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• Extract frames from a video results in abnormaly more frames for each fps by using ffmpeg

  15 juin 2021, par alanzzz

  I have a job of using ffmpeg to extract the frames averagely from a video, with different fps. I use this command for it.

  


  ffmpeg -i input.mp4 -r specified_fps -q:v 2 image %4d.png

  


  And I have 3 questions about this task.

  


  

  1. What I expect is that if I double the fps, the number of extracted frames will also get doubled. However, that's not the case. Take one of the input videos as an example. I get 2 extra frames for all the sample factors (80 / 158 / 236 / 392 v.s. 78 / 156 / 234 / 390). Does it related to the mechanism of picking/dropping frames when extracting frames from a video？ (credit to @Tom Yan)

  


  


  video info

  


  

  • Duration : 1min18s

  


  • Frame rate mode : constant (CFR)

  


  • Frame rate : 30.0 FPS

  


  • Total number of frames : 2340

  


  


  Config setting & results

  


  





  


  


  


  


  


  



  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  FPS	Actual num of frames	correct num of frames
  1	80	78
  2	158	156
  3	236	234
  5	392	390

  


  


  


  2. I check for the output images, the extracted frames for different fps are totally different from each other. In other words, for example, the 1st image for fps=1 is not the same as the 1st image for fps=2. Is that legitimate ? And is it possible for me the get some identical images for different fps ?

     


  


  3. The last problem is that for some videos I use, the difference between the 1st and 2nd image is different from the difference between the 2nd and 3rd. While for the remaining images, the differences become average. To be specific, there is only a slight change from 1st to 2nd frame, while for 2nd to 3rd, 3rd to 4th, and so on, the changes are the same, which is normally distributed according to the specified FPS. I am wondering why such a case happens ? Does it relate to the I-frame, B-frame, P-frame, GOP, or IDR ?

     


  


  


  I am new to this field and cannot find some useful info from other places. I've tried my best to describe my questions clearly. Feel free to leave some comments. Any help would do me a great favor. Thanks in advance !

  


• UnsupportedAudioFileException in LIUM Speaker Diarization after re-sampling

  14 septembre 2016, par RAVI D PARIKH

  I am trying to configure LIUM tool for speaker diarization. This question is a follow up of UnsupportedAudioFileException in LIUM Speaker Diarization

  I have tried re sampling the file using sox and ffmpeg

  I am new to any sorts of programming and i have followed all steps described in LIUM quick start guide and the above link. I still get the same error. I think my input file has issues related to header as mentioned by Nikolay Shmyrev in the above link however i have no clue on how to solve it.

  My code is as below :

  java –jar  C:\Users\Ravi\Desktop\LIUM_SpkDiarization-8.4.1.jar \ --fInputMask= C:\Users\Ravi\Desktop\converted_f2.wav--sOutputMask= C:\Users\Ravi\Desktop\converted_converted_2.seg -–help --doCEClustering

  Error :

  10:52.037 SEVERE AudioFeatureSetFa  FileNotFoundException
  
  java.io.FileNotFoundException:
  
          at java.io.FileInputStream.open0(Native Method)
  
          at java.io.FileInputStream.open(Unknown Source)
  
          at java.io.FileInputStream.<init>(Unknown Source)
  
          at com.sun.media.codec.audio.mp3.JS_MP3FileReader.getAudioFileFormat(JS_MP3FileReader.java:82)
  
          at javax.sound.sampled.AudioSystem.getAudioFileFormat(Unknown Source)
  
          at fr.lium.spkDiarization.libFeature.AudioFeatureSetFactory.getAudio(AudioFeatureSetFactory.java:162)
  
          at fr.lium.spkDiarization.libFeature.AudioFeatureSetFactory.MakeFeature(AudioFeatureSetFactory.java:207)
  
  </init>

  The input file is at https://drive.google.com/file/d/0B7Fqe9EX5JbgT09BcXpSREd4em8/view?usp=sharing

  Input File Name:converted_f2.wav

  I have put the command and the full output of the prompt in a word document at

  https://drive.google.com/file/d/0B7Fqe9EX5JbgUUl6THNCZFgxRnM/view?usp=sharing

  The inpiut file has correct sampling rate and other parameters and thus i am not able to understand the cause of the error.
  Thanks a lot for the help

  Regards,
  Ravi

• Python ffmpeg https

  30 novembre 2022, par mor15Euro

  I want to download a streaming video from a website using python and ffmpeg. I can download this video using the ffmpeg command in my shell but as soon as I try to use python ffmpeg i get this error :

  


  https protocol not found, recompile FFmpeg with openssl, gnutls or securetransport enabled.


  


  Using this code :

  


  ffmpeg.input(url).output("demo.mp4", vcodec="copy", acodec="copy").overwrite_output().run()


  


  How can I enable https support for python ffmpeg

  


  If you need more information, let me know

  


  Thank you in advance