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• How do I compose three overlapping videos w/audio in ffmpeg ?

  10 avril 2021, par Idan Gazit

  I have three videos : let's call them intro, recording and outro. My ultimate goal is to stitch them together like so :

  


  

  


  Both intro and outro have alpha (prores 4444) and a "wipe" to transition, so when overlaying, they must be on top of the recording. The recording is h264, and ultimately I'm encoding out for youtube with these recommended settings.

  


  I've figured out how to make the thing work correctly for intro + recording :

  


  $ ffmpeg \
  -i intro.mov \
  -i recording.mp4 \
  -filter_complex \
  "[1:v]tpad=start_duration=10:start_mode=add:color=black[rv]; \
   [1:a]adelay=delays=10s:all=1[ra]; \
   [rv][0:v]overlay[v];[0:a][ra]amix[a]" \
  -map "[a]" -map "[v]" \
  -movflags faststart -c:v libx264 -profile:v high -bf 2 -g 30 -crf 18 -pix_fmt yuv420p \
  out.mp4 -y


  


  However I can't use the tpad trick for the outro because it would render black frames over everything.

  


  I've tried various iterations with setpts/asetpts as well as passing -itsoffset for the input, but haven't come up with a solution that works correctly for both video and audio. This tries to start the outro at 16 seconds into the recording (10s start + 16s of recording is how I got to setpts=PTS+26/TB). del, but doesn't work correctly, I get both intro and outro audio from the first frame, and the recording audio cuts out when the outro overlay begins :

  


  $ ffmpeg \
  -i intro.mov \
  -i recording.mp4 \
  -i outro.mov \
  -filter_complex \
  "[1:v]tpad=start_duration=10:start_mode=add:color=black[rv]; \
   [1:a]adelay=delays=10s:all=1[ra]; \
   [2:v]setpts=PTS+26/TB[outv]; \
   [2:a]asetpts=PTS+26/TB[outa]; \
   [rv][0:v]overlay[v4]; \
   [0:a][ra]amix[a4]; \
   [v4][outv]overlay[v]; \
   [a4][outa]amix[a]" \
  -map "[a]" -map "[v]" \
  -movflags faststart -c:v libx264 -profile:v high -bf 2 -g 30 -crf 18 -pix_fmt yuv420p \
  out.mp4 -y


  


  I think the right solution lies in the direction of using setpts correctly but I haven't been able to wrap my brain fully around it. Or, maybe I'm making life complicated and there's an easier approach ?

  


  In the nice-to-have realm, I'd love to be able to specify the start of the outro relative to the end of the recording. I will be doing this to a bunch of recordings of varying lengths. It would be nice to have one command to invoke on everything rather than figuring out a specific timestamp for each one.

  


  Thank you !

  


• FFmpeg producing a flickering video from images

  21 juin 2018, par jjohnn91

  So I’m trying to make a video of a fractal rotating through some values, much like seen here.

  I generate the frames (1000 of them) using a different program written in Java that works just fine, so for the purposes of this scenario assume that all the images are in the target folder and also in numerical order as they need to appear in the video.

  I found the following code on the web to stitch images into a video, and I haven’t the faintest idea how it works, and when I run it, all of the images are indeed stitched into a video and placed on the desktop, but the video appears to have one specific frame just jump in at random positions. I’m not totally sure which one, but its one of the earlier frames, somewhere between 1 and 200 of the 1000.

  I’ve also tested making two half videos, one using the first 500 frames, and the other using the second 500 frames. The first video (1 -> 500) has flickering, and the second video (501 -> 1000) appears not to have flickering to my observations.

  I am seeking help in fixing the flickering behavior, and I will upload the video file to google drive later if asked. The Images are all 1920x1080, and in proper numerical order.

  Thanks in advance !

  import static org.bytedeco.javacpp.opencv_imgcodecs.*;
  
  import java.io.File; 
  
  import org.bytedeco.javacpp.avcodec;
  
  import org.bytedeco.javacv.FFmpegFrameRecorder;
  
  import org.bytedeco.javacv.OpenCVFrameConverter;
  
  public class ImageToMovie{
  
      public static void main(String []args){
  
          String imgPath="C:\\Users\\John\\Images";
  
          String vidPath="C:\\Users\\John\\Desktop\\video.mp4";
  
          String[] links=new String[new File(imgPath).listFiles().length];
  
          File f=new File(imgPath);
  
          File[] f2=f.listFiles();
  
          for(int i=0;icode>

• Revision 122868 : Toujours sur ces vues de saisies fieldset. Champ extra se base sur le ...

  7 mars 2020, par Maïeul Rouquette — Log

  Toujours sur ces vues de saisies fieldset.
  Champ extra se base sur le classe vide pour ne pas afficher les saisies
  sans réponse. Le masquage est en css, contrairement à ce que je pensais
  (suis-je bête !)
  On ajoute donc la classe vide à la vie d’une saisie si l’ensemble de ses
  sous saisies sont vide.
  Permet d’éviter avec champ extra d’avoir un titre de fieldset qui se
  balade sans aucune réponse en dessous.