116 строки
2.6 KiB
C
116 строки
2.6 KiB
C
/*
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* Copyright (c) 2010 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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/****************************************************************************
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*
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* Module Title : vp9_boolhuff.h
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*
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* Description : Bool Coder header file.
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*
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****************************************************************************/
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#ifndef VP9_ENCODER_VP9_BOOLHUFF_H_
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#define VP9_ENCODER_VP9_BOOLHUFF_H_
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#include "vpx_ports/mem.h"
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typedef struct {
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unsigned int lowvalue;
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unsigned int range;
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unsigned int value;
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int count;
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unsigned int pos;
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uint8_t *buffer;
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// Variables used to track bit costs without outputing to the bitstream
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unsigned int measure_cost;
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unsigned long bit_counter;
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} vp9_writer;
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extern const unsigned int vp9_prob_cost[256];
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void vp9_start_encode(vp9_writer *bc, uint8_t *buffer);
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void vp9_stop_encode(vp9_writer *bc);
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DECLARE_ALIGNED(16, extern const unsigned char, vp9_norm[256]);
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static void vp9_write(vp9_writer *br, int bit, int probability) {
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unsigned int split;
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int count = br->count;
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unsigned int range = br->range;
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unsigned int lowvalue = br->lowvalue;
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register unsigned int shift;
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#ifdef ENTROPY_STATS
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#if defined(SECTIONBITS_OUTPUT)
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if (bit)
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Sectionbits[active_section] += vp9_prob_cost[255 - probability];
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else
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Sectionbits[active_section] += vp9_prob_cost[probability];
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#endif
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#endif
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split = 1 + (((range - 1) * probability) >> 8);
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range = split;
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if (bit) {
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lowvalue += split;
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range = br->range - split;
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}
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shift = vp9_norm[range];
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range <<= shift;
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count += shift;
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if (count >= 0) {
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int offset = shift - count;
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if ((lowvalue << (offset - 1)) & 0x80000000) {
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int x = br->pos - 1;
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while (x >= 0 && br->buffer[x] == 0xff) {
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br->buffer[x] = 0;
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x--;
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}
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br->buffer[x] += 1;
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}
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br->buffer[br->pos++] = (lowvalue >> (24 - offset));
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lowvalue <<= offset;
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shift = count;
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lowvalue &= 0xffffff;
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count -= 8;
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}
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lowvalue <<= shift;
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br->count = count;
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br->lowvalue = lowvalue;
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br->range = range;
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}
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static void vp9_write_bit(vp9_writer *w, int bit) {
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vp9_write(w, bit, 128); // vp9_prob_half
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}
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static void vp9_write_literal(vp9_writer *w, int data, int bits) {
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int bit;
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for (bit = bits - 1; bit >= 0; bit--)
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vp9_write_bit(w, 1 & (data >> bit));
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}
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#endif // VP9_ENCODER_VP9_BOOLHUFF_H_
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