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• v4l2loopback+ffmpeg input for uvc gadget

  13 mai, par Mosi

  I'm trying to use an MP4 video file as the input for a UVC Gadget setup on my Raspberry Pi 4 Model B, but I'm running into an issue when streaming through V4L2.

  


  Goal :

  


  To emulate a webcam that streams a looping MP4 video file to a Windows 11 host.

  


  My setup :

  


  

  • Hardware : Raspberry Pi 4 Model B

  


  • OS : Raspberry Pi OS Lite 64-bit (2025-05-06-raspios-bookworm-arm64-lite)

  


  • Kernel : 6.12.25+rpt-rpi-v8

  


  • Host System : Windows 11

  


  • UVC Gadget version : v0.3.0

  


  


  Workflow :

  


  [MP4 Video] → [FFmpeg] → [V4L2 Loopback] → [UVC Gadget] → Windows sees virtual webcam


  


  What works :

  


  The UVC Gadget works perfectly when I use a real webcam as the source (e.g., /dev/video0). Windows detects the virtual webcam and displays a smooth video stream.

  


  The problem :

  


  When I try to use an MP4 video file through FFmpeg and send it to the loopback device (/dev/video3), the UVC Gadget fails with the following error :

  


  ---

  


  Command I'm using :

  


  ffmpeg -re -stream_loop -1 -i input.mp4 -vf scale=640:480 \
  -c:v rawvideo -pix_fmt yuyv422 -r 30 -f v4l2 /dev/video3


  


  Then I run :

  


  sudo uvc-gadget -d /dev/video3 uvc.0


  


  Output :

  


  bRequestType 21 bRequest 01 wValue 0200 wIndex 0001 wLength 0022
streaming request (req SET_CUR cs 02)
setting commit control, length = 34
Setting format to 0x56595559 640x480
=== Setting frame rate to 30 fps
Starting video stream.
--> [At this point I open the camera on the Windows host]
/dev/video3: 2 buffers requested.
Failed to export buffer 0.
Failed to export buffers on source: Inappropriate ioctl for device (25)


  


  ---

  


  Things I've tried :

  


  

  • Multiple FFmpeg formats, resolutions, and pixel formats

  


  • Various ffmpeg buffer and framerate tweaks

  


  • Different UVC Gadget versions

  


  • GitHub related projects (showcamera, etc.)

  


  • Older Raspberry Pi OS versions

  


  


  Most guides and GitHub projects I found are outdated (5+ years old), and newer methods seem undocumented or incompatible with current kernel/UVC gadget tools.

  


  ---

  


  My question :

  


  How can I stream an MP4 file as a virtual webcam using UVC Gadget without getting ioctl errors ?
  
Is there a proper way to set up FFmpeg and loopback devices so that UVC Gadget can read the stream correctly ?

  


  Any modern working example or tips would be very appreciated. Thanks in advance !

  


• Could not find com.arthenica:ffmpeg-kit-full:6.0-2

  23 juin, par gabocalero

  I started receiving this message when I build my project

  


  > Could not find com.arthenica:ffmpeg-kit-full:6.0-2.
  Searched in the following locations:
    - https://dl.google.com/dl/android/maven2/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://repo.maven.apache.org/maven2/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://jcenter.bintray.com/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://jitpack.io/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://pkgs.dev.azure.com/MicrosoftDeviceSDK/DuoSDK-Public/_packaging/Duo-SDK-Feed/maven/v1/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
    - https://oss.sonatype.org/content/repositories/snapshots/com/arthenica/ffmpeg-kit-full/6.0-2/ffmpeg-kit-full-6.0-2.pom
  Required by:
      project :presentation > project :domain


  


  These are the project's repositories

  


  allprojects {     
   repositories {
      google()
      mavenCentral()
      jcenter()
      maven { url 'https://jitpack.io' }
      maven { url "https://oss.sonatype.org/content/repositories/snapshots" }     
   } 
}


  


  And this is the dependency I'm adding

  


      implementation(libs.arthenica.ffmpeg.full)


  


  This is my libs.version.toml

  


  ffmpeg = "6.0-2"
arthenica-ffmpeg-full = {  group = "com.arthenica", name = "ffmpeg-kit-full", version.ref = "ffmpeg" }


  


  AFAICS in the project's github page, it will not be maintained anymore


  


  In the short term, do you know any other repository that still servers this dependency ?

  


  On the other hand, do you know any other project to replace Arthenica ffmpeg-kit-full dependency ?

  


  Thank you very much

  


• RTMP Disconnects quickly when the stream is turned on and No index.m3u8 files are being generated in the assigned directory [closed]

  23 avril, par Kartik Salve

  23/4/2025 09:52:58 9408 [INFO] [rtmp connect] id=7K1RWSO1 ip=::1 app=live args={"app":"live","flashVer":"LNX 9,0,124,2","tcUrl":"rtmp://localhost:1935/live","fpad":false,"capabilities":15,"audioCodecs":4071,"videoCodecs":252,"videoFunction":1}
23/4/2025 09:52:58 9408 [INFO] [rtmp play] Join stream. id=7K1RWSO1 streamPath=/live/test  streamId=1 
23/4/2025 09:52:59 9408 [INFO] [rtmp play] Close stream. id=7K1RWSO1 streamPath=/live/test streamId=1
23/4/2025 09:52:59 9408 [INFO] [rtmp disconnect] id=7K1RWSO1


  


  These are the logs, ffmpeg pushes the stream in a different folder when tried manually.

  


  

  • I tried changing the location of my file outside of oneDrive to avoid any permission conflicts.

  


  • Manually checked if FFmpeg is correct with this command : C:\ffmpeg\bin\ffmpeg.exe -i rtmp://localhost/live/test -c:v copy -c:a aac -f hls -hls_time 2 -hls_list_size 5 -hls_flags delete_segments output/index.m3u8

  


  • Downgraded NMS to a stable version.