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• 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;

• C - FFmpeg streaming from a C program ?

  8 août 2016, par golmschenk

  I’m looking to replicate an FFmpeg command-line command in my C code. Specifically I would like to be able to run :

  ffmpeg -re -i video.mp4 -f mpegts udp://localhost:7777

  One thing I’ve noticed when looking at people’s code who have used the libraries of FFmpeg in their own code is that they often have a few hundred lines of code for a single command similar to an FFmpeg command-line command. I’m guessing this is just because they are doing something very specific, because if I can run that short command on my command line and get what I want it should probably only take about ten lines of code to do the same thing in my C code. This should only take about that much work right ? Why would it take much more ?

  I’m having a bit of difficulty finding explanations on how to use the streaming capabilities of the FFmpeg libraries that aren’t overly complex because they’re for a very specific purpose. Can anyone explain how I might go about writing the code for the above command ? Or at the very least point me to some documentation explaining how to write such a script/program ? Thank you much !

  EDIT : I do hope to run this from an iPhone app eventually so I won’t just be able to straight up call FFmpeg from my program. I’ll need to use the libraries used by FFmpeg.