Patent ID: 12244852

The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted.

DETAILED DESCRIPTION

“Global motion” in video refers to motion and/or a motion model common to all pixels of a region, where a region may be a picture, a frame, or any portion of a picture or frame such as a block, CTU, or other subset of contiguous pixels. Global motion may be caused by camera motion; for example, camera panning and zooming creates motion in a frame may typically affect the entire frame. Motion present in portions of a video may be referred to as local motion. Local motion may be caused by moving objects in a scene, such as an object moving from left to right in the scene. Videos may contain a combination of local and global motion. Some implementations of the current subject matter may provide for efficient approaches to communicate global motion to the decoder and use of global motion vectors in improving compression efficiency.

FIG.1is a diagram illustrating motion vectors of an example frame100with global and local motion. Frame100may include a number of blocks of pixels illustrated as squares, and their associated motion vectors illustrated as arrows. Squares (e.g., blocks of pixels) with arrows pointing up and to the left may indicate blocks with motion that may be considered to be global motion and squares with arrows pointing in other directions (indicated by104) may indicate blocks with local motion. In the illustrated example ofFIG.1, many blocks have identical global motions. Signaling global motion in a header, such as a picture parameter set (PPS) or sequence parameter set (SPS), and using signal global motion may reduce motion vector information needed by blocks and may result in improved prediction. Although for illustrative purposes examples described below refer to determination and/or application of global or local motion vectors at a block level, global motion vectors may be determined and/or applied for any region of a frame and/or picture, including regions made up of multiple blocks, regions bounded by any geometric form such as without limitation regions defined by geometric and/or exponential coding in which one or more lines and/or curves bounding the shape may be angled and/or curved, and/or an entirety of a frame and/or picture. Although signaling is described herein as being performed at a frame level and/or in a header and/or parameter set of a frame, signaling may alternatively or additionally be performed at a sub-picture level, where a sub-picture may include any region of a frame and/or picture as described above.

As an example, and still referring toFIG.1, simple translational motion may be described using a motion vector (MV) with two components MVx, MVy that describes displacement of blocks and/or pixels in a current frame. More complex motion such as rotation, zooming, and warping may be described using affine motion vectors, where an “affine motion vector,” as used in this disclosure, is a vector describing a uniform displacement of a set of pixels or points represented in a video picture and/or picture, such as a set of pixels illustrating an object moving across a view in a video without changing apparent shape during motion. Some approaches to video encoding and/or decoding use 4-parameter or 6-parameter affine models for motion compensation in inter picture coding.

For example, a six parameter affine motion may be described as:
x′=ax+by+c
y′=dx+ey+f
A four parameter affine motion may be described as:
x′=ax+by+c
y′=−bx+ay+f
where (x,y) and (x′,y′) are pixel locations in current and reference pictures, respectively; a, b, c, d, e, and f are parameters of the affine motion model.

With continued reference toFIG.1, parameters used describe affine motion may be signaled to a decoder to apply affine motion compensation at the decoder. In some approaches, motion parameters may be signaled explicitly or by signaling translational control point motion vectors (CPMVs) and then deriving the affine motion parameters from the translational motion vectors. Two control point motion vectors (CPMVs) may be utilized to derive affine motion parameters for a four-parameter affine motion model and three control point translational motion vectors (CPMVs) may be utilized to obtain parameters for a six-parameter motion model. Signaling affine motion parameters using control point motion vectors may allow use of efficient motion vector coding methods to signal affine motion parameters. In some implementations, and without limitation a translational motion model may be indexed by 0, a 4-parameter affine model may be indexed by 1, and a 6-parameter affine model may be indexed by 2.

In an embodiment, and still referring toFIG.1, anin a PPS and/or SPS may specify whether affine model based motion compensation may be used for inter prediction. If sps_affine_enabled_flag is equal to 0, the syntax may be constrained such that no affine model based motion compensation is used in the code later video sequence (CLVS), and inter_affine_flag and cu_affine_type_flag may not be present in coding unit syntax of the CLVS. Otherwise (sps_affine_enabled_flag is equal to 1), affine model based motion compensation can be used in the CLVS.

Further referring toFIG.1,in a PPS and/or SPS may specify whether 6-parameter affine model based motion compensation may be used for inter prediction. If sps_affine_type_flag is equal to 0, syntax may be constrained such that no 6-parameter affine model based motion compensation is used in the CLVS, and cu_affine_type_flag may not present in coding unit syntax in the CLVS. Otherwise (sps_affine_type_flag equal to 1), 6-parameter affine model based motion compensation may be used in CLVS. When not present, the value of sps_affine_type_flag may be inferred to be equal to 0.

Continuing to refer toFIG.1, creating a list of MV prediction candidates may be a step performed in some compression approaches that utilize motion compensation at a decoder. Some prior approaches may define use of spatial and temporal motion vector candidates. Global motion signaled in a header, such as an SPS or a PPS, may indicate presence of global motion in video. Such global motion is expected to be common to most blocks in a frame. Motion vector coding may be improved and bitrate reduced by using global motion as prediction candidate. Candidate MV added to MV prediction list may selected depending on motion model used to represent global motion and motion model used in inter coding.

Still referring toFIG.1, some implementations of global motion may be described with one or more control point motion vectors (CPMVs) depending on a motion model used. Therefore, depending on a motion model used, one to three control point motion vectors may be available and may be used as candidates for prediction. In some implementations, all available CPMVs may be added as prediction candidates to list. The general case of adding all available CPMVs may increase the likelihood of finding a good motion vector prediction and improve compression efficiency.

Global Motion Model UsedGM Prediction(MM, available MVs)PU MV Being codedcandidate addedMM = 0, MV0MV0 (MM = 0)MV0MM = 0, MV0MV1 (MM = 1 or 2)MV0MM = 0, MV0MV2 (MM = 2)MV0MM = 1, MV0, MV1MV0 (MM = 0)MV0, MV1MM = 1, MV0, MV1MV1 (MM = 1 or 2)MV0, MV1MM = 1, MV0, MV1MV2 (MM = 2)MV0, MV1MM = 2, MV0, MV1,MV0 (MM = 0)MV0, MV1, MV2MV2MM = 2, MV0, MV1,MV1 (MM = 1 or 2)MV0, MV1, MV2MV2MM = 2, MV0, MV1,MV2 (MM = 2)MV0, MV1, MV2MV2

Continuing to refer toFIG.1, creating a list of motion vector (MV) prediction candidates is a step in performing motion compensation at a decoder. Some existing approaches (e.g., prior compression standards) define use of spatial and temporal motion vector candidates.

Continuing to refer toFIG.1, global motion may signaled in a header, such as an SPS, may indicate presence of global motion in video. Such global motion may likely be present in many blocks in a frame. Thus, a given block may be likely to have motion similar to global motion. Motion vector coding may be improved and bitrate reduced by using global motion as prediction candidate. Candidate MV may be added to a MV prediction list and the candidate MV may be selected depending on a motion model used to represent global motion and a motion model used in inter coding.

Still referring toFIG.1, global motion may be described with one or more control point motion vectors (CPMVs) depending on a motion model used. Therefore, depending on a motion model used, one to three control point motion vectors may be available and may be used as candidates for prediction. List of MV prediction candidates may be reduced by selectively adding one CPMV to prediction candidate list. Reducing list size may reduce computational complexity and improves compression efficiency.

In some implementations, and further referring toFIG.1, a CPMV selected as candidate may be according to a predefined mapping, such as is illustrated in the following table 1:

Global Motion Model UsedGM Prediction(M, available MVs)PU MV Being codedcandidate addedM = 0, MV0MV0 (M = 0, or 1, or 2)MV0M = 0, MV0MV1 (M = 1 or 2)MV0M = 0, MV0MV2 (M = 2)MV0M = 1, MV0, MV1MV0 (M = 0, or 1, or 2)MV0M = 1, MV0, MV1MV1 (M = 1 or 2)MV1M = 1, MV0, MV1MV2 (M = 2)MV0M = 2, MV0, MV1,MV0 (M = 0, or 1, or 2)MV0MV2M = 2, MV0, MV1,MV1 (M = 1 or 2)MV1MV2M = 2, MV0, MV1,MV2 (M = 2)MV2MV2

Use of selective prediction candidate from global motion may be signaled in picture parameter set of sequence parameter set, thereby reducing encoding and decoding complexity.

Still referring toFIG.1, since a block is likely to have motion similar to global motion, adding global motion vector as a first candidate in a prediction list may reduce bits necessary to signal prediction candidates used and/or may reduce bits necessary to encode motion vector differences. As a further non-limiting example,FIG.2illustrates three example motion models200that can be utilized for global motion including their index value (0, 1, or 2).

Still referring toFIG.2, PPSs may be used to signal parameters that can change between pictures of a sequence. Parameters that remain the same for a sequence of pictures may be signaled in a sequence parameter set to reduce a size of PPS and reduce video bitrate. An example picture parameter set (PPS) is shown in Table 2:

Descriptorpic_parameter_set_rbsp( ) {pps_pic_parameter_set_idue(v)pps_seq_parameter_set_idu(4)mixed_nalu_types_in_pic_flagu(1)pic_width_in_luma_samplesue(v)pic_height_in_luma_samplesue(v)pps_conformance_window_flagu(1)if( pps_conformance_window_flag ) {pps_conf_win_left_offsetue(v)pps_conf_win_right_offsetue(v)pps_conf_win_top_offsetue(v)pps_conf_win_bottom_offsetue(v)}scaling_window_explicit_signalling_flagu(1)if( scaling_window_explicit_signalling_flag ) {scaling_win_left_offsetue(v)scaling_win_right_offsetue(v)scaling_win_top_offsetue(v)scaling_win_bottom_offsetue(v)}output_flag_present_flagu(1)subpic_id_mapping_in_pps_flagu(1)if( subpic_id_mapping_in_pps_flag ) {pps_num_subpics_minus1ue(v)pps_subpic_id_len_minus1ue(v)for( i = 0; i <= pps_num_subpic_minus1; i++ )pps_subpic_id[ i ]u(v)}no_pic_partition_flagu(1)if( !no_pic_partition_flag ) {pps_log2_ctu_size_minus5u(2)num_exp_tile_columns_minus1ue(v)num_exp_tile_rows_minus1ue(v)for( i = 0; i <= num_exp_tile_columns_minus1; i++ )tile_column_width_minus1[ i ]ue(v)for( i = 0; i <= num_exp_tile_rows_minus1; i++ )tile_row_height_minus1[ i ]ue(v)if( NumTilesInPic > 1 )rect_slice_flagu(1)if( rect_slice_flag )single_slice_per_subpic_flagu(1)if( rect_slice_flag && !single_slice_per_subpic_flag ) {num_slices_in_pic_minus1ue(v)if( num_slices_in_pic_minus1 > 0 )tile_idx_delta_present_flagu(1)for( i = 0; i < num_slices_in_pic_minus1; i++ ) {if( NumTileColumns > 1 )slice_width_in_tiles_minus1[ i ]ue(v)if( NumTileRows > 1 && ( tile_idx_delta_present_flag | |SliceTopLeftTileldx[ i ] % NumTileColumns = = 0 ) )slice_height_in_tiles_minus1[ i ]ue(v)if( slice_width_in_tiles_minus1[ i ] = = 0 &&slice_height_in_tiles_minus1[ i ] = = 0 &&RowHeight[ SliceTopLeftTileIdx[ i ] / NumTileColumns ] > 1 ) {num_exp_slices_in_tile[ i ]ue(v)for( j = 0; j < num_exp_slices_in_tile[ i ]; j++ )exp_slice_height_in_ctus_minus1[ i ][ j ]ue(v)i += NumSlicesInTile[ i ] − 1}if( tile_idx_delta_present flag && i < num_slices_in_pic_minus1 )tile_idx_delta[ i ]se(v)}}loop_filter_across_tiles_enabled_flagu(1)loop_filter_across_slices_enabled_flagu(1)}cabac_init_present_flagu(1)for( i = 0; i < 2; i++ )num_ref_idx_default_active_minus1[ i ]ue(v)rpl1_idx_present_flagu(1)init_qp_minus26se(v)cu_qp_delta_enabled_flagu(1)pps_chroma_tool_offsets_present_flagu(1)if( pps_chroma_tool_offsets_present_flag ) {pps_cb_qp_offsetse(v)pps_cr_qp_offsetse(v)pps_joint_cbcr_qp_offset_present_flagu(1)if( pps_joint_cbcr_qp_offset_present_flag )pps_joint_cbcr_qp_offset_valuese(v)pps_slice_chroma_qp_offsets_present_flagu(1)pps_cu_chroma_qp_offset_list_enabled_flagu(1)}if( pps_cu_chroma_qp_offset_list_enabled_flag ) {chroma_qp_offset_list_len_minus1ue(v)for( i = 0; i <= chroma_qp_offset_list_len_minus1; i++ ) {cb_qp_offset_list[ i ]se(v)cr_qp_offset_list[ i ]se(v)if( pps_joint_cbcr_qp_offset_present_flag )joint_cbcr_qp_offset_list[ i ]se(v)}}pps_weighted_pred_flagu(1)pps_weighted_bipred_flagu(1)deblocking_filter_control_present_flagu(1)if( deblocking_filter_control_present_flag ) {deblocking_filter_override_enabled_flagu(1)pps_deblocking_filter_disabled_flagu(1)if( !pps_deblocking_filter_disabled_flag ) {pps_beta_offset_div2se(v)pps_tc_offset_div2se(v)pps_cb_beta_offset_div2se(v)pps_cb_tc_offset_div2se(v)pps_cr_beta_offset_div2se(v)pps_cr_tc_offset_div2se(v)}}rpl_info_in_ph_flagu(1)if( deblocking_filter_override_enabled_flag )dbf_info_in_ph_flagu(1)sao_info_in_ph_flagu(1)alf_info_in_ph_flagu(1)if( ( pps_weighted_pred_flag | | pps_weighted_bipred_flag ) &&rpl_info_in_ph_flag )wp_info_in_ph_flagu(1)qp_delta_info_in_ph_flagu(1)pps_ref_wraparound_enabled_flagu(1)if( pps_ref_wraparound_enabled_flag )pps_ref_wraparound_offsetue(v)picture_header_extension_present_flagu(1)slice_header_extension_present_flagu(1)pps_extension_flagu(1)if( pps_extension_flag )while( more_rbsp_data( ) )pps_extension_data_flagu(1)rbsp_trailing_bits( )}

Additional fields may be added to the PPS to signal global motion. In case of global motion, presence of global motion parameters in a sequence of pictures may be signaled in a SPS and a PPS may reference the SPS by SPS ID. SPS in some approaches to decoding may be modified to add a field to signal presence of global motion parameters in SPS. For example a one-bit field may be added to the SPS. If global_motion_present bit is 1, global motion related parameters may be expected in a PPS. If global_motion_present bit is 0, no global motion parameter related fields may be present in PPS. For example, the PPS of Table 2 may be extended to include a global_motion_present field, for example, as shown in Table 3:

Descriptorsequence_parameter_set_rbsp( ) {sps_sequence_parameter_set_idue(v)...global_motion_presentu(1)rbsp_trailing_bits( )}

Similarly, the PPS can include a pps_global_motion_parameters field for a frame, for example as shown in Table 4:

Descriptorpic_parameter_set_rbsp( ) {pps_pic_parameter_set_idue(v)pps_seq_parameter_set_idue(v)...pps_global_motion_parameters ( )rbsp_trailing_bits( )}

In more detail, a PPS may include fields to characterize global motion parameters using control point motion vectors, for example as shown in Table 5:

Descriptorpps_global_motion_parameters ( ) {motion_model_usedu(2)mv0_xse(v)mv1_yse(v)if(motion_model_used == 1){mv1_xse(v)mv1_yse(v)}if(motion_model_used == 2){mv2_xse(v)mv2_yse(v)}}

As a further non-limiting example, Table 6 below may represent an exemplary SPS:

Descriptorseq_parameter_set_rbsp( ) {sps_seq_parameter_set_idu(4)sps_video_parameter_set_idu(4)sps_max_sublayers_minus1u(3)sps_reserved_zero_4bitsu(4)sps_ptl_dpb_hrd_params_present_flagu(1)if( sps_ptl_dpb_hrd_params_present_flag )profile_tier_level( 1, sps_max_sublayers_minus1 )gdr_enabled_flagu(1)chroma_format_idcu(2)if( chroma_format_idc = = 3 )separate_colour_plane_flagu(1)res_change_in_clvs_allowed_flagu(1)pic_width_max_in_luma_samplesue(v)pic_height_max_in_luma_samplesue(v)sps_conformance_window_flagu(1)if( sps_conformance_window_flag ) {sps_conf_win_left_offsetue(v)sps_conf_win_right_offsetue(v)sps_conf_win_top_offsetue(v)sps_conf_win_bottom_offsetue(v)}sps_log2_ctu_size_minus5u(2)subpic_info_present_flagu(1)if( subpic_info_present_flag ) {sps_num_subpics_minus1ue(v)sps_independent_subpics_flagu(1)for( i = 0; sps_num_subpics_minus1 > 0 && i <=sps_num_subpics_minus1; i++ ) {if( i > 0 && pic_width_max_in_luma_samples > CtbSizeY )subpic_ctu_top_left_x[ i ]u(v)if( i > 0 && pic_height_max_in_luma_samples > CtbSizeY ) {subpic_ctu_top_left_y[ i ]u(v)if( i < sps_num_subpics_minus1 &&pic_width_max_in_luma_samples > CtbSizeY )subpic_width_minus1[ i ]u(v)if( i < sps_num_subpics_minus1 &&pic_height_max_in_luma_samples > CtbSizeY )subpic_height_minus1[ i ]u(v)if( !sps_independent_subpics_flag ) {subpic_treated_as_pic_flag[ i ]u(1)loop_filter_across_subpic_enabled_flag[ i ]u(1)}}sps_subpic_id_len_minus1ue(v)subpic_id_mapping_explicitly_signalled_flagu(1)if( subpic_id_mapping_explicitly_signalled_flag ) {subpic_id_mapping_in_sps_flagu(1)if( subpic_id_mapping_in_sps_flag )for( i = 0; i <= sps_num_subpics_minus1; i++ )sps_subpic_id[ i ]u(v)}}bit_depth_minus8ue(v)sps_entropy_coding_sync_enabled_flagu(1)if( sps_entropy_coding_sync_enabled_flag )sps_wpp_entry_point_offsets_present_flagu(1)sps_weighted_pred_flagu(1)sps_weighted_bipred_flagu(1)log2_max_pic_order_cnt_lsb_minus4u(4)sps_poc_msb_flagu(1)if( sps_poc_msb_flag )poc_msb_len_minus1ue(v)num_extra_ph_bits_bytesu(2)extra_ph_bits_struct( num_extra_ph_bits_bytes )num_extra_sh_bits_bytesu(2)extra_sh_bits_struct( num_extra_sh_bits_bytes )if( sps_max_sublayers_minus1 > 0 )sps_sublayer_dpb_params_flagu(1)if( sps_ptl_dpb_hrd_params_present_flag )dpb_parameters( sps_max_sublayers_minus1,sps_sublayer_dpb_params_flag )long_term_ref_pics_flagu(1)inter_layer_ref_pics_present_flagu(1)sps_idr_rpl_present_flagu(1)rpl1_same_as_rp10_flagu(1)for( i = 0; i < rpl1_same_as_rp10_flag ? 1 : 2; i++ ) {num_ref_pic_lists_in_sps[ i ]ue(v)for( j = 0; j < num_ref_pic_lists_in_sps[ i ]; j++)ref_pic_list_struct( i, j )}if( ChromaArrayType != 0 )qtbtt_dual_tree_intra_flagu(1)log2_min_luma_coding_block_size_minus2ue(v)partition_constraints_override_enabled_flagu(1)sps_log2_diff_min_qt_min_cb_intra _slice_lumaue(v)sps_max_mtt_hierarchy_depth_intra_slice_lumaue(v)if( sps_max _mtt_hierarchy_depth_intra_slice_luma != 0 ) {sps_log2_diff_max_bt_min_qt_intra_slice_lumaue(v)sps_log2_diff_max_tt_min_qt_intra_slice_lumaue(v)}sps_log2_diff_min_qt_min_cb_inter_sliceue(v)sps_max_mtt_hierarchy_depth_inter_sliceue(v)if( sps_max_mtt_hierarchy_depth_inter_slice != 0 ) {sps_log2_diff_max_bt_min_qt_inter_sliceue(v)sps_log2_diff_max_tt_min_qt_inter_sliceue(v)}if( qtbtt_dual_tree_intra_flag ) {sps_log2_diff_min_qt_min_cb_intra_slice_chromaue(v)sps_max_mtt_hierarchy_depth_intra_slice_chromaue(v)if( sps_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) {sps_log2_diff_max_bt_min_qt_intra_slice_chromaue(v)sps_log2_diff_max_tt_min_qt_intra_slice_chromaue(v)}}sps_max_luma_transform_size_64_flagu(1)if( ChromaArrayType != 0 ) {sps_joint_cbcr_enabled_flagu(1)same_qp_table_for_chromau(1)numQpTables = same_qp_table_for_chroma ? 1 : (sps_joint_cbcr_enabled_flag ? 3 : 2 )for( i = 0; i < numQpTables; i++ ) {qp_table_start_minus26[ i ]se(v)num_points_in_qp_table_minus1[ i ]ue(v)for( j = 0; j <= num_points_in_qp_table_minus1[ i ]; j++ ) {delta_qp_in_val_minus1[ i ][ j ]ue(v)delta_qp_diff_val[ i ][ j ]ue(v)}}}sps_sao_enabled_flagu(1)sps_alf_enabled_flagu(1)if( sps_alf_enabled_flag && ChromaArrayType != 0 )sps_ccalf_enabled_flagu(1)sps_transform_skip_enabled_flagu(1)if( sps_transform_skip_enabled_flag ) {log2_transform_skip_max_size_minus2ue(v)sps_bdpcm_enabled_flagu(1)}sps_ref_wraparound_enabled_flagu(1)sps_temporal_mvp_enabled_flagu(1)if( sps_temporal_mvp_enabled_flag )sps_sbtmvp_enabled_flagu(1)sps_amvr_enabled_flagu(1)sps_bdof_enabled_flagu(1)if( sps_bdof_enabled_flag )sps_bdof_pic_present_flagu(1)sps_smvd_enabled_flagu(1)sps_dmvr_enabled_flagu(1)if( sps_dmvr_enabled_flag)sps_dmvr_pic_present_flagu(1)sps_mmvd_enabled_flagu(1)sps_isp_enabled_flagu(1)sps_mrl_enabled_flagu(1)sps_mip_enabled_flagu(1)if( ChromaArrayType != 0 )sps_cclm_enabled_flagu(1)if( chroma_format_idc = = 1 ) {sps_chroma_horizontal_collocated_flagu(1)sps_chroma_vertical_collocated_flagu(1)}sps_mts_enabled_flagu(1)if( sps_mts_enabled_flag ) {sps_explicit_mts_intra_enabled_flagu(1)sps_explicit_mts_inter_enabled_flagu(1)}six_minus_max_num_merge_candue(v)sps_sbt_enabled_flagu(1)sps_affine_enabled_flagu(1)if( sps_affine_enabled_flag ) {five_minus_max_num_subblock_merge_candue(v)sps_affine_type_flagu(1)if( sps_amvr_enabled_flag )sps_affine_amvr_enabled_flagu(1)sps_affine_prof_enabled_flagu(1)if( sps_affine_prof_enabled_flag )sps_prof_pic_present_flagu(1)}sps_palette_enabled_flagu(1)if( ChromaArrayType = = 3 && !sps_max_luma_transform_size_64_flag )sps_act_enabled_flagu(1)if( sps_transform_skip_enabled_flag | | sps_palette_enabled_flag )min_qp_prime_ts_minus4ue(v)sps_bcw_enabled_flagu(1)sps_ibc_enabled_flagu(1)if( sps_ibc_enabled_flag )six_minus_max_num_ibc_merge_candue(v)sps_ciip_enabled_flagu(1)if( sps_mmvd_enabled_flag )sps_fpel_mmvd_enabled_flagu(1)if( MaxNumMergeCand >= 2 ) {sps_gpm_enabled_flagu(1)if( sps_gpm_enabled_flag && MaxNumMergeCand >= 3 )max_num_merge_cand_minus_max_num_gpm_candue(v)}sps_lmcs_enabled_flagu(1)sps_lfnst_enabled_flagu(1)sps_ladf_enabled_flagu(1)if( sps_ladf_enabled_flag ) {sps_num_ladf_intervals_minus2u(2)sps_ladf_lowest_interval_qp_offsetse(v)for( i = 0; i < sps_num_ladf_intervals_minus2 + 1; i++ ) {sps_ladf_qp_offset[ i ]se(v)sps_ladf_delta_threshold_minus1[ i ]ue(v)}}log2_parallel_merge_level_minus2ue(v)sps_explicit_scaling_list_enabled_flagu(1)sps_dep_quant_enabled_flagu(1)if( !sps_dep_quant_enabled_flag )sps_sign_data_hiding_enabled_flagu(1)sps_virtual_boundaries_enabled_flagu(1)if( sps_virtual_boundaries_enabled_flag ) {sps_virtual_boundaries_present_flagu(1)if( sps_virtual_boundaries_present_flag ) {sps_num_ver_virtual_boundariesu(2)for( i = 0; i < sps_num_ver_virtual_boundaries; i++ )sps_virtual_boundaries_pos_x[ i ]u(13)sps_num_hor_virtual_boundariesu(2)for( i = 0; i < sps_num_hor_virtual_boundaries; i++ )sps_virtual_boundaries_pos_y[ i ]u(13)}}if( sps_ptl_dpb_hrd_params_present_flag ) {sps_general_hrd_params_present_flagu(1)if( sps_general_hrd_params_present_flag ) {general_hrd_parameters( )if( sps_max_sublayers_minus1 > 0 )sps_sublayer_cpb_params_present_flagu(1)firstSubLayer = sps_sublayer_cpb_params_present_flag ? 0 :sps_max_sublayers_minus1ols_hrd_parameters( firstSubLayer, sps_max_sublayers_minus1 )}}field_seq_flagu(1)vui_parameters_present_flagu(1)if( vui_parameters_present_flag )vui_parameters( ) /* Specified in ITU-T H.SEI | ISO/IEC 23002-7 */sps_extension_flagu(1)if( sps_ extension_flag )while( more_rbsp_data( ) )sps_extension_data_flagu(1)rbsp_trailing_bits( )}

An SPS table as above may be expanded as described above to incorporate a global motion present indicator as shown in Table 7:

Descriptorsequence_parameter_set_rbsp( ) {sps_sequence_parameter_set_idue(v)...global_motion_presentu(1)rbsp_trailing_bits( )}

Additional fields may be incorporated in an SPS to reflect further indicators as described in this disclosure.

In an embodiment, and still referring toFIG.2, an sps_affine_enabled_flag in a PPS and/or SPS may specify whether affine model based motion compensation may be used for inter prediction. If sps_affine_enabled_flag is equal to 0, the syntax may be constrained such that no affine model based motion compensation is used in the code later video sequence (CLVS), and inter_affine_flag and cu_affine_type_flag may not be present in coding unit syntax of the CLVS. Otherwise (sps_affine_enabled_flag is equal to 1), affine model based motion compensation can be used in the CLVS.

Continuing to refer toFIG.2, sps_affine_type_flag in a PPS and/or SPS may specify whether 6-parameter affine model based motion compensation may be used for inter prediction. If sps_affine_type_flag is equal to 0, syntax may be constrained such that no 6-parameter affine model based motion compensation is used in the CLVS, and cu_affine_type_flag may not present in coding unit syntax in the CLVS. Otherwise (sps_affine_type_flag equal to 1), 6-parameter affine model based motion compensation may be used in CLVS. When not present, the value of sps_affine_type_flag may be inferred to be equal to 0.

Still referring toFIG.2, translational CPMVs may be signaled in PPS. Control points may be predefined. For example, control point MV0may be relative to a top left corner of a picture, MV1may be relative to a top right corner, and MV3may be relative to a bottom left corner of the picture. Table 5 illustrates an example approach for signaling CPMV data depending on a motion model used.

In an exemplary embodiment, and still referring toFIG.2, an array amvr_precision_idx, which may be signaled in coding unit, coding tree, or the like, may specify a resolution AmvrShift of a motion vector difference, which may be defined as a non-limiting example as shown in Table 8 as shown below. Array indices x0, y0 may specify the location (x0, y0) of a top-left luma sample of a considered coding block relative to a top-left luma sample of the picture; when amvr_precision_idx[x0][y0] is not present, it may be inferred to be equal to 0. Where an inter_affine_flag[x0][y0] is equal to 0, variables MvdL0[x0][y0][0], MvdL0[x0][y0][1], MvdL1[x0][y0][0], MvdL1[x0][y0][1] representing modsion vector difference values corresponding to consered block, may be modified by shifting such values by AmvrShift, for instance using MvdL0[x0][y0][0]=MvdL0[x0][y0][0]<<AmvrShift; MvdL0[x0][y0][1]=MvdL0[x0][y0][1]<<AmvrShift; MvdL1[x0][y0][0]=MvdL1[x0][y0][0]<<AmvrShift; and MvdL1[x0][y0][1]=MvdL1[x0][y0][1]<<AmvrShift. Where inter_affine_flag[x0][y0] is equal to 1, variables MvdCpL0[x0][y0][0][0], MvdCpL0[x0][y0][0][1], MvdCpL0[x0][y0][1][0], MvdCpL0[x0][y0][1][1], MvdCpL0[x0][y0][2][0] and MvdCpL0[x0][y0][2][1] may be modified via shifting, for instance as follows: MvdCpL0[x0][y0][0][0]=MvdCpL0[x0][y0][0][0]<<AmvrShift; MvdCpL1[x0][y0] [0][1]=MvdCpL1[x0][y0][0][1]<<AmvrShift; MvdCpL0[x0][y0][1][0]=MvdCpL0[x0][y0][1][0]<<AmvrShift; MvdCpL1[x0][y0] [1][1]=MvdCpL1[x0][y0][1][1]<<AmvrShift; MvdCpL0[x0][y0][2][0]=MvdCpL0[x0][y0][2][0]<<AmvrShift; and MvdCpL1[x0][y0] [2][1]=MvdCpL1[x0][y0][2][1]<<AmvrShift

AmvrShiftinter_affine_flag = =0&&CuPredMode[ chType ][ x0 ]CuPredMode[ chType ][ x0 ]amvr_flagamvr_precision_idinter_affine_flag ==1[ y0 ] = = MODE_IBC)[ y0 ] != MODE_IBC0—2(¼ luma sample)—2(¼ luma sample)100( 1/16 luma sample)4(1 luma sample)3(½ luma sample)114(1 luma sample)6(4 luma samples)4(1 luma sample)12——6(4 luma samples)

FIG.3is a process flow diagram illustrating an exemplary embodiment of a process300of constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list.

At step305, a current block is received by a decoder. Current block may be contained within a bitstream that a decoder receives. Bitstream may include, for example, data found in a stream of bits that is an input to a decoder when using data compression. Bitstream may include information necessary to decode a video. Receiving may include extracting and/or parsing a block and associated signaling information from bit stream. In some implementations, a current block may include a coding tree unit (CTU), a coding unit (CU), or a prediction unit (PU).

At step310, a motion vector candidate list may be constructed for a current block; constructing may include adding a single global motion vector candidate to the motion vector candidate list. Single global motion vector candidate may be selected based on a global motion model utilized by a current block. At step315, pixel data of current block may be reconstructed using motion vector candidate list.

FIG.4is a system block diagram illustrating an example decoder400capable of decoding a bitstream428by at least constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list. Decoder400may include an entropy decoder processor404, an inverse quantization and inverse transformation processor408, a deblocking filter412, a frame buffer416, a motion compensation processor420and/or an intra prediction processor424.

In operation, and still referring toFIG.4, bit stream428may be received by decoder400and input to entropy decoder processor404, which may entropy decode portions of bit stream into quantized coefficients. Quantized coefficients may be provided to inverse quantization and inverse transformation processor408, which may perform inverse quantization and inverse transformation to create a residual signal, which may be added to an output of motion compensation processor420or intra prediction processor424according to a processing mode. An output of the motion compensation processor420and intra prediction processor424may include a block prediction based on a previously decoded block. A sum of prediction and residual may be processed by deblocking filter412and stored in a frame buffer416.

FIG.5is a process flow diagram illustrating an exemplary embodiment of a process500of encoding a video by at least constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list according to some aspects of the current subject matter that may reduce encoding complexity while increasing compression efficiency. At step505, a video frame may undergo initial block segmentation, for example by using a tree-structured macro block partitioning scheme that may include partitioning a picture frame into CTUs and CUs. At step510, global motion may be determined. At step515, a block may be encoded and included in bitstream. Encoding may include constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list. Encoding may include utilizing inter prediction and intra prediction modes, for example.

FIG.6is a system block diagram illustrating an exemplary embodiment of a video encoder600capable of constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list. Example video encoder600may receive an input video604, which may be initially segmented and/or dividing according to a processing scheme, such as a tree-structured macro block partitioning scheme (e.g., quad-tree plus binary tree). An example of a tree-structured macro block partitioning scheme may include partitioning a picture frame into large block elements called coding tree units (CTU). In some implementations, each CTU may be further partitioned one or more times into a number of sub-blocks called coding units (CU). A final result of this portioning may include a group of sub-blocks that may be called predictive units (PU). Transform units (TU) may also be utilized.

Still referring toFIG.6, example video encoder600may include an intra prediction processor612, a motion estimation/compensation processor612(also referred to as an inter prediction processor) capable of constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list, a transform/quantization processor616, an inverse quantization/inverse transform processor620, an in-loop filter624, a decoded picture buffer628, and/or an entropy coding processor632. Bit stream parameters may be input to entropy coding processor632for inclusion in an output bit stream636.

In operation, and with continued reference toFIG.6, for each block of a frame of input video604, whether to process block via intra picture prediction or using motion estimation/compensation may be determined. Block may be provided to intra prediction processor608or motion estimation/compensation processor612. If block is to be processed via intra prediction, intra prediction processor608may perform processing to output a predictor. If block is to be processed via motion estimation/compensation, motion estimation/compensation processor612may perform processing including constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list, if applicable.

Still referring toFIG.6, a residual may be formed by subtracting predictor from input video. Residual may be received by transform/quantization processor616, which may perform transformation processing (e.g., discrete cosine transform (DCT)) to produce coefficients, which may be quantized. Quantized coefficients and any associated signaling information may be provided to entropy coding processor632for entropy encoding and inclusion in an output bit stream636. Entropy encoding processor632may support encoding of signaling information related to encoding a current block. In addition, quantized coefficients may be provided to inverse quantization/inverse transformation processor620, which may reproduce pixels, which may be combined with predictor and processed by in loop filter624, an output of which may be stored in decoded picture buffer628for use by motion estimation/compensation processor612that is capable of constructing a motion vector candidate list including adding a single global motion vector candidate to the motion vector candidate list.

Further referencingFIG.6, although a few variations have been described in detail above, other modifications or additions are possible. For example, in some implementations, current blocks may include any symmetric blocks (8×8, 16×16, 32×32, 64×64, 128×128, and the like) as well as any asymmetric block (8×4, 16×8, and the like).

In some implementations, and still referring toFIG.6, a quadtree plus binary decision tree (QTBT) may be implemented. In QTBT, at a Coding Tree Unit level, partition parameters of QTBT may be dynamically derived to adapt to local characteristics without transmitting any overhead. Subsequently, at a Coding Unit level, a joint-classifier decision tree structure may eliminate unnecessary iterations and control risk of false prediction. In some implementations, LTR frame block update mode may be available as an additional option available at every leaf node of a QTBT.

In some implementations, and still referring toFIG.6, additional syntax elements may be signaled at different hierarchy levels of a bitstream. For example, a flag may be enabled for an entire sequence by including an enable flag coded in a Sequence Parameter Set (SPS). Further, a CTU flag may be coded at a coding tree unit (CTU) level.

It is to be noted that any one or more of the aspects and embodiments described herein may be conveniently implemented using digital electronic circuitry, integrated circuitry, specially designed application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) computer hardware, firmware, software, and/or combinations thereof, as realized and/or implemented in one or more machines (e.g., one or more computing devices that are utilized as a user computing device for an electronic document, one or more server devices, such as a document server, etc.) programmed according to the teachings of the present specification, as will be apparent to those of ordinary skill in the computer art. These various aspects or features may include implementation in one or more computer programs and/or software that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, coupled to receive data and instructions from, and to transmit data and instructions to, a storage system, at least one input device, and at least one output device. Appropriate software coding may readily be prepared by skilled programmers based on the teachings of the present disclosure, as will be apparent to those of ordinary skill in the software art. Aspects and implementations discussed above employing software and/or software modules may also include appropriate hardware for assisting in the implementation of the machine executable instructions of the software and/or software module.

Such software may be a computer program product that employs a machine-readable storage medium. A machine-readable storage medium may be any medium that is capable of storing and/or encoding a sequence of instructions for execution by a machine (e.g., a computing device) and that causes the machine to perform any one of the methodologies and/or embodiments described herein. Examples of a machine-readable storage medium include, but are not limited to, a magnetic disk, an optical disc (e.g., CD, CD-R, DVD, DVD-R, etc.), a magneto-optical disk, a read-only memory “ROM” device, a random access memory “RAM” device, a magnetic card, an optical card, a solid-state memory device, an EPROM, an EEPROM, Programmable Logic Devices (PLDs), and/or any combinations thereof. A machine-readable medium, as used herein, is intended to include a single medium as well as a collection of physically separate media, such as, for example, a collection of compact discs or one or more hard disk drives in combination with a computer memory. As used herein, a machine-readable storage medium does not include transitory forms of signal transmission.

Such software may also include information (e.g., data) carried as a data signal on a data carrier, such as a carrier wave. For example, machine-executable information may be included as a data-carrying signal embodied in a data carrier in which the signal encodes a sequence of instruction, or portion thereof, for execution by a machine (e.g., a computing device) and any related information (e.g., data structures and data) that causes the machine to perform any one of the methodologies and/or embodiments described herein.

Examples of a computing device include, but are not limited to, an electronic book reading device, a computer workstation, a terminal computer, a server computer, a handheld device (e.g., a tablet computer, a smartphone, etc.), a web appliance, a network router, a network switch, a network bridge, any machine capable of executing a sequence of instructions that specify an action to be taken by that machine, and any combinations thereof. In one example, a computing device may include and/or be included in a kiosk.

FIG.7shows a diagrammatic representation of one embodiment of a computing device in the exemplary form of a computer system700within which a set of instructions for causing a control system to perform any one or more of the aspects and/or methodologies of the present disclosure may be executed. It is also contemplated that multiple computing devices may be utilized to implement a specially configured set of instructions for causing one or more of the devices to perform any one or more of the aspects and/or methodologies of the present disclosure. Computer system700includes a processor704and a memory708that communicate with each other, and with other components, via a bus712. Bus712may include any of several types of bus structures including, but not limited to, a memory bus, a memory controller, a peripheral bus, a local bus, and any combinations thereof, using any of a variety of bus architectures.

Memory708may include various components (e.g., machine-readable media) including, but not limited to, a random-access memory component, a read only component, and any combinations thereof. In one example, a basic input/output system716(BIOS), including basic routines that help to transfer information between elements within computer system700, such as during start-up, may be stored in memory708. Memory708may also include (e.g., stored on one or more machine-readable media) instructions (e.g., software)720embodying any one or more of the aspects and/or methodologies of the present disclosure. In another example, memory708may further include any number of program modules including, but not limited to, an operating system, one or more application programs, other program modules, program data, and any combinations thereof.

Computer system700may also include a storage device724. Examples of a storage device (e.g., storage device724) include, but are not limited to, a hard disk drive, a magnetic disk drive, an optical disc drive in combination with an optical medium, a solid-state memory device, and any combinations thereof. Storage device724may be connected to bus712by an appropriate interface (not shown). Example interfaces include, but are not limited to, SCSI, advanced technology attachment (ATA), serial ATA, universal serial bus (USB), IEEE 1394 (FIREWIRE), and any combinations thereof. In one example, storage device724(or one or more components thereof) may be removably interfaced with computer system700(e.g., via an external port connector (not shown)). Particularly, storage device724and an associated machine-readable medium728may provide nonvolatile and/or volatile storage of machine-readable instructions, data structures, program modules, and/or other data for computer system700. In one example, software720may reside, completely or partially, within machine-readable medium728. In another example, software720may reside, completely or partially, within processor704.

Computer system700may also include an input device732. In one example, a user of computer system700may enter commands and/or other information into computer system700via input device732. Examples of an input device732include, but are not limited to, an alpha-numeric input device (e.g., a keyboard), a pointing device, a joystick, a gamepad, an audio input device (e.g., a microphone, a voice response system, etc.), a cursor control device (e.g., a mouse), a touchpad, an optical scanner, a video capture device (e.g., a still camera, a video camera), a touchscreen, and any combinations thereof. Input device732may be interfaced to bus712via any of a variety of interfaces (not shown) including, but not limited to, a serial interface, a parallel interface, a game port, a USB interface, a FIREWIRE interface, a direct interface to bus712, and any combinations thereof. Input device732may include a touch screen interface that may be a part of or separate from display736, discussed further below. Input device732may be utilized as a user selection device for selecting one or more graphical representations in a graphical interface as described above.

A user may also input commands and/or other information to computer system700via storage device724(e.g., a removable disk drive, a flash drive, etc.) and/or network interface device740. A network interface device, such as network interface device740, may be utilized for connecting computer system700to one or more of a variety of networks, such as network744, and one or more remote devices748connected thereto. Examples of a network interface device include, but are not limited to, a network interface card (e.g., a mobile network interface card, a LAN card), a modem, and any combination thereof. Examples of a network include, but are not limited to, a wide area network (e.g., the Internet, an enterprise network), a local area network (e.g., a network associated with an office, a building, a campus or other relatively small geographic space), a telephone network, a data network associated with a telephone/voice provider (e.g., a mobile communications provider data and/or voice network), a direct connection between two computing devices, and any combinations thereof. A network, such as network744, may employ a wired and/or a wireless mode of communication. In general, any network topology may be used. Information (e.g., data, software720, etc.) may be communicated to and/or from computer system700via network interface device740.

Computer system700may further include a video display adapter752for communicating a displayable image to a display device, such as display device736. Examples of a display device include, but are not limited to, a liquid crystal display (LCD), a cathode ray tube (CRT), a plasma display, a light emitting diode (LED) display, and any combinations thereof. Display adapter752and display device736may be utilized in combination with processor704to provide graphical representations of aspects of the present disclosure. In addition to a display device, computer system700may include one or more other peripheral output devices including, but not limited to, an audio speaker, a printer, and any combinations thereof. Such peripheral output devices may be connected to bus712via a peripheral interface756. Examples of a peripheral interface include, but are not limited to, a serial port, a USB connection, a FIREWIRE connection, a parallel connection, and any combinations thereof.

The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope of this invention. Features of each of the various embodiments described above may be combined with features of other described embodiments as appropriate in order to provide a multiplicity of feature combinations in associated new embodiments. Furthermore, while the foregoing describes a number of separate embodiments, what has been described herein is merely illustrative of the application of the principles of the present invention. Additionally, although particular methods herein may be illustrated and/or described as being performed in a specific order, the ordering is highly variable within ordinary skill to achieve embodiments as disclosed herein. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.

In the descriptions above and in the claims, phrases such as “at least one of” or “one or more of” may occur followed by a conjunctive list of elements or features. The term “and/or” may also occur in a list of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such a phrase is intended to mean any of the listed elements or features individually or any of the recited elements or features in combination with any of the other recited elements or features. For example, the phrases “at least one of A and B;” “one or more of A and B;” and “A and/or B” are each intended to mean “A alone, B alone, or A and B together.” A similar interpretation is also intended for lists including three or more items. For example, the phrases “at least one of A, B, and C;” “one or more of A, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, B alone, C alone, A and B together, A and C together, B and C together, or A and B and C together.” In addition, use of the term “based on,” above and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems, apparatus, methods, and/or articles depending on the desired configuration. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail above, other modifications or additions are possible. In particular, further features and/or variations can be provided in addition to those set forth herein. For example, the implementations described above can be directed to various combinations and sub-combinations of the disclosed features and/or combinations and sub-combinations of several further features disclosed above. In addition, the logic flows depicted in the accompanying figures and/or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims