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• Render YUV video in OpenGL of ffmpeg using CVPixelBufferRef and Shaders

  4 septembre 2012, par resident_

  I'm using to render YUV frames of ffmpeg with the iOS 5.0 method "CVOpenGLESTextureCacheCreateTextureFromImage".

  I'm using like the apple example GLCameraRipple

  My result in iPhone screen is this : iPhone Screen

  I need to know I'm doing wrong.

  I put part of my code to find errors.

  ffmpeg configure frames :

  ctx->p_sws_ctx = sws_getContext(ctx->p_video_ctx->width, 
  
                                  ctx->p_video_ctx->height, 
  
                                  ctx->p_video_ctx->pix_fmt, 
  
                                  ctx->p_video_ctx->width, 
  
                                  ctx->p_video_ctx->height,
  
                                  PIX_FMT_YUV420P, SWS_FAST_BILINEAR, NULL, NULL, NULL);
  
  
  
  
  
  // Framebuffer for RGB data
  
  ctx->p_frame_buffer = malloc(avpicture_get_size(PIX_FMT_YUV420P,
  
                                                  ctx->p_video_ctx->width, 
  
                                                  ctx->p_video_ctx->height));
  
  
  
  avpicture_fill((AVPicture*)ctx->p_picture_rgb, ctx->p_frame_buffer,PIX_FMT_YUV420P, 
  
                 ctx->p_video_ctx->width, 
  
                 ctx->p_video_ctx->height);

  My render method :

  if (NULL == videoTextureCache) {
  
      NSLog(@"displayPixelBuffer error");
  
      return;
  
  }    
  
  
  
  
  
  CVPixelBufferRef pixelBuffer;    
  
     CVPixelBufferCreateWithBytes(kCFAllocatorDefault, mTexW, mTexH, kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange, buffer, mFrameW * 3, NULL, 0, NULL, &pixelBuffer);
  
  
  
  
  
  
  
  CVReturn err;    
  
  // Y-plane
  
  glActiveTexture(GL_TEXTURE0);
  
  err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, 
  
                                                     videoTextureCache,
  
                                                     pixelBuffer,
  
                                                     NULL,
  
                                                     GL_TEXTURE_2D,
  
                                                     GL_RED_EXT,
  
                                                     mTexW,
  
                                                     mTexH,
  
                                                     GL_RED_EXT,
  
                                                     GL_UNSIGNED_BYTE,
  
                                                     0,
  
                                                     &_lumaTexture);
  
  if (err) 
  
  {
  
      NSLog(@"Error at CVOpenGLESTextureCacheCreateTextureFromImage %d", err);
  
  }   
  
  
  
  glBindTexture(CVOpenGLESTextureGetTarget(_lumaTexture), CVOpenGLESTextureGetName(_lumaTexture));
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);     
  
  
  
  // UV-plane
  
  glActiveTexture(GL_TEXTURE1);
  
  err = CVOpenGLESTextureCacheCreateTextureFromImage(kCFAllocatorDefault, 
  
                                                     videoTextureCache,
  
                                                     pixelBuffer,
  
                                                     NULL,
  
                                                     GL_TEXTURE_2D,
  
                                                     GL_RG_EXT,
  
                                                     mTexW/2,
  
                                                     mTexH/2,
  
                                                     GL_RG_EXT,
  
                                                     GL_UNSIGNED_BYTE,
  
                                                     1,
  
                                                     &_chromaTexture);
  
  if (err) 
  
  {
  
      NSLog(@"Error at CVOpenGLESTextureCacheCreateTextureFromImage %d", err);
  
  }
  
  
  
  glBindTexture(CVOpenGLESTextureGetTarget(_chromaTexture), CVOpenGLESTextureGetName(_chromaTexture));
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
  
  glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);     
  
  
  
  glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer);
  
  
  
  // Set the view port to the entire view
  
  glViewport(0, 0, backingWidth, backingHeight);
  
  
  
  static const GLfloat squareVertices[] = {
  
      1.0f, 1.0f,
  
      -1.0f, 1.0f,
  
      1.0f,  -1.0f,
  
      -1.0f,  -1.0f,
  
  };
  
  
  
  GLfloat textureVertices[] = {
  
      1, 1,
  
      1, 0,
  
      0, 1,
  
      0, 0,
  
  };
  
  
  
  // Draw the texture on the screen with OpenGL ES 2
  
  [self renderWithSquareVertices:squareVertices textureVertices:textureVertices];
  
  
  
  
  
  // Flush the CVOpenGLESTexture cache and release the texture
  
  CVOpenGLESTextureCacheFlush(videoTextureCache, 0);    
  
  CVPixelBufferRelease(pixelBuffer);     
  
  
  
   [moviePlayerDelegate bufferDone];

  RenderWithSquareVertices method

      - (void)renderWithSquareVertices:(const GLfloat*)squareVertices textureVertices:(const GLfloat*)textureVertices
  
  {
  
  
  
  
  
    // Use shader program.
  
      glUseProgram(shader.program);
  
  
  
  // Update attribute values.
  
  glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, squareVertices);
  
  glEnableVertexAttribArray(ATTRIB_VERTEX);
  
  glVertexAttribPointer(ATTRIB_TEXTUREPOSITON, 2, GL_FLOAT, 0, 0, textureVertices);
  
  glEnableVertexAttribArray(ATTRIB_TEXTUREPOSITON);
  
  
  
  glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
  
  
  
  // Present
  
  glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
  
  [context presentRenderbuffer:GL_RENDERBUFFER];

  }

  My fragment shader :

  uniform sampler2D SamplerY;
  
  uniform sampler2D SamplerUV;
  
  
  
  
  
  varying highp vec2 _texcoord;
  
  
  
  void main()
  
  {
  
  
  
  mediump vec3 yuv;
  
  lowp vec3 rgb;
  
  
  
  yuv.x = texture2D(SamplerY, _texcoord).r;
  
  yuv.yz = texture2D(SamplerUV, _texcoord).rg - vec2(0.5, 0.5);
  
  
  
  // BT.601, which is the standard for SDTV is provided as a reference
  
  
  
  /* rgb = mat3(    1,       1,     1,
  
   0, -.34413, 1.772,
  
   1.402, -.71414,     0) * yuv;*/
  
  
  
  
  
  // Using BT.709 which is the standard for HDTV
  
  rgb = mat3(      1,       1,      1,
  
             0, -.18732, 1.8556,
  
             1.57481, -.46813,      0) * yuv;
  
  
  
     gl_FragColor = vec4(rgb, 1);
  
  
  
  }

  Very thanks,

• is it possible to play h264-mpegts format in ios ?

  11 octobre 2012, par jAckOdE

  Server transcodes the video to the h264/aac, and send video data to client simultaneously. To play and save the video data at the same time, I use mpegts as the container format, but the problem is that ios MediaPlayer can not play mpegts file.

  Google said that i can used ios-build of ffmpeg to do the task, but it seem to be an overkill. is there any other ways to play mpegts in iphone using just iOS SDK ?

• Getting accurate time from FFMPeg with Objective C (Audio Queue Services)

  2 avril 2012, par Winston

  My iPhone app plays an audio file using FFMPeg.

  I'm getting the elapsed time (to show to user) from the playing audio (in minutes and seconds after converting from microseconds, given by FFMPeg) like so :

  AudioTimeStamp currentTimeStamp;
  
  AudioQueueGetCurrentTime (audioQueue, NULL, &currentTimeStamp, NULL);
  
  
  
  getFFMPEGtime = currentTimeStamp.mSampleTime/self.basicAudioDescription.mSampleRate;
  
  
  
  self.currentAudioTime = [NSString stringWithFormat: @"%02d:%02d",
  
                              (int) getFFMPEGtime / (int)60000000,
  
                              (int) ((getFFMPEGtime % 60000000)/1000000)];

  Everything works fine, but when I scrub back or forward to play another portion of the song, the elapsed time will go back to zero, no matter the current position. The timer will always zero out.

  I know I'm suposed to do some math to keep track of the old time and the new time, maybe constructing another clock or so, perhaps implementing another callback function, etc... I'm not sure what way I should go.

  My questions are :

  1) What's the best approach to keep track of the elapsed time when going back/forward in a song, avoiding the clock to always going back to zero ?

  2) Should I look deeply into FFMPeg functions or should I stick with Objective-C and Cocoa Touch for solving this problem ?

  Please, I need some advices/ideas from experienced programmers. I'm stuck. Thanks beforehand !