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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 #include "vpx_dsp/psnr.h"
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 
get_max_filter_level(const VP9_COMP * cpi)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 
try_filter_frame(const YV12_BUFFER_CONFIG * sd,VP9_COMP * const cpi,int filt_level,int partial_frame)36 static int64_t try_filter_frame(const YV12_BUFFER_CONFIG *sd,
37                                 VP9_COMP *const cpi, int filt_level,
38                                 int partial_frame) {
39   VP9_COMMON *const cm = &cpi->common;
40   int64_t filt_err;
41 
42   vp9_build_mask_frame(cm, filt_level, partial_frame);
43 
44   if (cpi->num_workers > 1)
45     vp9_loop_filter_frame_mt(cm->frame_to_show, cm, cpi->td.mb.e_mbd.plane,
46                              filt_level, 1, partial_frame, cpi->workers,
47                              cpi->num_workers, &cpi->lf_row_sync);
48   else
49     vp9_loop_filter_frame(cm->frame_to_show, cm, &cpi->td.mb.e_mbd, filt_level,
50                           1, partial_frame);
51 
52 #if CONFIG_VP9_HIGHBITDEPTH
53   if (cm->use_highbitdepth) {
54     filt_err = vpx_highbd_get_y_sse(sd, cm->frame_to_show);
55   } else {
56     filt_err = vpx_get_y_sse(sd, cm->frame_to_show);
57   }
58 #else
59   filt_err = vpx_get_y_sse(sd, cm->frame_to_show);
60 #endif  // CONFIG_VP9_HIGHBITDEPTH
61 
62   // Re-instate the unfiltered frame
63   vpx_yv12_copy_y(&cpi->last_frame_uf, cm->frame_to_show);
64 
65   return filt_err;
66 }
67 
search_filter_level(const YV12_BUFFER_CONFIG * sd,VP9_COMP * cpi,int partial_frame)68 static int search_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
69                                int partial_frame) {
70   const VP9_COMMON *const cm = &cpi->common;
71   const struct loopfilter *const lf = &cm->lf;
72   const int min_filter_level = 0;
73   const int max_filter_level = get_max_filter_level(cpi);
74   int filt_direction = 0;
75   int64_t best_err;
76   int filt_best;
77 
78   // Start the search at the previous frame filter level unless it is now out of
79   // range.
80   int filt_mid = clamp(lf->last_filt_level, min_filter_level, max_filter_level);
81   int filter_step = filt_mid < 16 ? 4 : filt_mid / 4;
82   // Sum squared error at each filter level
83   int64_t ss_err[MAX_LOOP_FILTER + 1];
84 
85   // Set each entry to -1
86   memset(ss_err, 0xFF, sizeof(ss_err));
87 
88   //  Make a copy of the unfiltered / processed recon buffer
89   vpx_yv12_copy_y(cm->frame_to_show, &cpi->last_frame_uf);
90 
91   best_err = try_filter_frame(sd, cpi, filt_mid, partial_frame);
92   filt_best = filt_mid;
93   ss_err[filt_mid] = best_err;
94 
95   while (filter_step > 0) {
96     const int filt_high = VPXMIN(filt_mid + filter_step, max_filter_level);
97     const int filt_low = VPXMAX(filt_mid - filter_step, min_filter_level);
98 
99     // Bias against raising loop filter in favor of lowering it.
100     int64_t bias = (best_err >> (15 - (filt_mid / 8))) * filter_step;
101 
102     if ((cpi->oxcf.pass == 2) && (cpi->twopass.section_intra_rating < 20))
103       bias = (bias * cpi->twopass.section_intra_rating) / 20;
104 
105     // yx, bias less for large block size
106     if (cm->tx_mode != ONLY_4X4) 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) best_err = ss_err[filt_low];
118 
119         filt_best = filt_low;
120       }
121     }
122 
123     // Now look at filt_high
124     if (filt_direction >= 0 && filt_high != filt_mid) {
125       if (ss_err[filt_high] < 0) {
126         ss_err[filt_high] = try_filter_frame(sd, cpi, filt_high, partial_frame);
127       }
128       // Was it better than the previous best?
129       if (ss_err[filt_high] < (best_err - bias)) {
130         best_err = ss_err[filt_high];
131         filt_best = filt_high;
132       }
133     }
134 
135     // Half the step distance if the best filter value was the same as last time
136     if (filt_best == filt_mid) {
137       filter_step /= 2;
138       filt_direction = 0;
139     } else {
140       filt_direction = (filt_best < filt_mid) ? -1 : 1;
141       filt_mid = filt_best;
142     }
143   }
144 
145   return filt_best;
146 }
147 
vp9_pick_filter_level(const YV12_BUFFER_CONFIG * sd,VP9_COMP * cpi,LPF_PICK_METHOD method)148 void vp9_pick_filter_level(const YV12_BUFFER_CONFIG *sd, VP9_COMP *cpi,
149                            LPF_PICK_METHOD method) {
150   VP9_COMMON *const cm = &cpi->common;
151   struct loopfilter *const lf = &cm->lf;
152 
153   lf->sharpness_level = cm->frame_type == KEY_FRAME ? 0 : cpi->oxcf.sharpness;
154 
155   if (method == LPF_PICK_MINIMAL_LPF && lf->filter_level) {
156     lf->filter_level = 0;
157   } else if (method >= LPF_PICK_FROM_Q) {
158     const int min_filter_level = 0;
159     const int max_filter_level = get_max_filter_level(cpi);
160     const int q = vp9_ac_quant(cm->base_qindex, 0, cm->bit_depth);
161 // These values were determined by linear fitting the result of the
162 // searched level, filt_guess = q * 0.316206 + 3.87252
163 #if CONFIG_VP9_HIGHBITDEPTH
164     int filt_guess;
165     switch (cm->bit_depth) {
166       case VPX_BITS_8:
167         filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 1015158, 18);
168         break;
169       case VPX_BITS_10:
170         filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 4060632, 20);
171         break;
172       case VPX_BITS_12:
173         filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 16242526, 22);
174         break;
175       default:
176         assert(0 &&
177                "bit_depth should be VPX_BITS_8, VPX_BITS_10 "
178                "or VPX_BITS_12");
179         return;
180     }
181 #else
182     int filt_guess = ROUND_POWER_OF_TWO(q * 20723 + 1015158, 18);
183 #endif  // CONFIG_VP9_HIGHBITDEPTH
184     if (cpi->oxcf.pass == 0 && cpi->oxcf.rc_mode == VPX_CBR &&
185         cpi->oxcf.aq_mode == CYCLIC_REFRESH_AQ && cm->seg.enabled &&
186         cpi->oxcf.content != VP9E_CONTENT_SCREEN && cm->frame_type != KEY_FRAME)
187       filt_guess = 5 * filt_guess >> 3;
188 
189     if (cm->frame_type == KEY_FRAME) filt_guess -= 4;
190     lf->filter_level = clamp(filt_guess, min_filter_level, max_filter_level);
191   } else {
192     lf->filter_level =
193         search_filter_level(sd, cpi, method == LPF_PICK_FROM_SUBIMAGE);
194   }
195 }
196