FFmpeg
mqcenc.c
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1 /*
2  * MQ-coder encoder
3  * Copyright (c) 2007 Kamil Nowosad
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * MQ-coder encoder
24  * @file
25  * @author Kamil Nowosad
26  */
27 
28 #include <string.h>
29 
30 #include "libavutil/avassert.h"
31 #include "mqc.h"
32 
33 static void byteout(MqcState *mqc)
34 {
35 retry:
36  if (*mqc->bp == 0xff){
37  mqc->bp++;
38  *mqc->bp = mqc->c >> 20;
39  mqc->c &= 0xfffff;
40  mqc->ct = 7;
41  } else if ((mqc->c & 0x8000000)){
42  (*mqc->bp)++;
43  mqc->c &= 0x7ffffff;
44  goto retry;
45  } else{
46  mqc->bp++;
47  *mqc->bp = mqc->c >> 19;
48  mqc->c &= 0x7ffff;
49  mqc->ct = 8;
50  }
51 }
52 
53 static void renorme(MqcState *mqc)
54 {
55  do{
56  mqc->a += mqc->a;
57  mqc->c += mqc->c;
58  if (!--mqc->ct)
59  byteout(mqc);
60  } while (!(mqc->a & 0x8000));
61 }
62 
63 static void setbits(MqcState *mqc)
64 {
65  int tmp = mqc->c + mqc->a;
66  mqc->c |= 0xffff;
67  if (mqc->c >= tmp)
68  mqc->c -= 0x8000;
69 }
70 
71 void ff_mqc_initenc(MqcState *mqc, uint8_t *bp)
72 {
74  mqc->a = 0x8000;
75  mqc->c = 0;
76  mqc->bp = bp-1;
77  mqc->bpstart = bp;
78  mqc->ct = 12 + (*mqc->bp == 0xff);
79 }
80 
81 void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)
82 {
83  int qe;
84 
85  qe = ff_mqc_qe[*cxstate];
86  mqc->a -= qe;
87  if ((*cxstate & 1) == d){
88  if (!(mqc->a & 0x8000)){
89  if (mqc->a < qe)
90  mqc->a = qe;
91  else
92  mqc->c += qe;
93  *cxstate = ff_mqc_nmps[*cxstate];
94  renorme(mqc);
95  } else
96  mqc->c += qe;
97  } else{
98  if (mqc->a < qe)
99  mqc->c += qe;
100  else
101  mqc->a = qe;
102  *cxstate = ff_mqc_nlps[*cxstate];
103  renorme(mqc);
104  }
105 }
106 
107 static int mqc_flush(MqcState *mqc)
108 {
109  setbits(mqc);
110  mqc->c = mqc->c << mqc->ct;
111  byteout(mqc);
112  mqc->c = mqc->c << mqc->ct;
113  byteout(mqc);
114  if (*mqc->bp != 0xff)
115  mqc->bp++;
116  return mqc->bp - mqc->bpstart;
117 }
118 
119 int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)
120 {
121  MqcState mqc2 = *mqc;
122  mqc2.bpstart=
123  mqc2.bp = dst;
124  *mqc2.bp = *mqc->bp;
125  mqc_flush(&mqc2);
126  *dst_len = mqc2.bp - dst;
127  if (mqc->bp < mqc->bpstart) {
128  av_assert1(mqc->bpstart - mqc->bp == 1);
129  av_assert1(*dst_len > 0);
130  av_assert1(mqc->bp[0] == 0 && dst[0] == 0);
131  (*dst_len) --;
132  memmove(dst, dst+1, *dst_len);
133  return mqc->bp - mqc->bpstart + 1 + *dst_len;
134  }
135  return mqc->bp - mqc->bpstart + *dst_len;
136 }
mqc.h
MQ-coder.
mqc_flush
static int mqc_flush(MqcState *mqc)
Definition: mqcenc.c:107
ff_mqc_flush_to
int ff_mqc_flush_to(MqcState *mqc, uint8_t *dst, int *dst_len)
flush the encoder [returns number of bytes encoded]
Definition: mqcenc.c:119
setbits
static void setbits(MqcState *mqc)
Definition: mqcenc.c:63
tmp
static uint8_t tmp[11]
Definition: aes_ctr.c:28
ff_mqc_qe
const uint16_t ff_mqc_qe[2 *47]
Definition: mqc.c:33
ff_mqc_nmps
const uint8_t ff_mqc_nmps[2 *47]
Definition: mqc.c:55
MqcState::bpstart
uint8_t * bpstart
Definition: mqc.h:41
avassert.h
MqcState::bp
uint8_t * bp
Definition: mqc.h:41
renorme
static void renorme(MqcState *mqc)
Definition: mqcenc.c:53
dst
uint8_t ptrdiff_t const uint8_t ptrdiff_t int intptr_t intptr_t int int16_t * dst
Definition: dsp.h:83
ff_mqc_initenc
void ff_mqc_initenc(MqcState *mqc, uint8_t *bp)
initialize the encoder
Definition: mqcenc.c:71
MqcState::ct
unsigned int ct
Definition: mqc.h:44
ff_mqc_nlps
const uint8_t ff_mqc_nlps[2 *47]
Definition: mqc.c:47
ff_mqc_encode
void ff_mqc_encode(MqcState *mqc, uint8_t *cxstate, int d)
code bit d with context cx
Definition: mqcenc.c:81
av_assert1
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:56
MqcState::c
unsigned int c
Definition: mqc.h:43
MqcState::a
unsigned int a
Definition: mqc.h:42
MqcState
Definition: mqc.h:40
ff_mqc_init_contexts
void ff_mqc_init_contexts(MqcState *mqc)
MQ-coder context initialisations.
Definition: mqc.c:64
byteout
static void byteout(MqcState *mqc)
Definition: mqcenc.c:33