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• Different filesizes for images generated using octave and python

  22 février 2017, par Lakshay Garg

  I am using python (scikit-image) and octave to generate 200 images as follows

  Python3

  import numpy as np
  
  from skimage.io import imsave
  
  
  
  images = [255*np.ones((100,100), dtype=np.uint8),  # white
  
               np.zeros((100,100), dtype=np.uint8)]  # black
  
  
  
  for i in range(200): # save alternating black and white images
  
      imsave('%04d.png'%(i+1), images[i%2])

  Octave

  pkg load image;
  
  
  
  im1 = 255*ones(100,100); # white
  
  im2 = zeros(100,100);    # black
  
  for i=1:200
  
      name = sprintf('%04d.png', i);
  
      if mod(i,2) == 0
  
          imwrite(im1, name);
  
      else
  
          imwrite(im2, name);
  
      end
  
  end

  Next, I use ffmpeg to generate two videos (alternating white and black frames) from these two sets of images using the following command

  ffmpeg -r 10 -loglevel quiet \
  
         -i ./%04d.png -c:v libx264 \
  
         -preset ultrafast -crf 0 ./out.mkv

  1. Sizes of image files generated by both these codes are different.

     • Octave white : 192 bytes, black : 98 bytes
     • Python white : 120 bytes, black : 90 bytes

  2. Sizes of video files generated from these octave and python images are significantly different from each other.

     • Octave filesize : 60 kilobytes
     • Python filesize : 116 kilobytes

  Why do we have this apparently very strange behavior ?

  EDIT

  Since it was suggested that the behavior might be dues to octave and python using different bit-depths to store the images, I changes the octave code to use 8 bit numbers

  im1 = uint8(255*ones(100,100)); # white
  
  im2 = uint8(zeros(100,100));    # black

  and now the image file sizes are nearly the same

  • Octave white : 118 bytes, black : 90 bytes
  • Python white : 120 bytes, black : 90 bytes

  but the problem is still the same for video files, octave : 60K, python : 116K

• ffmpeg one draw text to multiple outputs

  31 juillet 2023, par kRicha

  I've created command with ffmpeg-fluent, which connects video file with music, use shortest(video) duration, and output this to result file

  


  const newVideo = Ffmpeg(`./source/video/${category}/${dayNumber}.mp4`)
                .addInput(`./source/audio/${category}.mp3`)
                .addOption([
                    '-map 0:v:0',
                    '-map 1:a:0',
                    '-shortest'
                ]);

            newVideo.videoFilters({
                filter: 'drawtext',
                options: { ...FONT_OPTIONS, ...{ text: '1', boxcolor: 'black@1', y: 280 } }
            }).output('out1.mp4')
                .output('out2.mp4');


  


  generated command line :

  


  ffmpeg \
-i ./source/video/women/1.mp4 \
-i ./source/audio/women.mp3 -y \
-filter:v drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=1:boxcolor=black@1:y=280,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=a0:boxcolor=black@0.8:enable='between(t,0,6.5)':y=700,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=a1:boxcolor=black@0.8:enable='between(t,0,6.5)':y=800,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=a2:boxcolor=black@0.8:enable='between(t,0,6.5)':y=900,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=a3:boxcolor=black@0.8:enable='between(t,0,6.5)':y=1000,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=b0:boxcolor=black@0.8:enable='between(t,7,10)':y=1000,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=b1:boxcolor=black@0.8:enable='between(t,7,10)':y=1100,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=b2:boxcolor=black@0.8:enable='between(t,7,10)':y=1200,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=b3:boxcolor=black@0.8:enable='between(t,7,10)':y=1300,drawtext=fontsize=80:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=b4:boxcolor=black@0.8:enable='between(t,7,10)':y=1400,drawtext=fontsize=30:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=c:enable='between(t,10.2,inf)':boxcolor=black@1:y=1500,drawtext=fontsize=30:fontcolor=white:x=(w-tw)/2:box=1:boxborderw=20:fontfile=./OpenSans-Light.ttf:text=d:enable='between(t,10.2,inf)':boxcolor=black@1:y=1550 \
-map 0:v:0 \
-map 1:a:0 \
-shortest out2/_.mp4


  


  if I add second output it works, but without audio and drawtext ? How could I fixe this and get draw text works on both outputs

  


• Audio in ffmpeg

  1er octobre 2020, par Konduri Sai Aditya

  I need to add audio as an input to below command, How can I achieve it

  


  ffmpeg -i test.png -i test.mp4 -y -filter_complex "[1:v]scale=1422:800[scale1],[scale1]rotate=0:c=black@0:ow=rotw(0):oh=roth(0)[rotate0],[0:v][rotate0]overlay=258.04:107.71[mediaoverlayout0],color=black@0:451x137[c1],[c1]setsar=1,drawtext=fontfile='/Windows/fonts/Peddana-Regular.ttf':text='ADITYA':fontsize=121.19999999999999:fontcolor=#1e8bc3:line_spacing=16.91,rotate=0:ow=rotw(0):oh=roth(0):c=black@0[rottext1],[mediaoverlayout0][rottext1]overlay=x=544.63:y=263.076:shortest=1" -pix_fmt yuv420p op.mp4