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• How to limit FFMPEG CPU usage on Android

  17 mai 2022, par Björn

  I am recording video on Android and saving it to mp4 files using MediaMuxer.
This works great but a few times I also need to proccess these mp4 files to cut/combine them into a new mp4 while still recording. The speed of this proccessing is not vital.

  


  For cutting and combining I use FFMPEG, specifically
https://github.com/tanersener/ffmpeg-kit. com.arthenica:ffmpeg-kit-full-gpl:4.5

  


  The problem is that this sometimes causes 100% CPU usage and the recording to freeze. I have set maximum priority on the thread handling recording and minumum priority on the one starting FFMPEG. But the problem still occurs. The ffmpeg command seams to start many threads (despite me trying to limit it to one) as seen in the Android studio inspector.

  


  The command I use :

  


  FFmpegKit.execute("-threads 1 -hide_banner -loglevel error -y"
                        + " -ss " + convertMSToString(startTimeMs)
                        + " -t " + convertMSToString(lenghtMs)
                        + " -i " + inputFilePath
                        + " -c copy " + outputFilePath)


  


  

  


  Any ideas how I can limit the CPU usage of ffmpeg, or ensure that the camera thread/threads get higher priority so they do not freeze ?

  


• Feeding content of an X-Window to a virtual camera

  11 mai 2022, par Ingo

  I want to feed a virtual webcam device from an application window (under Linux/Xorg). I have so far just maximised the window and then used ffmpeg to grab the whole screen like this :

  


  ffmpeg \
    -f x11grab -framerate 15 -video_size 1280x1024 -i :0+0,0 \
    -f v4l2 -vcodec rawvideo -pix_fmt yuv420p /dev/video6


  


  where /dev/video6 is my v4l2loopback device. This works and I can use the virtual camera in video calls in chrome. This also indicates that the v4l2loopback module is correctly loaded into the kernel.

  


  Unfortunately, it seems that ffmpeg can only read the whole screen, but not an application window. gstreamer on the other hand can. Playing around with gst-launch-1.0, I was hoping that I could get away with something like this :

  


  gst-launch-1.0 ximagesrc xid=XID_OF_MY_WINDOW \
    ! "video/x-raw" \
    ! v4l2sink device=/dev/video6


  


  However, that complains that Device '/dev/video6' is not an output device.

  


  Given that ffmpeg seems happy to write to /dev/video6 I also tried piping the gst output to ffmpeg like this :

  


  gst-launch-1.0 ximagesrc xid=XID_OF_MY_WINDOW \
    ! "video/x-raw" \
    ! filesink location=/dev/stdout \
    | ffmpeg -i - -codec copy -f v4l2 -vcodec rawvideo -pix_fmt yuv420p /dev/video6


  


  But then ffmpeg complains about Invalid data found when processing input.

  


  This is running inside an xvfb headless environment, so mouse interactions will not work. This rules out obs as far as I can see.

  


  I'm adding the chrome tag, because I see that chrome in principle would also provide a virtual camera via the --use-fake-device-for-media-stream switch. However, it seems that this switch only supports a static file rather than a stream.

  


  Although I don't see why, it might be relevant that the other "application window" window is simply a second browser window. So the setup is google meet (or similar) in one browser window and the virtual camera gets fed vrom a second browser window.

  


• How to convert animated webp to gif in android / java ?

  21 avril 2022, par UHS

  I want to convert the animated webp files to gif file and looking for solution since couple of days but did not get any easy straight solution yet.

  


  I tried ffmpeg but it could not do the job and after looking for solution I found that webp decoder is not implemented in ffmpeg yet.
https://trac.ffmpeg.org/ticket/4907

  


  I also checked libwebp library by google and they also says animated webp is not supported. https://developers.google.com/speed/webp/docs/dwebp

  


  I tried demo of aspose this library also fail to convert animated webp to gif.
https://products.aspose.com/imaging/java/conversion/webp-to-gif/

  


  I think ImageMagick can convert animated webp to gif but do not know how to implement that in my project.
How can I avoid dropouts when using (imagemagick) `mogrify` to convert webp files to animated gif ?

  


  So is there any easy way to convert webp to gif