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• Android editing video files

  25 novembre 2013, par Kernald

  I'm working on an Android application in which the user should be able to edit a video (cut and reorder some parts of a video taken with the phone).

  I have no idea how to do this : the media package doesn't seems to contain anything related to this. The videoeditor package could probably help me, but it's not public in the SDK. ffmpeg could maybe be a solution, but I'd like to avoid using NDK if I can.

  Any directions on how to do it ?

• how to make live rtsp player using ffmpeg ?

  20 avril 2018, par geeeek

  I am creating an rtsp live viewer using ffmpeg. I have a question about video delay, so I ask.

  At beginning play live rtsp, Video delay is about 2 seconds on general movie player(vlc, gom). However, when the playback speed is increased, the delay is reduced and the video delay is shortened to about 300 ms.

  I do not know how to reduce the delay to speed up or speed up this playback on my ffmpeg player.

  It seems like I can use something like av_seek_frame, but it does not work.
  How can I reduce live rtsp video delay with ffmpeg ?

  In summary, I’d like to get the latest frame to be av_read_frame in live rtsp.

• How do I get FFMPEG to build a video using the same timing as my input ?

  15 avril 2016, par Forest J. Handford

  I’m trying to create a video of screen actions a user takes by piping screenshots to FFMPEG from a C# console application. I’m sending 10 frames per second. The final video has exactly as many frames as I sent (ie : a 10 second vid has 100 frames). The time, however, of the video does not match. With the below code I get 7m 47s worth of video from 490751 ms of input. I’ve found that PTS gets me a little closer, but it feels like I’m doing something wrong.

      private const int VID_FRAME_FPS = 10;
  
      private const double PTS = 2.4444;
  
  
  
      /// <summary>
  
      /// Generates the Videos by gathering frames and processing via FFMPEG.
  
      /// Deletes the generated Frame images after successfully compiling the video.
  
      /// </summary>
  
      public static void RecordScreen(string pathToOutput)
  
      {
  
          Logger.log.Info("Launching FFMPEG ....");
  
          String arg = "-f image2pipe -i pipe:.bmp -filter:v \"setpts = " + PTS + " * PTS\" -r " + VID_FRAME_FPS + " -pix_fmt yuv420p -qscale:v 5 -vcodec libvpx -bufsize 30000k -y \"" + pathToOutput + "\\VidOut.webm\"";
  
          //String arg = "-f image2pipe -i pipe:.bmp -filter:v \"setpts = " + PTS + " * PTS\" -r " + VID_FRAME_FPS + " -pix_fmt yuv420p -qscale:v 5 -vcodec libx264 -bufsize 30000k -y \"" + pathToOutput + "\\VidOut.mp4\"";
  
          Process launchingFFMPEG = new Process
  
          {
  
              StartInfo = new ProcessStartInfo
  
              {
  
                  FileName = "ffmpeg",
  
                  Arguments = arg,
  
                  UseShellExecute = false,
  
                  CreateNoWindow = true,
  
                  RedirectStandardInput = true
  
              }
  
          };
  
          launchingFFMPEG.Start();
  
  
  
          System.Drawing.Image img;
  
          Stopwatch stopWatch = Stopwatch.StartNew(); //creates and start the instance of Stopwatch
  
          int sleep;
  
  
  
          Stopwatch vidTime = Stopwatch.StartNew();
  
  
  
          do
  
          {
  
              img = Capture.GetScreen();
  
              img.Save(launchingFFMPEG.StandardInput.BaseStream, System.Drawing.Imaging.ImageFormat.Bmp);
  
              img.Dispose();
  
  
  
              sleep = 10 * VID_FRAME_FPS - (int)stopWatch.ElapsedMilliseconds;
  
              if (sleep > 0)
  
              {
  
                  Logger.log.Info("Captured frame, sleeping " + sleep + " milliseconds.");
  
                  Thread.Sleep(sleep);
  
              }
  
              stopWatch.Restart();
  
          } while (workerThread.IsAlive);
  
          Logger.log.Debug("Video Time: " + vidTime.ElapsedMilliseconds);
  
          launchingFFMPEG.StandardInput.Flush();
  
          launchingFFMPEG.StandardInput.Close();
  
          launchingFFMPEG.Close();
  
      }

  Is there a way to do this without PTS ? If I need PTS, what is the correct value ? It seems that PTS of 2.565656 is close to correct.

  All the related documentation points to just using -r (the framerate command) but that doesn’t work (as I’m using it).

  Note : I’m only using H.264 for debugging with ffprobe, I plan to switch back to webm when this is resolved. I’m trying to avoid H.256 and MP4 patents.