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• FFmpeg's trim filter to handle movie files with non-zero start_time for a transcoding task ?

  19 août 2014, par Drake

  For a movie file (ex, ooxx.mp4) with non-zero start_time in video stream, the negative start_time (ex, -0.5) can mean skipping first 0.5s frames, and the positive start_time (ex, 0.7s) can mean postponing the playback for 0.7s.

  I’m wondering if we can make use of FFmpeg’s trim filter (or something else) to strip out some video frames (for negative start_time) or put some empty (ex, black) frames ahead (for positive start_time) automatically ?

• lavfi/movie : Use filter thread count for decoding threads.

  25 août 2019, par Carl Eugen Hoyos

  lavfi/movie : Use filter thread count for decoding threads.
  Fixes ticket #7542.
  

  • [DH] libavfilter/src_movie.c

• Using ffmepg wrapper to convert images to movie file

  24 mai 2020, par reborn

  I have recently been using the ffmpeg wrapper by Vitaliy Fedorchenko called NReco.VideoConverter. It's pretty great and I have managed to write another application with it that I hope to release soon after some testing and I purchase the license for the wrapper (it's a cool watermarker for videos).

  



  I am now trying to use that same wrapper to encode a video from still images, but sadly there is very little documentation available and I am feeling my way int he dark a little. I am hopeful that someone familiar with the wrapper might be able to help.

  



  I collect the images using the fileOpenDialogue and picking images to populate a listView. When I am ready, I then take these images to build an array and create the movie.

  



  application picture

  



      void ConvertToMovie()
    {
        if(listImages.Items.Count > 1)
        {
            var ffMpeg = new NReco.VideoConverter.FFMpegConverter();

            NReco.VideoConverter.FFMpegInput[] ffMpegInputs = new NReco.VideoConverter.FFMpegInput[listImages.Items.Count]; 

            for (int i = 0; i < listImages.Items.Count; i++)
            {
                var SSAImage = new NReco.VideoConverter.FFMpegInput(listImages.Items[i].SubItems[2].Text.ToString());
                ffMpegInputs[i] = SSAImage;
            }


            ConvertSettings csettings = new ConvertSettings();
            csettings.SetVideoFrameSize((int)MovieWidth.Value, (int)MovieHeight.Value);
            csettings.VideoFrameCount = listImages.Items.Count;
            csettings.VideoFrameRate = (int)FPS.Value;

            /*
            string argument = " -profile:v high ";
            csettings.CustomOutputArgs = argument;
            */

            if (FormatChooser.SelectedIndex == 0)
            {
                //This just takes the first picture and converts that single frame into a movie.
                ffMpeg.ConvertMedia(ffMpegInputs, @"Converted.avi", Format.avi, csettings);
                //ffMpeg.ConvertMedia(listImages.Items[0].SubItems[2].Text.ToString(), ffMpegInput.Format, @"Converted.avi", Format.avi, csettings);
            }
        }
        else
        {
            MessageBox.Show("You need at least two images to make a movie.", Title);
        }
    }


  



  Passing the images as an array to the function seems logical. At list of the methods are here : https://www.nrecosite.com/doc/NReco.VideoConverter/

  



  However, the only method that allows you to pass an array of the inputs is here :
https://www.nrecosite.com/doc/NReco.VideoConverter/html/M_NReco_VideoConverter_FFMpegConverter_ConvertMedia.htm

  



  So this makes sense to me that it would be the one to use.

  



  This does generate a .avi file, but the movie only contains the first frame from the array.

  



  I saw someone else had the same issue here : Nreco video converter make video from image sequence

  



  However, the responses seemed to suggest using a different method that allows you to pass a single image file only, then somehow the ffmpeg.exe will sequence the rest of them ? I couldn't get that to work at all.

  



  At this stage the only way I can see of making it work is creating a single frame movie file for each frame, and then concating all of the movie files together using :

  



  https://www.nrecosite.com/doc/NReco.VideoConverter/?topic=html/M_NReco_VideoConverter_FFMpegConverter_ConcatMedia.htm

  



  That's a pretty ridiculous notion though.