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Bitstream Syntax

2009-05-22
2013-06-04
  • Anita Ralph
    Anita Ralph
    2009-05-22

    I want to know the bitstream syntax generated from Dirac Encoder. From the documentation of Dirac, I came to know about the codes (marker) for frame headers and start of sequence. I want to know that how can I find the start of various components (Y, U and V component)  in the encoded bitstream of Dirac. I may also require to find the  start/end code (marker) of each band (the bands generated after Wavelet Transform in Dirac) in the encoded bitstream.  

     
    • Marco Gerards
      Marco Gerards
      2009-05-29

      The start of both the components and bands are not marked. In order to find them, you have to parse the picture. This is well documented in the Dirac specification, but it requires quite some work.

       
    • It is not possible to find the start and or end of subbands within the encoded bitstream without processing the bitstream. Unlike start of sequence and start of parse units (e.g. frames), subbands do not have marker delineating them. You'll have to process the frame header, and the subband headers to get information about the subbands e.g size of the subband, if the subband is present or not.

      It is also not possible to access individual YUV components in the Dirac bit-stream. An encoded frame in Dirac bitstream usually consists of MV information for the frame, followed by the subbands of the picture prediction in the order of Y subbands, followed by U and then V.