title: Smooth scale animation in ffmpeg
body: <p>How can I smooth the animations of scale?</p>
  
  <pre><code>ffmpeg -i bg.mp4 -loop 1 -i blank.png -filter_complex "[1:v]drawtext=fontfile=ariblk.ttf:text=EXAMPLE:x=(main_w-text_w)/2:y=(main_h-max_glyph_a)/2:fontcolor=0xFFFFFF:fontsize=200:alpha=1[txt];[txt]sendcmd=f=data.cmd,scale=w=0:h=-1[txtscale];[0:v][txtscale]overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2:shortest=1" preview.mp4
  </code></pre>
  
  <p>Video resolution 1280 * 720 -> scale w = '12.8 * X', X - scale value (data from the After Effects)</p>
  
  <p>data.cmd</p>
  
  <pre><code>0   scale w '   12.8*   72  '; 0.040    scale w '   12.8*   72.3944 '; 0.080    scale w '   12.8*   72.7887 '; 0.120    scale w '   12.8*   73.1831 '; 0.160    scale w '   12.8*   73.5775 '; 0.200    scale w '   12.8*   73.9718 '; 0.240    scale w '   12.8*   74.3662 '; 0.280    scale w '   12.8*   74.7606 '; 0.320    scale w '   12.8*   75.1549 '; 0.360    scale w '   12.8*   75.5493 '; 0.400    scale w '   12.8*   75.9437 '; 0.440    scale w '   12.8*   76.338  '; 0.480    scale w '   12.8*   76.7324 '; 0.520    scale w '   12.8*   77.1268 '; 0.560    scale w '   12.8*   77.5211 '; 0.600    scale w '   12.8*   77.9155 '; 0.640    scale w '   12.8*   78.3099 '; 0.680    scale w '   12.8*   78.7042 '; 0.720    scale w '   12.8*   79.0986 '; 0.760    scale w '   12.8*   79.493  '; 0.800    scale w '   12.8*   79.8873 '; 0.840    scale w '   12.8*   80.2817 '; 0.880    scale w '   12.8*   80.6761 '; 0.920    scale w '   12.8*   81.0704 '; 0.960    scale w '   12.8*   81.4648 '; 1.000    scale w '   12.8*   81.8592 '; 1.040    scale w '   12.8*   82.2535 '; 1.080    scale w '   12.8*   82.6479 '; 1.120    scale w '   12.8*   83.0423 '; 1.160    scale w '   12.8*   83.4366 '; 1.200    scale w '   12.8*   83.831  '; 1.240    scale w '   12.8*   84.2254 '; 1.280    scale w '   12.8*   84.6197 '; 1.320    scale w '   12.8*   85.0141 '; 1.360    scale w '   12.8*   85.4085 '; 1.400    scale w '   12.8*   85.8028 '; 1.440    scale w '   12.8*   86.1972 '; 1.480    scale w '   12.8*   86.5915 '; 1.520    scale w '   12.8*   86.9859 '; 1.560    scale w '   12.8*   87.3803 '; 1.600    scale w '   12.8*   87.7746 '; 1.640    scale w '   12.8*   88.169  '; 1.680    scale w '   12.8*   88.5634 '; 1.720    scale w '   12.8*   88.9577 '; 1.760    scale w '   12.8*   89.3521 '; 1.800    scale w '   12.8*   89.7465 '; 1.840    scale w '   12.8*   90.1408 '; 1.880    scale w '   12.8*   90.5352 '; 1.920    scale w '   12.8*   90.9296 '; 1.960    scale w '   12.8*   91.3239 '; 2.000    scale w '   12.8*   91.7183 '; 2.040    scale w '   12.8*   92.1127 '; 2.080    scale w '   12.8*   92.507  '; 2.120    scale w '   12.8*   92.9014 '; 2.160    scale w '   12.8*   93.2958 '; 2.200    scale w '   12.8*   93.6901 '; 2.240    scale w '   12.8*   94.0845 '; 2.280    scale w '   12.8*   94.4789 '; 2.320    scale w '   12.8*   94.8732 '; 2.360    scale w '   12.8*   95.2676 '; 2.400    scale w '   12.8*   95.662  '; 2.440    scale w '   12.8*   96.0563 '; 2.480    scale w '   12.8*   96.4507 '; 2.520    scale w '   12.8*   96.8451 '; 2.560    scale w '   12.8*   97.2394 '; 2.600    scale w '   12.8*   97.6338 '; 2.640    scale w '   12.8*   98.0282 '; 2.680    scale w '   12.8*   98.4225 '; 2.720    scale w '   12.8*   98.8169 '; 2.760    scale w '   12.8*   99.2113 '; 2.800    scale w '   12.8*   99.6056 '; 2.840    scale w '   12.8*   100 '; 
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/BPIjH.gif" alt="enter image description here"></p>