458 lines
14 KiB
C
458 lines
14 KiB
C
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/*
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* Copyright (c) 2012 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "vp9/common/vp9_common.h"
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#include "vp9/common/vp9_pred_common.h"
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#include "vp9/common/vp9_seg_common.h"
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#include "vp9/common/vp9_treecoder.h"
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// TBD prediction functions for various bitstream signals
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// Returns a context number for the given MB prediction signal
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unsigned char vp9_get_pred_context(const VP9_COMMON *const cm,
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const MACROBLOCKD *const xd,
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PRED_ID pred_id) {
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int pred_context;
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MODE_INFO *m = xd->mode_info_context;
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// Note:
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// The mode info data structure has a one element border above and to the
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// left of the entries correpsonding to real macroblocks.
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// The prediction flags in these dummy entries are initialised to 0.
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switch (pred_id) {
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case PRED_SEG_ID:
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pred_context = (m - 1)->mbmi.seg_id_predicted +
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(m - cm->mode_info_stride)->mbmi.seg_id_predicted;
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break;
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case PRED_REF:
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pred_context = (m - 1)->mbmi.ref_predicted +
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(m - cm->mode_info_stride)->mbmi.ref_predicted;
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break;
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case PRED_COMP:
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// Context based on use of comp pred flag by neighbours
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// pred_context =
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// ((m - 1)->mbmi.second_ref_frame > INTRA_FRAME) +
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// ((m - cm->mode_info_stride)->mbmi.second_ref_frame > INTRA_FRAME);
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// Context based on mode and reference frame
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// if ( m->mbmi.ref_frame == LAST_FRAME )
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// pred_context = 0 + (m->mbmi.mode != ZEROMV);
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// else if ( m->mbmi.ref_frame == GOLDEN_FRAME )
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// pred_context = 2 + (m->mbmi.mode != ZEROMV);
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// else
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// pred_context = 4 + (m->mbmi.mode != ZEROMV);
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if (m->mbmi.ref_frame == LAST_FRAME)
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pred_context = 0;
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else
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pred_context = 1;
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break;
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case PRED_MBSKIP:
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pred_context = (m - 1)->mbmi.mb_skip_coeff +
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(m - cm->mode_info_stride)->mbmi.mb_skip_coeff;
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break;
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case PRED_SWITCHABLE_INTERP:
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{
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int left_in_image = (m - 1)->mbmi.mb_in_image;
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int above_in_image = (m - cm->mode_info_stride)->mbmi.mb_in_image;
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int left_mode = (m - 1)->mbmi.mode;
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int above_mode = (m - cm->mode_info_stride)->mbmi.mode;
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int left_interp, above_interp;
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if (left_in_image && left_mode >= NEARESTMV && left_mode <= SPLITMV)
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left_interp = vp9_switchable_interp_map[(m - 1)->mbmi.interp_filter];
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else
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left_interp = VP9_SWITCHABLE_FILTERS;
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assert(left_interp != -1);
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if (above_in_image && above_mode >= NEARESTMV && above_mode <= SPLITMV)
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above_interp = vp9_switchable_interp_map[
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(m - cm->mode_info_stride)->mbmi.interp_filter];
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else
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above_interp = VP9_SWITCHABLE_FILTERS;
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assert(above_interp != -1);
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if (left_interp == above_interp)
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pred_context = left_interp;
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else if (left_interp == VP9_SWITCHABLE_FILTERS &&
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above_interp != VP9_SWITCHABLE_FILTERS)
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pred_context = above_interp;
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else if (left_interp != VP9_SWITCHABLE_FILTERS &&
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above_interp == VP9_SWITCHABLE_FILTERS)
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pred_context = left_interp;
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else
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pred_context = VP9_SWITCHABLE_FILTERS;
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}
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break;
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default:
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// TODO *** add error trap code.
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pred_context = 0;
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break;
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}
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return pred_context;
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}
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// This function returns a context probability for coding a given
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// prediction signal
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vp9_prob vp9_get_pred_prob(const VP9_COMMON *const cm,
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const MACROBLOCKD *const xd,
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PRED_ID pred_id) {
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vp9_prob pred_probability;
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int pred_context;
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// Get the appropriate prediction context
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pred_context = vp9_get_pred_context(cm, xd, pred_id);
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switch (pred_id) {
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case PRED_SEG_ID:
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pred_probability = cm->segment_pred_probs[pred_context];
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break;
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case PRED_REF:
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pred_probability = cm->ref_pred_probs[pred_context];
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break;
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case PRED_COMP:
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// In keeping with convention elsewhre the probability returned is
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// the probability of a "0" outcome which in this case means the
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// probability of comp pred off.
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pred_probability = cm->prob_comppred[pred_context];
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break;
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case PRED_MBSKIP:
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pred_probability = cm->mbskip_pred_probs[pred_context];
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break;
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default:
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// TODO *** add error trap code.
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pred_probability = 128;
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break;
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}
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return pred_probability;
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}
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// This function returns a context probability ptr for coding a given
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// prediction signal
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const vp9_prob *vp9_get_pred_probs(const VP9_COMMON *const cm,
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const MACROBLOCKD *const xd,
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PRED_ID pred_id) {
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const vp9_prob *pred_probability;
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int pred_context;
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// Get the appropriate prediction context
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pred_context = vp9_get_pred_context(cm, xd, pred_id);
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switch (pred_id) {
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case PRED_SEG_ID:
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pred_probability = &cm->segment_pred_probs[pred_context];
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break;
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case PRED_REF:
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pred_probability = &cm->ref_pred_probs[pred_context];
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break;
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case PRED_COMP:
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// In keeping with convention elsewhre the probability returned is
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// the probability of a "0" outcome which in this case means the
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// probability of comp pred off.
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pred_probability = &cm->prob_comppred[pred_context];
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break;
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case PRED_MBSKIP:
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pred_probability = &cm->mbskip_pred_probs[pred_context];
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break;
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case PRED_SWITCHABLE_INTERP:
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pred_probability = &cm->fc.switchable_interp_prob[pred_context][0];
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break;
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default:
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// TODO *** add error trap code.
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pred_probability = NULL;
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break;
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}
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return pred_probability;
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}
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// This function returns the status of the given prediction signal.
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// I.e. is the predicted value for the given signal correct.
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unsigned char vp9_get_pred_flag(const MACROBLOCKD *const xd,
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PRED_ID pred_id) {
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unsigned char pred_flag = 0;
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switch (pred_id) {
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case PRED_SEG_ID:
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pred_flag = xd->mode_info_context->mbmi.seg_id_predicted;
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break;
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case PRED_REF:
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pred_flag = xd->mode_info_context->mbmi.ref_predicted;
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break;
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case PRED_MBSKIP:
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pred_flag = xd->mode_info_context->mbmi.mb_skip_coeff;
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break;
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default:
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// TODO *** add error trap code.
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pred_flag = 0;
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break;
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}
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return pred_flag;
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}
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// This function sets the status of the given prediction signal.
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// I.e. is the predicted value for the given signal correct.
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void vp9_set_pred_flag(MACROBLOCKD *const xd,
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PRED_ID pred_id,
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unsigned char pred_flag) {
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const int mis = xd->mode_info_stride;
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switch (pred_id) {
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case PRED_SEG_ID:
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xd->mode_info_context->mbmi.seg_id_predicted = pred_flag;
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if (xd->mode_info_context->mbmi.sb_type) {
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#define sub(a, b) (b) < 0 ? (a) + (b) : (a)
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const int n_mbs = 1 << xd->mode_info_context->mbmi.sb_type;
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const int x_mbs = sub(n_mbs, xd->mb_to_right_edge >> 7);
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const int y_mbs = sub(n_mbs, xd->mb_to_bottom_edge >> 7);
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int x, y;
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for (y = 0; y < y_mbs; y++) {
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for (x = !y; x < x_mbs; x++) {
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xd->mode_info_context[y * mis + x].mbmi.seg_id_predicted =
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pred_flag;
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}
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}
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}
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break;
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case PRED_REF:
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xd->mode_info_context->mbmi.ref_predicted = pred_flag;
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if (xd->mode_info_context->mbmi.sb_type) {
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const int n_mbs = 1 << xd->mode_info_context->mbmi.sb_type;
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const int x_mbs = sub(n_mbs, xd->mb_to_right_edge >> 7);
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const int y_mbs = sub(n_mbs, xd->mb_to_bottom_edge >> 7);
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int x, y;
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for (y = 0; y < y_mbs; y++) {
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for (x = !y; x < x_mbs; x++) {
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xd->mode_info_context[y * mis + x].mbmi.ref_predicted = pred_flag;
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}
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}
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}
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break;
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case PRED_MBSKIP:
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xd->mode_info_context->mbmi.mb_skip_coeff = pred_flag;
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if (xd->mode_info_context->mbmi.sb_type) {
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const int n_mbs = 1 << xd->mode_info_context->mbmi.sb_type;
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const int x_mbs = sub(n_mbs, xd->mb_to_right_edge >> 7);
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const int y_mbs = sub(n_mbs, xd->mb_to_bottom_edge >> 7);
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int x, y;
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for (y = 0; y < y_mbs; y++) {
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for (x = !y; x < x_mbs; x++) {
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xd->mode_info_context[y * mis + x].mbmi.mb_skip_coeff = pred_flag;
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}
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}
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}
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break;
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default:
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// TODO *** add error trap code.
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break;
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}
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}
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// The following contain the guts of the prediction code used to
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// peredict various bitstream signals.
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// Macroblock segment id prediction function
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unsigned char vp9_get_pred_mb_segid(const VP9_COMMON *const cm,
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const MACROBLOCKD *const xd, int MbIndex) {
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// Currently the prediction for the macroblock segment ID is
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// the value stored for this macroblock in the previous frame.
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if (!xd->mode_info_context->mbmi.sb_type) {
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return cm->last_frame_seg_map[MbIndex];
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} else {
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const int n_mbs = 1 << xd->mode_info_context->mbmi.sb_type;
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const int mb_col = MbIndex % cm->mb_cols;
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const int mb_row = MbIndex / cm->mb_cols;
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const int x_mbs = MIN(n_mbs, cm->mb_cols - mb_col);
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const int y_mbs = MIN(n_mbs, cm->mb_rows - mb_row);
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int x, y;
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unsigned seg_id = -1;
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for (y = mb_row; y < mb_row + y_mbs; y++) {
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for (x = mb_col; x < mb_col + x_mbs; x++) {
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seg_id = MIN(seg_id, cm->last_frame_seg_map[cm->mb_cols * y + x]);
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}
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}
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return seg_id;
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}
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}
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MV_REFERENCE_FRAME vp9_get_pred_ref(const VP9_COMMON *const cm,
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const MACROBLOCKD *const xd) {
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MODE_INFO *m = xd->mode_info_context;
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MV_REFERENCE_FRAME left;
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MV_REFERENCE_FRAME above;
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MV_REFERENCE_FRAME above_left;
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MV_REFERENCE_FRAME pred_ref = LAST_FRAME;
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int segment_id = xd->mode_info_context->mbmi.segment_id;
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int seg_ref_active;
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int i;
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unsigned char frame_allowed[MAX_REF_FRAMES] = {1, 1, 1, 1};
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unsigned char ref_score[MAX_REF_FRAMES];
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unsigned char best_score = 0;
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unsigned char left_in_image;
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unsigned char above_in_image;
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unsigned char above_left_in_image;
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// Is segment coding ennabled
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seg_ref_active = vp9_segfeature_active(xd, segment_id, SEG_LVL_REF_FRAME);
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// Special case treatment if segment coding is enabled.
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// Dont allow prediction of a reference frame that the segment
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// does not allow
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if (seg_ref_active) {
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for (i = 0; i < MAX_REF_FRAMES; i++) {
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frame_allowed[i] =
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vp9_check_segref(xd, segment_id, i);
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// Score set to 0 if ref frame not allowed
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ref_score[i] = cm->ref_scores[i] * frame_allowed[i];
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}
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} else
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vpx_memcpy(ref_score, cm->ref_scores, sizeof(ref_score));
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// Reference frames used by neighbours
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left = (m - 1)->mbmi.ref_frame;
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above = (m - cm->mode_info_stride)->mbmi.ref_frame;
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above_left = (m - 1 - cm->mode_info_stride)->mbmi.ref_frame;
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// Are neighbours in image
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left_in_image = (m - 1)->mbmi.mb_in_image;
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above_in_image = (m - cm->mode_info_stride)->mbmi.mb_in_image;
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above_left_in_image = (m - 1 - cm->mode_info_stride)->mbmi.mb_in_image;
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// Adjust scores for candidate reference frames based on neigbours
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if (frame_allowed[left] && left_in_image) {
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ref_score[left] += 16;
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if (above_left_in_image && (left == above_left))
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ref_score[left] += 4;
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}
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if (frame_allowed[above] && above_in_image) {
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ref_score[above] += 16;
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if (above_left_in_image && (above == above_left))
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ref_score[above] += 4;
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}
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// Now choose the candidate with the highest score
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for (i = 0; i < MAX_REF_FRAMES; i++) {
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if (ref_score[i] > best_score) {
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pred_ref = i;
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best_score = ref_score[i];
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}
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}
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return pred_ref;
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}
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// Functions to computes a set of modified reference frame probabilities
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// to use when the prediction of the reference frame value fails
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void vp9_calc_ref_probs(int *count, vp9_prob *probs) {
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int tot_count;
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tot_count = count[0] + count[1] + count[2] + count[3];
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probs[0] = get_prob(count[0], tot_count);
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tot_count -= count[0];
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probs[1] = get_prob(count[1], tot_count);
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tot_count -= count[1];
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probs[2] = get_prob(count[2], tot_count);
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}
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// Computes a set of modified conditional probabilities for the reference frame
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// Values willbe set to 0 for reference frame options that are not possible
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// because wither they were predicted and prediction has failed or because
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// they are not allowed for a given segment.
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void vp9_compute_mod_refprobs(VP9_COMMON *const cm) {
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int norm_cnt[MAX_REF_FRAMES];
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int intra_count;
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int inter_count;
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int last_count;
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int gfarf_count;
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int gf_count;
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int arf_count;
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intra_count = cm->prob_intra_coded;
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inter_count = (255 - intra_count);
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last_count = (inter_count * cm->prob_last_coded) / 255;
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gfarf_count = inter_count - last_count;
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gf_count = (gfarf_count * cm->prob_gf_coded) / 255;
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arf_count = gfarf_count - gf_count;
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// Work out modified reference frame probabilities to use where prediction
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// of the reference frame fails
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norm_cnt[0] = 0;
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norm_cnt[1] = last_count;
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norm_cnt[2] = gf_count;
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norm_cnt[3] = arf_count;
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vp9_calc_ref_probs(norm_cnt, cm->mod_refprobs[INTRA_FRAME]);
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cm->mod_refprobs[INTRA_FRAME][0] = 0; // This branch implicit
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norm_cnt[0] = intra_count;
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norm_cnt[1] = 0;
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norm_cnt[2] = gf_count;
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norm_cnt[3] = arf_count;
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vp9_calc_ref_probs(norm_cnt, cm->mod_refprobs[LAST_FRAME]);
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cm->mod_refprobs[LAST_FRAME][1] = 0; // This branch implicit
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norm_cnt[0] = intra_count;
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norm_cnt[1] = last_count;
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norm_cnt[2] = 0;
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norm_cnt[3] = arf_count;
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vp9_calc_ref_probs(norm_cnt, cm->mod_refprobs[GOLDEN_FRAME]);
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cm->mod_refprobs[GOLDEN_FRAME][2] = 0; // This branch implicit
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norm_cnt[0] = intra_count;
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norm_cnt[1] = last_count;
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norm_cnt[2] = gf_count;
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norm_cnt[3] = 0;
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vp9_calc_ref_probs(norm_cnt, cm->mod_refprobs[ALTREF_FRAME]);
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cm->mod_refprobs[ALTREF_FRAME][2] = 0; // This branch implicit
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// Score the reference frames based on overal frequency.
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// These scores contribute to the prediction choices.
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// Max score 17 min 1
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cm->ref_scores[INTRA_FRAME] = 1 + (intra_count * 16 / 255);
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cm->ref_scores[LAST_FRAME] = 1 + (last_count * 16 / 255);
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cm->ref_scores[GOLDEN_FRAME] = 1 + (gf_count * 16 / 255);
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cm->ref_scores[ALTREF_FRAME] = 1 + (arf_count * 16 / 255);
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}
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