Recherche avancée

Sur d’autres sites (7602)

• FFMPEG - Download video in parts and concat, stutter at concat points

  23 juillet 2022, par rnbwSmn

  My goal is to download a video (or M3U8) in parts/chunks which I can later concat.

  


  For context, I would like to download videos in an Android Service which may be stopped at any time, so I think chunking is the right approach.

  


  After some time I got the "downloading the parts" right, using this. I would later put that in a function, and for now I chose the chunks to be 30 seconds long.

  


  %offset% = 30 * %part%

ffmpeg -ss %offset% -t 30 -i INPUT_FILE -avoid_negative_ts 1 out%part%.mp4


  


  The first line is just pseudocode, part is starting at 0.
This works fine, downloading 30 second long .mp4 files.

  


  After that I tried merging them together into a single .mp4. For the tests I only downloaded the first few parts.

  


  Concat command :

  


  ffmpeg -safe 0 -f concat -i concat.txt -c copy final.mp4


  


  This would be a very short concat.txt file :

  


  file 'out0.mp4'
file 'out1.mp4'


  


  The concat works but has one problem : At the point where both files are actually combined, so at 30 seconds, there is a small stutter in video and audio.

  


  So what I think is going on is that I download parts that are 30s long, starting at multiples of 30s so there is a small overlap ? In the "Details" part of the Windows file properties it also shows a length of 31 seconds, so the video is even longer than I want.

  


  I tried setting the duration of each part in the concat.txt, both to 30s and to 30s - 1 frame

  


  23.98 fps -> 1/23.98 spf = 0.0417s


  


  But with a duration of 30 as well as 29.9583, although it is better, there is still a small stutter.

  


  file 'out0.mp4'
duration 29.9583
file 'out1.mp4'
duration 29.9583


  


  I also tried with a different fileformat, .ts files, but the stutter was still there. I still think my timings are not quite right, but at this point I don't know where the problem is exactly. What do I need to change to remove the small stutter ?

  


• asp.net ffmpeg : The system cannot find the file specified

  19 juin 2016, par Malik

  I am doing code for extracting image from video using ffmpeg. But gone stuck what this means. I also have checked

  ffmpeg -i F:\MIC\stream\finalstream\casper\small.mp4  -an -ss 00:00:03 -s 108*80 -vframes 1 -f image2 -vcodec mjpeg F:/MIC/stream/finalstream/caspe
  
  r/output11.png 

  on cmd line and working fine but dont understand why this is not happening in asp.net ?

  here is my code this function happens on button click event :

  protected void Capture(object sender, EventArgs e)
  
          {
  
  
  
              string InputFile = @"F:\MIC\stream\finalstream\casper\small.mp4";
  
              string ThumbnailsPath = @"F:\MIC\stream\finalstream\casper\testimage.jpg";
  
              System.Diagnostics.Process proc = new System.Diagnostics.Process();
  
              proc.EnableRaisingEvents = false;
  
              proc.StartInfo.FileName = Page.MapPath("~/ffmpeg.exe");
  
              proc.StartInfo.Arguments = "-i F:/MIC/stream/finalstream/casper/small.mp4  -an -ss 00:00:03 -s 108*80 -vframes 1 -f image2 -vcodec mjpeg F:/MIC/stream/finalstream/casper/ output11.png";
  
              proc.Start();
  
  
  
  
  
          }

  while running i got this Error :
  

  Any idea ????

• Playing MP4 file in Powerpoint

  28 août 2014, par BrewGold

  I have a huge MP4 file (4GB) an hour long video. I want to extract port of the file. So I used the following command to extract 70 seconds(00:01:10) of video starting from 11 minutes

  ffmpeg -i INPUT.mp4 -ss 00:11:00 -t 00:01:10 -c:v copy -c:a copy OUTPUT.mp4

  Now I got a small file extracted from Input.MP4
  The output.mp4 file size is still big(90 MB). So I used the following command

  ffmpeg -i OUTPUT.mp4 -c:v libx264 -crf 30 SmallSizeVideo.avi

  I got SmallSizeVideo.avi file which is approximately 6MB.

  I am using Powerpoint 2010. I want to insert the video in Powerpoint and play.

  Unfortunately when I embed SmallSizeVideo.avi Powerpoint is unable to play

  1) Is my approach correct ?
  2) What is the best way to situation like me to play small portion of clips in powerpoint

  Thank you