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webp-src/src/dec/vp8i.h  view on Meta::CPAN

// version numbers
#define DEC_MAJ_VERSION 0
#define DEC_MIN_VERSION 3
#define DEC_REV_VERSION 0

#define ONLY_KEYFRAME_CODE      // to remove any code related to P-Frames

// intra prediction modes
enum { B_DC_PRED = 0,   // 4x4 modes
       B_TM_PRED,
       B_VE_PRED,
       B_HE_PRED,
       B_RD_PRED,
       B_VR_PRED,
       B_LD_PRED,
       B_VL_PRED,
       B_HD_PRED,
       B_HU_PRED,
       NUM_BMODES = B_HU_PRED + 1 - B_DC_PRED,  // = 10

       // Luma16 or UV modes
       DC_PRED = B_DC_PRED, V_PRED = B_VE_PRED,
       H_PRED = B_HE_PRED, TM_PRED = B_TM_PRED,
       B_PRED = NUM_BMODES,   // refined I4x4 mode

       // special modes
       B_DC_PRED_NOTOP = 4,
       B_DC_PRED_NOLEFT = 5,
       B_DC_PRED_NOTOPLEFT = 6,
       NUM_B_DC_MODES = 7 };

enum { MB_FEATURE_TREE_PROBS = 3,
       NUM_MB_SEGMENTS = 4,
       NUM_REF_LF_DELTAS = 4,
       NUM_MODE_LF_DELTAS = 4,    // I4x4, ZERO, *, SPLIT
       MAX_NUM_PARTITIONS = 8,
       // Probabilities
       NUM_TYPES = 4,
       NUM_BANDS = 8,
       NUM_CTX = 3,
       NUM_PROBAS = 11,
       NUM_MV_PROBAS = 19 };

// YUV-cache parameters.
// Constraints are: We need to store one 16x16 block of luma samples (y),
// and two 8x8 chroma blocks (u/v). These are better be 16-bytes aligned,
// in order to be SIMD-friendly. We also need to store the top, left and
// top-left samples (from previously decoded blocks), along with four
// extra top-right samples for luma (intra4x4 prediction only).
// One possible layout is, using 32 * (17 + 9) bytes:
//
//   .+------   <- only 1 pixel high
//   .|yyyyt.
//   .|yyyyt.
//   .|yyyyt.
//   .|yyyy..
//   .+--.+--   <- only 1 pixel high
//   .|uu.|vv
//   .|uu.|vv
//
// Every character is a 4x4 block, with legend:
//  '.' = unused
//  'y' = y-samples   'u' = u-samples     'v' = u-samples
//  '|' = left sample,   '-' = top sample,    '+' = top-left sample
//  't' = extra top-right sample for 4x4 modes
// With this layout, BPS (=Bytes Per Scan-line) is one cacheline size.
#define BPS       32    // this is the common stride used by yuv[]
#define YUV_SIZE (BPS * 17 + BPS * 9)
#define Y_SIZE   (BPS * 17)
#define Y_OFF    (BPS * 1 + 8)
#define U_OFF    (Y_OFF + BPS * 16 + BPS)
#define V_OFF    (U_OFF + 16)

//------------------------------------------------------------------------------
// Headers

typedef struct {
  uint8_t key_frame_;
  uint8_t profile_;
  uint8_t show_;
  uint32_t partition_length_;
} VP8FrameHeader;

typedef struct {
  uint16_t width_;
  uint16_t height_;
  uint8_t xscale_;
  uint8_t yscale_;
  uint8_t colorspace_;   // 0 = YCbCr
  uint8_t clamp_type_;
} VP8PictureHeader;

// segment features
typedef struct {
  int use_segment_;
  int update_map_;        // whether to update the segment map or not
  int absolute_delta_;    // absolute or delta values for quantizer and filter
  int8_t quantizer_[NUM_MB_SEGMENTS];        // quantization changes
  int8_t filter_strength_[NUM_MB_SEGMENTS];  // filter strength for segments
} VP8SegmentHeader;

// Struct collecting all frame-persistent probabilities.
typedef struct {
  uint8_t segments_[MB_FEATURE_TREE_PROBS];
  // Type: 0:Intra16-AC  1:Intra16-DC   2:Chroma   3:Intra4
  uint8_t coeffs_[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS];
#ifndef ONLY_KEYFRAME_CODE
  uint8_t ymode_[4], uvmode_[3];
  uint8_t mv_[2][NUM_MV_PROBAS];
#endif
} VP8Proba;

// Filter parameters
typedef struct {
  int simple_;                  // 0=complex, 1=simple
  int level_;                   // [0..63]
  int sharpness_;               // [0..7]
  int use_lf_delta_;
  int ref_lf_delta_[NUM_REF_LF_DELTAS];
  int mode_lf_delta_[NUM_MODE_LF_DELTAS];
} VP8FilterHeader;