerK (2025-04-25 11:21:39)

Arch Linux

#1 2025-03-18 01:26:48

ffmpeg -f v4l2 -list_formats all -i /dev/video1 -> L. of Formats & Err

#2 2025-03-18 08:00:37

Re: ffmpeg -f v4l2 -list_formats all -i /dev/video1 -> L. of Formats & Err

#3 2025-04-25 09:56:06

Re: ffmpeg -f v4l2 -list_formats all -i /dev/video1 -> L. of Formats & Err

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