Recherche avancée

Sur d’autres sites (10283)

• movie2avi - how to fix the frame size ?

  18 décembre 2019, par Ed Mendes

  I have searched stackoverflow for a similar question and I found question "movie2avi-frame-size-error-and-keeping-frame-size-constant". Unfortunately the answer given there did not solve my problem (it has been suggested the use of xlim, ylim and zlim).

  In what follows I send a lightly modified version of a well-known example given elsewhere.

  %# figure
  
  figure, set(gcf, 'Color','white')
  
  Z = peaks; surf(Z);  axis tight
  
  set(gca, 'nextplot','replacechildren', 'Visible','off');
  
  [az,el]=view;
  
  xl=xlim;
  
  yl=ylim;
  
  zl=zlim;
  
  
  
  %# preallocate
  
  nFrames = 20;
  
  mov(1:nFrames) = struct('cdata',[], 'colormap',[]);
  
  
  
  %# create movie
  
  for k=1:nFrames
  
     view([(az-k*10) el]);
  
     xlim(xl);ylim(yl);zlim(zl);
  
     drawnow;pause(0.1);
  
     mov(k) = getframe(gca);
  
  end
  
  close(gcf)
  
  
  
  %# save as AVI file, and open it using system video player
  
  movie2avi(mov, 'myPeaks1.avi', 'compression','None', 'fps',10);

  The idea is to rotate the figure and create a movie. Everything works fine except for the last command, that is, movie2avi. The error msg is

  Error using avifile/addframe>ValidateFrame (line 290)
  
  Frame must be 435 by 344.
  
  
  
  Error in avifile/addframe (line 158)
  
  ValidateFrame(aviobj,width, height,dims);
  
  
  
  Error in movie2avi (line 67)
  
  avimov = addframe(avimov,mov);
  
  
  
  Error in more_video_test (line 24)
  
  movie2avi(mov, 'myPeaks1.avi', 'compression','None', 'fps',10); 

  I have looked at approaches-to-create-a-video-in-matlab here in stackoverflow and found that :

  a) Solution ffmpeg works but I would like to avoid it.
  b) All other solutions failed even QTWriter. How can I fix the frame size so that all these other solutions work ?

  Many thanks.

  Ed

• movie2avi - how to fix the frame size ?

  2 octobre 2013, par Ed Mendes

  I have searched stackoverflow for a similar question and I found question "movie2avi-frame-size-error-and-keeping-frame-size-constant". Unfortunately the answer given there did not solve my problem (it has been suggested the use of xlim, ylim and zlim).

  In what follows I send a lightly modified version of a well-known example given elsewhere.

  %# figure
  
  figure, set(gcf, 'Color','white')
  
  Z = peaks; surf(Z);  axis tight
  
  set(gca, 'nextplot','replacechildren', 'Visible','off');
  
  [az,el]=view;
  
  xl=xlim;
  
  yl=ylim;
  
  zl=zlim;
  
  
  
  %# preallocate
  
  nFrames = 20;
  
  mov(1:nFrames) = struct('cdata',[], 'colormap',[]);
  
  
  
  %# create movie
  
  for k=1:nFrames
  
     view([(az-k*10) el]);
  
     xlim(xl);ylim(yl);zlim(zl);
  
     drawnow;pause(0.1);
  
     mov(k) = getframe(gca);
  
  end
  
  close(gcf)
  
  
  
  %# save as AVI file, and open it using system video player
  
  movie2avi(mov, 'myPeaks1.avi', 'compression','None', 'fps',10);

  The idea is to rotate the figure and create a movie. Everything works fine except for the last command, that is, movie2avi. The error msg is

  Error using avifile/addframe>ValidateFrame (line 290)
  
  Frame must be 435 by 344.
  
  
  
  Error in avifile/addframe (line 158)
  
  ValidateFrame(aviobj,width, height,dims);
  
  
  
  Error in movie2avi (line 67)
  
  avimov = addframe(avimov,mov);
  
  
  
  Error in more_video_test (line 24)
  
  movie2avi(mov, 'myPeaks1.avi', 'compression','None', 'fps',10); 

  I have looked at approaches-to-create-a-video-in-matlab here in stackoverflow and found that :

  a) Solution ffmpeg works but I would like to avoid it.
  b) All other solutions failed even QTWriter. How can I fix the frame size so that all these other solutions work ?

  Many thanks.

  Ed

• How to stop perl buffering ffmpeg output

  4 février 2017, par Sebastian King

  I am trying to have a Perl program process the output of an ffmpeg encode, however my test program only seems to receive the output of ffmpeg in periodic chunks, thus I am assuming there is some sort of buffering going on. How can I make it process it in real-time ?

  My test program (the tr command is there because I thought maybe ffmpeg’s carriage returns were causing perl to see one big long line or something) :

  #!/usr/bin/perl
  
  
  
  $i = "test.mkv"; # big file, long encode time
  
  $o = "test.mp4";
  
  
  
  open(F, "-|", "ffmpeg -y -i '$i' '$o' 2>&1 | tr '\r' '\n'")
  
          or die "oh no";
  
  
  
  while(<f>) {
  
          print "A12345: $_"; # some random text so i know the output was processed in perl
  
  }
  
  </f>

  Everything works fine when I replace the ffmpeg command with this script :

  #!/bin/bash
  
  
  
  echo "hello";
  
  
  
  for i in `seq 1 10`; do
  
          sleep 1;
  
          echo "hello $i";
  
  done
  
  
  
  echo "bye";

  When using the above script I see the output each second as it happens. With ffmpeg it is some 5-10 seconds or so until it outputs and will output sometimes 100 lines each output.

  I have tried using the program unbuffer ahead of ffmpeg in the command call but it seems to have no effect. Is it perhaps the 2>&1 that might be buffering ?
  Any help is much appreciated.

  If you are unfamiliar with ffmpeg’s output, it outputs a bunch of file information and stuff to STDOUT and then during encoding it outputs lines like

  frame=  332 fps= 93 q=28.0 size=     528kB time=00:00:13.33 bitrate= 324.2kbits/s speed=3.75x

  which begin with carriage returns instead of new lines (hence tr) on STDERR (hence 2>&1).