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decodetxb.c (13487B)

---

/*
* Copyright (c) 2017, Alliance for Open Media. All rights reserved.
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/

#include "av1/decoder/decodetxb.h"

#include "aom_ports/mem.h"
#include "av1/common/idct.h"
#include "av1/common/scan.h"
#include "av1/common/txb_common.h"
#include "av1/decoder/decodemv.h"

#define ACCT_STR __func__

static int read_golomb(MACROBLOCKD *xd, aom_reader *r) {
 int x = 1;
 int length = 0;
 int i = 0;

 while (!i) {
   i = aom_read_bit(r, ACCT_STR);
   ++length;
   if (length > 20) {
     aom_internal_error(xd->error_info, AOM_CODEC_CORRUPT_FRAME,
                        "Invalid length in read_golomb");
     break;
   }
 }

 for (i = 0; i < length - 1; ++i) {
   x <<= 1;
   x += aom_read_bit(r, ACCT_STR);
 }

 return x - 1;
}

static inline int rec_eob_pos(const int eob_token, const int extra) {
 int eob = av1_eob_group_start[eob_token];
 if (eob > 2) {
   eob += extra;
 }
 return eob;
}

static inline int get_dqv(const int16_t *dequant, int coeff_idx,
                         const qm_val_t *iqmatrix) {
 int dqv = dequant[!!coeff_idx];
 if (iqmatrix != NULL)
   dqv =
       ((iqmatrix[coeff_idx] * dqv) + (1 << (AOM_QM_BITS - 1))) >> AOM_QM_BITS;
 return dqv;
}

static inline void read_coeffs_reverse_2d(aom_reader *r, TX_SIZE tx_size,
                                         int start_si, int end_si,
                                         const int16_t *scan, int bhl,
                                         uint8_t *levels,
                                         base_cdf_arr base_cdf,
                                         br_cdf_arr br_cdf) {
 for (int c = end_si; c >= start_si; --c) {
   const int pos = scan[c];
   const int coeff_ctx = get_lower_levels_ctx_2d(levels, pos, bhl, tx_size);
   const int nsymbs = 4;
   int level = aom_read_symbol(r, base_cdf[coeff_ctx], nsymbs, ACCT_STR);
   if (level > NUM_BASE_LEVELS) {
     const int br_ctx = get_br_ctx_2d(levels, pos, bhl);
     aom_cdf_prob *cdf = br_cdf[br_ctx];
     for (int idx = 0; idx < COEFF_BASE_RANGE; idx += BR_CDF_SIZE - 1) {
       const int k = aom_read_symbol(r, cdf, BR_CDF_SIZE, ACCT_STR);
       level += k;
       if (k < BR_CDF_SIZE - 1) break;
     }
   }
   levels[get_padded_idx(pos, bhl)] = level;
 }
}

static inline void read_coeffs_reverse(aom_reader *r, TX_SIZE tx_size,
                                      TX_CLASS tx_class, int start_si,
                                      int end_si, const int16_t *scan, int bhl,
                                      uint8_t *levels, base_cdf_arr base_cdf,
                                      br_cdf_arr br_cdf) {
 for (int c = end_si; c >= start_si; --c) {
   const int pos = scan[c];
   const int coeff_ctx =
       get_lower_levels_ctx(levels, pos, bhl, tx_size, tx_class);
   const int nsymbs = 4;
   int level = aom_read_symbol(r, base_cdf[coeff_ctx], nsymbs, ACCT_STR);
   if (level > NUM_BASE_LEVELS) {
     const int br_ctx = get_br_ctx(levels, pos, bhl, tx_class);
     aom_cdf_prob *cdf = br_cdf[br_ctx];
     for (int idx = 0; idx < COEFF_BASE_RANGE; idx += BR_CDF_SIZE - 1) {
       const int k = aom_read_symbol(r, cdf, BR_CDF_SIZE, ACCT_STR);
       level += k;
       if (k < BR_CDF_SIZE - 1) break;
     }
   }
   levels[get_padded_idx(pos, bhl)] = level;
 }
}

static uint8_t read_coeffs_txb(const AV1_COMMON *const cm,
                              DecoderCodingBlock *dcb, aom_reader *const r,
                              const int blk_row, const int blk_col,
                              const int plane, const TXB_CTX *const txb_ctx,
                              const TX_SIZE tx_size) {
 MACROBLOCKD *const xd = &dcb->xd;
 FRAME_CONTEXT *const ec_ctx = xd->tile_ctx;
 const int32_t max_value = (1 << (7 + xd->bd)) - 1;
 const int32_t min_value = -(1 << (7 + xd->bd));
 const TX_SIZE txs_ctx = get_txsize_entropy_ctx(tx_size);
 const PLANE_TYPE plane_type = get_plane_type(plane);
 MB_MODE_INFO *const mbmi = xd->mi[0];
 struct macroblockd_plane *const pd = &xd->plane[plane];
 const int16_t *const dequant = pd->seg_dequant_QTX[mbmi->segment_id];
 tran_low_t *const tcoeffs = dcb->dqcoeff_block[plane] + dcb->cb_offset[plane];
 const int shift = av1_get_tx_scale(tx_size);
 const int bhl = get_txb_bhl(tx_size);
 const int width = get_txb_wide(tx_size);
 const int height = get_txb_high(tx_size);
 int cul_level = 0;
 int dc_val = 0;
 uint8_t levels_buf[TX_PAD_2D];
 uint8_t *const levels = set_levels(levels_buf, height);
 const int all_zero = aom_read_symbol(
     r, ec_ctx->txb_skip_cdf[txs_ctx][txb_ctx->txb_skip_ctx], 2, ACCT_STR);
 eob_info *eob_data = dcb->eob_data[plane] + dcb->txb_offset[plane];
 uint16_t *const eob = &(eob_data->eob);
 uint16_t *const max_scan_line = &(eob_data->max_scan_line);
 *max_scan_line = 0;
 *eob = 0;

#if CONFIG_INSPECTION
 if (plane == 0) {
   const int txk_type_idx =
       av1_get_txk_type_index(mbmi->bsize, blk_row, blk_col);
   mbmi->tx_skip[txk_type_idx] = all_zero;
 }
#endif

 if (all_zero) {
   *max_scan_line = 0;
   if (plane == 0) {
     xd->tx_type_map[blk_row * xd->tx_type_map_stride + blk_col] = DCT_DCT;
   }
   return 0;
 }

 if (plane == AOM_PLANE_Y) {
   // only y plane's tx_type is transmitted
   av1_read_tx_type(cm, xd, blk_row, blk_col, tx_size, r);
 }
 const TX_TYPE tx_type =
     av1_get_tx_type(xd, plane_type, blk_row, blk_col, tx_size,
                     cm->features.reduced_tx_set_used);
 const TX_CLASS tx_class = tx_type_to_class[tx_type];
 const qm_val_t *iqmatrix =
     av1_get_iqmatrix(&cm->quant_params, xd, plane, tx_size, tx_type);
 const SCAN_ORDER *const scan_order = get_scan(tx_size, tx_type);
 const int16_t *const scan = scan_order->scan;
 int eob_extra = 0;
 int eob_pt = 1;

 const int eob_multi_size = txsize_log2_minus4[tx_size];
 const int eob_multi_ctx = (tx_class == TX_CLASS_2D) ? 0 : 1;
 switch (eob_multi_size) {
   case 0:
     eob_pt =
         aom_read_symbol(r, ec_ctx->eob_flag_cdf16[plane_type][eob_multi_ctx],
                         5, ACCT_STR) +
         1;
     break;
   case 1:
     eob_pt =
         aom_read_symbol(r, ec_ctx->eob_flag_cdf32[plane_type][eob_multi_ctx],
                         6, ACCT_STR) +
         1;
     break;
   case 2:
     eob_pt =
         aom_read_symbol(r, ec_ctx->eob_flag_cdf64[plane_type][eob_multi_ctx],
                         7, ACCT_STR) +
         1;
     break;
   case 3:
     eob_pt =
         aom_read_symbol(r, ec_ctx->eob_flag_cdf128[plane_type][eob_multi_ctx],
                         8, ACCT_STR) +
         1;
     break;
   case 4:
     eob_pt =
         aom_read_symbol(r, ec_ctx->eob_flag_cdf256[plane_type][eob_multi_ctx],
                         9, ACCT_STR) +
         1;
     break;
   case 5:
     eob_pt =
         aom_read_symbol(r, ec_ctx->eob_flag_cdf512[plane_type][eob_multi_ctx],
                         10, ACCT_STR) +
         1;
     break;
   case 6:
   default:
     eob_pt = aom_read_symbol(
                  r, ec_ctx->eob_flag_cdf1024[plane_type][eob_multi_ctx], 11,
                  ACCT_STR) +
              1;
     break;
 }

 const int eob_offset_bits = av1_eob_offset_bits[eob_pt];
 if (eob_offset_bits > 0) {
   const int eob_ctx = eob_pt - 3;
   int bit = aom_read_symbol(
       r, ec_ctx->eob_extra_cdf[txs_ctx][plane_type][eob_ctx], 2, ACCT_STR);
   if (bit) {
     eob_extra += (1 << (eob_offset_bits - 1));
   }

   for (int i = 1; i < eob_offset_bits; i++) {
     bit = aom_read_bit(r, ACCT_STR);
     if (bit) {
       eob_extra += (1 << (eob_offset_bits - 1 - i));
     }
   }
 }
 *eob = rec_eob_pos(eob_pt, eob_extra);

 if (*eob > 1) {
   memset(levels_buf, 0,
          sizeof(*levels_buf) *
              ((height + TX_PAD_HOR) * (width + TX_PAD_VER) + TX_PAD_END));
 }

 {
   // Read the non-zero coefficient with scan index eob-1
   // TODO(angiebird): Put this into a function
   const int c = *eob - 1;
   const int pos = scan[c];
   const int coeff_ctx = get_lower_levels_ctx_eob(bhl, width, c);
   const int nsymbs = 3;
   aom_cdf_prob *cdf =
       ec_ctx->coeff_base_eob_cdf[txs_ctx][plane_type][coeff_ctx];
   int level = aom_read_symbol(r, cdf, nsymbs, ACCT_STR) + 1;
   if (level > NUM_BASE_LEVELS) {
     const int br_ctx = get_br_ctx_eob(pos, bhl, tx_class);
     cdf = ec_ctx->coeff_br_cdf[AOMMIN(txs_ctx, TX_32X32)][plane_type][br_ctx];
     for (int idx = 0; idx < COEFF_BASE_RANGE; idx += BR_CDF_SIZE - 1) {
       const int k = aom_read_symbol(r, cdf, BR_CDF_SIZE, ACCT_STR);
       level += k;
       if (k < BR_CDF_SIZE - 1) break;
     }
   }
   levels[get_padded_idx(pos, bhl)] = level;
 }
 if (*eob > 1) {
   base_cdf_arr base_cdf = ec_ctx->coeff_base_cdf[txs_ctx][plane_type];
   br_cdf_arr br_cdf =
       ec_ctx->coeff_br_cdf[AOMMIN(txs_ctx, TX_32X32)][plane_type];
   if (tx_class == TX_CLASS_2D) {
     read_coeffs_reverse_2d(r, tx_size, 1, *eob - 1 - 1, scan, bhl, levels,
                            base_cdf, br_cdf);
     read_coeffs_reverse(r, tx_size, tx_class, 0, 0, scan, bhl, levels,
                         base_cdf, br_cdf);
   } else {
     read_coeffs_reverse(r, tx_size, tx_class, 0, *eob - 1 - 1, scan, bhl,
                         levels, base_cdf, br_cdf);
   }
 }

 for (int c = 0; c < *eob; ++c) {
   const int pos = scan[c];
   uint8_t sign;
   tran_low_t level = levels[get_padded_idx(pos, bhl)];
   if (level) {
     *max_scan_line = AOMMAX(*max_scan_line, pos);
     if (c == 0) {
       const int dc_sign_ctx = txb_ctx->dc_sign_ctx;
       sign = aom_read_symbol(r, ec_ctx->dc_sign_cdf[plane_type][dc_sign_ctx],
                              2, ACCT_STR);
     } else {
       sign = aom_read_bit(r, ACCT_STR);
     }
     if (level >= MAX_BASE_BR_RANGE) {
       level += read_golomb(xd, r);
     }

     if (c == 0) dc_val = sign ? -level : level;

     // Bitmasking to clamp level to valid range:
     //   The valid range for 8/10/12 bit vdieo is at most 14/16/18 bit
     level &= 0xfffff;
     cul_level += level;
     tran_low_t dq_coeff;
     // Bitmasking to clamp dq_coeff to valid range:
     //   The valid range for 8/10/12 bit video is at most 17/19/21 bit
     dq_coeff =
         (tran_low_t)((int64_t)level * get_dqv(dequant, scan[c], iqmatrix) &
                      0xffffff);
     dq_coeff = dq_coeff >> shift;
     if (sign) {
       dq_coeff = -dq_coeff;
     }
     tcoeffs[pos] = clamp(dq_coeff, min_value, max_value);
   }
 }

 cul_level = AOMMIN(COEFF_CONTEXT_MASK, cul_level);

 // DC value
 set_dc_sign(&cul_level, dc_val);

 return cul_level;
}

void av1_read_coeffs_txb(const AV1_COMMON *const cm, DecoderCodingBlock *dcb,
                        aom_reader *const r, const int plane, const int row,
                        const int col, const TX_SIZE tx_size) {
#if TXCOEFF_TIMER
 struct aom_usec_timer timer;
 aom_usec_timer_start(&timer);
#endif
 MACROBLOCKD *const xd = &dcb->xd;
 MB_MODE_INFO *const mbmi = xd->mi[0];
 struct macroblockd_plane *const pd = &xd->plane[plane];

 const BLOCK_SIZE bsize = mbmi->bsize;
 assert(bsize < BLOCK_SIZES_ALL);
 const BLOCK_SIZE plane_bsize =
     get_plane_block_size(bsize, pd->subsampling_x, pd->subsampling_y);

 TXB_CTX txb_ctx;
 get_txb_ctx(plane_bsize, tx_size, plane, pd->above_entropy_context + col,
             pd->left_entropy_context + row, &txb_ctx);
 const uint8_t cul_level =
     read_coeffs_txb(cm, dcb, r, row, col, plane, &txb_ctx, tx_size);
 av1_set_entropy_contexts(xd, pd, plane, plane_bsize, tx_size, cul_level, col,
                          row);

 if (is_inter_block(mbmi)) {
   const PLANE_TYPE plane_type = get_plane_type(plane);
   // tx_type will be read out in av1_read_coeffs_txb_facade
   const TX_TYPE tx_type = av1_get_tx_type(xd, plane_type, row, col, tx_size,
                                           cm->features.reduced_tx_set_used);

   if (plane == 0) {
     const int txw = tx_size_wide_unit[tx_size];
     const int txh = tx_size_high_unit[tx_size];
     // The 16x16 unit is due to the constraint from tx_64x64 which sets the
     // maximum tx size for chroma as 32x32. Coupled with 4x1 transform block
     // size, the constraint takes effect in 32x16 / 16x32 size too. To solve
     // the intricacy, cover all the 16x16 units inside a 64 level transform.
     if (txw == tx_size_wide_unit[TX_64X64] ||
         txh == tx_size_high_unit[TX_64X64]) {
       const int tx_unit = tx_size_wide_unit[TX_16X16];
       const int stride = xd->tx_type_map_stride;
       for (int idy = 0; idy < txh; idy += tx_unit) {
         for (int idx = 0; idx < txw; idx += tx_unit) {
           xd->tx_type_map[(row + idy) * stride + col + idx] = tx_type;
         }
       }
     }
   }
 }

#if TXCOEFF_TIMER
 aom_usec_timer_mark(&timer);
 const int64_t elapsed_time = aom_usec_timer_elapsed(&timer);
 cm->txcoeff_timer += elapsed_time;
 ++cm->txb_count;
#endif
}