linux how to show video to webcam

Question

I am trying the following command, so that my webcam shows a video when i access it from network or android emulator.

I am using archlinux. I have installed v4l2loopback-dkms. and added the module to the kernel. then i launched

gst-launch-0.10 filesrc location=/home/simha/1.3gp ! decodebin2 ! ffmpegcolorspace ! videoscale ! ffmpegcolorspace ! v4l2sink device=/dev/video0

but no sucess.

Setting pipeline to PAUSED ...
ERROR: Pipeline doesn't want to pause.
ERROR: from element /GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0: Device '/dev/video0' is not a output device.
Additional debug info:
v4l2_calls.c(528): gst_v4l2_open (): /GstPipeline:pipeline0/GstV4l2Sink:v4l2sink0:
Capabilities: 0x85200001
Setting pipeline to NULL ...
Freeing pipeline ...

Also tried:

ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0

but not working

ffmpeg version 2.8 Copyright (c) 2000-2015 the FFmpeg developers
  built with gcc 5.2.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --enable-avresample --enable-fontconfig --enable-gnutls --enable-gpl --enable-ladspa --enable-libass --enable-libbluray --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-shared --enable-version3 --enable-x11grab
  libavutil      54. 31.100 / 54. 31.100
  libavcodec     56. 60.100 / 56. 60.100
  libavformat    56. 40.101 / 56. 40.101
  libavdevice    56.  4.100 / 56.  4.100
  libavfilter     5. 40.101 /  5. 40.101
  libavresample   2.  1.  0 /  2.  1.  0
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  2.101 /  1.  2.101
  libpostproc    53.  3.100 / 53.  3.100
Input #0, x11grab, from ':0.0+0,0':
  Duration: N/A, start: 1456374857.672770, bitrate: N/A
    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1280x720, 15 fps, 15 tbr, 1000k tbn, 15 tbc
[v4l2 @ 0x55f5129180a0] ioctl(VIDIOC_G_FMT): Invalid argument
Output #0, v4l2, to '/dev/video0':
  Metadata:
    encoder         : Lavf56.40.101
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1280x720, q=2-31, 200 kb/s, 15 fps, 15 tbn, 15 tbc
    Metadata:
      encoder         : Lavc56.60.100 rawvideo
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> rawvideo (native))
Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument

Answer 1

You might be using the wrong driver for your webcam. Use the lsusb command to identify your webcam. Then find out what driver you need to get it working. You can find out more information about this by reading the Webcam Arch Wiki Page