2. Terms

Questa sezione conserva il testo RFC su APV, includendo bitstream syntax, syntax element processing, decoding and parsing processes, metadata, profiles, levels, bands, raw bitstream format e implementation references.

Testo RFC originale

2.  Terms

2.1.  Terms and Definitions

   access unit (AU):  a collection of primitive bitstream units (PBU)
      including various types of frames, metadata, filler, and access
      unit information, associated with a specific time

   band:  a defined set of constraints on the value of the maximum coded
      data rate of each level

   block:  MxN (M-column by N-row) array of samples, or an MxN array of
      transform coefficients

   byte-aligned:  a position in a bitstream that is an integer multiple
      of 8 bits from the position of the first bit in the bitstream

   chroma:  a sample array or single sample representing one of the two
      color difference signals related to the primary colors,
      represented by the symbols Cb and Cr in 4:2:2 or 4:4:4 color
      format

   coded frame:  a coded representation of a frame containing all
      macroblocks of the frame

   coded representation:  a data element as represented in its coded
      form

   component:  an array or a single sample from one of the three arrays
      (luma and two chroma) that compose a frame in 4:2:2, or 4:4:4
      color format, or an array or a single sample from an array that
      compose a frame in 4:0:0 color format, or an array or a single
      sample from one of the four arrays that compose a frame in 4:4:4:4
      color format.

   decoded frame:  a frame derived by decoding a coded frame

   decoder:  an embodiment of a decoding process

   decoding process:  a process specified that reads a bitstream and
      derives decoded frames from it

   encoder:  an embodiment of an encoding process

   encoding process:  a process that produces a bitstream conforming to
      this document

   flag:  a variable or single-bit syntax element that can take one of
      the two possible values: 0 and 1

   frame:  an array of luma samples and two corresponding arrays of
      chroma samples in 4:2:2 and 4:4:4 color format, or an array of
      samples in 4:0:0 color format, or four arrays of samples in
      4:4:4:4 color format

   level:  a defined set of constraints on the values that are taken by
      the syntax elements and variables of this document, or the value
      of a transform coefficient prior to scaling

   luma:  a sample array or single sample representing the monochrome
      signal related to the primary colors, represented by the symbol or
      subscript Y or L

   macroblock (MB):  a square block of luma samples and two
      corresponding blocks of chroma samples of a frame in 4:2:2 or
      4:4:4 color format, or a square block of samples of a frame in
      4:0:0 color format, or four square blocks of samples of a frame in
      4:4:4:4 color format

   metadata:  data describing various characteristics related to a
      bitstream without directly affecting the decoding process of it.

   partitioning:  a division of a set into subsets such that each
      element of the set is in exactly one of the subsets

   prediction:  an embodiment of the prediction process

   prediction process:  use of a predictor to provide an estimate of the
      data element currently being decoded

   predictor:  a combination of specified values or previously decoded
      data elements used in the decoding process of subsequent data
      elements

   primitive bitstream unit (PBU):  a data structure to construct an
      access unit with frame and metadata

   profile:  a specified subset of the syntax of this document

   quantization parameter (QP):  a variable used by the decoding process
      for the scaling value of transform coefficients

   raster scan:  a mapping of a rectangular two-dimensional pattern to a
      one-dimensional pattern such that the first entries in the one-
      dimensional pattern are from the top row of the two-dimensional
      pattern scanned from left to right, followed by the second, third,
      etc., rows of the pattern each scanned from left to right

   raw bitstream:  an encapsulation of a sequence of access units where
      a field indicating the size of an access unit precedes each access
      unit as defined in Appendix A

   source:  a term used to describe the video material or some of its
      attributes before the encoding process

   syntax element:  an element of data represented in the bitstream

   syntax structure:  zero or more syntax elements present together in a
      bitstream in a specified order

   tile:  a rectangular region of MBs within a particular tile column
      and a particular tile row in a frame

   tile column:  a rectangular region of MBs having a height equal to
      the height of the frame and width specified by syntax elements in
      the frame header

   tile row:  a rectangular region of MBs having a height specified by
      syntax elements in the frame header and a width equal to the width
      of the frame

   tile scan:  a specific sequential ordering of MBs partitioning a
      frame in which the MBs are ordered consecutively in MB raster scan
      in a tile and the tiles in a frame are ordered consecutively in a
      raster scan of the tiles of the frame

   transform coefficient:  a scalar quantity, considered to be in a
      frequency domain, that is associated with a particular one-
      dimensional or two-dimensional index

2.2.  Abbreviated Terms

   LSB:  least significant bit

   MSB:  most significant bit

   RGB:  Red, Green and Blue