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• How to calculate bit-rate for ffmpeg ?

  2 juin 2015, par rs41

  I want to convert one video to 4 formats( webm low/high, mp4 low/high)

  When I execute last mp4 high conversion for small files, which looks like this (line-breaks added for readability) :

  ffmpeg -i Weird9.3gp -codec:v libx264 -b:v 10k -maxrate 1000k -bufsize 2000k 
  
         -movflags +faststart -vprofile high -preset slow -vf 'scale=trunc(iw/2)*2:720' 
  
         -threads 0 -codec:a aac -strict -2 -b:a 128k -ac 2 -f mp4 -threads 0 
  
         -y /Users/guest/high/movie.mp4

  It shows something like this

  Error while opening encoder for output stream #0:1 - maybe incorrect parameters
  such as bit_rate, rate, width or height

  If I change "-b:a 128k" to "-b:a 32k" everything is ok.

  How do I calculate the bit-rate properly ? Does it depends on source video file size ?

• How to make video with fixed duration

  27 juin 2013, par Alex

  I have videos :

  video1 - 923 seconds

  video2 - 1457 seconds

  video3 - 860 seconds

  I need to cut these videos and fix its duration - 600 seconds. But the difficulty is that I need to cut them under the scheme

  

  Where :

  1. blue segments is always 120 seconds (fixed) ;

  2. red segments I should to cut ;

  3. green segments I shouldn't cut.

  After that I need to join blue and green segments in new 600 seconds video, example

  

  As the video1, video2, video3 have a different duration, then the red and green segments must have different duration, they must be in equal proportion to the duration of the video.

  I need pure ffmpeg (avconv) command or bash script. I have no ideas how to make it.

• Vertically stack two images, draw a box on the bottom image then write multiline text in that box

  31 août 2020, par Sarmad S.

  I am trying to make a video from two images, where the two images should be vertically stacked. This is easy and can be done with the vstack command. I also managed to write text on the bottom image with the drawtext command. However I want to draw a blue box that covers half of the bottom image (the bottom part of the image) and write the text in that blue box.

  


  How do I go about doing so ?

  


  My code so far :

  


  ffmpeg -loop 1 -i image1 -i image2 -c:v libx264 -t 3 -pix_fmt yuv420p -filter_complex "[1]drawtext=my-font.otf: text='some multiline text': fontcolor=white: fontsize=50: x=(w-text_w)/2: y=(h-text_h)/2[v1], drawbox; [0][v1]vstack" -s 1080:1920 output.mp4"


  


  I also want to zoom slowly in the images (not the box or the text). Anyone can help me connect things ?

  


  I am able to zoom, drawbox, write text etc, but not able to combine them together.