FFmpeg
pcm_tablegen.h
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1 /*
2  * Header file for hardcoded PCM tables
3  *
4  * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #ifndef AVCODEC_PCM_TABLEGEN_H
24 #define AVCODEC_PCM_TABLEGEN_H
25 
26 #include <stdint.h>
27 #include "libavutil/attributes.h"
28 
29 /* from g711.c by SUN microsystems (unrestricted use) */
30 
31 #define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */
32 #define QUANT_MASK (0xf) /* Quantization field mask. */
33 #define NSEGS (8) /* Number of A-law segments. */
34 #define SEG_SHIFT (4) /* Left shift for segment number. */
35 #define SEG_MASK (0x70) /* Segment field mask. */
36 
37 #define BIAS (0x84) /* Bias for linear code. */
38 
39 #define VIDC_SIGN_BIT (1)
40 #define VIDC_QUANT_MASK (0x1E)
41 #define VIDC_QUANT_SHIFT (1)
42 #define VIDC_SEG_SHIFT (5)
43 #define VIDC_SEG_MASK (0xE0)
44 
45 /* alaw2linear() - Convert an A-law value to 16-bit linear PCM */
46 static av_cold int alaw2linear(unsigned char a_val)
47 {
48  int t;
49  int seg;
50 
51  a_val ^= 0x55;
52 
53  t = a_val & QUANT_MASK;
54  seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT;
55  if(seg) t= (t + t + 1 + 32) << (seg + 2);
56  else t= (t + t + 1 ) << 3;
57 
58  return (a_val & SIGN_BIT) ? t : -t;
59 }
60 
61 static av_cold int ulaw2linear(unsigned char u_val)
62 {
63  int t;
64 
65  /* Complement to obtain normal u-law value. */
66  u_val = ~u_val;
67 
68  /*
69  * Extract and bias the quantization bits. Then
70  * shift up by the segment number and subtract out the bias.
71  */
72  t = ((u_val & QUANT_MASK) << 3) + BIAS;
73  t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT;
74 
75  return (u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS);
76 }
77 
78 static av_cold int vidc2linear(unsigned char u_val)
79 {
80  int t;
81 
82  /*
83  * Extract and bias the quantization bits. Then
84  * shift up by the segment number and subtract out the bias.
85  */
86  t = (((u_val & VIDC_QUANT_MASK) >> VIDC_QUANT_SHIFT) << 3) + BIAS;
87  t <<= ((unsigned)u_val & VIDC_SEG_MASK) >> VIDC_SEG_SHIFT;
88 
89  return (u_val & VIDC_SIGN_BIT) ? (BIAS - t) : (t - BIAS);
90 }
91 
92 #if CONFIG_HARDCODED_TABLES
93 #define pcm_alaw_tableinit()
94 #define pcm_ulaw_tableinit()
95 #define pcm_vidc_tableinit()
96 #include "libavcodec/pcm_tables.h"
97 #else
98 /* 16384 entries per table */
99 static uint8_t linear_to_alaw[16384];
100 static uint8_t linear_to_ulaw[16384];
101 static uint8_t linear_to_vidc[16384];
102 
103 static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw,
104  int (*xlaw2linear)(unsigned char),
105  int mask)
106 {
107  int i, j, v, v1, v2;
108 
109  j = 1;
110  linear_to_xlaw[8192] = mask;
111  for(i=0;i<127;i++) {
112  v1 = xlaw2linear(i ^ mask);
113  v2 = xlaw2linear((i + 1) ^ mask);
114  v = (v1 + v2 + 4) >> 3;
115  for(;j<v;j+=1) {
116  linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80));
117  linear_to_xlaw[8192 + j] = (i ^ mask);
118  }
119  }
120  for(;j<8192;j++) {
121  linear_to_xlaw[8192 - j] = (127 ^ (mask ^ 0x80));
122  linear_to_xlaw[8192 + j] = (127 ^ mask);
123  }
124  linear_to_xlaw[0] = linear_to_xlaw[1];
125 }
126 
127 static void pcm_alaw_tableinit(void)
128 {
130 }
131 
132 static void pcm_ulaw_tableinit(void)
133 {
135 }
136 
137 static void pcm_vidc_tableinit(void)
138 {
140 }
141 #endif /* CONFIG_HARDCODED_TABLES */
142 
143 #endif /* AVCODEC_PCM_TABLEGEN_H */
static av_cold int vidc2linear(unsigned char u_val)
Definition: pcm_tablegen.h:78
static void pcm_alaw_tableinit(void)
Definition: pcm_tablegen.h:127
#define VIDC_QUANT_SHIFT
Definition: pcm_tablegen.h:41
static void pcm_ulaw_tableinit(void)
Definition: pcm_tablegen.h:132
#define VIDC_SIGN_BIT
Definition: pcm_tablegen.h:39
static av_cold int ulaw2linear(unsigned char u_val)
Definition: pcm_tablegen.h:61
#define VIDC_SEG_SHIFT
Definition: pcm_tablegen.h:42
Macro definitions for various function/variable attributes.
uint8_t
#define av_cold
Definition: attributes.h:82
#define SEG_SHIFT
Definition: pcm_tablegen.h:34
static uint8_t linear_to_ulaw[16384]
Definition: pcm_tablegen.h:100
#define SEG_MASK
Definition: pcm_tablegen.h:35
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
static const uint16_t mask[17]
Definition: lzw.c:38
#define VIDC_QUANT_MASK
Definition: pcm_tablegen.h:40
static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw, int(*xlaw2linear)(unsigned char), int mask)
Definition: pcm_tablegen.h:103
static void pcm_vidc_tableinit(void)
Definition: pcm_tablegen.h:137
#define BIAS
Definition: pcm_tablegen.h:37
static av_cold int alaw2linear(unsigned char a_val)
Definition: pcm_tablegen.h:46
#define SIGN_BIT
Definition: pcm_tablegen.h:31
#define QUANT_MASK
Definition: pcm_tablegen.h:32
static uint8_t linear_to_vidc[16384]
Definition: pcm_tablegen.h:101
static uint8_t linear_to_alaw[16384]
Definition: pcm_tablegen.h:99