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| #### A.3 Macroblock Data {#h-0a-03} |
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| | Macroblock Data | Type | |
| |-------------------- --------------------------|-------| |
| | `macroblock_header()` | | |
| | `residual_data()` | | |
| {:.col1-pre} |
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| | macroblock_header() | Type | |
| |------------------------ ----------------------|-------| |
| | `if (segmentation_map_update) {` | | |
| | ` segment_id` | T | |
| | `if (mb_no_coeff_skip) {` | | |
| | ` mb_coeff_skip` | B(p) | |
| | `}` | | |
| | `if (!key_frame) {` | | |
| | ` is_inter_mb` | B(p) | |
| | `if (is_inter_mb) {` | | |
| | ` mb_ref_frame_sel1` | B(p) | |
| | ` if (mb_ref_frame_sel1)` | | |
| | ` mb_ref_frame_sel2` | B(p) | |
| | ` mv_mode` | T | |
| | ` if (mv_mode == SPLITMV) {` | | |
| | ` mv_split_mode` | T | |
| | ` for (i = 0; i < numMvs; i++) {` | | |
| | ` sub_mv_mode` | T | |
| | ` if (sub_mv_mode == NEWMV4x4) {` | | |
| | ` read_mvcomponent()` | | |
| | ` read_mvcomponent()` | | |
| | ` }` | | |
| | ` }` | | |
| | ` } else if (mv_mode == NEWMV) {` | | |
| | ` read_mvcomponent()` | | |
| | ` read_mvcomponent()` | | |
| | ` }` | | |
| | `} else { /* intra mb */` | | |
| | ` intra_y_mode` | T | |
| {:.col1-pre} |
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| | macroblock_header() | Type | |
| |------------------------------------------------|-------| |
| | ` if (intra_y_mode == B_PRED) {` | | |
| | ` for (i = 0; i < 16; i++)` | | |
| | ` intra_b_mode` | T | |
| | ` }` | | |
| | ` intra_uv_mode` | T | |
| | `}` | | |
| {:.col1-pre} |
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| * `segment_id` indicates to which segment the macroblock belongs ([10](#h-10-00)) |
| * `mb_coeff_skip` indicates if the macroblock contains any coded coefficients or not ([11.1](#h-11-01)) |
| * `is_inter_mb` indicates if the macroblock is intra or inter coded ([16](#h-16-00)) |
| * `mb_ref_frame_sel1` selects the reference frame to be used; last frame (0), golden/alternate (1) ([16.2](#h-16-02)) |
| * `mb_ref_frame_sel2` selects whether the golden (0) or alternate reference frame (1) is used ([16.2](#h-16-02)) |
| * `mv_mode` determines the macroblock motion vector mode ([16.2](#h-16-02)) |
| * `mv_split_mode` gives macroblock partitioning specification and determines number of motion vectors used (numMvs)([16.2](#h-16-02)) |
| * `sub_mv_mode` determines the sub-macroblock motion vector mode for macroblocks coded using `SPLITMV` motion vector mode ([16.2](#h-16-02)) |
| * `intra_y_mode` selects the luminance intra prediction mode ([16.1](#h-16-01)) |
| * `intra_b_mode` selects the sub-macroblock luminance prediction mode for macroblocks coded using `B_PRED` mode ([16.1](#h-16-01)) |
| * `intra_uv_mode` selects the chrominance intra prediction mode ([16.1](#h-16-01)) |
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| | residual_data() | Type | |
| | ----------------------------------------------------- | ----- | |
| | `if (!mb_coeff_skip) {` | | |
| | ` if ( (is_inter_mb && mv_mode != SPLITMV) \|\|` | | |
| | ` (!is_inter_mb && intra_y_mode != B_PRED) ) {` | | |
| | ` residual_block() /* Y2 */` | | |
| | ` }` | | |
| | ` for (i = 0; i < 24; i++)` | | |
| | ` residual_block() /* 16 Y, 4 U, 4 V */` | | |
| | `}` | | |
| {:.col1-pre} |
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| | residual_block() | Type | |
| | ----------------------------------------------------- | ----- | |
| | `for (i = firstCoeff; i < 16; i++) {` | | |
| | ` token` | T | |
| | ` if (token == EOB) break;` | | |
| | ` if (token_has_extra_bits) {` | | |
| | ` extra_bits` | L(n) | |
| | ` sign` | L(1) | |
| {:.col1-pre} |
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| * firstCoeff is 1 for luma blocks of macroblocks containing Y2 subblock, otherwise 0 |
| * `token` defines the value of the coefficient, the value range of the coefficient or the end of block ([13.2](#h-13-02)) |
| * `extra_bits` determine the value of the coefficient within the value range defined by `token` ([13.2](#h-13-02)) |
| * `sign` indicates the sign of the coefficient ([13.2](#h-13-02)) |
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