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• ffmpeg Get time of frames from trimmed video

  17 novembre 2017, par TheOtherguyz4kj

  I am using FFmpeg in my application to extract frames from a video, the frames will be added to a trim video view where you get an illustration as to what is happening in the video at a specific time within the video. So each frame needs to represent some time within the video.

  I dont quite understand how FFmpeg is producing the frames. Here is my code :

  "-i",
  
  videoCroppedFile.getAbsolutePath(),
  
  "-vf",
  
  "fps=1/" + frameSeperation,
  
  mediaStorageDir.getAbsolutePath() +
  
  "/%d.jpg"

  My app allows you to record a video at a max length of 20s. The number of frames extracted from the video depnds on how long the captured video is. frameSeperation is calculated doing the below code.

  String time = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
  
      long videoLength = Long.parseLong(time) / 1000;
  
      double frameSeperationDouble = (double) videoLength;
  
      // Divide by 11 because there is a maximum of 11 frames on trim video view
  
      frameSeperationDouble /= 11;
  
      frameSeperationDouble = Math.ceil(frameSeperationDouble);
  
      int frameSeperation = (int) frameSeperationDouble;

  Maybe the above logic is very bad, if there is a better way please can somebody tell me.

  Anyway I run the code and below are a few test cases :

  • A video captured with a length of 6 seconds has 7 frames.
  • A video captured with a length of 2 seconds has 3 frames.
  • A video captured with a length of 10 seconds has 12 frames.
  • A video captured with a length of 15 seconds has 9 frames.
  • A video captured with a length of 20 seconds has 11 frames.

  There is no consistency, and I find it hard to put timestamps against each frame because of this. I feel like my logic is wrong or im not understanding. Any help is much appreciated

  Update 1

  So I did what you said in comments :

   final FFmpeg ffmpeg = FFmpeg.getInstance(mContext);
  
          final File mediaStorageDir = new File(Environment.getExternalStorageDirectory()
  
                  + "/Android/data/"
  
                  + mContext.getPackageName()
  
                  + "/vFrames");
  
  
  
      if (!mediaStorageDir.exists()){
  
          mediaStorageDir.mkdirs();
  
      }
  
  
  
      MediaMetadataRetriever retriever = new MediaMetadataRetriever();
  
      retriever.setDataSource(mContext, Uri.fromFile(videoCroppedFile));
  
      String time = retriever.extractMetadata(MediaMetadataRetriever.METADATA_KEY_DURATION);
  
      long videoLength = Long.parseLong(time) / 1000;
  
      double frameSeperationDouble = (double) videoLength / 8;
  
  
  
      retriever.release();
  
  
  
      final String cmd[] = {
  
  
  
              "-i",
  
              videoCroppedFile.getAbsolutePath(),
  
              "-vf",
  
              "fps=1/" + frameSeperationDouble,
  
              "-vframes," + 8,
  
              mediaStorageDir.getAbsolutePath() +
  
              "/%d.jpg"
  
      };

  I also tried "-vframes=" + 8 at the same point where I put vFrames in cmd. It doesnt seem to work at all now no frames are being extracted from the video

• How to get time stamp of closet keyframe before a given timestamp with ffmpeg ?

  20 février 2013, par jAckOdE

  I want a ffmpeg seeking command that fast and accurate. I found this

  The solution is that we apply -ss for both input (fast seeking) and output (accurate seeking). The question is that if the input seeking is not accurate how can we be sure that the seeking position is accurate.

  For example : as the example used in the link, if we want to seek to 00:03:00, the command is something likes

  ffmpeg -ss 00:02:30 -i ... -ss 00:00:30
  As said, the first seeking will seek to somewhere else not 00:02:30, say 00:02:31. and after applying second seek, the final result would be 00:03:01- NOT what we want. Is that correct ?

  Where does fist seeking seek to ? Does it seek to k-frame that closet to 00:02:30 ?

  If so, here is my thought, correct me if i'm wrong : after first seeking, we get the timestamp of the result (in this example : 00:02:31), then we apply second seeking with appropriate time, in this case 00:00:29.

  Question is how do we get time stamp of first seeking's result ?

• FFMPEG - how to add a text and crop a video at the same time

  18 janvier 2023, par ProgramadorLIXO

  Im trying to learn FFMPEG.
I am having trouble figuring out how to add a text on top of a cropped video with only one line code.

  


  I want to know how to do both at the same time !

  


  I tried something but it did not work.

  


  This is what I tried :

  


  -i GoopDeer.mp4 -ss 00:03:23 -to 00:03:33 -filter_complex "[0:v]scale=iw*2:-1,crop=1920:1088:1920:1088[Vídeo];
drawtext=text='IT'S NATHAN!!!': fontsize=100: fontcolor=white[texto];[Vídeo][texto]overlay" 10.mp4


  


  but is not correct, it's not rendering.
This is the error i got -

  


  


  bash : !' : event not found

  


  


  How do i do this ?