Symbols & Abbreviated Terms

DCT

Discrete Cosine Transform

ADST

Asymmetric Discrete Sine Transform

LSB

Least Significant Bit

MSB

Most Significant Bit

WHT

Walsh Hadamard Transform

The specification makes use of a number of constant integers. Constants that relate to the semantics of a particular syntax element are defined in Syntax Structures Semantics.

Additional constants are defined below:

Symbol name Value Description
REFS_PER_FRAME 7 Number of reference frames that can be used for inter prediction
TOTAL_REFS_PER_FRAME 8 Number of reference frame types (including intra type)
BLOCK_SIZE_GROUPS 4 Number of contexts when decoding y_mode
BLOCK_SIZES 22 Number of different block sizes used
BLOCK_INVALID 22 Sentinel value to mark partition choices that are not allowed
MAX_SB_SIZE 128 Maximum size of a superblock in luma samples
MI_SIZE 4 Smallest size of a mode info block in luma samples
MI_SIZE_LOG2 2 Base 2 logarithm of smallest size of a mode info block
MAX_TILE_WIDTH 4096 Maximum width of a tile in units of luma samples
MAX_TILE_AREA 4096 * 2304 Maximum area of a tile in units of luma samples
MAX_TILE_ROWS 64 Maximum number of tile rows
MAX_TILE_COLS 64 Maximum number of tile columns
INTRABC_DELAY_PIXELS 256 Number of horizontal luma samples before intra block copy can be used
INTRABC_DELAY_SB64 4 Number of 64 by 64 blocks before intra block copy can be used
NUM_REF_FRAMES 8 Number of frames that can be stored for future reference
IS_INTER_CONTEXTS 4 Number of contexts for is_inter
REF_CONTEXTS 3 Number of contexts for single_ref, comp_ref, comp_bwdref, uni_comp_ref, uni_comp_ref_p1 and uni_comp_ref_p2
MAX_SEGMENTS 8 Number of segments allowed in segmentation map
SEGMENT_ID_CONTEXTS 3 Number of contexts for segment_id
SEG_LVL_ALT_Q 0 Index for quantizer segment feature
SEG_LVL_ALT_LF_Y_V 1 Index for vertical luma loop filter segment feature
SEG_LVL_REF_FRAME 5 Index for reference frame segment feature
SEG_LVL_SKIP 6 Index for skip segment feature
SEG_LVL_GLOBALMV 7 Index for global mv feature
SEG_LVL_MAX 8 Number of segment features
PLANE_TYPES 2 Number of different plane types (luma or chroma)
TX_SIZE_CONTEXTS 3 Number of contexts for transform size
INTERP_FILTERS 3 Number of values for interp_filter
INTERP_FILTER_CONTEXTS 16 Number of contexts for interp_filter
SKIP_MODE_CONTEXTS 3 Number of contexts for decoding skip_mode
SKIP_CONTEXTS 3 Number of contexts for decoding skip
PARTITION_CONTEXTS 4 Number of contexts when decoding partition
TX_SIZES 5 Number of square transform sizes
TX_SIZES_ALL 19 Number of transform sizes (including non-square sizes)
TX_MODES 3 Number of values for tx_mode
DCT_DCT 0 Inverse transform rows with DCT and columns with DCT
ADST_DCT 1 Inverse transform rows with DCT and columns with ADST
DCT_ADST 2 Inverse transform rows with ADST and columns with DCT
ADST_ADST 3 Inverse transform rows with ADST and columns with ADST
FLIPADST_DCT 4 Inverse transform rows with DCT and columns with FLIPADST
DCT_FLIPADST 5 Inverse transform rows with FLIPADST and columns with DCT
FLIPADST_FLIPADST 6 Inverse transform rows with FLIPADST and columns with FLIPADST
ADST_FLIPADST 7 Inverse transform rows with FLIPADST and columns with ADST
FLIPADST_ADST 8 Inverse transform rows with ADST and columns with FLIPADST
IDTX 9 Inverse transform rows with identity and columns with identity
V_DCT 10 Inverse transform rows with identity and columns with DCT
H_DCT 11 Inverse transform rows with DCT and columns with identity
V_ADST 12 Inverse transform rows with identity and columns with ADST
H_ADST 13 Inverse transform rows with ADST and columns with identity
V_FLIPADST 14 Inverse transform rows with identity and columns with FLIPADST
H_FLIPADST 15 Inverse transform rows with FLIPADST and columns with identity
TX_TYPES 16 Number of inverse transform types
MB_MODE_COUNT 17 Number of values for YMode
INTRA_MODES 13 Number of values for y_mode
UV_INTRA_MODES_CFL_NOT_ALLOWED 13 Number of values for uv_mode when chroma from luma is not allowed
UV_INTRA_MODES_CFL_ALLOWED 14 Number of values for uv_mode when chroma from luma is allowed
COMPOUND_MODES 8 Number of values for compound_mode
COMPOUND_MODE_CONTEXTS 8 Number of contexts for compound_mode
COMP_NEWMV_CTXS 5 Number of new mv values used when constructing context for compound_mode
NEW_MV_CONTEXTS 6 Number of contexts for new_mv
ZERO_MV_CONTEXTS 2 Number of contexts for zero_mv
REF_MV_CONTEXTS 6 Number of contexts for ref_mv
DRL_MODE_CONTEXTS 3 Number of contexts for drl_mode
MV_CONTEXTS 2 Number of contexts for decoding motion vectors including one for intra block copy
MV_INTRABC_CONTEXT 1 Motion vector context used for intra block copy
MV_JOINTS 4 Number of values for mv_joint
MV_CLASSES 11 Number of values for mv_class
CLASS0_SIZE 2 Number of values for mv_class0_bit
MV_OFFSET_BITS 10 Maximum number of bits for decoding motion vectors
MAX_LOOP_FILTER 63 Maximum value used for loop filtering
REF_SCALE_SHIFT 14 Number of bits of precision when scaling reference frames
SUBPEL_BITS 4 Number of bits of precision when choosing an inter prediction filter kernel
SUBPEL_MASK 15 ( 1 << SUBPEL_BITS ) - 1
SCALE_SUBPEL_BITS 10 Number of bits of precision when computing inter prediction locations
MV_BORDER 128 Value used when clipping motion vectors
PALETTE_COLOR_CONTEXTS 5 Number of values for color contexts
PALETTE_MAX_COLOR_CONTEXT_HASH 8 Number of mappings between color context hash and color context
PALETTE_BLOCK_SIZE_CONTEXTS 7 Number of values for palette block size
PALETTE_Y_MODE_CONTEXTS 3 Number of values for palette Y plane mode contexts
PALETTE_UV_MODE_CONTEXTS 2 Number of values for palette U and V plane mode contexts
PALETTE_SIZES 7 Number of values for palette_size
PALETTE_COLORS 8 Number of values for palette_color
PALETTE_NUM_NEIGHBORS 3 Number of neighbors considered within palette computation
DELTA_Q_SMALL 3 Value indicating alternative encoding of quantizer index delta values
DELTA_LF_SMALL 3 Value indicating alternative encoding of loop filter delta values
QM_TOTAL_SIZE 3344 Number of values in the quantizer matrix
MAX_ANGLE_DELTA 3 Maximum magnitude of AngleDeltaY and AngleDeltaUV
DIRECTIONAL_MODES 8 Number of directional intra modes
ANGLE_STEP 3 Number of degrees of step per unit increase in AngleDeltaY or AngleDeltaUV.
TX_SET_TYPES_INTRA 3 Number of intra transform set types
TX_SET_TYPES_INTER 4 Number of inter transform set types
WARPEDMODEL_PREC_BITS 16 Internal precision of warped motion models
IDENTITY 0 Warp model is just an identity transform
TRANSLATION 1 Warp model is a pure translation
ROTZOOM 2 Warp model is a rotation + symmetric zoom + translation
AFFINE 3 Warp model is a general affine transform
GM_ABS_TRANS_BITS 12 Number of bits encoded for translational components of global motion models, if part of a ROTZOOM or AFFINE model
GM_ABS_TRANS_ONLY_BITS 9 Number of bits encoded for translational components of global motion models, if part of a TRANSLATION model
GM_ABS_ALPHA_BITS 12 Number of bits encoded for non-translational components of global motion models
DIV_LUT_PREC_BITS 14 Number of fractional bits of entries in divisor lookup table
DIV_LUT_BITS 8 Number of fractional bits for lookup in divisor lookup table
DIV_LUT_NUM 257 Number of entries in divisor lookup table
MOTION_MODES 3 Number of values for motion modes
SIMPLE 0 Use translation or global motion compensation
OBMC 1 Use overlapped block motion compensation
LOCALWARP 2 Use local warp motion compensation
LEAST_SQUARES_SAMPLES_MAX 8 Largest number of samples used when computing a local warp
LS_MV_MAX 256 Largest motion vector difference to include in local warp computation
WARPEDMODEL_TRANS_CLAMP 1<<23 Clamping value used for translation components of warp
WARPEDMODEL_NONDIAGAFFINE_CLAMP 1<<13 Clamping value used for matrix components of warp
WARPEDPIXEL_PREC_SHIFTS 1<<6 Number of phases used in warped filtering
WARPEDDIFF_PREC_BITS 10 Number of extra bits of precision in warped filtering
GM_ALPHA_PREC_BITS 15 Number of fractional bits for sending non-translational warp model coefficients
GM_TRANS_PREC_BITS 6 Number of fractional bits for sending translational warp model coefficients
GM_TRANS_ONLY_PREC_BITS 3 Number of fractional bits used for pure translational warps
INTERINTRA_MODES 4 Number of inter intra modes
MASK_MASTER_SIZE 64 Size of MasterMask array
SEGMENT_ID_PREDICTED_CONTEXTS 3 Number of contexts for segment_id_predicted
IS_INTER_CONTEXTS 4 Number of contexts for is_inter
SKIP_CONTEXTS 3 Number of contexts for skip
FWD_REFS 4 Number of syntax elements for forward reference frames
BWD_REFS 3 Number of syntax elements for backward reference frames
SINGLE_REFS 7 Number of syntax elements for single reference frames
UNIDIR_COMP_REFS 4 Number of syntax elements for unidirectional compound reference frames
COMPOUND_TYPES 2 Number of values for compound_type
CFL_JOINT_SIGNS 8 Number of values for cfl_alpha_signs
CFL_ALPHABET_SIZE 16 Number of values for cfl_alpha_u and cfl_alpha_v
COMP_INTER_CONTEXTS 5 Number of contexts for comp_mode
COMP_REF_TYPE_CONTEXTS 5 Number of contexts for comp_ref_type
CFL_ALPHA_CONTEXTS 6 Number of contexts for cfl_alpha_u and cfl_alpha_v
INTRA_MODE_CONTEXTS 5 Number of each of left and above contexts for intra_frame_y_mode
COMP_GROUP_IDX_CONTEXTS 6 Number of contexts for comp_group_idx
COMPOUND_IDX_CONTEXTS 6 Number of contexts for compound_idx
INTRA_EDGE_KERNELS 3 Number of filter kernels for the intra edge filter
INTRA_EDGE_TAPS 5 Number of kernel taps for the intra edge filter
FRAME_LF_COUNT 4 Number of loop filter strength values
MAX_VARTX_DEPTH 2 Maximum depth for variable transform trees
TXFM_PARTITION_CONTEXTS 21 Number of contexts for txfm_split
REF_CAT_LEVEL 640 Bonus weight for close motion vectors
MAX_REF_MV_STACK_SIZE 8 Maximum number of motion vectors in the stack
MFMV_STACK_SIZE 3 Stack size for motion field motion vectors
MAX_TX_DEPTH 2 Maximum times the transform can be split
WEDGE_TYPES 16 Number of directions for the wedge mask process
FILTER_BITS 7 Number of bits used in Wiener filter coefficients
WIENER_COEFFS 3 Number of Wiener filter coefficients to read
SGRPROJ_PARAMS_BITS 4 Number of bits needed to specify self guided filter set
SGRPROJ_PRJ_SUBEXP_K 4 Controls how self guided deltas are read
SGRPROJ_PRJ_BITS 7 Precision bits during self guided restoration
SGRPROJ_RST_BITS 4 Restoration precision bits generated higher than source before projection
SGRPROJ_MTABLE_BITS 20 Precision of mtable division table
SGRPROJ_RECIP_BITS 12 Precision of division by n table
SGRPROJ_SGR_BITS 8 Internal precision bits for core selfguided_restoration
EC_PROB_SHIFT 6 Number of bits to reduce CDF precision during arithmetic coding
EC_MIN_PROB 4 Minimum probability assigned to each symbol during arithmetic coding
SELECT_SCREEN_CONTENT_TOOLS 2 Value that indicates the allow_screen_content_tools syntax element is coded
SELECT_INTEGER_MV 2 Value that indicates the force_integer_mv syntax element is coded
RESTORATION_TILESIZE_MAX 256 Maximum size of a loop restoration tile
MAX_FRAME_DISTANCE 31 Maximum distance when computing weighted prediction
MAX_OFFSET_WIDTH 8 Maximum horizontal offset of a projected motion vector
MAX_OFFSET_HEIGHT 0 Maximum vertical offset of a projected motion vector
WARP_PARAM_REDUCE_BITS 6 Rounding bitwidth for the parameters to the shear process
NUM_BASE_LEVELS 2 Number of quantizer base levels
COEFF_BASE_RANGE 12 The quantizer range above NUM_BASE_LEVELS above which the Exp-Golomb coding process is activated
BR_CDF_SIZE 4 Number of values for coeff_br
SIG_COEF_CONTEXTS_EOB 4 Number of contexts for coeff_base_eob
SIG_COEF_CONTEXTS_2D 26 Context offset for coeff_base for horizontal-only or vertical-only transforms.
SIG_COEF_CONTEXTS 42 Number of contexts for coeff_base
SIG_REF_DIFF_OFFSET_NUM 5 Maximum number of context samples to be used in determining the context index for coeff_base and coeff_base_eob.
SUPERRES_NUM 8 Numerator for upscaling ratio
SUPERRES_DENOM_MIN 9 Smallest denominator for upscaling ratio
SUPERRES_DENOM_BITS 3 Number of bits sent to specify denominator of upscaling ratio
SUPERRES_FILTER_BITS 6 Number of bits of fractional precision for upscaling filter selection
SUPERRES_FILTER_SHIFTS 1 << SUPERRES_FILTER_BITS Number of phases of upscaling filters
SUPERRES_FILTER_TAPS 8 Number of taps of upscaling filters
SUPERRES_FILTER_OFFSET 3 Sample offset for upscaling filters
SUPERRES_SCALE_BITS 14 Number of fractional bits for computing position in upscaling
SUPERRES_SCALE_MASK (1 << 14) - 1 Mask for computing position in upscaling
SUPERRES_EXTRA_BITS 8 Difference in precision between SUPERRES_SCALE_BITS and SUPERRES_FILTER_BITS
TXB_SKIP_CONTEXTS 13 Number of contexts for all_zero
EOB_COEF_CONTEXTS 9 Number of contexts for eob_extra
DC_SIGN_CONTEXTS 3 Number of contexts for dc_sign
LEVEL_CONTEXTS 21 Number of contexts for coeff_br
TX_CLASS_2D 0 Transform class for transform types performing non-identity transforms in both directions
TX_CLASS_HORIZ 1 Transform class for transforms performing only a horizontal non-identity transform
TX_CLASS_VERT 2 Transform class for transforms performing only a vertical non-identity transform
REFMVS_LIMIT ( 1 << 12 ) - 1 Largest reference MV component that can be saved
INTRA_FILTER_SCALE_BITS 4 Scaling shift for intra filtering process
INTRA_FILTER_MODES 5 Number of types of intra filtering
COEFF_CDF_Q_CTXS 4 Number of selectable context types for the coeff( ) syntax structure
PRIMARY_REF_NONE 7 Value of primary_ref_frame indicating that there is no primary reference frame
BUFFER_POOL_MAX_SIZE 10 Number of frames in buffer pool