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• How to create FFMPEG command that position a movie in a frame

  31 janvier 2019, par S.T

  I want to create FFMPEG command that takes 2 movies and position it inside a frame at a specified x and y next to each other and then create one movie from it.

  This is a command i did which create a movie that puts 2 movies next to each other with a space of 10 pixels between them.

  complexCommand = new String[]
  "-i", tempPath1, "-i", tempPath2, "-strict","experimental",
  "-filter_complex",
  "[0:v:0]pad=iw*2:ih+20:color=white[bg] ;"+
  "[bg][1:v:0]overlay=w+10:h+10",
  "-s", "320x240","-r", "30", "-b", "15496k", "-vcodec", "mpeg4",
  "-ab", "48000", "-ac", "2", "-ar", "22050",

  The problem is that i want more abilities like control the position of each movies (multiple movies), an explanation or an example how to use the padding and the position of the movies.

  Thanks a lot.

• What CRF matches with a JPEG compression rate

  21 janvier 2017, par Xlsx

  I have a very basic program that I wrote in python that takes a video from a webcam and saves it to an mp4 file. Each frame is saved as a jpeg file, and then I use ffmpeg to merge all the frames together. There are two different compression options - the JPEG compression quality, and the mp4 CRF. Which CRF should I use relative to the JPEG compression quality so that the mp4 file is the smallest file size it can be, while not losing data from the already lossy jpeg and not adding extra data to the mp4 ?

  For example, I save my JPEGs with a quality of 30
  When I use ffmpeg, I set the -crf parameter to 38
  When I look at the final mp4 file, I have lost quality from the JPEGs

• android - ffmpeg overlay videos not working properly

  2 janvier 2017, par MickSt

  What I’m trying to do : I have 2 videos (the first one is recorded in the app itself, the second was pre-recorded and it’s shorter than the first). I’m trying to overlay it with the following FFMpeg command :

  finalCommand = new String[]{"-y",
  
                  "-i", vid1,
  
                  "-i", vid2,
  
                  "-i", aud1,
  
                  "-i", aud2,
  
                  "-strict", "experimental", "-filter_complex",
  
                          "[0:a] volume=0.2 [a8];"
  
                          +"[3:a] atrim=end="+String.valueOf(newTimePause)+" [a12];"
  
                          +"[3:a] atrim=start="+String.valueOf(newTimePause)+" [a14];"
  
                          +"[a14] adelay="+String.valueOf(newDelayInt)+"|"
  
                          +String.valueOf(newDelayInt)+" [a16];"
  
                          + "[a8][a12][a16][2:a:0] amix=inputs=4 [a];"
  
                          + "movie=" + watermark + " [watermark];"
  
                          + "[0:v][watermark] overlay=main_w-overlay_w-10:main_h-overlay_h-10 [outv0];"
  
                          + "[1] fifo, scale=iw/2.5:ih/2.5 [vid2];"
  
                          + "[vid2]fifo, trim=end=80.5 [vid5];"
  
                          + "[vid2] fifo, trim=start=80.5 [vid6];"
  
                          + "[outv0][vid5] overlay=10:10:enable=\'between(t,0,84)\' [outv6];"
  
                          + "[outv6][vid6] overlay=10:10:enable=\'between(t,84,101)\' [outv]",
  
                  "-map", "[outv]",
  
                  "-map", "[a]",
  
                  "-r", "30",
  
                  "-b",
  
                  "4000k",
  
                  "-vcodec", "mpeg4",
  
                  "-ab", "44100", "-ac", "2", "-ar", "44100",
  
                  IOUtils.getFINALdir(this)+"/finalvid.mp4"
  
          };

  So : vid1 is an mp4 video recorded in the app, watermark is a png image that should be overlayed during all vid1, and vid2 is the one pre-recorded. And the difference in length between vid1 and vid2 depends on the user. So I need to split vid2 at 80.5 seconds into 2 pieces, then overlay the first piece of vid2 from the beginning of vid1 to the time user clicked the button (here it’s hardcoded as 84 for convenience, and I know that from 80.5 to 84 the last frame will remain overlaid - it’s ok), then overlay the second piece from this "84" till the end. (it’s almost the same for aud2 - the corresponding audio for vid2 - but aud2 works fine)

  But with this piece of code it looks like it takes a lot of memory and lots of frames of overlaid vid2 just get lost - it just freezes. And the line + "[outv6][vid6] overlay=10:10:enable=\'between(t,84,101)\' [outv]", ruins everything so that from 84 till the end nothing is finally overlaid including the watermark (why so ?)

  And the other problem is this is too slow. Idk how to export a video of 720p or 1080p and that it be not too slow, not be of a big file size and not stop with OOM (now it’s about 480p and takes about 50Mb - I want a larger resolution with a smaller size).

  I think the whole command can be rewritten better, but how ? What am I doing wrong and how to fix it all ? Thanks in advance !