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• ffmpeg how to end video with a black frame/solid color

  10 mai 2021, par request

  I'm scaling 2 videos of different sizes and hstack them side by side together.

  


  If the length of the two videos is different and for example the first one is over, then it shows the last frame of that video the whole time. I want it to show nothing / a black frame until the other video is over

  


  My code so far :

  


  ffmpeg -i vid1.mp4 -i vid2.mp4 -filter_complex "[1][0]scale2ref[2nd][ref];[ref][2nd]hstack" -vsync 0 output.mp4


  


  How could this be achieved ? (something with tpad or stop_mode maybe ?)

  


  Here are two sample videos to test with :

  


  testvid1

  


  testvid1

  


• Using GDIgrab in FFmpeg with dshow Audio produces black screen

  16 mars 2016, par Spreadys

  here is my command :

  ffmpeg -f gdigrab -framerate 25 -offset_x 10 -offset_y 10 -show_region 1 -draw_mouse 1 -video_size 1280x720 -i desktop -f dshow -i audio="Microphone (2- ATR USB microphone)" -r 25 -threads 4 -c:v libx264 -pix_fmt yuv422p -preset superfast -tune fastdecode -x264opts keyint=25:min-keyint=1 -crf 4 -c:a aac -profile:a aac_low -async 25 "C:\Users\david\Desktop\%output%.mp4"

  The gdigrab video works great when it is on its own (no audio). The audio works fine when it is on its own (no video). When I join the two commands to capture both together, as soon as I move a window within my capture area, the area goes black.

  In Windows 7, I used to get around this by stopping the desktop composition service prior to capture, (SC stop uxsms), but this is now not possible in Win10.

  I thought it may be something graphics card related.
  My main monitor is on an Nvidia card, with my second running from the onboard Intel. This is setup for Quicksync H264 playback and encoding with my NLE.

  I know that I could use a dshow screen capture driver such as UScreen but am trying to avoid that as I need the capture area to be specified each time from a simple batch.

  Any help appreciated to solve this black area problem- its driving me crazy !
  David

• YUV to RGB by Shader on iPhone

  27 octobre 2012, par user1333656

  Currently I am developing a video player using FFMPEG.
  I'm trying to convert YUV420P to RGB by Shader to reduce performance hit and I could see it works fine. The problem is caused when I try to change image size.

  Case 1. YUV to RGB is perfect. but the image is not exactly fit to Texture Bounds.
  For example, if i play 640x360 video, right (640-512) part is cropped and bottom (512-360) is filled with green colored rectangle.

  FRAME_X=512; //This is texture size
  
  FRAME_Y=512;
  
  
  
      avpicture_fill((AVPicture *) f, [currentVideoBuffer.data mutableBytes],
  
                 enc->pix_fmt,
  
                 FRAME_X, FRAME_Y);
  
  
  
      av_picture_copy((AVPicture *) f, (AVPicture *) avFrame,
  
                  enc->pix_fmt,
  
                  enc->width, enc->height);

  ....

  int yuvWidth= FRAME_X ;
  
  int  yuvHeight= FRAME_Y;
  
  glBindTexture ( GL_TEXTURE_2D, textureIdY );
  
  glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 
  
  yuvWidth, yuvHeight, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, y_channel);
  
  
  
  
  
  glBindTexture ( GL_TEXTURE_2D, textureIdU );
  
  glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE,
  
  yuvWidth/2, yuvHeight/2, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, u_channel);
  
  
  
  glBindTexture ( GL_TEXTURE_2D, textureIdV );
  
  glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 
  
  yuvWidth/2, yuvHeight/2, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, v_channel);

  Case 2. If i set actual image size to texture size, then image is exactly fit to texture but the color of image is a little bit strange. It has too much green color.

  Does anybody give me some clues for this ??
  Thanks in advance.