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• ffmpeg : combine portrait and landscape video files in one file by adding a black frame

  18 juillet 2021, par Oliver

  i use my iPhone to record videos. Usually i get a lot of short clips, which I upload to my pc and then concatenate them with ffmpeg using this command :

  


  ffmpeg -f concat -safe 0 -i filelist.txt -c:v libx265 -preset slow -x265-params strong-intra-smoothing=0:merange=58 -crf 25 -c:a aac -b:a 320k -tag:v hvc1 output.mp4


  


  filelist contains a list of these clips sorted by date. This works fine, but recently a had some clips recorded in portrait mode. The result was an output video which contained the portrait clips stretched to fill the full horizontal space. Instead of that i would like to just have the horizontal space filled with black borders. Is that possible by changing the command posted above ? Or do i have to convert those portrait clips before ?

  


• Why do file length appears to be longer after using ffmpeg convert HEIC to PNG ?

  15 octobre 2024, par BrinyFish

  I have been moving all my photos from iphone to my windows PC. Because I don't like to keep all the files in HEIC format, so I used ffmpeg to try to batch convert all the photos from HEIC to PNG.

  


  Get-ChildItem *.heic | ForEach-Object {
    ffmpeg -i $_.FullName -map_metadata 0 -q:v 1 "$($_.BaseName).png"
}


  


  File size difference
After testing this chatGPT generated code on a small sample set of photos, I realize that the length of the PNG photos are smaller than the length of the HEIC photos. I have always believed that HEIC is the compressed format, which should be smaller. However, this size difference really makes me wonder if I am losing resultion or meta data. Do anyone know why would this be the case ?

  


  I have googled and most articles are saying that HEIC should be smaller than PNG, which don't help me in this case.

  


• How do I use -analyzeduration from ffmpeg with FFmpegDecoder.framework from mooncatventures ?

  29 décembre 2013, par user3143010

  I have been playing with the RtspPlay1 from mooncatventures to try and stream a live stream from an ffmpeg streaming source with as little delay as possible. The problem is even when I modify the code to indicate the -analyzedelay 0 flags in RtspPlay1 it does not seem to do anything. I came to this conclusion because the delay is the same on my computer without the -analyzeduration 0 flag as the iOS device. Any thoughts would be helpful.

  Here is the command I am trying to emulate on the iPhone :
  ffplay rtp :///224.1.1.1:11326 -analyzeduration 0

  Here is the modified code I tried with RtspPlay1 :

  forward_argc=1;
  
  
  
  forward_argv[1] = "-analyzeduration";
  
  forward_argv[2] = "0";
  
  //forward_argv[3] = "30";
  
  //forward_argv[4] = "-fast";
  
  //forward_argv[5] = "-sync";
  
  //forward_argv[6] = "video";
  
  //forward_argv[7] = "-drp";
  
  //forward_argv[8] = "-skipidct";
  
  //forward_argv[9] = "10";
  
  //forward_argv[10] = "-skiploop";
  
  //forward_argv[11] = "50";
  
  //forward_argv[12] = "-threads";
  
  //forward_argv[13] = "5";
  
  //argv[14] = "-an";
  
  forward_argv[3] = cString;
  
  
  
  NSLog(@"glflag %@\n ",[parms objectForKey:@"glflag"] );
  
  if ([parms objectForKey:@"glflag"]!=@"1") {
  
     forward_argv[4]="0";
  
  }else {
  
  forward_argv[4]="1";
  
  }
  
  
  
  
  
  forward_argc += 4;