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• Revision 37293 : Retour en arrière (suppression de la noisette)

  15 avril 2010, par joseph@… — Log

  Retour en arrière (suppression de la noisette)

• How to create CVPixelBuffer from raw YUV(YCbCr) NSData

  30 octobre 2018, par Andy

  I’m reading a yuv4mpeg2 pipe from ffmpeg and having problems creating a CVPixelBuffer from the NSData I have parsed from a single frame.

  Fairly certain I should be using CVPixelBufferCreateWithPlanarBytes ? I’m unsure how to compute the plane widths and heights, and how to pass in the planeBaseAddresses. I just have a single frame in an NSData wrapper. Here’s what I’ve pieced together so far.

  func createPixelBuffer(frameData: NSData) -> CVPixelBuffer? {
  
      let height = 1080
  
      let width = 1920
  
      let numberOfPlanes = 3
  
      var planeBaseAddresses: UnsafeMutableRawPointer?
  
      var planeWidths = [Int]()
  
      var planeHeights = [Int]()
  
      var planeBytesPerRows = [Int]()
  
      var pixelBuffer : CVPixelBuffer? = nil
  
      let result = CVPixelBufferCreateWithPlanarBytes(kCFAllocatorDefault,
  
                                                      width,
  
                                                      height,
  
                                                      kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange,
  
                                                      nil,
  
                                                      0,
  
                                                      numberOfPlanes,
  
                                                      &planeBaseAddresses,
  
                                                      &planeWidths,
  
                                                      &planeHeights,
  
                                                      &planeBytesPerRows,
  
                                                      nil,
  
                                                      nil,
  
                                                      nil,
  
                                                      &pixelBuffer)
  
      if result != kCVReturnSuccess {
  
          return nil
  
      }
  
      return pixelBuffer
  
  }

  This doesn’t return an an error, but is obviously incomplete and doesn’t produce an image.

  Help greatly appreciated. Please comment if you’d like a full working sample code.

• Correct way to dump yuv values after avcodec_decode_video2

  27 juin 2017, par Peter

  I am decoding H.265 raw data :

   avcodec_decode_video2(decoderCtx, pictYUV, &gotPicture, &packet)

  After the call, the value for pictYUV->format is AV_PIX_FMT_YUV420P as expected.

  I dump raw yuv values to a file as follows :

  fwrite(pictYUV->data[0], 1, w*h, f);
  
  fwrite(pictYUV->data[2], 1, w*h/4, f);
  
  fwrite(pictYUV->data[1], 1, w*h/4, f);

  For an input size of 640x480, when the file is viewed (using ImageMagick display utility), the image is what was expected.

  However, for an input size of 864x480, the image appears to be corrupted.

  What is interesting is if I run pictYUV through sws_scale, and dump the resulting yuv output, the image appears to be fine.

  sws_scale(swsCtx, pictYUV->data, pictYUV->linesize, 0, pictYUV->height,
  
    pictNewYUV->data, pictNewYUV->linesize);

  All I need is yuv data. I am hoping I can avoid the extra call to sws_scale. Wondering what is it that I am missing. Regards.