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| #### A.2 Frame Header {#h-0a-02} |
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| | Frame Header | Type | |
| |----------------------------------------------|-------| |
| | `if (key_frame) {` | | |
| | ` color_space` | L(1) | |
| | ` clamping_type` | L(1) | |
| | `}` | | |
| | `segmentation_enabled` | L(1) | |
| | `if (segmentation_enabled) {` | | |
| | ` update_segmentation()` | | |
| | `}` | | |
| | `filter_type` | L(1) | |
| | `loop_filter_level` | L(6) | |
| | `sharpness_level` | L(3) | |
| | `mb_lf_adjustments()` | | |
| | `log2_nbr_of_dct_partitions` | L(2) | |
| | `quant_indices()` | | |
| | `if (key_frame) {` | | |
| | ` refresh_entropy_probs` | L(1) | |
| | `} else {` | | |
| | ` refresh_golden_frame` | L(1) | |
| | ` refresh_alternate_frame` | L(1) | |
| | ` if (!refresh_golden_frame)` | | |
| | ` copy_buffer_to_golden` | L(2) | |
| | ` if (!refresh_alternate_frame)` | | |
| | ` copy_buffer_to_alternate` | L(2) | |
| | ` sign_bias_golden` | L(1) | |
| | ` sign_bias_alternate` | L(1) | |
| | ` refresh_entropy_probs` | L(1) | |
| | ` refresh_last` | L(1) | |
| | `}` | | |
| | `token_prob_update()` | | |
| | `mb_no_coeff_skip` | L(1) | |
| {:.col1-pre} |
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| | Frame Header | Type | |
| |----------------------------------------------|-------| |
| | `prob_skip_false` | L(8) | |
| | `if (!key_frame) {` | | |
| | ` prob_intra` | L(8) | |
| | ` prob_last` | L(8) | |
| | ` prob_golden` | L(8) | |
| | ` intra_16x16_prob_update_flag` | L(1) | |
| | ` if (intra_16x16_prob_update_flag) {` | | |
| | ` for (i = 0; i < 4; i++)` | | |
| | ` intra_16x16_prob` | L(8) | |
| | } | | |
| | ` intra_chroma prob_update_flag` | L(1) | |
| | ` if (intra_chroma_prob_update_flag) {` | | |
| | ` for (i = 0; i < 3; i++)` | | |
| | ` intra_chroma_prob` | L(8) | |
| | ` }` | | |
| | ` mv_prob_update()` | | |
| | `}` | | |
| {:.col1-pre} |
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| * `color_space` defines the YUV color space of the sequence ([9.2](#h-09-02)) |
| * `clamping_type` specifies if the decoder is required to clamp the reconstructed pixel values ([9.2](#h-09-02)) |
| * `segmentation_enabled` enables the segmentation feature for the current frame ([9.3](#h-09-03)) |
| * `filter_type` determines whether the normal or the simple loop filter is used ([9.4](#h-09-04), [15](#h-15-00)) |
| * `loop_filter_level` controls the deblocking filter ([9.4](#h-09-04), [15](#h-15-00)) |
| * `sharpness_level` controls the deblocking filter ([9.4](#h-09-04), [15](#h-15-00)) |
| * `log2_nbr_of_dct_partitions` determines the number of separate partitions containing the DCT coefficients of the macroblocks ([9.5](#h-09-05)) |
| * `refresh_entropy_probs` determines whether updated token probabilities are used only for this frame or until further update |
| * `refresh_golden_frame` determines if the current decoded frame refreshes the golden frame ([9.7](#h-09-07)) |
| * `refresh_alternate_frame` determines if the current decoded frame refreshes the alternate reference frame ([9.7](#h-09-07)) |
| * `copy_buffer_to_golden` determines if the golden reference is replaced by another reference ([9.7](#h-09-07)) |
| * `copy_buffer_to_alternate` determines if the alternate reference is replaced by another reference ([9.7](#h-09-07)) |
| * `sign_bias_golden` controls the sign of motion vectors when the golden frame is referenced ([9.7](#h-09-07)) |
| * `sign_bias_alternate` controls the sign of motion vectors when the alternate frame is referenced ([9.7](#h-09-07)) |
| * `refresh_last` determines if the current decoded frame refreshes the last frame reference buffer ([9.8](#h-09-08)) |
| * `mb_no_coeff_skip` enables or disables the skipping of macroblocks containing no non-zero coefficients ([9.10](#h-09-10)) |
| * `prob_skip_false` the probability that the macroblock is not skipped (flag indicating skipped macroblock is false) ([9.10](#h-09-10)) |
| * `prob_intra` the probability of an intra macroblock ([9.10](#h-09-10)) |
| * `prob_last` the probability that the last reference frame is used for inter prediction ([9.10](#h-09-10)) |
| * `prob_golden` the probability that the golden reference frame is used for inter prediction ([9.10](#h-09-10)) |
| * `intra_16x16_prob_update_flag` indicates if the branch probabilies used in the decoding of luma intra prediction mode are updated ([9.10](#h-09-10)) |
| * `intra_16x16_prob` the branch probabilities of the luma intra prediction mode decoding tree |
| * `intra_chroma_prob_update_flag` indicates if the branch probabilies used in the decoding of chroma intra prediction mode are updated ([9.10](#h-09-10)) |
| * `intra_chroma_prob` the branch probabilities of the chroma intra prediction mode decoding tree |
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| | update_segmentation() | Type | |
| | -------------------------------------------- | ----- | |
| | `update_mb_segmentation_map` | L(1) | |
| | `update_segment_feature_data` | L(1) | |
| | `if (update_segment_feature_data) {` | | |
| | ` segment_feature_mode` | L(1) | |
| | ` for (i = 0; i < 4; i++) {` | | |
| | ` quantizer_update` | L(1) | |
| | ` if (quantizer_update) {` | | |
| | ` quantizer_update_value` | L(7) | |
| | ` quantizer_update_sign` | L(1) | |
| | ` }` | | |
| | ` }` | | |
| | ` for (i = 0; i < 4; i++) {` | | |
| | ` loop_filter_update` | L(1) | |
| | ` if (loop_filter_update) {` | | |
| | ` lf_update_value` | L(6) | |
| | ` lf_update_sign` | L(1) | |
| | ` }` | | |
| | ` }` | | |
| | `}` | | |
| | `if (update_mb_segmentation_map) {` | | |
| | ` for (i = 0; i < 3; i++) {` | | |
| | ` segment_prob_update` | L(1) | |
| | ` if (segment_prob_update) {` | | |
| | ` segment_prob` | L(8) | |
| | ` }` | | |
| | ` }` | | |
| | `}` | | |
| {:.col1-pre} |
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| * `update_mb_segmentation_map` determines if the MB segmentation map is updated in the current frame ([9.3](#h-09-03)) |
| * `update_segment_feature_data` indicates if the segment feature data is updated in the current frame ([9.3](#h-09-03)) |
| * `segment_feature_mode` indicates the feature data update mode, 0 for delta and 1 for the absolute value ([9.3](#h-09-03)) |
| * `quantizer_update` indicates if the quantizer value is updated for the [[ i^(th) ]] segment ([9.3](#h-09-03)) |
| * `quantizer_update_value` indicates the update value for the segment quantizer ([9.3](#h-09-03)) |
| * `quantizer_update_sign` indicates the update sign for the segment quantizer ([9.3](#h-09-03)) |
| * `loop_filter_update` indicates if the loop filter level value is updated for the [[ i^(th) ]] segment ([9.3](#h-09-03)) |
| * `lf_update_value` indicates the update value for the loop filter level ([9.3](#h-09-03)) |
| * `lf_update_sign` indicates the update sign for the loop filter level ([9.3](#h-09-03)) |
| * `segment_prob_update` indicates if the branch probabilities used to decode the `segment_id` in the MB header are decoded from the stream or use the default value of 255 ([9.3](#h-09-03)) |
| * `segment_prob` the branch probabilities of the `segment_id` decoding tree ([9.3](#h-09-03)) |
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| | mb_lf_adjustments() | Type | |
| |----------------------------------------------|-------| |
| | `loop_filter_adj_enable` | L(1) | |
| | `if (loop_filter_adj_enable) {` | | |
| | ` mode_ref_lf_delta_update` | L(1) | |
| | ` if (mode_ref_lf_delta_update) {` | | |
| | ` for (i = 0; i < 4; i++) {` | | |
| | ` ref_frame_delta_update_flag` | L(1) | |
| | ` if (ref_frame_delta_update_flag) {` | | |
| | ` delta_magnitude` | L(6) | |
| | ` delta_sign` | L(1) | |
| | ` }` | | |
| | ` }` | | |
| | ` for (i = 0; i < 4; i++) {` | | |
| | ` mb_mode_delta_update_flag` | L(1) | |
| | ` if (mb_mode_delta_update_flag) {` | | |
| | ` delta_magnitude` | L(6) | |
| | ` delta_sign` | L(1) | |
| | ` }` | | |
| | ` }` | | |
| | ` }` | | |
| | `}` | | |
| {:.col1-pre} |
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| * `loop_filter_adj_enable` indicates if the MB-level loop filter adjustment (based on the used reference frame and coding mode) is on for the current frame ([9.4](#h-09-04)) |
| * `mode_ref_lf_delta_update` indicates if the delta values used in adjustment are updated in the current frame ([9.4](#h-09-04)) |
| * `ref_frame_delta_update_flag` indicates if the adjustment delta value corresponding to a certain used reference frame is updated ([9.4](#h-09-04)) |
| * `delta_magnitude` is the absolute value of the delta value |
| * `delta_sign` is the sign of the delta value |
| * `mb_mode_delta_update_flag` indicates if the adjustment delta value corresponding to certain MB prediction mode is updated ([9.4](#h-09-04)) |
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| | quant_indices() | Type | |
| |----------------------------------------------|-------| |
| | `y_ac_qi` | L(7) | |
| | `y_dc_delta_present` | L(1) | |
| | `if (y_dc_delta_present) {` | | |
| | ` y_dc_delta_magnitude` | L(4) | |
| | ` y_dc_delta_sign` | L(1) | |
| | `}` | | |
| | `y2_dc_delta_present` | L(1) | |
| | `if (y2_dc_delta_present) {` | | |
| | ` y2_dc_delta_magnitude` | L(4) | |
| | ` y2_dc_delta_sign` | L(1) | |
| | `}` | | |
| | `y2_ac_delta_present` | L(1) | |
| | `if (y2_ac_delta_present) {` | | |
| | ` y2_ac_delta_magnitude` | L(4) | |
| | ` y2_ac_delta_sign` | L(1) | |
| | `}` | | |
| | `uv_dc_delta_present` | L(1) | |
| | `if (uv_dc_delta_present) {` | | |
| | ` uv_dc_delta_magnitude` | L(4) | |
| | ` uv_dc_delta_sign` | L(1) | |
| | `}` | | |
| | `uv_ac_delta_present` | L(1) | |
| | `if (uv_ac_delta_present) {` | | |
| | ` uv_ac_delta_magnitude` | L(4) | |
| | ` uv_ac_delta_sign` | L(1) | |
| | } | | |
| {:.col1-pre} |
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| * `y_ac_qi` is the dequantization table index used for the luma AC coefficients (and other coefficient groups if no delta value is present) ([9.6](#h-09-06)) |
| * `y_dc_delta_present` indicates if the stream contains a delta value that is added to the baseline index to obtain the luma DC coefficient dequantization index ([9.6](#h-09-06)) |
| * `y_dc_delta_magnitude` the magnitude of the delta value ([9.6](#h-09-06)) |
| * `y_dc_delta_sign` the sign of the delta value ([9.6](#h-09-06)) |
| * `y2_dc_delta_present` indicates if the stream contains a delta value that is added to the baseline index to obtain the Y2 block DC coefficient dequantization index ([9.6](#h-09-06)) |
| * `y2_ac_delta_present` indicates if the stream contains a delta value that is added to the baseline index to obtain the Y2 block AC coefficient dequantization index ([9.6](#h-09-06)) |
| * `uv_dc_delta_present` indicates if the stream contains a delta value that is added to the baseline index to obtain the chroma DC coefficient dequantization index ([9.6](#h-09-06)) |
| * `uv_ac_delta_present` indicates if the stream contains a delta value that is added to the baseline index to obtain the chroma AC coefficient dequantization index ([9.6](#h-09-06)) |
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| | token_prob_update() | Type | |
| | -------------------------------------------- | ----- | |
| | `for (i = 0; i < 4; i++) {` | | |
| | ` for (j = 0; j < 8; j++) {` | | |
| | ` for (k = 0; k < 3; k++) {` | | |
| | ` for (l = 0; l < 11; l++) {` | | |
| | ` coeff_prob_update_flag` | L(1) | |
| | ` if (coeff_prob_update_flag) {` | | |
| | ` coeff_prob` | L(8) | |
| | ` }` | | |
| | ` }` | | |
| | ` }` | | |
| | ` }` | | |
| | `}` | | |
| {:.col1-pre} |
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| * `coeff_prob_update_flag` indicates if the corresponding branch probability is updated in the current frame ([13.4](#h-13-04)) |
| * `coeff_prob` is the new branch probability ([13.4](#h-13-04)) |
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| | mv_prob_update() | Type | |
| | -------------------------------------------- | ----- | |
| | `for (i = 0; i < 2; i++) {` | | |
| | ` for (j = 0; j < 19; j++) {` | | |
| | ` mv_prob_update_flag` | L(1) | |
| | ` if (mv_prob_update_flag) {` | | |
| | ` prob` | L(7) | |
| | ` }` | | |
| | ` }` | | |
| | `}` | | |
| {:.col1-pre} |
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| * `mv_prob_update_flag` indicates if the corresponding MV decoding probability is updated in the current frame ([17.2](#h-17-02)) |
| * `prob` is the updated probability ([17.2](#h-17-02)) |
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