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• a lot of GREEN Color at YUV420p —> RGB in OpenGL 2.0 Shader on iOS

  25 octobre 2012, par 이형근

  I want to make a movie player for iOS using ffmpeg and OpenGL ES 2.0
  but I have some problem. Output RGB image has a lot of GREEN color.
  This is code and images

  • 480x320 width & height :
  • 512x512 Texture width & height

  I got a YUV420p row data from ffmpeg AVFrame.

      for (int i = 0, nDataLen = 0; i < 3; i++) {
  
          int nShift = (i == 0) ? 0 : 1;
  
          uint8_t *pYUVData = (uint8_t *)_frame->data[i];
  
          for (int j = 0; j < (mHeight >> nShift); j++) {
  
              memcpy(&pData->pOutBuffer[nDataLen], pYUVData, (mWidth >> nShift));
  
              pYUVData += _frame->linesize[i];
  
              nDataLen += (mWidth >> nShift);
  
          }
  
      }

  and prepare texture for Y, U & V channel.

  //: U Texture
  
      if (sampler1Texture) glDeleteTextures(1, &sampler1Texture);
  
  
  
      glActiveTexture(GL_TEXTURE1);
  
      glGenTextures(1, &sampler1Texture);
  
      glBindTexture(GL_TEXTURE_2D, sampler1Texture);
  
  
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
      // This is necessary for non-power-of-two textures
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  
      glEnable(GL_TEXTURE_2D);
  
  
  
      glTexImage2D(GL_TEXTURE_2D, 
  
                   0, 
  
                   GL_LUMINANCE, 
  
                   texW / 2, 
  
                   texH / 2, 
  
                   0, 
  
                   GL_LUMINANCE, 
  
                   GL_UNSIGNED_BYTE,
  
                   NULL);
  
  
  
      //: V Texture
  
      if (sampler2Texture) glDeleteTextures(1, &sampler2Texture);
  
  
  
      glActiveTexture(GL_TEXTURE2);
  
      glGenTextures(1, &sampler2Texture);
  
      glBindTexture(GL_TEXTURE_2D, sampler2Texture);
  
  
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
      // This is necessary for non-power-of-two textures
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  
      glEnable(GL_TEXTURE_2D);
  
  
  
      glTexImage2D(GL_TEXTURE_2D, 
  
                   0, 
  
                   GL_LUMINANCE, 
  
                   texW / 2, 
  
                   texH / 2, 
  
                   0, 
  
                   GL_LUMINANCE,
  
                   GL_UNSIGNED_BYTE,
  
                   NULL);
  
  
  
      //: Y Texture
  
      if (sampler0Texture) glDeleteTextures(1, &sampler0Texture);
  
  
  
      glActiveTexture(GL_TEXTURE0);
  
      glGenTextures(1, &sampler0Texture);
  
      glBindTexture(GL_TEXTURE_2D, sampler0Texture);
  
  
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
      // This is necessary for non-power-of-two textures
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
  
      glEnable(GL_TEXTURE_2D);
  
  
  
      glTexImage2D(GL_TEXTURE_2D, 
  
                   0, 
  
                   GL_LUMINANCE, 
  
                   texW, 
  
                   texH, 
  
                   0, 
  
                   GL_LUMINANCE,
  
                   GL_UNSIGNED_BYTE, 
  
                   NULL);

  Rendering part is below.

  int _idxU = mFrameW * mFrameH;
  
  int _idxV = _idxU + (_idxU / 4);
  
  
  
  // U data
  
  glActiveTexture(GL_TEXTURE1);
  
  glBindTexture(GL_TEXTURE_2D, sampler1Texture);
  
  glUniform1i(sampler1Uniform, 1);
  
  
  
  glTexSubImage2D(
  
                  GL_TEXTURE_2D, 
  
                  0, 
  
                  0, 
  
                  0, 
  
                  mFrameW / 2,            // source width
  
                  mFrameH / 2,            // source height
  
                  GL_LUMINANCE,
  
                  GL_UNSIGNED_BYTE, 
  
                  &_frameData[_idxU]);
  
  
  
  // V data
  
  glActiveTexture(GL_TEXTURE2);
  
  glBindTexture(GL_TEXTURE_2D, sampler2Texture);
  
  glUniform1i(sampler2Texture, 2);
  
  
  
  glTexSubImage2D(
  
                  GL_TEXTURE_2D, 
  
                  0, 
  
                  0, 
  
                  0, 
  
                  mFrameW / 2,            // source width
  
                  mFrameH / 2,            // source height
  
                  GL_LUMINANCE,
  
                  GL_UNSIGNED_BYTE,
  
                  &_frameData[_idxV]);
  
  
  
  // Y data
  
  glActiveTexture(GL_TEXTURE0);
  
  glBindTexture(GL_TEXTURE_2D, sampler0Texture);
  
  glUniform1i(sampler0Uniform, 0);
  
  
  
  glTexSubImage2D(
  
                  GL_TEXTURE_2D, 
  
                  0, 
  
                  0, 
  
                  0, 
  
                  mFrameW,            // source width
  
                  mFrameH,            // source height
  
                  GL_LUMINANCE,
  
                  GL_UNSIGNED_BYTE,
  
                  _frameData);

  Vertex Shader & Fragment Shader is below.

  attribute vec4 Position;
  
  attribute vec2 TexCoordIn;
  
  
  
  varying vec2 TexCoordOut;
  
  varying vec2 TexCoordOut_UV;
  
  
  
  uniform mat4 Projection;
  
  uniform mat4 Modelview;
  
  
  
  void main()
  
  {
  
      gl_Position = Projection * Modelview * Position;
  
      TexCoordOut = TexCoordIn;
  
  }
  
  
  
  
  
  
  
  uniform sampler2D sampler0; // Y Texture Sampler
  
  uniform sampler2D sampler1; // U Texture Sampler
  
  uniform sampler2D sampler2; // V Texture Sampler
  
  
  
  varying highp vec2 TexCoordOut;
  
  
  
  void main()
  
  {
  
      highp float y = texture2D(sampler0, TexCoordOut).r;
  
      highp float u = texture2D(sampler2, TexCoordOut).r - 0.5;
  
      highp float v = texture2D(sampler1, TexCoordOut).r - 0.5;
  
  
  
      //y = 0.0;
  
      //u = 0.0;
  
      //v = 0.0;
  
  
  
      highp float r = y + 1.13983 * v;
  
      highp float g = y - 0.39465 * u - 0.58060 * v;
  
      highp float b = y + 2.03211 * u;
  
  
  
      gl_FragColor = vec4(r, g, b, 1.0);
  
  }

  Y Texture (Grayscale) is correct but U & V has a lot of Green Color.
  So final RGB image (Y+U+V) has a lot of GREEN Color.
  What's the problem ?

  Please help.
  thanks.

• libaomenc : Add support for tiles

  23 octobre 2018, par Mark Thompson

  libaomenc : Add support for tiles
  Adds an option to specify the number of tile rows and columns, then uses
  
  a uniform tiling if possible and otherwise a fixed tiling with equal-sized
  
  tiles to fill the frame.
  Also adds -tile-columns and -tile-rows options to make tilings with
  
  power-of-two numbers of tiles, matching the behaviour of the libvpx/VP9
  
  encoder.
  

  • [DH] libavcodec/libaomenc.c

• exporting ogg videos from video slideshow (mp4) and audio (wav) using ffmpeg in python

  17 septembre 2018, par jtz

  I have tried to find a solution already, but just cannot make it work. I want to export an .ogg-video by combining a video slideshow (mp4) with an audio file (wav) by using ffmpeg in python. The audio is shorter than the video and should have an offset of 2000 milliseconds, so that it starts approximately in the middle of the video. The code that I tried is essentially this :

  subprocess.call(’ffmpeg.exe -itsoffset 0 -i slideshows/slideshow.mp4 -itsoffset 2000 -i sounds/audio.wav -codec:v libtheora -codec:a libvorbis output.ogg’, shell= True)

  FYI : I need to create a couple of different video formats from the video and audio input, so substituting the ogg with a different format is no option. I have already successfully created .mp4-video-files and .webm-video-files from the material, but need the .ogg in addition. Also, Power Point does not like any of the exported videos, maybe this might be relevant for finding the problem here (I also unsuccessfully tried to fix this issue).