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• What is the commmand line to record destop screen with watermark using ffmpeg ?

  11 septembre 2020, par Yong Ju

  I tried to record screen using ffmpeg commmand line. So, I have complete it using this commmand.
ffmpeg.exe -rtbufsize 1500M -f -y -rtbufsize 100M -f gdigrab -t 00:02:00 -framerate 30 0 0 -probesize 10M 1920 1080 -draw_mouse 1 -i desktop -c:v libx264 -r 30 -preset ultrafast -tune zerolatency -crf 30 -pix_fmt yuv420p output.avi".

  


  Now, I want to add watermark while recording video.
If you have good experience this field, Please give me good advice.
Thanks for your attention.
Sincerely.

  


• How to create ffmpeg mosaic with empty cells ?

  7 septembre 2020, par DenVebber

  I try to create video mosaic with ffmpeg.

  


  Two videos with horizontal stack :

  


  ffmpeg -i vid1.mp4 -i vid2.mp4 -filter_complex "[0]scale=-1:1080[v0];[1]scale=-1:1080[v1];[v0][v1]hstack=inputs=2[vmap]" -map "[vmap]" output.mp4

  


  How can I replace vid1.mp4 with black background and save the stack with 2 elements ?
I can add blackvideo.mp4, but it should be easier, right ?

  


• How to write v4l2 application with vivid (virtual video driver) for capturing video ?

  8 janvier 2016, par ransh

  I am trying to understand how to write v4l2 application.
  There is very well example in http://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html , so I wanted to try to use it for capturing video with vivid (virtual device driver).

  I tried several resolution, pixelformat, different inputs,
  but on trying to display the captured file, it always has a sync problems ( the test bars of the video are keep moving in the horizontal axis).
  I tried to change resolution, pixelformat, in both capture application or player , but nothing helps.

  I compiled the v4l2 API example AS-IS from :
  http://linuxtv.org/downloads/v4l-dvb-apis/capture-example.html
  with minor modification in the —force part of the example (I also tried the example as is without modifications but it did not help), so that I choose hd input , and 1920x1080 resolution, V4L2_PIX_FMT_YUV420 (also tried V4L2_PIX_FMT_YUV422P) , progressive.

    if (force_format) {
  
              input = 3;  // <<-- HD input device
  
              if (-1==xioctl(fd,VIDIOC_S_INPUT,&input))
  
              {
  
               errno_exit("VIDIOC_S_INPUT");
  
              }
  
              fmt.fmt.pix.width       = 1920;
  
              fmt.fmt.pix.height      = 1080;
  
              fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_YUV420; // <<- tried also V4L2_PIX_FMT_YUV422P
  
              fmt.fmt.pix.field       = V4L2_FIELD_NONE; // <- trying to capture progressive
  
  
  
              if (-1 == xioctl(fd, VIDIOC_S_FMT, &fmt))
  
                      errno_exit("VIDIOC_S_FMT");
  
  
  
      } else {

  I run the application with (the compiled code using pixelformat = V4L2_PIX_FMT_YUV420 trial ) :

  ./v4l2_example -f -o -c 10  > cap_yuv420p.yuv 

  And (the compiled code using pixelformat = V4L2_PIX_FMT_YUV422P trial )

  ./v4l2_example -f -o -c 10  > cap_yuv422p.yuv 

  I’ve tried to play them with :

  ffplay -f rawvideo -pixel_format yuv420p -video_size 1920x1080 -i cap_yuv420p.yuv 

  And

  ffplay -f rawvideo -pixel_format yuv422p -video_size 1920x1080 -i cap_yuv422p.yuv 

  These are the captured video files from my above trials :

  https://drive.google.com/folderview?id=0B22GsWueReZTUS1tSHBraTAyZ00&usp=sharing

  I probably am doing something wrong.
  Is there any idea what’s wrong in my configurations or how I can debug it better ?