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• How do i compress a video file in c# (Xamarin android)

  1er août 2016, par stackOverNo

  I’m currently working on a xamarin.android project, and am attempting to upload a video to an aws server, and then also be able to play it back. The upload is working correctly as far as I can tell.

  I’m retrieving the file from the user’s phone, turning it into a byte array, and uploading that. This is the code to upload :

  if (isImageAttached || isVideoAttached)
  
              {
  
                  //upload the file 
  
                  byte[] fileInfo = System.IO.File.ReadAllBytes(filePath);
  
                  Task<media> task = client.SaveMediaAsync(fileInfo, nameOfFile);
  
                  mediaObj = await task;
  
  
  
                  //other code below is irrelevant to example
  
              }
  
  </media>

  and SaveMediaAsync is a function I wrote in a PCL :

  public async Task<media> SaveMediaAsync(byte[] fileInfo, string fName)
  
      {        
  
          Media a = new Media();
  
          var uri = new Uri(RestUrl);
  
  
  
          try
  
          {
  
  
  
              MultipartFormDataContent form = new MultipartFormDataContent();
  
              form.Add(new StreamContent(new MemoryStream(fileInfo)), "file", fName);  //add file
  
  
  
              var response = await client.PostAsync(uri, form);            //post the form   client is an httpclient object
  
              string info = await response.Content.ReadAsStringAsync();
  
  
  
      //save info to media object
  
              string[] parts = info.Split('\"');
  
              a.Name = parts[3];
  
              a.Path = parts[7];
  
              a.Size = Int32.Parse(parts[10]);
  
  
  
          }
  
          catch(Exception ex)
  
          {
  
      //handle exception
  
          }
  
  
  
          return a;
  
  
  
      }
  
  </media>

  After uploading the video like that, I’m able to view it in a browser using the public url. The quality is the same, and there is no issue with lag or load time. However when I try to play back the video using the same public url on my app on an android device, it takes an unbelievably long time to load the video. Even once it is loaded, it plays less than a second of it, and then seems to start loading the video again(the part of the progress bar that shows how much of the video has loaded jumps back to the current position and starts loading again).

   VideoView myVideo = FindViewById<videoview>(Resource.Id.TestVideo);
  
  
  
   myVideo.SetVideoURI(Android.Net.Uri.Parse(url));
  
  
  
   //add media controller
  
   MediaController cont = new MediaController(this);
  
   cont.SetAnchorView(myVideo);
  
   myVideo.SetMediaController(cont);
  
  
  
   //start video
  
   myVideo.Start();
  
  </videoview>

  Now I’m trying to play a 15 second video that is 5.9mb. When I try to play a 5 second video that’s 375kb it plays with no issue. This leads me to believe I need to make the video file smaller before playing it back, but I’m not sure how to do that. I’m trying to allow the user to upload their own videos, so I’ll have all different file formats and sizes.

  I’ve seen some people suggesting ffmpeg for a c# library to alter video files, but I’m not quite sure what it is I need to do to the video file. Can anyone fill in the gaps in my knowledge here ?

  Thanks for your time, it’s greatly appreciated !

• How to use ffmpeg to split a video and then merge it smoothly ? [duplicate]

  16 juin 2017, par leandro moreira

  This question is an exact duplicate of :

  • How to segment a video and then concatenate back into original one with ffmpeg
    
    1 answer
    

  The idea is to split a video into n segments and process them separated and when the process is done to merge the segments into a full video.

  I tried using the following approach :

  ```

  // spliting
  
  ffmpeg -i video.mp4 -c:v copy -c:a copy -ss 0 -t 10 video_0_10.mp4
  
  ffmpeg -i video.mp4 -c:v copy -c:a copy -ss 10 -t 20 video_10_20.mp4
  
  
  
  vim video_list.txt (with all files)
  
  
  
  // joining (merging them)
  
  ffmpeg -f concat -safe 0 -i video_list.txt -c:v copy -c:a copy new_video.mp4

  ```

  But when I tried to play the new_video.mp4 it didn’t play (using VLC) smooth, it froze seemly at the moment of the joining.

  What’s the best way to split a bigger video into several smaller, work on them and after joining the smaller into a new ?

• How can I split a series of clips from a video and then stitch them together without audio or video gaps ?

  16 avril 2020, par Dr. Cyber Sec

  I'm developing an application where I take a video and (1) split it up into a bunch of 1 second chunks. Then, I need to (2) stitch a subset of those chunks back together, resulting in a slice of the original video.

  



  For example, let's say I have an original, 10s clip. I split it up into 1s chunks for each second (a clip from 0s to 1s, a clip from 1s to 2s, etc.). I now need to stitch, say, seconds 2-4 together into one video.

  



  I'm currently attempting both steps using ffmpeg.

  



  For clip-cutting :

  



  ffmpeg -ss 33 -i video.ts -t 1 33to34.ts


  



  This should seek to second 33 and output a 1s clip duration, yielding a video clip containing seconds 33-34 of the original video. I noticed that ffmpeg doesn't always seek accurately, so after following the instructions in this post, which says to manually add keyframes to the parts of the video you want to cut, I tried this :

  



  First, setting the keyframes :

  



  ffmpeg -i video.ts -force_key_frames 00:00:01.000,00:00:02.000,00:00:03.000,00:00:04.000 out.ts


  



  And then cutting the clips as I did before with the new output clip.

  



  While this did get the videos to be exactly 1s long each, (which I wanted) there is a small gap (just a slight jitter) in audio when I combine the clips back together. I cannot have this, and am looking for a solution.

  



  Can anyone help me understand why this is happening and help me find a solution ? Thank you so much in advance.