2. Terms

この節では APV の RFC テキストを保持し, bitstream syntax, syntax element processing, decoding and parsing processes, metadata, profiles, levels, bands, raw bitstream format, implementation references を扱う.

RFC 原文

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