vp9_firstpass.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include <limits.h>
#include <math.h>
#include <stdio.h>

#include "./vpx_scale_rtcd.h"

#include "vpx_mem/vpx_mem.h"
#include "vpx_scale/vpx_scale.h"
#include "vpx_scale/yv12config.h"

#include "vp9/common/vp9_entropymv.h"
#include "vp9/common/vp9_quant_common.h"
#include "vp9/common/vp9_reconinter.h"  // vp9_setup_dst_planes()
#include "vp9/common/vp9_systemdependent.h"
#include "vp9/encoder/vp9_aq_variance.h"
#include "vp9/encoder/vp9_block.h"
#include "vp9/encoder/vp9_encodeframe.h"
#include "vp9/encoder/vp9_encodemb.h"
#include "vp9/encoder/vp9_encodemv.h"
#include "vp9/encoder/vp9_encoder.h"
#include "vp9/encoder/vp9_extend.h"
#include "vp9/encoder/vp9_firstpass.h"
#include "vp9/encoder/vp9_mcomp.h"
#include "vp9/encoder/vp9_quantize.h"
#include "vp9/encoder/vp9_rd.h"
#include "vp9/encoder/vp9_variance.h"

#define OUTPUT_FPF          0
#define ARF_STATS_OUTPUT    0

#define GROUP_ADAPTIVE_MAXQ 0

#define BOOST_BREAKOUT      12.5
#define BOOST_FACTOR        12.5
#define ERR_DIVISOR         128.0
#define FACTOR_PT_LOW       0.70
#define FACTOR_PT_HIGH      0.90
#define FIRST_PASS_Q        10.0
#define GF_MAX_BOOST        96.0
#define INTRA_MODE_PENALTY  1024
#define KF_MAX_BOOST        128.0
#define MIN_ARF_GF_BOOST    240
#define MIN_DECAY_FACTOR    0.01
#define MIN_GF_INTERVAL     4
#define MIN_KF_BOOST        300
#define NEW_MV_MODE_PENALTY 32
#define SVC_FACTOR_PT_LOW   0.45
#define DARK_THRESH         64
#define DEFAULT_GRP_WEIGHT  1.0
#define RC_FACTOR_MIN       0.75
#define RC_FACTOR_MAX       1.75

#define DOUBLE_DIVIDE_CHECK(x) ((x) < 0 ? (x) - 0.000001 : (x) + 0.000001)

#if ARF_STATS_OUTPUT
unsigned int arf_count = 0;
#endif

// Resets the first pass file to the given position using a relative seek from
// the current position.
static void reset_fpf_position(TWO_PASS *p,
                               const FIRSTPASS_STATS *position) {
  p->stats_in = position;
}

// Read frame stats at an offset from the current position.
static const FIRSTPASS_STATS *read_frame_stats(const TWO_PASS *p, int offset) {
  if ((offset >= 0 && p->stats_in + offset >= p->stats_in_end) ||
      (offset < 0 && p->stats_in + offset < p->stats_in_start)) {
    return NULL;
  }

  return &p->stats_in[offset];
}

static int input_stats(TWO_PASS *p, FIRSTPASS_STATS *fps) {
  if (p->stats_in >= p->stats_in_end)
    return EOF;

  *fps = *p->stats_in;
  ++p->stats_in;
  return 1;
}

static void output_stats(FIRSTPASS_STATS *stats,
                         struct vpx_codec_pkt_list *pktlist) {
  struct vpx_codec_cx_pkt pkt;
  pkt.kind = VPX_CODEC_STATS_PKT;
  pkt.data.twopass_stats.buf = stats;
  pkt.data.twopass_stats.sz = sizeof(FIRSTPASS_STATS);
  vpx_codec_pkt_list_add(pktlist, &pkt);

// TEMP debug code
#if OUTPUT_FPF
  {
    FILE *fpfile;
    fpfile = fopen("firstpass.stt", "a");

    fprintf(fpfile, "%12.0lf %12.4lf %12.0lf %12.0lf %12.0lf %12.4lf %12.4lf"
            "%12.4lf %12.4lf %12.4lf %12.4lf %12.4lf %12.4lf %12.4lf"
            "%12.4lf %12.0lf %12.0lf %12.0lf %12.4lf\n",
            stats->frame,
            stats->weight,
            stats->intra_error,
            stats->coded_error,
            stats->sr_coded_error,
            stats->pcnt_inter,
            stats->pcnt_motion,
            stats->pcnt_second_ref,
            stats->pcnt_neutral,
            stats->MVr,
            stats->mvr_abs,
            stats->MVc,
            stats->mvc_abs,
            stats->MVrv,
            stats->MVcv,
            stats->mv_in_out_count,
            stats->new_mv_count,
            stats->count,
            stats->duration);
    fclose(fpfile);
  }
#endif
}

#if CONFIG_FP_MB_STATS
static void output_fpmb_stats(uint8_t *this_frame_mb_stats, VP9_COMMON *cm,
                         struct vpx_codec_pkt_list *pktlist) {
  struct vpx_codec_cx_pkt pkt;
  pkt.kind = VPX_CODEC_FPMB_STATS_PKT;
  pkt.data.firstpass_mb_stats.buf = this_frame_mb_stats;
  pkt.data.firstpass_mb_stats.sz = cm->initial_mbs * sizeof(uint8_t);
  vpx_codec_pkt_list_add(pktlist, &pkt);
}
#endif

static void zero_stats(FIRSTPASS_STATS *section) {
  section->frame = 0.0;
  section->weight = 0.0;
  section->intra_error = 0.0;
  section->coded_error = 0.0;
  section->sr_coded_error = 0.0;
  section->pcnt_inter  = 0.0;
  section->pcnt_motion  = 0.0;
  section->pcnt_second_ref = 0.0;
  section->pcnt_neutral = 0.0;
  section->MVr        = 0.0;
  section->mvr_abs     = 0.0;
  section->MVc        = 0.0;
  section->mvc_abs     = 0.0;
  section->MVrv       = 0.0;
  section->MVcv       = 0.0;
  section->mv_in_out_count  = 0.0;
  section->new_mv_count = 0.0;
  section->count      = 0.0;
  section->duration   = 1.0;
  section->spatial_layer_id = 0;
}

static void accumulate_stats(FIRSTPASS_STATS *section,
                             const FIRSTPASS_STATS *frame) {
  section->frame += frame->frame;
  section->weight += frame->weight;
  section->spatial_layer_id = frame->spatial_layer_id;
  section->intra_error += frame->intra_error;
  section->coded_error += frame->coded_error;
  section->sr_coded_error += frame->sr_coded_error;
  section->pcnt_inter  += frame->pcnt_inter;
  section->pcnt_motion += frame->pcnt_motion;
  section->pcnt_second_ref += frame->pcnt_second_ref;
  section->pcnt_neutral += frame->pcnt_neutral;
  section->MVr        += frame->MVr;
  section->mvr_abs     += frame->mvr_abs;
  section->MVc        += frame->MVc;
  section->mvc_abs     += frame->mvc_abs;
  section->MVrv       += frame->MVrv;
  section->MVcv       += frame->MVcv;
  section->mv_in_out_count  += frame->mv_in_out_count;
  section->new_mv_count += frame->new_mv_count;
  section->count      += frame->count;
  section->duration   += frame->duration;
}

static void subtract_stats(FIRSTPASS_STATS *section,
                           const FIRSTPASS_STATS *frame) {
  section->frame -= frame->frame;
  section->weight -= frame->weight;
  section->intra_error -= frame->intra_error;
  section->coded_error -= frame->coded_error;
  section->sr_coded_error -= frame->sr_coded_error;
  section->pcnt_inter  -= frame->pcnt_inter;
  section->pcnt_motion -= frame->pcnt_motion;
  section->pcnt_second_ref -= frame->pcnt_second_ref;
  section->pcnt_neutral -= frame->pcnt_neutral;
  section->MVr        -= frame->MVr;
  section->mvr_abs     -= frame->mvr_abs;
  section->MVc        -= frame->MVc;
  section->mvc_abs     -= frame->mvc_abs;
  section->MVrv       -= frame->MVrv;
  section->MVcv       -= frame->MVcv;
  section->mv_in_out_count  -= frame->mv_in_out_count;
  section->new_mv_count -= frame->new_mv_count;
  section->count      -= frame->count;
  section->duration   -= frame->duration;
}


// Calculate a modified Error used in distributing bits between easier and
// harder frames.
static double calculate_modified_err(const TWO_PASS *twopass,
                                     const VP9EncoderConfig *oxcf,
                                     const FIRSTPASS_STATS *this_frame) {
  const FIRSTPASS_STATS *const stats = &twopass->total_stats;
  const double av_weight = stats->weight / stats->count;
  const double av_err = (stats->coded_error * av_weight) / stats->count;
  const double modified_error =
    av_err * pow(this_frame->coded_error * this_frame->weight /
                 DOUBLE_DIVIDE_CHECK(av_err), oxcf->two_pass_vbrbias / 100.0);
  return fclamp(modified_error,
                twopass->modified_error_min, twopass->modified_error_max);
}

// This function returns the maximum target rate per frame.
static int frame_max_bits(const RATE_CONTROL *rc,
                          const VP9EncoderConfig *oxcf) {
  int64_t max_bits = ((int64_t)rc->avg_frame_bandwidth *
                          (int64_t)oxcf->two_pass_vbrmax_section) / 100;
  if (max_bits < 0)
    max_bits = 0;
  else if (max_bits > rc->max_frame_bandwidth)
    max_bits = rc->max_frame_bandwidth;

  return (int)max_bits;
}

void vp9_init_first_pass(VP9_COMP *cpi) {
  zero_stats(&cpi->twopass.total_stats);
}

void vp9_end_first_pass(VP9_COMP *cpi) {
  if (is_two_pass_svc(cpi)) {
    int i;
    for (i = 0; i < cpi->svc.number_spatial_layers; ++i) {
      output_stats(&cpi->svc.layer_context[i].twopass.total_stats,
                   cpi->output_pkt_list);
    }
  } else {
    output_stats(&cpi->twopass.total_stats, cpi->output_pkt_list);
  }
}

static vp9_variance_fn_t get_block_variance_fn(BLOCK_SIZE bsize) {
  switch (bsize) {
    case BLOCK_8X8:
      return vp9_mse8x8;
    case BLOCK_16X8:
      return vp9_mse16x8;
    case BLOCK_8X16:
      return vp9_mse8x16;
    default:
      return vp9_mse16x16;
  }
}

static unsigned int get_prediction_error(BLOCK_SIZE bsize,
                                         const struct buf_2d *src,
                                         const struct buf_2d *ref) {
  unsigned int sse;
  const vp9_variance_fn_t fn = get_block_variance_fn(bsize);
  fn(src->buf, src->stride, ref->buf, ref->stride, &sse);
  return sse;
}

#if CONFIG_VP9_HIGHBITDEPTH
static vp9_variance_fn_t highbd_get_block_variance_fn(BLOCK_SIZE bsize,
                                                      int bd) {
  switch (bd) {
    default:
      switch (bsize) {
        case BLOCK_8X8:
          return vp9_highbd_mse8x8;
        case BLOCK_16X8:
          return vp9_highbd_mse16x8;
        case BLOCK_8X16:
          return vp9_highbd_mse8x16;
        default:
          return vp9_highbd_mse16x16;
      }
      break;
    case 10:
      switch (bsize) {
        case BLOCK_8X8:
          return vp9_highbd_10_mse8x8;
        case BLOCK_16X8:
          return vp9_highbd_10_mse16x8;
        case BLOCK_8X16:
          return vp9_highbd_10_mse8x16;
        default:
          return vp9_highbd_10_mse16x16;
      }
      break;
    case 12:
      switch (bsize) {
        case BLOCK_8X8:
          return vp9_highbd_12_mse8x8;
        case BLOCK_16X8:
          return vp9_highbd_12_mse16x8;
        case BLOCK_8X16:
          return vp9_highbd_12_mse8x16;
        default:
          return vp9_highbd_12_mse16x16;
      }
      break;
  }
}

static unsigned int highbd_get_prediction_error(BLOCK_SIZE bsize,
                                                const struct buf_2d *src,
                                                const struct buf_2d *ref,
                                                int bd) {
  unsigned int sse;
  const vp9_variance_fn_t fn = highbd_get_block_variance_fn(bsize, bd);
  fn(src->buf, src->stride, ref->buf, ref->stride, &sse);
  return sse;
}
#endif  // CONFIG_VP9_HIGHBITDEPTH

// Refine the motion search range according to the frame dimension
// for first pass test.
static int get_search_range(const VP9_COMP *cpi) {
  int sr = 0;
  const int dim = MIN(cpi->initial_width, cpi->initial_height);

  while ((dim << sr) < MAX_FULL_PEL_VAL)
    ++sr;
  return sr;
}

static void first_pass_motion_search(VP9_COMP *cpi, MACROBLOCK *x,
                                     const MV *ref_mv, MV *best_mv,
                                     int *best_motion_err) {
  MACROBLOCKD *const xd = &x->e_mbd;
  MV tmp_mv = {0, 0};
  MV ref_mv_full = {ref_mv->row >> 3, ref_mv->col >> 3};
  int num00, tmp_err, n;
  const BLOCK_SIZE bsize = xd->mi[0].src_mi->mbmi.sb_type;
  vp9_variance_fn_ptr_t v_fn_ptr = cpi->fn_ptr[bsize];
  const int new_mv_mode_penalty = NEW_MV_MODE_PENALTY;

  int step_param = 3;
  int further_steps = (MAX_MVSEARCH_STEPS - 1) - step_param;
  const int sr = get_search_range(cpi);
  step_param += sr;
  further_steps -= sr;

  // Override the default variance function to use MSE.
  v_fn_ptr.vf = get_block_variance_fn(bsize);
#if CONFIG_VP9_HIGHBITDEPTH
  if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) {
    v_fn_ptr.vf = highbd_get_block_variance_fn(bsize, xd->bd);
  }
#endif  // CONFIG_VP9_HIGHBITDEPTH

  // Center the initial step/diamond search on best mv.
  tmp_err = cpi->diamond_search_sad(x, &cpi->ss_cfg, &ref_mv_full, &tmp_mv,
                                    step_param,
                                    x->sadperbit16, &num00, &v_fn_ptr, ref_mv);
  if (tmp_err < INT_MAX)
    tmp_err = vp9_get_mvpred_var(x, &tmp_mv, ref_mv, &v_fn_ptr, 1);
  if (tmp_err < INT_MAX - new_mv_mode_penalty)
    tmp_err += new_mv_mode_penalty;

  if (tmp_err < *best_motion_err) {
    *best_motion_err = tmp_err;
    *best_mv = tmp_mv;
  }

  // Carry out further step/diamond searches as necessary.
  n = num00;
  num00 = 0;

  while (n < further_steps) {
    ++n;

    if (num00) {
      --num00;
    } else {
      tmp_err = cpi->diamond_search_sad(x, &cpi->ss_cfg, &ref_mv_full, &tmp_mv,
                                        step_param + n, x->sadperbit16,
                                        &num00, &v_fn_ptr, ref_mv);
      if (tmp_err < INT_MAX)
        tmp_err = vp9_get_mvpred_var(x, &tmp_mv, ref_mv, &v_fn_ptr, 1);
      if (tmp_err < INT_MAX - new_mv_mode_penalty)
        tmp_err += new_mv_mode_penalty;

      if (tmp_err < *best_motion_err) {
        *best_motion_err = tmp_err;
        *best_mv = tmp_mv;
      }
    }
  }
}

static BLOCK_SIZE get_bsize(const VP9_COMMON *cm, int mb_row, int mb_col) {
  if (2 * mb_col + 1 < cm->mi_cols) {
    return 2 * mb_row + 1 < cm->mi_rows ? BLOCK_16X16
                                        : BLOCK_16X8;
  } else {
    return 2 * mb_row + 1 < cm->mi_rows ? BLOCK_8X16
                                        : BLOCK_8X8;
  }
}

static int find_fp_qindex(vpx_bit_depth_t bit_depth) {
  int i;

  for (i = 0; i < QINDEX_RANGE; ++i)
    if (vp9_convert_qindex_to_q(i, bit_depth) >= FIRST_PASS_Q)
      break;

  if (i == QINDEX_RANGE)
    i--;

  return i;
}

static void set_first_pass_params(VP9_COMP *cpi) {
  VP9_COMMON *const cm = &cpi->common;
  if (!cpi->refresh_alt_ref_frame &&
      (cm->current_video_frame == 0 ||
       (cpi->frame_flags & FRAMEFLAGS_KEY))) {
    cm->frame_type = KEY_FRAME;
  } else {
    cm->frame_type = INTER_FRAME;
  }
  // Do not use periodic key frames.
  cpi->rc.frames_to_key = INT_MAX;
}

void vp9_first_pass(VP9_COMP *cpi, const struct lookahead_entry *source) {
  int mb_row, mb_col;
  MACROBLOCK *const x = &cpi->td.mb;
  VP9_COMMON *const cm = &cpi->common;
  MACROBLOCKD *const xd = &x->e_mbd;
  TileInfo tile;
  struct macroblock_plane *const p = x->plane;
  struct macroblockd_plane *const pd = xd->plane;
  const PICK_MODE_CONTEXT *ctx = &cpi->td.pc_root->none;
  int i;

  int recon_yoffset, recon_uvoffset;
  int64_t intra_error = 0;
  int64_t coded_error = 0;
  int64_t sr_coded_error = 0;

  int sum_mvr = 0, sum_mvc = 0;
  int sum_mvr_abs = 0, sum_mvc_abs = 0;
  int64_t sum_mvrs = 0, sum_mvcs = 0;
  int mvcount = 0;
  int intercount = 0;
  int second_ref_count = 0;
  const int intrapenalty = INTRA_MODE_PENALTY;
  int neutral_count = 0;
  int new_mv_count = 0;
  int sum_in_vectors = 0;
  MV lastmv = {0, 0};
  TWO_PASS *twopass = &cpi->twopass;
  const MV zero_mv = {0, 0};
  int recon_y_stride, recon_uv_stride, uv_mb_height;

  YV12_BUFFER_CONFIG *const lst_yv12 = get_ref_frame_buffer(cpi, LAST_FRAME);
  YV12_BUFFER_CONFIG *gld_yv12 = get_ref_frame_buffer(cpi, GOLDEN_FRAME);
  YV12_BUFFER_CONFIG *const new_yv12 = get_frame_new_buffer(cm);
  const YV12_BUFFER_CONFIG *first_ref_buf = lst_yv12;

  LAYER_CONTEXT *const lc = is_two_pass_svc(cpi) ?
        &cpi->svc.layer_context[cpi->svc.spatial_layer_id] : NULL;
  double intra_factor;
  double brightness_factor;
  BufferPool *const pool = cm->buffer_pool;

  // First pass code requires valid last and new frame buffers.
  assert(new_yv12 != NULL);
  assert((lc != NULL) || frame_is_intra_only(cm) || (lst_yv12 != NULL));

#if CONFIG_FP_MB_STATS
  if (cpi->use_fp_mb_stats) {
    vp9_zero_array(cpi->twopass.frame_mb_stats_buf, cm->initial_mbs);
  }
#endif

  vp9_clear_system_state();

  intra_factor = 0.0;
  brightness_factor = 0.0;

  set_first_pass_params(cpi);
  vp9_set_quantizer(cm, find_fp_qindex(cm->bit_depth));

  if (lc != NULL) {
    twopass = &lc->twopass;

    cpi->lst_fb_idx = cpi->svc.spatial_layer_id;
    cpi->ref_frame_flags = VP9_LAST_FLAG;

    if (cpi->svc.number_spatial_layers + cpi->svc.spatial_layer_id <
        REF_FRAMES) {
      cpi->gld_fb_idx =
          cpi->svc.number_spatial_layers + cpi->svc.spatial_layer_id;
      cpi->ref_frame_flags |= VP9_GOLD_FLAG;
      cpi->refresh_golden_frame = (lc->current_video_frame_in_layer == 0);
    } else {
      cpi->refresh_golden_frame = 0;
    }

    if (lc->current_video_frame_in_layer == 0)
      cpi->ref_frame_flags = 0;

    vp9_scale_references(cpi);

    // Use either last frame or alt frame for motion search.
    if (cpi->ref_frame_flags & VP9_LAST_FLAG) {
      first_ref_buf = vp9_get_scaled_ref_frame(cpi, LAST_FRAME);
      if (first_ref_buf == NULL)
        first_ref_buf = get_ref_frame_buffer(cpi, LAST_FRAME);
    }

    if (cpi->ref_frame_flags & VP9_GOLD_FLAG) {
      gld_yv12 = vp9_get_scaled_ref_frame(cpi, GOLDEN_FRAME);
      if (gld_yv12 == NULL) {
        gld_yv12 = get_ref_frame_buffer(cpi, GOLDEN_FRAME);
      }
    } else {
      gld_yv12 = NULL;
    }

    set_ref_ptrs(cm, xd,
                 (cpi->ref_frame_flags & VP9_LAST_FLAG) ? LAST_FRAME: NONE,
                 (cpi->ref_frame_flags & VP9_GOLD_FLAG) ? GOLDEN_FRAME : NONE);

    cpi->Source = vp9_scale_if_required(cm, cpi->un_scaled_source,
                                        &cpi->scaled_source);
  }

  vp9_setup_block_planes(&x->e_mbd, cm->subsampling_x, cm->subsampling_y);

  vp9_setup_src_planes(x, cpi->Source, 0, 0);
  vp9_setup_dst_planes(xd->plane, new_yv12, 0, 0);

  if (!frame_is_intra_only(cm)) {
    vp9_setup_pre_planes(xd, 0, first_ref_buf, 0, 0, NULL);
  }

  xd->mi = cm->mi;
  xd->mi[0].src_mi = &xd->mi[0];

  vp9_frame_init_quantizer(cpi);

  for (i = 0; i < MAX_MB_PLANE; ++i) {
    p[i].coeff = ctx->coeff_pbuf[i][1];
    p[i].qcoeff = ctx->qcoeff_pbuf[i][1];
    pd[i].dqcoeff = ctx->dqcoeff_pbuf[i][1];
    p[i].eobs = ctx->eobs_pbuf[i][1];
  }
  x->skip_recode = 0;

  vp9_init_mv_probs(cm);
  vp9_initialize_rd_consts(cpi);

  // Tiling is ignored in the first pass.
  vp9_tile_init(&tile, cm, 0, 0);

  recon_y_stride = new_yv12->y_stride;
  recon_uv_stride = new_yv12->uv_stride;
  uv_mb_height = 16 >> (new_yv12->y_height > new_yv12->uv_height);

  for (mb_row = 0; mb_row < cm->mb_rows; ++mb_row) {
    MV best_ref_mv = {0, 0};

    // Reset above block coeffs.
    xd->up_available = (mb_row != 0);
    recon_yoffset = (mb_row * recon_y_stride * 16);
    recon_uvoffset = (mb_row * recon_uv_stride * uv_mb_height);

    // Set up limit values for motion vectors to prevent them extending
    // outside the UMV borders.
    x->mv_row_min = -((mb_row * 16) + BORDER_MV_PIXELS_B16);
    x->mv_row_max = ((cm->mb_rows - 1 - mb_row) * 16)
                    + BORDER_MV_PIXELS_B16;

    for (mb_col = 0; mb_col < cm->mb_cols; ++mb_col) {
      int this_error;
      const int use_dc_pred = (mb_col || mb_row) && (!mb_col || !mb_row);
      const BLOCK_SIZE bsize = get_bsize(cm, mb_row, mb_col);
      double log_intra;
      int level_sample;

#if CONFIG_FP_MB_STATS
      const int mb_index = mb_row * cm->mb_cols + mb_col;
#endif

      vp9_clear_system_state();

      xd->plane[0].dst.buf = new_yv12->y_buffer + recon_yoffset;
      xd->plane[1].dst.buf = new_yv12->u_buffer + recon_uvoffset;
      xd->plane[2].dst.buf = new_yv12->v_buffer + recon_uvoffset;
      xd->left_available = (mb_col != 0);
      xd->mi[0].src_mi->mbmi.sb_type = bsize;
      xd->mi[0].src_mi->mbmi.ref_frame[0] = INTRA_FRAME;
      set_mi_row_col(xd, &tile,
                     mb_row << 1, num_8x8_blocks_high_lookup[bsize],
                     mb_col << 1, num_8x8_blocks_wide_lookup[bsize],
                     cm->mi_rows, cm->mi_cols);

      // Do intra 16x16 prediction.
      x->skip_encode = 0;
      xd->mi[0].src_mi->mbmi.mode = DC_PRED;
      xd->mi[0].src_mi->mbmi.tx_size = use_dc_pred ?
         (bsize >= BLOCK_16X16 ? TX_16X16 : TX_8X8) : TX_4X4;
      vp9_encode_intra_block_plane(x, bsize, 0);
      this_error = vp9_get_mb_ss(x->plane[0].src_diff);
#if CONFIG_VP9_HIGHBITDEPTH
      if (cm->use_highbitdepth) {
        switch (cm->bit_depth) {
          case VPX_BITS_8:
            break;
          case VPX_BITS_10:
            this_error >>= 4;
            break;
          case VPX_BITS_12:
            this_error >>= 8;
            break;
          default:
            assert(0 && "cm->bit_depth should be VPX_BITS_8, "
                        "VPX_BITS_10 or VPX_BITS_12");
            return;
        }
      }
#endif  // CONFIG_VP9_HIGHBITDEPTH

      vp9_clear_system_state();
      log_intra = log(this_error + 1.0);
      if (log_intra < 10.0)
        intra_factor += 1.0 + ((10.0 - log_intra) * 0.05);
      else
        intra_factor += 1.0;

#if CONFIG_VP9_HIGHBITDEPTH
      if (cm->use_highbitdepth)
        level_sample = CONVERT_TO_SHORTPTR(x->plane[0].src.buf)[0];
      else
        level_sample = x->plane[0].src.buf[0];
#else
      level_sample = x->plane[0].src.buf[0];
#endif
      if ((level_sample < DARK_THRESH) && (log_intra < 9.0))
        brightness_factor += 1.0 + (0.01 * (DARK_THRESH - level_sample));
      else
        brightness_factor += 1.0;

      // Intrapenalty below deals with situations where the intra and inter
      // error scores are very low (e.g. a plain black frame).
      // We do not have special cases in first pass for 0,0 and nearest etc so
      // all inter modes carry an overhead cost estimate for the mv.
      // When the error score is very low this causes us to pick all or lots of
      // INTRA modes and throw lots of key frames.
      // This penalty adds a cost matching that of a 0,0 mv to the intra case.
      this_error += intrapenalty;

      // Accumulate the intra error.
      intra_error += (int64_t)this_error;

#if CONFIG_FP_MB_STATS
      if (cpi->use_fp_mb_stats) {
        // initialization
        cpi->twopass.frame_mb_stats_buf[mb_index] = 0;
      }
#endif

      // Set up limit values for motion vectors to prevent them extending
      // outside the UMV borders.
      x->mv_col_min = -((mb_col * 16) + BORDER_MV_PIXELS_B16);
      x->mv_col_max = ((cm->mb_cols - 1 - mb_col) * 16) + BORDER_MV_PIXELS_B16;

      // Other than for the first frame do a motion search.
      if ((lc == NULL && cm->current_video_frame > 0) ||
          (lc != NULL && lc->current_video_frame_in_layer > 0)) {
        int tmp_err, motion_error, raw_motion_error;
        // Assume 0,0 motion with no mv overhead.
        MV mv = {0, 0} , tmp_mv = {0, 0};
        struct buf_2d unscaled_last_source_buf_2d;

        xd->plane[0].pre[0].buf = first_ref_buf->y_buffer + recon_yoffset;
#if CONFIG_VP9_HIGHBITDEPTH
        if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) {
          motion_error = highbd_get_prediction_error(
              bsize, &x->plane[0].src, &xd->plane[0].pre[0], xd->bd);
        } else {
          motion_error = get_prediction_error(
              bsize, &x->plane[0].src, &xd->plane[0].pre[0]);
        }
#else
        motion_error = get_prediction_error(
            bsize, &x->plane[0].src, &xd->plane[0].pre[0]);
#endif  // CONFIG_VP9_HIGHBITDEPTH

        // Compute the motion error of the 0,0 motion using the last source
        // frame as the reference. Skip the further motion search on
        // reconstructed frame if this error is small.
        unscaled_last_source_buf_2d.buf =
            cpi->unscaled_last_source->y_buffer + recon_yoffset;
        unscaled_last_source_buf_2d.stride =
            cpi->unscaled_last_source->y_stride;
#if CONFIG_VP9_HIGHBITDEPTH
        if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) {
          raw_motion_error = highbd_get_prediction_error(
              bsize, &x->plane[0].src, &unscaled_last_source_buf_2d, xd->bd);
        } else {
          raw_motion_error = get_prediction_error(
              bsize, &x->plane[0].src, &unscaled_last_source_buf_2d);
        }
#else
        raw_motion_error = get_prediction_error(
            bsize, &x->plane[0].src, &unscaled_last_source_buf_2d);
#endif  // CONFIG_VP9_HIGHBITDEPTH

        // TODO(pengchong): Replace the hard-coded threshold
        if (raw_motion_error > 25 || lc != NULL) {
          // Test last reference frame using the previous best mv as the
          // starting point (best reference) for the search.
          first_pass_motion_search(cpi, x, &best_ref_mv, &mv, &motion_error);

          // If the current best reference mv is not centered on 0,0 then do a
          // 0,0 based search as well.
          if (!is_zero_mv(&best_ref_mv)) {
            tmp_err = INT_MAX;
            first_pass_motion_search(cpi, x, &zero_mv, &tmp_mv, &tmp_err);

            if (tmp_err < motion_error) {
              motion_error = tmp_err;
              mv = tmp_mv;
            }
          }

          // Search in an older reference frame.
          if (((lc == NULL && cm->current_video_frame > 1) ||
               (lc != NULL && lc->current_video_frame_in_layer > 1))
              && gld_yv12 != NULL) {
            // Assume 0,0 motion with no mv overhead.
            int gf_motion_error;

            xd->plane[0].pre[0].buf = gld_yv12->y_buffer + recon_yoffset;
#if CONFIG_VP9_HIGHBITDEPTH
            if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) {
              gf_motion_error = highbd_get_prediction_error(
                  bsize, &x->plane[0].src, &xd->plane[0].pre[0], xd->bd);
            } else {
              gf_motion_error = get_prediction_error(
                  bsize, &x->plane[0].src, &xd->plane[0].pre[0]);
            }
#else
            gf_motion_error = get_prediction_error(
                bsize, &x->plane[0].src, &xd->plane[0].pre[0]);
#endif  // CONFIG_VP9_HIGHBITDEPTH

            first_pass_motion_search(cpi, x, &zero_mv, &tmp_mv,
                                     &gf_motion_error);

            if (gf_motion_error < motion_error && gf_motion_error < this_error)
              ++second_ref_count;

            // Reset to last frame as reference buffer.
            xd->plane[0].pre[0].buf = first_ref_buf->y_buffer + recon_yoffset;
            xd->plane[1].pre[0].buf = first_ref_buf->u_buffer + recon_uvoffset;
            xd->plane[2].pre[0].buf = first_ref_buf->v_buffer + recon_uvoffset;

            // In accumulating a score for the older reference frame take the
            // best of the motion predicted score and the intra coded error
            // (just as will be done for) accumulation of "coded_error" for
            // the last frame.
            if (gf_motion_error < this_error)
              sr_coded_error += gf_motion_error;
            else
              sr_coded_error += this_error;
          } else {
            sr_coded_error += motion_error;
          }
        } else {
          sr_coded_error += motion_error;
        }

        // Start by assuming that intra mode is best.
        best_ref_mv.row = 0;
        best_ref_mv.col = 0;

#if CONFIG_FP_MB_STATS
        if (cpi->use_fp_mb_stats) {
          // intra predication statistics
          cpi->twopass.frame_mb_stats_buf[mb_index] = 0;
          cpi->twopass.frame_mb_stats_buf[mb_index] |= FPMB_DCINTRA_MASK;
          cpi->twopass.frame_mb_stats_buf[mb_index] |= FPMB_MOTION_ZERO_MASK;
          if (this_error > FPMB_ERROR_LARGE_TH) {
            cpi->twopass.frame_mb_stats_buf[mb_index] |= FPMB_ERROR_LARGE_MASK;
          } else if (this_error < FPMB_ERROR_SMALL_TH) {
            cpi->twopass.frame_mb_stats_buf[mb_index] |= FPMB_ERROR_SMALL_MASK;
          }
        }
#endif

        if (motion_error <= this_error) {
          // Keep a count of cases where the inter and intra were very close
          // and very low. This helps with scene cut detection for example in
          // cropped clips with black bars at the sides or top and bottom.
          if (((this_error - intrapenalty) * 9 <= motion_error * 10) &&
              this_error < 2 * intrapenalty)
            ++neutral_count;

          mv.row *= 8;
          mv.col *= 8;
          this_error = motion_error;
          xd->mi[0].src_mi->mbmi.mode = NEWMV;
          xd->mi[0].src_mi->mbmi.mv[0].as_mv = mv;
          xd->mi[0].src_mi->mbmi.tx_size = TX_4X4;
          xd->mi[0].src_mi->mbmi.ref_frame[0] = LAST_FRAME;
          xd->mi[0].src_mi->mbmi.ref_frame[1] = NONE;
          vp9_build_inter_predictors_sby(xd, mb_row << 1, mb_col << 1, bsize);
          vp9_encode_sby_pass1(x, bsize);
          sum_mvr += mv.row;
          sum_mvr_abs += abs(mv.row);
          sum_mvc += mv.col;
          sum_mvc_abs += abs(mv.col);
          sum_mvrs += mv.row * mv.row;
          sum_mvcs += mv.col * mv.col;
          ++intercount;

          best_ref_mv = mv;

#if CONFIG_FP_MB_STATS
          if (cpi->use_fp_mb_stats) {
            // inter predication statistics
            cpi->twopass.frame_mb_stats_buf[mb_index] = 0;
            cpi->twopass.frame_mb_stats_buf[mb_index] &= ~FPMB_DCINTRA_MASK;
            cpi->twopass.frame_mb_stats_buf[mb_index] |= FPMB_MOTION_ZERO_MASK;
            if (this_error > FPMB_ERROR_LARGE_TH) {
              cpi->twopass.frame_mb_stats_buf[mb_index] |=
                  FPMB_ERROR_LARGE_MASK;
            } else if (this_error < FPMB_ERROR_SMALL_TH) {
              cpi->twopass.frame_mb_stats_buf[mb_index] |=
                  FPMB_ERROR_SMALL_MASK;
            }
          }
#endif

          if (!is_zero_mv(&mv)) {
            ++mvcount;

#if CONFIG_FP_MB_STATS
            if (cpi->use_fp_mb_stats) {
              cpi->twopass.frame_mb_stats_buf[mb_index] &=
                  ~FPMB_MOTION_ZERO_MASK;
              // check estimated motion direction
              if (mv.as_mv.col > 0 && mv.as_mv.col >= abs(mv.as_mv.row)) {
                // right direction
                cpi->twopass.frame_mb_stats_buf[mb_index] |=
                    FPMB_MOTION_RIGHT_MASK;
              } else if (mv.as_mv.row < 0 &&
                         abs(mv.as_mv.row) >= abs(mv.as_mv.col)) {
                // up direction
                cpi->twopass.frame_mb_stats_buf[mb_index] |=
                    FPMB_MOTION_UP_MASK;
              } else if (mv.as_mv.col < 0 &&
                         abs(mv.as_mv.col) >= abs(mv.as_mv.row)) {
                // left direction
                cpi->twopass.frame_mb_stats_buf[mb_index] |=
                    FPMB_MOTION_LEFT_MASK;
              } else {
                // down direction
                cpi->twopass.frame_mb_stats_buf[mb_index] |=
                    FPMB_MOTION_DOWN_MASK;
              }
            }
#endif

            // Non-zero vector, was it different from the last non zero vector?
            if (!is_equal_mv(&mv, &lastmv))
              ++new_mv_count;
            lastmv = mv;

            // Does the row vector point inwards or outwards?
            if (mb_row < cm->mb_rows / 2) {
              if (mv.row > 0)
                --sum_in_vectors;
              else if (mv.row < 0)
                ++sum_in_vectors;
            } else if (mb_row > cm->mb_rows / 2) {
              if (mv.row > 0)
                ++sum_in_vectors;
              else if (mv.row < 0)
                --sum_in_vectors;
            }

            // Does the col vector point inwards or outwards?
            if (mb_col < cm->mb_cols / 2) {
              if (mv.col > 0)
                --sum_in_vectors;
              else if (mv.col < 0)
                ++sum_in_vectors;
            } else if (mb_col > cm->mb_cols / 2) {
              if (mv.col > 0)
                ++sum_in_vectors;
              else if (mv.col < 0)
                --sum_in_vectors;
            }
          }
        }
      } else {
        sr_coded_error += (int64_t)this_error;
      }
      coded_error += (int64_t)this_error;

      // Adjust to the next column of MBs.
      x->plane[0].src.buf += 16;
      x->plane[1].src.buf += uv_mb_height;
      x->plane[2].src.buf += uv_mb_height;