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• FFmpeg - Create Thumbnail Grid from Videos [duplicate]

  28 février 2021, par John Doe

  Is it possible to create a grid of 9 videos to form one big video, then snapshot the first frame to create a thumbnail showing the first frames of all 9 videos ? I wish to take the first 9 videos from a contact.txt file

  


  I started by trying with 4 videos but it still doesnt work :

  


  ffmpeg -y -ss 00:00:01 -protocol_whitelist file,pipe -f concat -safe 0 -i "concat.txt" -filter_complex "[0:v][1:v]hstack=inputs=2[top];[2:v][3:v]hstack=inputs=2[bottom];[top][bottom]vstack=inputs=2[v]" -map "[v]" -s 1280x720 "thumb.jpg"


  


  Trying to get this layout :


  


  MUST use files from concat list in text file

  


• FFMPEG : Create silent .ogg audio file

  29 mai 2016, par James Newton

  In answer to the question "How-to make a silent mp3 or wav-file" on ubuntuforums.org FakeOutdoorsman provided the following recipe :

  Another method by using FFmpeg. 60 seconds of silent audio in WAV :

  ffmpeg -ar 48000 -t 60 -f s16le -acodec pcm_s16le -ac 2 -i /dev/zero -acodec copy output.wav

  60 seconds of silent audio in MP3 :

  ffmpeg -ar 48000 -t 60 -f s16le -acodec pcm_s16le -ac 2 -i /dev/zero -acodec libmp3lame -aq 4 output.mp3

  How could I do something similar to create a silent .ogg audio file ?

  For a web app, I want to create a very short file for testing whether the browser will preload an audio file, or whether it will wait until the file is actually played before starting to stream it.

• How to create a video in .net6 [closed]

  22 mai 2023, par mans

  I am trying to create a video from a series of images i .net core (6.0)

  


  I am looking for a solution like this :

  


  VideoCreator video=new VideoCreator("MyVideo.mp4");

for (int i=0;i<1000;i++)
{
     var image=getImage();
     video.addFrame(image);
}
video.close();


  


  I already tried these solutions, and I could not make them work or compile :

  


  OpenCVSharp

  


  This is compiling properly in .net 6 but is sot reliable when writing videos. I could get a blank video, especially if the getImage function took a long time to return an image (for example, 20 sec) and the above code is run in a thread. All in one : the system did not produce video reliably.

  


  AForge.net

  


  This library and its related library (Accord.NET) don't work on.net core. My attempt to use them did not produce any compilable software (for example AForge.video.ffmpeg or AForge.Video.VFW) are not available in .net core).

  


  So my questions :

  


  

  1. What is the best way to create a video in .net core reliably ?

  


  2. I am using .net core as I am using Microsoft ML engine, is the ML engine available for framework ?

  


  3. My target platform is Windows, is there any way that I can combine .net and framework applications/libraries ?