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• C# Process output redirected to console instead of stream

  18 juillet 2017, par w0ffen

  I am trying to use FFmpeg to get video data using the following code :

  var ffmpeg = new Process();
  
          ProcessStartInfo sInfo = new ProcessStartInfo();
  
  
  
          sInfo.FileName = @"C:\FFmpeg\ffmpeg.exe";
  
          sInfo.Arguments = string.Format("-i {0}", filePath);
  
          sInfo.UseShellExecute = false;
  
          sInfo.RedirectStandardOutput = true;
  
  
  
          ffmpeg.StartInfo = sInfo;
  
          ffmpeg.Start();
  
  
  
          string output = ffmpeg.StandardOutput.ReadToEnd();
  
  
  
          ffmpeg.WaitForExit();

  The process output goes through, but it is a console application, and the output gets redirected to the console window. Then, when I check the contents of output, it is empty, but ffmpeg’s output is displayed on the console window of the program I’m working on.

  How do I fix this ?

• What is the GLFW screen format for ffmpeg encoding ?

  3 septembre 2022, par Turgut

  I have a program where I have a GLFW window and read that window using glReadPixels(0, 0,window_width, window_height, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*) Buffer); then use that Buffer to encode a frame via ffmpeg. It works fine however the resolution is a bit low.

  


  I tried changing bit-rates to no avail so I started experimenting with formats. Normally I'm using AV_PIX_FMT_YUV420P in my encoder as my format since the data that comes from the glfw window is RGBA but this format result in the said low resolution video. The result video is a lot more pixelated than whats seen on the GLFW window.

  


  What could be the optimal pixel format for reading GLFW window ? Some formats straight up not work resulting in Specified pixel format  yuyv422 is invalid or not supported error.

  


  And here is where I got that error from :

  


  ret = avcodec_open2(c, codec, &opt);


  


  This line causes me to get Specified pixel format  yuyv422 is invalid or not supported error when I use something other than YUV420.

  


  I also have this setting #define SCALE_FLAGS SWS_BICUBIC which im not sure what it does but may also cause my error. (Not likeliy since this comes after the line mentioned above, but I could just keep the format at YUV420 and change SWS_BICUBIC instead.)

  


  I'm using ubuntu, ffmpeg, glfw and glad (GLSL) to render the texture writeen in the frames. I got the encoder from ffmpegs muxing.c example.

  


  Edit : Using AV_PIX_FMT_RGBA also results in a similar error.

  


  Edit : Here is my sample code where I convert Buffer to ffmepg format :

  


  #define STREAM_PIX_FMT AV_PIX_FMT_YUV420P
...
void video_encoder::set_frame_yuv_from_rgb(AVFrame *frame, struct SwsContext *sws_context) {
    const int in_linesize[1] = { 4 * width };

    sws_context = sws_getContext(
            width, height, AV_PIX_FMT_RGBA,
            width, height, STREAM_PIX_FMT,
            SWS_BICUBIC, 0, 0, 0);

    sws_scale(sws_context, (const uint8_t * const *)&rgb_data, in_linesize, 0,
            height, frame->data, frame->linesize);
}


  


• Android video saves as type "file" instead of video format

  25 novembre 2015, par Marc Rasmussen

  So I have a website where I allow people to upload a video from their phone and send it to their friends.

  Now Iphone works well because it is usually an .mov file. However when I attempt on my android (Samsung galaxy) I get FileType : file

  Howere is an image from my filezilla as to what has been uploaded :

  

  The highlighted are the files uploaded from the android device.

  Can anyone tell me why this is happening ? and how I can make sure that it is a video ? and/or convert it into a mp4 format.