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• Using FFMPEG with QT

  7 mai 2018, par DearChild

  I’m having a problem with linking FFmpeg libraries to Qt 5.10 Projects.
  I downloaded the source code from the official website and successfully compiled and installed to my Ubuntu. I used : ./configure --enable-libvpx --disable-x86asm them : make && make install
  I’m able to find the installed libraries in /usr/local/lib (which are .a libs).

  my .pro looks like this :

  INCLUDEPATH += /usr/local/include
  
  LIBS += -L/usr/local/lib -lavformat -lavcodec -lavutil

  but i get the output :

  /usr/bin/x86_64-linux-gnu-ld: 
  
  /usr/loca/lib/libavformat.a(http.o):undefined reference to symbol 'inflateEnd'
  
  //lib/x86_64-linux-gnu/libz.so.1: error adding symbols: DSO missing from command line

  Does anyone know how to solve it ? Thanks for the attention !

  Note : I would like to static link it to my project

• Writing to two standard input pipes from C#

  3 janvier 2021, par Den Delimarsky

  I am using FFMPEG from my C# application to build out the video stream from raw unencoded frames. For just one input stream this is fairly straightforward :

  


  var argumentBuilder = new List<string>();&#xA;argumentBuilder.Add("-loglevel panic");&#xA;argumentBuilder.Add("-f h264");&#xA;argumentBuilder.Add("-i pipe:");&#xA;argumentBuilder.Add("-c:v libx264");&#xA;argumentBuilder.Add("-bf 0");&#xA;argumentBuilder.Add("-pix_fmt yuv420p");&#xA;argumentBuilder.Add("-an");&#xA;argumentBuilder.Add(filename);&#xA;&#xA;startInfo.Arguments = string.Join(" ", argumentBuilder.ToArray());&#xA;&#xA;var _ffMpegProcess = new Process();&#xA;_ffMpegProcess.EnableRaisingEvents = true;&#xA;_ffMpegProcess.OutputDataReceived &#x2B;= (s, e) => { Debug.WriteLine(e.Data); };&#xA;_ffMpegProcess.ErrorDataReceived &#x2B;= (s, e) => { Debug.WriteLine(e.Data); };&#xA;&#xA;_ffMpegProcess.StartInfo = startInfo;&#xA;&#xA;Console.WriteLine($"[log] Starting write to {filename}...");&#xA;&#xA;_ffMpegProcess.Start();&#xA;_ffMpegProcess.BeginOutputReadLine();&#xA;_ffMpegProcess.BeginErrorReadLine();&#xA;&#xA;for (int i = 0; i &lt; videoBuffer.Count; i&#x2B;&#x2B;)&#xA;{&#xA;    _ffMpegProcess.StandardInput.BaseStream.Write(videoBuffer[i], 0, videoBuffer[i].Length);&#xA;}&#xA;&#xA;_ffMpegProcess.StandardInput.BaseStream.Close();&#xA;</string>

  


  One of the challenges that I am trying to address is writing to two input pipes, similar to how I could do that from, say, Node.js, by referring to pipe:4 or pipe:5. It seems that I can only write to standard input directly but not split it into "channels".

  


  What's the approach to do this in C# ?

  


• Create video with size based on image and place a video somewhere with an offset

  10 mars 2024, par NoKey

  I am trying out FFMPEG and I am unsure how hard it is to do what I want. I have some device frames and I want to play a video inside the frame. For example, this is a device frame :

  


  

  


  Now I want to play a video within the screen of the iPhone. I already got the exact X and Y offset where the video must be placed to show it correctly. I have the following challenges to make it work, and I want to make sure FFMPEG can do it before I spend to much time reinventing the wheel :

  


  


  • The output of the video must be as big as the PNG. This is already a
confusing part for me. I have the width and height already available,
but the things I saw is that FFMPEG will take over the input of the
video as final size. The final output of the video should of course
be the length of the input video.

    


  


  • The background must be transparant (so no black background, I want to
play the video on top of a website so it's nice if it's transparant and the corners are not black).

    


  


  • The ability to place a video somewhere with a specified X and Y
offset inside the device frame.

    


  


  • Not sure if it's possible in the same command, but maybe the video
needs to be resized to make it fit. I got the exact dimensions for
the video.

    


  


  


  The things I struggle most is point 1 where the output video must have a transparant background and where the device frame is placed in. Does anybody got tips ?