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• How to to add additional metadata to individual frames, DDB's, when creating an AVI file with ffmpeg

  6 décembre 2019, par Totte Karlsson

  I’m creating avi videos from device dependent bitmaps, DDB’s.

  The pipeline is quite simple, a GigE camera provides frame by frame, and each frame, a DDB, is piped to a ffmpeg process creating a final AVI file, using h264 compression.

  These videos are scientific in nature, and we would like to store/embed experimental hardware information, such as the states of a few digital lines, with each frame.
  This information need to be available in the final avi video

  Question is, is this possible ?

  Looking at this : https://docs.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmap it does not seem that adding additional data to the DDB themselves is possible, but I’m not sure.

• Change pitch of audio file without altering the duration of audio file (FFMPEG)

  13 janvier 2016, par VickyS

  I am in a bit of trouble.
  I am working on FFMPEG for android and now my task is to modify the pitch of the audio file without altering the duration of the audio file.

  I used these commands but they alter the duration :

  ffmpeg -i /sdcard/emoj/final.wav -filter:a atempo=1.5 -vn /sdcard/emoj/final1.wav
  
  
  
  ffmpeg -i /sdcard/emoj/final.wav -filter:a asetrate=r=35K -vn /sdcard/emoj/final1.wav

  I know I can use Sonic NDK for this purpose. But I want to know if its possible with the help of FFMPEG.
  In documentation I have seend something called "Rubberband" I think that can help. But I dont know how to use that.

  I just want the command to do that.
  I would appreciate any help in this regard.

• How to trim and merge using Fluent FFMpeg ?

  29 juillet 2016, par John D.

  Here’s what I want to do with fluent-ffmpeg :

  I have 3 input files. An intro, main, and outro video. I wish to merge the three, while trimming the main video. Here is my code :

  var ffmpegCommand = ffmpeg();
  
  ffmpegCommand.addInput(introVideo);
  
  ffmpegCommand.addInput(mainVideo).seekInput(20).duration(3);
  
  ffmpegCommand.addInput(outroVideo);
  
  ffmpegCommand.on('error', function(err, stdout, stderr){
  
    console.log("FAILED!\n\t"+err+"\n\t"+stdout+"\n\t"+stderr);
  
  });
  
  ffmpegCommand.on('end', function(){
  
    console.log('COMPLETE!');
  
  });
  
  ffmpegCommand.on('start', function(commandLine) {
  
    console.log('Spawned Ffmpeg with command: ' + commandLine);
  
  });
  
  ffmpegCommand.mergeToFile('final.mp4', './vid_files/tmp');

  The program executes fine, but when I ffplay final.mp4, the result is that introVideo plays then the video appears to freeze. According to the fluent-ffmpeg documentation, it states "Each of these [Input options] methods apply on the last input added". So I can’t figure out why that syntax doesn’t seem to work...

  How can I trim the main video to send to mergeToFile ?

  Note that this works fine if I don’t have .seekinput(20).duration(3) on the second addInput.

  Oh, here’s the outputted commandLine value :

  ffmpeg -i ./vid_files/intro.mp4 -ss 20 -i ./vid_files/main.mp4 -i ./vid_files/outro.mp4 -y -filter_complex concat=n=3:v=1:a=1 -t 3 final.mp4