vp9/encoder/vp9_picklpf.c

   1 /*
   2  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
   3  *
   4  *  Use of this source code is governed by a BSD-style license
   5  *  that can be found in the LICENSE file in the root of the source
   6  *  tree. An additional intellectual property rights grant can be found
   7  *  in the file PATENTS.  All contributing project authors may
   8  *  be found in the AUTHORS file in the root of the source tree.
   9  */
  10
  11 #include <assert.h>
  12 #include <limits.h>
  13
  14 #include "./vpx_scale_rtcd.h"
  15
  16 #include "vpx_mem/vpx_mem.h"
  17 #include "vpx_ports/mem.h"
  18
  19 #include "vp9/common/vp9_loopfilter.h"
  20 #include "vp9/common/vp9_onyxc_int.h"
  21 #include "vp9/common/vp9_quant_common.h"
  22
  23 #include "vp9/encoder/vp9_encoder.h"
  24 #include "vp9/encoder/vp9_picklpf.h"
  25 #include "vp9/encoder/vp9_quantize.h"
  26
  27 static int get_max_filter_level(const VP9_COMP *cpi) {
  28   if (cpi->oxcf.pass == 2) {
  29     return cpi->twopass.section_intra_rating > 8 ? MAX_LOOP_FILTER * 3 / 4
  30                                                  : MAX_LOOP_FILTER;
  31   } else {
  32     return MAX_LOOP_FILTER;
  33   }
  34 }
  35
  36
  37 static int64_t try_filter_frame(const YV12_BUFFER_CONFIG *sd,
  38                                 VP9_COMP *const cpi,
  39                                 int filt_level, int partial_frame) {
  40   VP9_COMMON *const cm = &cpi->common;
  41   int64_t filt_err;
  42
  43   if (cpi->num_workers > 1)
  44     vp9_loop_filter_frame_mt(cm->frame_to_show, cm, cpi->td.mb.e_mbd.plane,
  45                              filt_level, 1, partial_frame,
  46                              cpi->workers, cpi->num_workers, &cpi->lf_row_sync);
  47   else
  48     vp9_loop_filter_frame(cm->frame_to_show, cm, &cpi->td.mb.e_mbd, filt_level,
  49                           1, partial_frame);
  50
  51 #if CONFIG_VP9_HIGHBITDEPTH
  52   if (cm->use_highbitdepth) {
  53     filt_err = vp9_highbd_get_y_sse(sd, cm->frame_to_show);
  54   } else {
  55     filt_err = vp9_get_y_sse(sd, cm->frame_to_show);
  56   }
  57 #else
  58   filt_err = vp9_get_y_sse(sd, cm->frame_to_show);
  59 #endif  // CONFIG_VP9_HIGHBITDEPTH
  60
  61   // Re-instate the unfiltered frame
  62   vpx_yv12_copy_y(&cpi->last_frame_uf, cm->frame_to_show);
  63
  64   return filt_err;
  65 }
  66
  67 static int search_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
  68                                int partial_frame) {
  69   const VP9_COMMON *const cm = &cpi->common;
  70   const struct loopfilter *const lf = &cm->lf;
  71   const int min_filter_level = 0;
  72   const int max_filter_level = get_max_filter_level(cpi);
  73   int filt_direction = 0;
  74   int64_t best_err;
  75   int filt_best;
  76
  77   // Start the search at the previous frame filter level unless it is now out of
  78   // range.
  79   int filt_mid = clamp(lf->filter_level, min_filter_level, max_filter_level);
  80   int filter_step = filt_mid < 16 ? 4 : filt_mid / 4;
  81   // Sum squared error at each filter level
  82   int64_t ss_err[MAX_LOOP_FILTER + 1];
  83
  84   // Set each entry to -1
  85   memset(ss_err, 0xFF, sizeof(ss_err));
  86
  87   //  Make a copy of the unfiltered / processed recon buffer
  88   vpx_yv12_copy_y(cm->frame_to_show, &cpi->last_frame_uf);
  89
  90   best_err = try_filter_frame(sd, cpi, filt_mid, partial_frame);
  91   filt_best = filt_mid;
  92   ss_err[filt_mid] = best_err;
  93
  94   while (filter_step > 0) {
  95     const int filt_high = MIN(filt_mid + filter_step, max_filter_level);
  96     const int filt_low = MAX(filt_mid - filter_step, min_filter_level);
  97
  98     // Bias against raising loop filter in favor of lowering it.
  99     int64_t bias = (best_err >> (15 - (filt_mid / 8))) * filter_step;
 100
 101     if ((cpi->oxcf.pass == 2) && (cpi->twopass.section_intra_rating < 20))
 102       bias = (bias * cpi->twopass.section_intra_rating) / 20;
 103
 104     // yx, bias less for large block size
 105     if (cm->tx_mode != ONLY_4X4)
 106       bias >>= 1;
 107
 108     if (filt_direction <= 0 && filt_low != filt_mid) {
 109       // Get Low filter error score
 110       if (ss_err[filt_low] < 0) {
 111         ss_err[filt_low] = try_filter_frame(sd, cpi, filt_low, partial_frame);
 112       }
 113       // If value is close to the best so far then bias towards a lower loop
 114       // filter value.
 115       if ((ss_err[filt_low] - bias) < best_err) {
 116         // Was it actually better than the previous best?
 117         if (ss_err[filt_low] < best_err)
 118           best_err = ss_err[filt_low];
 119
 120         filt_best = filt_low;
 121       }
 122     }
 123
 124     // Now look at filt_high
 125     if (filt_direction >= 0 && filt_high != filt_mid) {
 126       if (ss_err[filt_high] < 0) {
 127         ss_err[filt_high] = try_filter_frame(sd, cpi, filt_high, partial_frame);
 128       }
 129       // Was it better than the previous best?
 130       if (ss_err[filt_high] < (best_err - bias)) {
 131         best_err = ss_err[filt_high];
 132         filt_best = filt_high;
 133       }
 134     }
 135
 136     // Half the step distance if the best filter value was the same as last time
 137     if (filt_best == filt_mid) {
 138       filter_step /= 2;
 139       filt_direction = 0;
 140     } else {
 141       filt_direction = (filt_best < filt_mid) ? -1 : 1;
 142       filt_mid = filt_best;
 143     }
 144   }
 145
 146   return filt_best;
 147 }
 148
 149 void vp9_pick_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
 150                            LPF_PICK_METHOD method) {
 151   VP9_COMMON *const cm = &cpi->common;
 152   struct loopfilter *const lf = &cm->lf;
 153
 154   lf->sharpness_level = cm->frame_type == KEY_FRAME ? 0
 155                                                     : cpi->oxcf.sharpness;
 156
 157   if (method == LPF_PICK_MINIMAL_LPF && lf->filter_level) {
 158       lf->filter_level = 0;
 159   } else if (method >= LPF_PICK_FROM_Q) {
 160     const int min_filter_level = 0;
 161     const int max_filter_level = get_max_filter_level(cpi);
 162     const int q = vp9_ac_quant(cm->base_qindex, 0, cm->bit_depth);
 163     // These values were determined by linear fitting the result of the
 164     // searched level, filt_guess = q * 0.316206 + 3.87252
 165 #if CONFIG_VP9_HIGHBITDEPTH
 166     int filt_guess;
 167     switch (cm->bit_depth) {
 168       case VPX_BITS_8:
 169         filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 1015158, 18);
 170         break;
 171       case VPX_BITS_10:
 172         filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 4060632, 20);
 173         break;
 174       case VPX_BITS_12:
 175         filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 16242526, 22);
 176         break;
 177       default:
 178         assert(0 && "bit_depth should be VPX_BITS_8, VPX_BITS_10 "
 179                     "or VPX_BITS_12");
 180         return;
 181     }
 182 #else
 183     int filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 1015158, 18);
 184 #endif  // CONFIG_VP9_HIGHBITDEPTH
 185     if (cm->frame_type == KEY_FRAME)
 186       filt_guess -= 4;
 187     lf->filter_level = clamp(filt_guess, min_filter_level, max_filter_level);
 188   } else {
 189     lf->filter_level = search_filter_level(sd, cpi,
 190                                            method == LPF_PICK_FROM_SUBIMAGE);
 191   }
 192 }