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• How to create thumbnails image or get metadat from videos url ? [closed]

  7 septembre 2021, par M Kasesang

  I can create video thumbnails and get metadat from my videos path in my website via ffmpeg and php.

  


  but how can I create thumbnails or get metadat from videos stored in my dl host or any url of videos like "dl.example.com/video.mp4" ?

  


  Thnx in advance.

  


• ffmpeg mjpeg encoding not recognized by VLC on other device

  25 juin 2023, par Harsh Kumar

  Let me describe the case scenerio first :

  


  I am using RaspberryPi as a USB-UVC gadget to stream a video to a host device connected via USB cable to the Pi .
For this i have a application(may see if you want) which is succesfully streaming the a USB camera live stream using ./uvc-gadget -d /dev/video0 on the Pi side where /dev/video0 is a real USB camera and the rest is just a syntax of application to take the input as some v4l2 capture device.On the Host side i have to just open the VLC and select capture device as the UVC-Camera made by the apllication and play the stream by selcting the MJPG option under the advanced options and only MJPEG format is supported by the application.

  


  So what i thought that is to make a virtual camera device using sudo modprobe v4l2loopback first (/dev/video1 for now ) and then feeding a my Raspberry desktop screen to it using ffmpeg and then feeding this /dev/video1 virtual video capture device to my application as ./uvc-gadget -d /dev/video1.

  


  More graphically,

  


  Desktop screen -> virtual camera -> apllication

  


  But unfortunately i am not getting the desired results given that this service is supported by the appllication (you may refer readme of application) .I get the trival error of 'Your input device can,t be opened ' in VLC when i do the same steps .

  


  Summary ,
I guess i may be doing something wrong for the MJPEG encoding using ffmpeg also ,
Here is the command i am using ,
ffmpeg -probesize 100M -framerate 30 -f x11grab -video_size 1280*720 -i :0.0+0,0 -c:v mjpeg -pix_fmt yuvj422p -f v4l2 /dev/video1.

  


  Also , i checked on raspberry the output of dev/video1 is fine and also tried removing the pix_fmt yuvj422p thinking that it might causing some conflict with color encoding but got the same error.

  


  Will be very thankful if someone can help me figuring out the erorr.
Thanks for your time and patience .

  


• I am getting "Stream specifier ' ' in filtergraph description" in ffmpeg

  1er avril 2020, par Dave B

  I am generating 10 seconds of silence using an image. Here is my command

  



  ffmpeg -loop 1 -framerate 24 -t 10 image.jpg -f lavfi -t 10 -i anullsrc -filter_complex "[0][1]concat=n=2:v=1:a=1" out.mp4


  



  Also, I have tried

  



  ffmpeg -loop 1 -framerate 24 -t 10 beach.jpg -f lavfi -t 10 -i anullsrc -filter_complex "[0:v][1:a]concat=n=2:v=1:a=1" out.mp4


  



  I am getting following errors

  



  ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.17)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.2_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, lavfi, from 'anullsrc':
  Duration: N/A, start: 0.000000, bitrate: 705 kb/s
    Stream #0:0: Audio: pcm_u8, 44100 Hz, stereo, u8, 705 kb/s
Stream specifier '' in filtergraph description [0][1]concat=n=2:v=1:a=1 matches no streams.

ffmpeg -loop 1 -framerate 24 -t 10 beach.jpg -f lavfi -t 10 -i anullsrc -filter_complex "[0:v][1:a]concat=n=2:v=1:a=1" out.mp4
ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.17)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.2.2_2 --enable-shared --enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr --enable-videotoolbox --disable-libjack --disable-indev=jack
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Input #0, lavfi, from 'anullsrc':
  Duration: N/A, start: 0.000000, bitrate: 705 kb/s
    Stream #0:0: Audio: pcm_u8, 44100 Hz, stereo, u8, 705 kb/s
Stream specifier ':v' in filtergraph description [0:v][1:a]concat=n=2:v=1:a=1 matches no streams.