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comparison: media/libvpx/vp9/encoder/vp9_ratectrl.c

media/libvpx/vp9/encoder/vp9_ratectrl.c

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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
12 #include <stdlib.h>
13 #include <stdio.h>
14 #include <string.h>
15 #include <limits.h>
16 #include <assert.h>
17 #include <math.h>
18
19 #include "vp9/common/vp9_alloccommon.h"
20 #include "vp9/common/vp9_common.h"
21 #include "vp9/encoder/vp9_ratectrl.h"
22 #include "vp9/common/vp9_entropymode.h"
23 #include "vpx_mem/vpx_mem.h"
24 #include "vp9/common/vp9_systemdependent.h"
25 #include "vp9/encoder/vp9_encodemv.h"
26 #include "vp9/common/vp9_quant_common.h"
27 #include "vp9/common/vp9_seg_common.h"
28
29 #define MIN_BPB_FACTOR 0.005
30 #define MAX_BPB_FACTOR 50
31
32 // Bits Per MB at different Q (Multiplied by 512)
33 #define BPER_MB_NORMBITS 9
34
35 static const unsigned int prior_key_frame_weight[KEY_FRAME_CONTEXT] =
36 { 1, 2, 3, 4, 5 };
37
38 // These functions use formulaic calculations to make playing with the
39 // quantizer tables easier. If necessary they can be replaced by lookup
40 // tables if and when things settle down in the experimental bitstream
41 double vp9_convert_qindex_to_q(int qindex) {
42 // Convert the index to a real Q value (scaled down to match old Q values)
43 return vp9_ac_quant(qindex, 0) / 4.0;
44 }
45
46 int vp9_gfboost_qadjust(int qindex) {
47 const double q = vp9_convert_qindex_to_q(qindex);
48 return (int)((0.00000828 * q * q * q) +
49 (-0.0055 * q * q) +
50 (1.32 * q) + 79.3);
51 }
52
53 static int kfboost_qadjust(int qindex) {
54 const double q = vp9_convert_qindex_to_q(qindex);
55 return (int)((0.00000973 * q * q * q) +
56 (-0.00613 * q * q) +
57 (1.316 * q) + 121.2);
58 }
59
60 int vp9_bits_per_mb(FRAME_TYPE frame_type, int qindex,
61 double correction_factor) {
62 const double q = vp9_convert_qindex_to_q(qindex);
63 int enumerator = frame_type == KEY_FRAME ? 3300000 : 2250000;
64
65 // q based adjustment to baseline enumerator
66 enumerator += (int)(enumerator * q) >> 12;
67 return (int)(0.5 + (enumerator * correction_factor / q));
68 }
69
70 void vp9_save_coding_context(VP9_COMP *cpi) {
71 CODING_CONTEXT *const cc = &cpi->coding_context;
72 VP9_COMMON *cm = &cpi->common;
73
74 // Stores a snapshot of key state variables which can subsequently be
75 // restored with a call to vp9_restore_coding_context. These functions are
76 // intended for use in a re-code loop in vp9_compress_frame where the
77 // quantizer value is adjusted between loop iterations.
78 vp9_copy(cc->nmvjointcost, cpi->mb.nmvjointcost);
79 vp9_copy(cc->nmvcosts, cpi->mb.nmvcosts);
80 vp9_copy(cc->nmvcosts_hp, cpi->mb.nmvcosts_hp);
81
82 vp9_copy(cc->segment_pred_probs, cm->seg.pred_probs);
83
84 vpx_memcpy(cpi->coding_context.last_frame_seg_map_copy,
85 cm->last_frame_seg_map, (cm->mi_rows * cm->mi_cols));
86
87 vp9_copy(cc->last_ref_lf_deltas, cm->lf.last_ref_deltas);
88 vp9_copy(cc->last_mode_lf_deltas, cm->lf.last_mode_deltas);
89
90 cc->fc = cm->fc;
91 }
92
93 void vp9_restore_coding_context(VP9_COMP *cpi) {
94 CODING_CONTEXT *const cc = &cpi->coding_context;
95 VP9_COMMON *cm = &cpi->common;
96
97 // Restore key state variables to the snapshot state stored in the
98 // previous call to vp9_save_coding_context.
99 vp9_copy(cpi->mb.nmvjointcost, cc->nmvjointcost);
100 vp9_copy(cpi->mb.nmvcosts, cc->nmvcosts);
101 vp9_copy(cpi->mb.nmvcosts_hp, cc->nmvcosts_hp);
102
103 vp9_copy(cm->seg.pred_probs, cc->segment_pred_probs);
104
105 vpx_memcpy(cm->last_frame_seg_map,
106 cpi->coding_context.last_frame_seg_map_copy,
107 (cm->mi_rows * cm->mi_cols));
108
109 vp9_copy(cm->lf.last_ref_deltas, cc->last_ref_lf_deltas);
110 vp9_copy(cm->lf.last_mode_deltas, cc->last_mode_lf_deltas);
111
112 cm->fc = cc->fc;
113 }
114
115 void vp9_setup_key_frame(VP9_COMP *cpi) {
116 VP9_COMMON *cm = &cpi->common;
117
118 vp9_setup_past_independence(cm);
119
120 // interval before next GF
121 cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
122 /* All buffers are implicitly updated on key frames. */
123 cpi->refresh_golden_frame = 1;
124 cpi->refresh_alt_ref_frame = 1;
125 }
126
127 void vp9_setup_inter_frame(VP9_COMP *cpi) {
128 VP9_COMMON *cm = &cpi->common;
129 if (cm->error_resilient_mode || cm->intra_only)
130 vp9_setup_past_independence(cm);
131
132 assert(cm->frame_context_idx < NUM_FRAME_CONTEXTS);
133 cm->fc = cm->frame_contexts[cm->frame_context_idx];
134 }
135
136 static int estimate_bits_at_q(int frame_kind, int q, int mbs,
137 double correction_factor) {
138 const int bpm = (int)(vp9_bits_per_mb(frame_kind, q, correction_factor));
139
140 // Attempt to retain reasonable accuracy without overflow. The cutoff is
141 // chosen such that the maximum product of Bpm and MBs fits 31 bits. The
142 // largest Bpm takes 20 bits.
143 return (mbs > (1 << 11)) ? (bpm >> BPER_MB_NORMBITS) * mbs
144 : (bpm * mbs) >> BPER_MB_NORMBITS;
145 }
146
147
148 static void calc_iframe_target_size(VP9_COMP *cpi) {
149 // boost defaults to half second
150 int target;
151
152 // Clear down mmx registers to allow floating point in what follows
153 vp9_clear_system_state(); // __asm emms;
154
155 // New Two pass RC
156 target = cpi->per_frame_bandwidth;
157
158 if (cpi->oxcf.rc_max_intra_bitrate_pct) {
159 int max_rate = cpi->per_frame_bandwidth
160 * cpi->oxcf.rc_max_intra_bitrate_pct / 100;
161
162 if (target > max_rate)
163 target = max_rate;
164 }
165
166 cpi->this_frame_target = target;
167 }
168
169
170 // Do the best we can to define the parameters for the next GF based
171 // on what information we have available.
172 //
173 // In this experimental code only two pass is supported
174 // so we just use the interval determined in the two pass code.
175 static void calc_gf_params(VP9_COMP *cpi) {
176 // Set the gf interval
177 cpi->frames_till_gf_update_due = cpi->baseline_gf_interval;
178 }
179
180
181 static void calc_pframe_target_size(VP9_COMP *cpi) {
182 const int min_frame_target = MAX(cpi->min_frame_bandwidth,
183 cpi->av_per_frame_bandwidth >> 5);
184 if (cpi->refresh_alt_ref_frame) {
185 // Special alt reference frame case
186 // Per frame bit target for the alt ref frame
187 cpi->per_frame_bandwidth = cpi->twopass.gf_bits;
188 cpi->this_frame_target = cpi->per_frame_bandwidth;
189 } else {
190 // Normal frames (gf,and inter)
191 cpi->this_frame_target = cpi->per_frame_bandwidth;
192 }
193
194 // Check that the total sum of adjustments is not above the maximum allowed.
195 // That is, having allowed for the KF and GF penalties, we have not pushed
196 // the current inter-frame target too low. If the adjustment we apply here is
197 // not capable of recovering all the extra bits we have spent in the KF or GF,
198 // then the remainder will have to be recovered over a longer time span via
199 // other buffer / rate control mechanisms.
200 if (cpi->this_frame_target < min_frame_target)
201 cpi->this_frame_target = min_frame_target;
202
203 if (!cpi->refresh_alt_ref_frame)
204 // Note the baseline target data rate for this inter frame.
205 cpi->inter_frame_target = cpi->this_frame_target;
206
207 // Adjust target frame size for Golden Frames:
208 if (cpi->frames_till_gf_update_due == 0) {
209 const int q = (cpi->oxcf.fixed_q < 0) ? cpi->last_q[INTER_FRAME]
210 : cpi->oxcf.fixed_q;
211
212 cpi->refresh_golden_frame = 1;
213
214 calc_gf_params(cpi);
215
216 // If we are using alternate ref instead of gf then do not apply the boost
217 // It will instead be applied to the altref update
218 // Jims modified boost
219 if (!cpi->source_alt_ref_active) {
220 if (cpi->oxcf.fixed_q < 0) {
221 // The spend on the GF is defined in the two pass code
222 // for two pass encodes
223 cpi->this_frame_target = cpi->per_frame_bandwidth;
224 } else {
225 cpi->this_frame_target =
226 (estimate_bits_at_q(1, q, cpi->common.MBs, 1.0)
227 * cpi->last_boost) / 100;
228 }
229 } else {
230 // If there is an active ARF at this location use the minimum
231 // bits on this frame even if it is a constructed arf.
232 // The active maximum quantizer insures that an appropriate
233 // number of bits will be spent if needed for constructed ARFs.
234 cpi->this_frame_target = 0;
235 }
236 }
237 }
238
239
240 void vp9_update_rate_correction_factors(VP9_COMP *cpi, int damp_var) {
241 const int q = cpi->common.base_qindex;
242 int correction_factor = 100;
243 double rate_correction_factor;
244 double adjustment_limit;
245
246 int projected_size_based_on_q = 0;
247
248 // Clear down mmx registers to allow floating point in what follows
249 vp9_clear_system_state(); // __asm emms;
250
251 if (cpi->common.frame_type == KEY_FRAME) {
252 rate_correction_factor = cpi->key_frame_rate_correction_factor;
253 } else {
254 if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame)
255 rate_correction_factor = cpi->gf_rate_correction_factor;
256 else
257 rate_correction_factor = cpi->rate_correction_factor;
258 }
259
260 // Work out how big we would have expected the frame to be at this Q given
261 // the current correction factor.
262 // Stay in double to avoid int overflow when values are large
263 projected_size_based_on_q = estimate_bits_at_q(cpi->common.frame_type, q,
264 cpi->common.MBs,
265 rate_correction_factor);
266
267 // Work out a size correction factor.
268 if (projected_size_based_on_q > 0)
269 correction_factor =
270 (100 * cpi->projected_frame_size) / projected_size_based_on_q;
271
272 // More heavily damped adjustment used if we have been oscillating either side
273 // of target.
274 switch (damp_var) {
275 case 0:
276 adjustment_limit = 0.75;
277 break;
278 case 1:
279 adjustment_limit = 0.375;
280 break;
281 case 2:
282 default:
283 adjustment_limit = 0.25;
284 break;
285 }
286
287 // if ( (correction_factor > 102) && (Q < cpi->active_worst_quality) )
288 if (correction_factor > 102) {
289 // We are not already at the worst allowable quality
290 correction_factor =
291 (int)(100 + ((correction_factor - 100) * adjustment_limit));
292 rate_correction_factor =
293 ((rate_correction_factor * correction_factor) / 100);
294
295 // Keep rate_correction_factor within limits
296 if (rate_correction_factor > MAX_BPB_FACTOR)
297 rate_correction_factor = MAX_BPB_FACTOR;
298 } else if (correction_factor < 99) {
299 // We are not already at the best allowable quality
300 correction_factor =
301 (int)(100 - ((100 - correction_factor) * adjustment_limit));
302 rate_correction_factor =
303 ((rate_correction_factor * correction_factor) / 100);
304
305 // Keep rate_correction_factor within limits
306 if (rate_correction_factor < MIN_BPB_FACTOR)
307 rate_correction_factor = MIN_BPB_FACTOR;
308 }
309
310 if (cpi->common.frame_type == KEY_FRAME) {
311 cpi->key_frame_rate_correction_factor = rate_correction_factor;
312 } else {
313 if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame)
314 cpi->gf_rate_correction_factor = rate_correction_factor;
315 else
316 cpi->rate_correction_factor = rate_correction_factor;
317 }
318 }
319
320
321 int vp9_regulate_q(VP9_COMP *cpi, int target_bits_per_frame) {
322 int q = cpi->active_worst_quality;
323
324 int i;
325 int last_error = INT_MAX;
326 int target_bits_per_mb;
327 int bits_per_mb_at_this_q;
328 double correction_factor;
329
330 // Select the appropriate correction factor based upon type of frame.
331 if (cpi->common.frame_type == KEY_FRAME) {
332 correction_factor = cpi->key_frame_rate_correction_factor;
333 } else {
334 if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame)
335 correction_factor = cpi->gf_rate_correction_factor;
336 else
337 correction_factor = cpi->rate_correction_factor;
338 }
339
340 // Calculate required scaling factor based on target frame size and size of
341 // frame produced using previous Q.
342 if (target_bits_per_frame >= (INT_MAX >> BPER_MB_NORMBITS))
343 target_bits_per_mb =
344 (target_bits_per_frame / cpi->common.MBs)
345 << BPER_MB_NORMBITS; // Case where we would overflow int
346 else
347 target_bits_per_mb =
348 (target_bits_per_frame << BPER_MB_NORMBITS) / cpi->common.MBs;
349
350 i = cpi->active_best_quality;
351
352 do {
353 bits_per_mb_at_this_q = (int)vp9_bits_per_mb(cpi->common.frame_type, i,
354 correction_factor);
355
356 if (bits_per_mb_at_this_q <= target_bits_per_mb) {
357 if ((target_bits_per_mb - bits_per_mb_at_this_q) <= last_error)
358 q = i;
359 else
360 q = i - 1;
361
362 break;
363 } else {
364 last_error = bits_per_mb_at_this_q - target_bits_per_mb;
365 }
366 } while (++i <= cpi->active_worst_quality);
367
368 return q;
369 }
370
371
372 static int estimate_keyframe_frequency(VP9_COMP *cpi) {
373 int i;
374
375 // Average key frame frequency
376 int av_key_frame_frequency = 0;
377
378 /* First key frame at start of sequence is a special case. We have no
379 * frequency data.
380 */
381 if (cpi->key_frame_count == 1) {
382 /* Assume a default of 1 kf every 2 seconds, or the max kf interval,
383 * whichever is smaller.
384 */
385 int key_freq = cpi->oxcf.key_freq > 0 ? cpi->oxcf.key_freq : 1;
386 av_key_frame_frequency = (int)cpi->output_framerate * 2;
387
388 if (cpi->oxcf.auto_key && av_key_frame_frequency > key_freq)
389 av_key_frame_frequency = cpi->oxcf.key_freq;
390
391 cpi->prior_key_frame_distance[KEY_FRAME_CONTEXT - 1]
392 = av_key_frame_frequency;
393 } else {
394 unsigned int total_weight = 0;
395 int last_kf_interval =
396 (cpi->frames_since_key > 0) ? cpi->frames_since_key : 1;
397
398 /* reset keyframe context and calculate weighted average of last
399 * KEY_FRAME_CONTEXT keyframes
400 */
401 for (i = 0; i < KEY_FRAME_CONTEXT; i++) {
402 if (i < KEY_FRAME_CONTEXT - 1)
403 cpi->prior_key_frame_distance[i]
404 = cpi->prior_key_frame_distance[i + 1];
405 else
406 cpi->prior_key_frame_distance[i] = last_kf_interval;
407
408 av_key_frame_frequency += prior_key_frame_weight[i]
409 * cpi->prior_key_frame_distance[i];
410 total_weight += prior_key_frame_weight[i];
411 }
412
413 av_key_frame_frequency /= total_weight;
414 }
415 return av_key_frame_frequency;
416 }
417
418
419 void vp9_adjust_key_frame_context(VP9_COMP *cpi) {
420 // Clear down mmx registers to allow floating point in what follows
421 vp9_clear_system_state();
422
423 cpi->frames_since_key = 0;
424 cpi->key_frame_count++;
425 }
426
427
428 void vp9_compute_frame_size_bounds(VP9_COMP *cpi, int *frame_under_shoot_limit,
429 int *frame_over_shoot_limit) {
430 // Set-up bounds on acceptable frame size:
431 if (cpi->oxcf.fixed_q >= 0) {
432 // Fixed Q scenario: frame size never outranges target (there is no target!)
433 *frame_under_shoot_limit = 0;
434 *frame_over_shoot_limit = INT_MAX;
435 } else {
436 if (cpi->common.frame_type == KEY_FRAME) {
437 *frame_over_shoot_limit = cpi->this_frame_target * 9 / 8;
438 *frame_under_shoot_limit = cpi->this_frame_target * 7 / 8;
439 } else {
440 if (cpi->refresh_alt_ref_frame || cpi->refresh_golden_frame) {
441 *frame_over_shoot_limit = cpi->this_frame_target * 9 / 8;
442 *frame_under_shoot_limit = cpi->this_frame_target * 7 / 8;
443 } else {
444 // Stron overshoot limit for constrained quality
445 if (cpi->oxcf.end_usage == USAGE_CONSTRAINED_QUALITY) {
446 *frame_over_shoot_limit = cpi->this_frame_target * 11 / 8;
447 *frame_under_shoot_limit = cpi->this_frame_target * 2 / 8;
448 } else {
449 *frame_over_shoot_limit = cpi->this_frame_target * 11 / 8;
450 *frame_under_shoot_limit = cpi->this_frame_target * 5 / 8;
451 }
452 }
453 }
454
455 // For very small rate targets where the fractional adjustment
456 // (eg * 7/8) may be tiny make sure there is at least a minimum
457 // range.
458 *frame_over_shoot_limit += 200;
459 *frame_under_shoot_limit -= 200;
460 if (*frame_under_shoot_limit < 0)
461 *frame_under_shoot_limit = 0;
462 }
463 }
464
465
466 // return of 0 means drop frame
467 int vp9_pick_frame_size(VP9_COMP *cpi) {
468 VP9_COMMON *cm = &cpi->common;
469
470 if (cm->frame_type == KEY_FRAME)
471 calc_iframe_target_size(cpi);
472 else
473 calc_pframe_target_size(cpi);
474
475 return 1;
476 }

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