Here is a list of all documented variables with links to the struct/union documentation for each field:

### - u -

- u_ac_delta_q : CommonQuantParams
- u_dc_delta_q : CommonQuantParams
- u_dequant_QTX : CommonQuantParams
- u_iqmatrix : CommonQuantParams
- under_shoot_pct : RateControlCfg
- unfiltered_source : AV1_COMP
- uni_comp_ref_cost : ModeCosts
- uniform_spacing : CommonTileParams
- unit_info : RestorationInfo
- unit_length : aom_sb_simple_motion_features
- unscaled_last_source : AV1_COMP
- unscaled_source : AV1_COMP
- up_available : macroblockd
- update_pending : ExtRefreshFrameFlagsInfo
- update_type : aom_partition_features
- upsample_pred : macroblock
- use_comp_pred : aom_svc_ref_frame_comp_pred
- use_default_intra_tx_type : TxfmSearchParams
- use_derived_intra_tx_type_set : TxfmSearchParams
- use_ducky_encode : AV1_COMP
- use_error_resilient : ExternalFlags
- use_external_ref : av1_ref_frame
- use_fixed_qp_offsets : aom_codec_enc_cfg
- use_inter_dct_only : TxfmSizeTypeCfg
- use_intra_dct_only : TxfmSizeTypeCfg
- use_intra_default_tx_only : TxfmSizeTypeCfg
- use_intrabc : MB_MODE_INFO
- use_mb_mode_cache : macroblock
- use_primary_ref_none : ExternalFlags
- use_qm_dist_metric : TxfmSearchParams
- use_ref_frame_mask : InterModeSearchStateNonrd
- use_ref_frame_mvs : ExternalFlags
- use_s_frame : ExternalFlags
- use_scaled_ref_frame : InterModeSearchStateNonrd
- use_screen_content_tools : AV1_COMP
- use_svc : AV1_PRIMARY
- use_transform_domain_distortion : TxfmSearchParams, WinnerModeParams
- use_wedge_interintra : MB_MODE_INFO
- user_priv : aom_image
- using_qmatrix : CommonQuantParams
- uv_angle_delta : IntraModeSearchState
- uv_dist : InterModeSearchStateNonrd
- uv_mode : MB_MODE_INFO