2 * This file is part of FFmpeg.
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 * @brief IntraX8 (J-Frame) subdecoder, used by WMV2 and VC-1
24 #include "libavutil/avassert.h"
28 #include "mpegvideo.h"
29 #include "msmpeg4data.h"
30 #include "intrax8huf.h"
32 #include "intrax8dsp.h"
34 #define MAX_TABLE_DEPTH(table_bits, max_bits) \
35 ((max_bits + table_bits - 1) / table_bits)
41 #define DC_VLC_MTD MAX_TABLE_DEPTH(DC_VLC_BITS, MAX_DC_VLC_BITS)
42 #define AC_VLC_MTD MAX_TABLE_DEPTH(AC_VLC_BITS, MAX_AC_VLC_BITS)
43 #define OR_VLC_MTD MAX_TABLE_DEPTH(OR_VLC_BITS, MAX_OR_VLC_BITS)
45 static VLC j_ac_vlc[2][2][8]; // [quant < 13], [intra / inter], [select]
46 static VLC j_dc_vlc[2][8]; // [quant], [select]
47 static VLC j_orient_vlc[2][4]; // [quant], [select]
49 static av_cold int x8_vlc_init(void)
54 static const uint16_t sizes[8 * 4 + 8 * 2 + 2 + 4] = {
55 576, 548, 582, 618, 546, 616, 560, 642,
56 584, 582, 704, 664, 512, 544, 656, 640,
57 512, 648, 582, 566, 532, 614, 596, 648,
58 586, 552, 584, 590, 544, 578, 584, 624,
60 528, 528, 526, 528, 536, 528, 526, 544,
61 544, 512, 512, 528, 528, 544, 512, 544,
63 128, 128, 128, 128, 128, 128,
66 static VLC_TYPE table[28150][2];
69 #define init_ac_vlc(dst, src) \
71 dst.table = &table[offset]; \
72 dst.table_allocated = sizes[sizeidx]; \
73 offset += sizes[sizeidx++]; \
74 init_vlc(&dst, AC_VLC_BITS, 77, &src[1], 4, 2, &src[0], 4, 2, \
75 INIT_VLC_USE_NEW_STATIC); \
78 for (i = 0; i < 8; i++) {
79 init_ac_vlc(j_ac_vlc[0][0][i], x8_ac0_highquant_table[i][0]);
80 init_ac_vlc(j_ac_vlc[0][1][i], x8_ac1_highquant_table[i][0]);
81 init_ac_vlc(j_ac_vlc[1][0][i], x8_ac0_lowquant_table[i][0]);
82 init_ac_vlc(j_ac_vlc[1][1][i], x8_ac1_lowquant_table[i][0]);
87 #define init_dc_vlc(dst, src) \
89 dst.table = &table[offset]; \
90 dst.table_allocated = sizes[sizeidx]; \
91 offset += sizes[sizeidx++]; \
92 init_vlc(&dst, DC_VLC_BITS, 34, &src[1], 4, 2, &src[0], 4, 2, \
93 INIT_VLC_USE_NEW_STATIC); \
96 for (i = 0; i < 8; i++) {
97 init_dc_vlc(j_dc_vlc[0][i], x8_dc_highquant_table[i][0]);
98 init_dc_vlc(j_dc_vlc[1][i], x8_dc_lowquant_table[i][0]);
103 #define init_or_vlc(dst, src) \
105 dst.table = &table[offset]; \
106 dst.table_allocated = sizes[sizeidx]; \
107 offset += sizes[sizeidx++]; \
108 init_vlc(&dst, OR_VLC_BITS, 12, &src[1], 4, 2, &src[0], 4, 2, \
109 INIT_VLC_USE_NEW_STATIC); \
112 for (i = 0; i < 2; i++)
113 init_or_vlc(j_orient_vlc[0][i], x8_orient_highquant_table[i][0]);
114 for (i = 0; i < 4; i++)
115 init_or_vlc(j_orient_vlc[1][i], x8_orient_lowquant_table[i][0]);
118 if (offset != sizeof(table) / sizeof(VLC_TYPE) / 2) {
119 av_log(NULL, AV_LOG_ERROR, "table size %zd does not match needed %i\n",
120 sizeof(table) / sizeof(VLC_TYPE) / 2, offset);
121 return AVERROR_INVALIDDATA;
127 static void x8_reset_vlc_tables(IntraX8Context *w)
129 memset(w->j_dc_vlc, 0, sizeof(w->j_dc_vlc));
130 memset(w->j_ac_vlc, 0, sizeof(w->j_ac_vlc));
131 w->j_orient_vlc = NULL;
134 static inline void x8_select_ac_table(IntraX8Context *const w, int mode)
138 av_assert2(mode < 4);
140 if (w->j_ac_vlc[mode])
143 table_index = get_bits(w->gb, 3);
144 // 2 modes use same tables
145 w->j_ac_vlc[mode] = &j_ac_vlc[w->quant < 13][mode >> 1][table_index];
146 av_assert2(w->j_ac_vlc[mode]);
149 static inline int x8_get_orient_vlc(IntraX8Context *w)
151 if (!w->j_orient_vlc) {
152 int table_index = get_bits(w->gb, 1 + (w->quant < 13));
153 w->j_orient_vlc = &j_orient_vlc[w->quant < 13][table_index];
156 return get_vlc2(w->gb, w->j_orient_vlc->table, OR_VLC_BITS, OR_VLC_MTD);
159 #define extra_bits(eb) (eb) // 3 bits
160 #define extra_run (0xFF << 8) // 1 bit
161 #define extra_level (0x00 << 8) // 1 bit
162 #define run_offset(r) ((r) << 16) // 6 bits
163 #define level_offset(l) ((l) << 24) // 5 bits
164 static const uint32_t ac_decode_table[] = {
165 /* 46 */ extra_bits(3) | extra_run | run_offset(16) | level_offset(0),
166 /* 47 */ extra_bits(3) | extra_run | run_offset(24) | level_offset(0),
167 /* 48 */ extra_bits(2) | extra_run | run_offset(4) | level_offset(1),
168 /* 49 */ extra_bits(3) | extra_run | run_offset(8) | level_offset(1),
170 /* 50 */ extra_bits(5) | extra_run | run_offset(32) | level_offset(0),
171 /* 51 */ extra_bits(4) | extra_run | run_offset(16) | level_offset(1),
173 /* 52 */ extra_bits(2) | extra_level | run_offset(0) | level_offset(4),
174 /* 53 */ extra_bits(2) | extra_level | run_offset(0) | level_offset(8),
175 /* 54 */ extra_bits(2) | extra_level | run_offset(0) | level_offset(12),
176 /* 55 */ extra_bits(3) | extra_level | run_offset(0) | level_offset(16),
177 /* 56 */ extra_bits(3) | extra_level | run_offset(0) | level_offset(24),
179 /* 57 */ extra_bits(2) | extra_level | run_offset(1) | level_offset(3),
180 /* 58 */ extra_bits(3) | extra_level | run_offset(1) | level_offset(7),
182 /* 59 */ extra_bits(2) | extra_run | run_offset(16) | level_offset(0),
183 /* 60 */ extra_bits(2) | extra_run | run_offset(20) | level_offset(0),
184 /* 61 */ extra_bits(2) | extra_run | run_offset(24) | level_offset(0),
185 /* 62 */ extra_bits(2) | extra_run | run_offset(28) | level_offset(0),
186 /* 63 */ extra_bits(4) | extra_run | run_offset(32) | level_offset(0),
187 /* 64 */ extra_bits(4) | extra_run | run_offset(48) | level_offset(0),
189 /* 65 */ extra_bits(2) | extra_run | run_offset(4) | level_offset(1),
190 /* 66 */ extra_bits(3) | extra_run | run_offset(8) | level_offset(1),
191 /* 67 */ extra_bits(4) | extra_run | run_offset(16) | level_offset(1),
193 /* 68 */ extra_bits(2) | extra_level | run_offset(0) | level_offset(4),
194 /* 69 */ extra_bits(3) | extra_level | run_offset(0) | level_offset(8),
195 /* 70 */ extra_bits(4) | extra_level | run_offset(0) | level_offset(16),
197 /* 71 */ extra_bits(2) | extra_level | run_offset(1) | level_offset(3),
198 /* 72 */ extra_bits(3) | extra_level | run_offset(1) | level_offset(7),
206 static void x8_get_ac_rlf(IntraX8Context *const w, const int mode,
207 int *const run, int *const level, int *const final)
211 // x8_select_ac_table(w, mode);
212 i = get_vlc2(w->gb, w->j_ac_vlc[mode]->table, AC_VLC_BITS, AC_VLC_MTD);
214 if (i < 46) { // [0-45]
218 (*final) = // prevent 'may be used unilitialized'
219 (*run) = 64; // this would cause error exit in the ac loop
224 * i == 0-15 r = 0-15 l = 0; r = i & %01111
225 * i == 16-19 r = 0-3 l = 1; r = i & %00011
226 * i == 20-21 r = 0-1 l = 2; r = i & %00001
227 * i == 22 r = 0 l = 3; r = i & %00000
234 /* l = lut_l[i / 2] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3 }[i >> 1];
235 * 11 10'01 01'00 00'00 00'00 00'00 00 => 0xE50000 */
236 l = (0xE50000 >> (i & (0x1E))) & 3; // 0x1E or (~1) or ((i >> 1) << 1)
238 /* t = lut_mask[l] = { 0x0f, 0x03, 0x01, 0x00 }[l];
239 * as i < 256 the higher bits do not matter */
240 t = (0x01030F >> (l << 3));
244 } else if (i < 73) { // [46-72]
249 sm = ac_decode_table[i];
251 e = get_bits(w->gb, sm & 0xF);
256 (*run) = (sm & 0xff) + (e & (mask)); // 6bits
257 (*level) = (sm >> 8) + (e & (~mask)); // 5bits
258 (*final) = i > (58 - 46);
259 } else if (i < 75) { // [73-74]
260 static const uint8_t crazy_mix_runlevel[32] = {
261 0x22, 0x32, 0x33, 0x53, 0x23, 0x42, 0x43, 0x63,
262 0x24, 0x52, 0x34, 0x73, 0x25, 0x62, 0x44, 0x83,
263 0x26, 0x72, 0x35, 0x54, 0x27, 0x82, 0x45, 0x64,
264 0x28, 0x92, 0x36, 0x74, 0x29, 0xa2, 0x46, 0x84,
268 e = get_bits(w->gb, 5); // get the extra bits
269 (*run) = crazy_mix_runlevel[e] >> 4;
270 (*level) = crazy_mix_runlevel[e] & 0x0F;
272 (*level) = get_bits(w->gb, 7 - 3 * (i & 1));
273 (*run) = get_bits(w->gb, 6);
274 (*final) = get_bits1(w->gb);
279 /* static const uint8_t dc_extra_sbits[] = {
280 * 0, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7,
282 static const uint8_t dc_index_offset[] = {
283 0, 1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
286 static int x8_get_dc_rlf(IntraX8Context *const w, const int mode,
287 int *const level, int *const final)
291 av_assert2(mode < 3);
292 if (!w->j_dc_vlc[mode]) {
293 int table_index = get_bits(w->gb, 3);
294 // 4 modes, same table
295 w->j_dc_vlc[mode] = &j_dc_vlc[w->quant < 13][table_index];
298 i = get_vlc2(w->gb, w->j_dc_vlc[mode]->table, DC_VLC_BITS, DC_VLC_MTD);
300 /* (i >= 17) { i -= 17; final =1; } */
309 c = (i + 1) >> 1; // hackish way to calculate dc_extra_sbits[]
312 e = get_bits(w->gb, c); // get the extra bits
313 i = dc_index_offset[i] + (e >> 1);
315 e = -(e & 1); // 0, 0xffffff
316 (*level) = (i ^ e) - e; // (i ^ 0) -0 , (i ^ 0xff) - (-1)
322 static int x8_setup_spatial_predictor(IntraX8Context *const w, const int chroma)
328 w->dsp.setup_spatial_compensation(w->dest[chroma], w->scratchpad,
329 w->frame->linesize[chroma > 0],
330 &range, &sum, w->edges);
332 w->orient = w->chroma_orient;
333 quant = w->quant_dc_chroma;
339 if (range < quant || range < 3) {
342 // yep you read right, a +-1 idct error may break decoding!
346 // ((1 << 17) + 9) / (8 + 8 + 1 + 2) = 6899
347 w->predicted_dc = (sum * 6899) >> 17;
353 av_assert2(w->orient < 3);
354 if (range < 2 * w->quant) {
355 if ((w->edges & 3) == 0) {
365 static const uint8_t prediction_table[3][12] = {
366 { 0, 8, 4, 10, 11, 2, 6, 9, 1, 3, 5, 7 },
367 { 4, 0, 8, 11, 10, 3, 5, 2, 6, 9, 1, 7 },
368 { 8, 0, 4, 10, 11, 1, 7, 2, 6, 9, 3, 5 },
370 w->raw_orient = x8_get_orient_vlc(w);
371 if (w->raw_orient < 0)
373 av_assert2(w->raw_orient < 12);
374 av_assert2(w->orient < 3);
375 w->orient=prediction_table[w->orient][w->raw_orient];
380 static void x8_update_predictions(IntraX8Context *const w, const int orient,
383 MpegEncContext *const s = w->s;
385 w->prediction_table[s->mb_x * 2 + (s->mb_y & 1)] = (est_run << 2) + 1 * (orient == 4) + 2 * (orient == 8);
387 * y = 2n + 0 -> // 0 2 4
388 * y = 2n + 1 -> // 1 3 5
392 static void x8_get_prediction_chroma(IntraX8Context *const w)
394 MpegEncContext *const s = w->s;
396 w->edges = 1 * (!(s->mb_x >> 1));
397 w->edges |= 2 * (!(s->mb_y >> 1));
398 w->edges |= 4 * (s->mb_x >= (2 * s->mb_width - 1)); // mb_x for chroma would always be odd
401 // lut_co[8] = {inv,4,8,8, inv,4,8,8} <- => {1,1,0,0;1,1,0,0} => 0xCC
403 w->chroma_orient = 4 << ((0xCC >> w->edges) & 1);
406 // block[x - 1][y | 1 - 1)]
407 w->chroma_orient = (w->prediction_table[2 * s->mb_x - 2] & 0x03) << 2;
410 static void x8_get_prediction(IntraX8Context *const w)
412 MpegEncContext *const s = w->s;
415 w->edges = 1 * (!s->mb_x);
416 w->edges |= 2 * (!s->mb_y);
417 w->edges |= 4 * (s->mb_x >= (2 * s->mb_width - 1));
419 switch (w->edges & 3) {
423 // take the one from the above block[0][y - 1]
424 w->est_run = w->prediction_table[!(s->mb_y & 1)] >> 2;
428 // take the one from the previous block[x - 1][0]
429 w->est_run = w->prediction_table[2 * s->mb_x - 2] >> 2;
438 b = w->prediction_table[2 * s->mb_x + !(s->mb_y & 1)]; // block[x ][y - 1]
439 a = w->prediction_table[2 * s->mb_x - 2 + (s->mb_y & 1)]; // block[x - 1][y ]
440 c = w->prediction_table[2 * s->mb_x - 2 + !(s->mb_y & 1)]; // block[x - 1][y - 1]
442 w->est_run = FFMIN(b, a);
443 /* This condition has nothing to do with w->edges, even if it looks
444 * similar it would trigger if e.g. x = 3; y = 2;
445 * I guess somebody wrote something wrong and it became standard. */
446 if ((s->mb_x & s->mb_y) != 0)
447 w->est_run = FFMIN(c, w->est_run);
454 i = (0xFFEAF4C4 >> (2 * b + 8 * a)) & 3;
458 w->orient = (0xFFEAD8 >> (2 * c + 8 * (w->quant > 12))) & 3;
461 * ->{ 0, 1, 0, pad },
468 * -> 11 10 '10 10 '11 11'01 00 '11 00'01 00 => 0xEAF4C4
476 * -> 11 10'10 10 '11 01'10 00 => 0xEAD8
480 static void x8_ac_compensation(IntraX8Context *const w, const int direction,
483 MpegEncContext *const s = w->s;
485 #define B(x,y) s->block[0][w->idct_permutation[(x) + (y) * 8]]
486 #define T(x) ((x) * dc_level + 0x8000) >> 16;
529 s->block_last_index[0] = FFMAX(s->block_last_index[0], 7 * 8);
537 s->block_last_index[0] = FFMAX(s->block_last_index[0], 7 * 8);
545 s->block_last_index[0] = FFMAX(s->block_last_index[0], 7);
552 static void dsp_x8_put_solidcolor(const uint8_t pix, uint8_t *dst,
556 for (k = 0; k < 8; k++) {
562 static const int16_t quant_table[64] = {
563 256, 256, 256, 256, 256, 256, 259, 262,
564 265, 269, 272, 275, 278, 282, 285, 288,
565 292, 295, 299, 303, 306, 310, 314, 317,
566 321, 325, 329, 333, 337, 341, 345, 349,
567 353, 358, 362, 366, 371, 375, 379, 384,
568 389, 393, 398, 403, 408, 413, 417, 422,
569 428, 433, 438, 443, 448, 454, 459, 465,
570 470, 476, 482, 488, 493, 499, 505, 511,
573 static int x8_decode_intra_mb(IntraX8Context *const w, const int chroma)
575 MpegEncContext *const s = w->s;
578 int final, run, level;
579 int ac_mode, dc_mode, est_run, dc_level;
582 int use_quant_matrix;
585 av_assert2(w->orient < 12);
586 w->bdsp.clear_block(s->block[0]);
591 dc_mode = !!w->est_run; // 0, 1
593 if (x8_get_dc_rlf(w, dc_mode, &dc_level, &final))
597 if (!final) { // decode ac
598 use_quant_matrix = w->use_quant_matrix;
601 est_run = 64; // not used
603 if (w->raw_orient < 3)
604 use_quant_matrix = 0;
606 if (w->raw_orient > 4) {
610 if (w->est_run > 1) {
612 est_run = w->est_run;
619 x8_select_ac_table(w, ac_mode);
620 /* scantable_selector[12] = { 0, 2, 0, 1, 1, 1, 0, 2, 2, 0, 1, 2 }; <-
621 * -> 10'01' 00'10' 10'00' 01'01' 01'00' 10'00 => 0x928548 */
622 scantable = w->scantable[(0x928548 >> (2 * w->orient)) & 3].permutated;
628 x8_select_ac_table(w, 3);
631 x8_get_ac_rlf(w, ac_mode, &run, &level, &final);
635 // this also handles vlc error in x8_get_ac_rlf
638 level = (level + 1) * w->dquant;
641 sign = -get_bits1(w->gb);
642 level = (level ^ sign) - sign;
644 if (use_quant_matrix)
645 level = (level * quant_table[pos]) >> 8;
647 s->block[0][scantable[pos]] = level;
650 s->block_last_index[0] = pos;
652 s->block_last_index[0] = 0;
653 if (w->flat_dc && ((unsigned) (dc_level + 1)) < 3) { // [-1; 1]
654 int32_t divide_quant = !chroma ? w->divide_quant_dc_luma
655 : w->divide_quant_dc_chroma;
656 int32_t dc_quant = !chroma ? w->quant
657 : w->quant_dc_chroma;
659 // original intent dc_level += predicted_dc/quant;
660 // but it got lost somewhere in the rounding
661 dc_level += (w->predicted_dc * divide_quant + (1 << 12)) >> 13;
663 dsp_x8_put_solidcolor(av_clip_uint8((dc_level * dc_quant + 4) >> 3),
665 w->frame->linesize[!!chroma]);
669 zeros_only = (dc_level == 0);
672 s->block[0][0] = dc_level * w->quant;
674 s->block[0][0] = dc_level * w->quant_dc_chroma;
676 // there is !zero_only check in the original, but dc_level check is enough
677 if ((unsigned int) (dc_level + 1) >= 3 && (w->edges & 3) != 3) {
679 /* ac_comp_direction[orient] = { 0, 3, 3, 1, 1, 0, 0, 0, 2, 2, 2, 1 }; <-
680 * -> 01'10' 10'10' 00'00' 00'01' 01'11' 11'00 => 0x6A017C */
681 direction = (0x6A017C >> (w->orient * 2)) & 3;
682 if (direction != 3) {
683 // modify block_last[]
684 x8_ac_compensation(w, direction, s->block[0][0]);
689 dsp_x8_put_solidcolor(w->predicted_dc, w->dest[chroma],
690 w->frame->linesize[!!chroma]);
692 w->dsp.spatial_compensation[w->orient](w->scratchpad,
694 w->frame->linesize[!!chroma]);
697 w->wdsp.idct_add(w->dest[chroma],
698 w->frame->linesize[!!chroma],
703 x8_update_predictions(w, w->orient, n);
706 uint8_t *ptr = w->dest[chroma];
707 int linesize = w->frame->linesize[!!chroma];
709 if (!((w->edges & 2) || (zeros_only && (w->orient | 4) == 4)))
710 w->dsp.h_loop_filter(ptr, linesize, w->quant);
712 if (!((w->edges & 1) || (zeros_only && (w->orient | 8) == 8)))
713 w->dsp.v_loop_filter(ptr, linesize, w->quant);
718 // FIXME maybe merge with ff_*
719 static void x8_init_block_index(IntraX8Context *w, AVFrame *frame, int mb_y)
721 // not parent codec linesize as this would be wrong for field pics
722 // not that IntraX8 has interlacing support ;)
723 const int linesize = frame->linesize[0];
724 const int uvlinesize = frame->linesize[1];
726 w->dest[0] = frame->data[0];
727 w->dest[1] = frame->data[1];
728 w->dest[2] = frame->data[2];
730 w->dest[0] += mb_y * linesize << 3;
731 // chroma blocks are on add rows
732 w->dest[1] += (mb_y & (~1)) * uvlinesize << 2;
733 w->dest[2] += (mb_y & (~1)) * uvlinesize << 2;
736 av_cold int ff_intrax8_common_init(AVCodecContext *avctx,
737 IntraX8Context *w, IDCTDSPContext *idsp,
738 MpegEncContext *const s)
740 int ret = x8_vlc_init();
748 //two rows, 2 blocks per cannon mb
749 w->prediction_table = av_mallocz(s->mb_width * 2 * 2);
750 if (!w->prediction_table)
751 return AVERROR(ENOMEM);
753 ff_wmv2dsp_init(&w->wdsp);
755 ff_init_scantable_permutation(w->idct_permutation,
758 ff_init_scantable(w->idct_permutation, &w->scantable[0],
759 ff_wmv1_scantable[0]);
760 ff_init_scantable(w->idct_permutation, &w->scantable[1],
761 ff_wmv1_scantable[2]);
762 ff_init_scantable(w->idct_permutation, &w->scantable[2],
763 ff_wmv1_scantable[3]);
765 ff_intrax8dsp_init(&w->dsp);
766 ff_blockdsp_init(&w->bdsp, avctx);
771 av_cold void ff_intrax8_common_end(IntraX8Context *w)
773 av_freep(&w->prediction_table);
776 int ff_intrax8_decode_picture(IntraX8Context *const w, Picture *pict,
778 int dquant, int quant_offset, int loopfilter)
780 MpegEncContext *const s = w->s;
785 w->quant = dquant >> 1;
786 w->qsum = quant_offset;
788 w->loopfilter = loopfilter;
789 w->use_quant_matrix = get_bits1(w->gb);
791 w->divide_quant_dc_luma = ((1 << 16) + (w->quant >> 1)) / w->quant;
793 w->quant_dc_chroma = w->quant;
794 w->divide_quant_dc_chroma = w->divide_quant_dc_luma;
796 w->quant_dc_chroma = w->quant + ((w->quant + 3) >> 3);
797 w->divide_quant_dc_chroma = ((1 << 16) + (w->quant_dc_chroma >> 1)) / w->quant_dc_chroma;
799 x8_reset_vlc_tables(w);
801 for (s->mb_y = 0; s->mb_y < s->mb_height * 2; s->mb_y++) {
802 x8_init_block_index(w, w->frame, s->mb_y);
803 mb_xy = (s->mb_y >> 1) * s->mb_stride;
805 for (s->mb_x = 0; s->mb_x < s->mb_width * 2; s->mb_x++) {
806 x8_get_prediction(w);
807 if (x8_setup_spatial_predictor(w, 0))
809 if (x8_decode_intra_mb(w, 0))
812 if (s->mb_x & s->mb_y & 1) {
813 x8_get_prediction_chroma(w);
815 /* when setting up chroma, no vlc is read,
816 * so no error condition can be reached */
817 x8_setup_spatial_predictor(w, 1);
818 if (x8_decode_intra_mb(w, 1))
821 x8_setup_spatial_predictor(w, 2);
822 if (x8_decode_intra_mb(w, 2))
828 /* emulate MB info in the relevant tables */
829 s->mbskip_table[mb_xy] = 0;
830 s->mbintra_table[mb_xy] = 1;
831 pict->qscale_table[mb_xy] = w->quant;
837 ff_mpeg_draw_horiz_band(s, (s->mb_y - 1) * 8, 16);