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• Revision 3606b78108 : Modified test for auto key frame detection. The existing test was triggering a

  16 avril 2015, par paulwilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
  
  Modified test for auto key frame detection.

  The existing test was triggering a lot of false positives on some types
  of animated material with very plain backgrounds. These were triggering
  code designed to catch key frames in letter box format clips.

  This patch tightens up the criteria and imposes a minimum requirement
  on the % blocks coded intra in the first pass and the ratio between the
  % coded intra and the modified inter % after discounting neutral (flat)
  blocks that are coded equally well either way.

  On a particular problem animation clip this change eliminated a large
  number of false positives including some cases where the old code
  selected kf several times in a row. Marginal false negatives are less
  damaging typically to compression and in the problem clip there are now
  a couple of cases where "visual" scene cuts are ignored because of well
  correlated content across the scene cut.

  Replaced some magic numbers related to this with #defines and added
  explanatory comments.

  Change-Id : Ia3d304ac60eb7e4323e3817eaf83b4752cd63ecf

• Fragmented MP4 has wrong duration in Windows Media Player

  3 février 2020, par Expressingx

  I’m streaming video from a camera to a file using ffmpeg. The case to use Fragmented MP4 is that there can be sudden power off and lose the video. I’ve configured the fragments to be at least 30 secs and this is how much the Windows Media Player reports for the duration even if its 2 hours long, after that it keeps streaming the video but is not seekable after the 30th second. How can be that fixed ?

  ffmpeg -c copy -movflags frag_keyframe+separate_moof+omit_tfhd_offset -min_frag_duration 30000000 -bsf:a aac_adtstoasc \ out.mp4

  If I use -movflags frag_keyframe+empty_moov then the video is not seekable at all and no duration reported.

  I aim for seekable video with correct duration both on VLC/Windows Media Player

  Version of ffmpeg : 3.3.4

• 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.