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 "config_components.h"
28 #include "libavutil/attributes.h"
29 
30 /* from g711.c by SUN microsystems (unrestricted use) */
31 
32 #define SIGN_BIT (0x80) /* Sign bit for a A-law byte. */
33 #define QUANT_MASK (0xf) /* Quantization field mask. */
34 #define NSEGS (8) /* Number of A-law segments. */
35 #define SEG_SHIFT (4) /* Left shift for segment number. */
36 #define SEG_MASK (0x70) /* Segment field mask. */
37 
38 #define BIAS (0x84) /* Bias for linear code. */
39 
40 #define VIDC_SIGN_BIT (1)
41 #define VIDC_QUANT_MASK (0x1E)
42 #define VIDC_QUANT_SHIFT (1)
43 #define VIDC_SEG_SHIFT (5)
44 #define VIDC_SEG_MASK (0xE0)
45 
46 #if CONFIG_PCM_ALAW_DECODER || CONFIG_PCM_ALAW_ENCODER
47 /* alaw2linear() - Convert an A-law value to 16-bit linear PCM */
48 static av_cold int alaw2linear(unsigned char a_val)
49 {
50  int t;
51  int seg;
52 
53  a_val ^= 0x55;
54 
55  t = a_val & QUANT_MASK;
56  seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT;
57  if(seg) t= (t + t + 1 + 32) << (seg + 2);
58  else t= (t + t + 1 ) << 3;
59 
60  return (a_val & SIGN_BIT) ? t : -t;
61 }
62 #endif
63 
64 #if CONFIG_PCM_MULAW_DECODER || CONFIG_PCM_MULAW_ENCODER
65 static av_cold int ulaw2linear(unsigned char u_val)
66 {
67  int t;
68 
69  /* Complement to obtain normal u-law value. */
70  u_val = ~u_val;
71 
72  /*
73  * Extract and bias the quantization bits. Then
74  * shift up by the segment number and subtract out the bias.
75  */
76  t = ((u_val & QUANT_MASK) << 3) + BIAS;
77  t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT;
78 
79  return (u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS);
80 }
81 #endif
82 
83 #if CONFIG_PCM_VIDC_DECODER || CONFIG_PCM_VIDC_ENCODER
84 static av_cold int vidc2linear(unsigned char u_val)
85 {
86  int t;
87 
88  /*
89  * Extract and bias the quantization bits. Then
90  * shift up by the segment number and subtract out the bias.
91  */
92  t = (((u_val & VIDC_QUANT_MASK) >> VIDC_QUANT_SHIFT) << 3) + BIAS;
93  t <<= ((unsigned)u_val & VIDC_SEG_MASK) >> VIDC_SEG_SHIFT;
94 
95  return (u_val & VIDC_SIGN_BIT) ? (BIAS - t) : (t - BIAS);
96 }
97 #endif
98 
99 #if CONFIG_HARDCODED_TABLES
100 #define pcm_alaw_tableinit()
101 #define pcm_ulaw_tableinit()
102 #define pcm_vidc_tableinit()
103 #include "libavcodec/pcm_tables.h"
104 #else
105 
106 #if CONFIG_PCM_ALAW_ENCODER || CONFIG_PCM_MULAW_ENCODER || \
107  CONFIG_PCM_VIDC_ENCODER
108 static av_cold void build_xlaw_table(uint8_t *linear_to_xlaw,
109  int (*xlaw2linear)(unsigned char),
110  int mask)
111 {
112  int i, j, v, v1, v2;
113 
114  j = 1;
115  linear_to_xlaw[8192] = mask;
116  for(i=0;i<127;i++) {
117  v1 = xlaw2linear(i ^ mask);
118  v2 = xlaw2linear((i + 1) ^ mask);
119  v = (v1 + v2 + 4) >> 3;
120  for(;j<v;j+=1) {
121  linear_to_xlaw[8192 - j] = (i ^ (mask ^ 0x80));
122  linear_to_xlaw[8192 + j] = (i ^ mask);
123  }
124  }
125  for(;j<8192;j++) {
126  linear_to_xlaw[8192 - j] = (127 ^ (mask ^ 0x80));
127  linear_to_xlaw[8192 + j] = (127 ^ mask);
128  }
129  linear_to_xlaw[0] = linear_to_xlaw[1];
130 }
131 #endif
132 
133 #if CONFIG_PCM_ALAW_ENCODER
134 static uint8_t linear_to_alaw[16384];
135 static void pcm_alaw_tableinit(void)
136 {
137  build_xlaw_table(linear_to_alaw, alaw2linear, 0xd5);
138 }
139 #endif
140 
141 #if CONFIG_PCM_MULAW_ENCODER
142 static uint8_t linear_to_ulaw[16384];
143 static void pcm_ulaw_tableinit(void)
144 {
145  build_xlaw_table(linear_to_ulaw, ulaw2linear, 0xff);
146 }
147 #endif
148 
149 #if CONFIG_PCM_VIDC_ENCODER
150 static uint8_t linear_to_vidc[16384];
151 static void pcm_vidc_tableinit(void)
152 {
153  build_xlaw_table(linear_to_vidc, vidc2linear, 0xff);
154 }
155 #endif
156 #endif /* CONFIG_HARDCODED_TABLES */
157 
158 #endif /* AVCODEC_PCM_TABLEGEN_H */
VIDC_SEG_SHIFT
#define VIDC_SEG_SHIFT
Definition: pcm_tablegen.h:43
SEG_SHIFT
#define SEG_SHIFT
Definition: pcm_tablegen.h:35
mask
int mask
Definition: mediacodecdec_common.c:154
VIDC_SEG_MASK
#define VIDC_SEG_MASK
Definition: pcm_tablegen.h:44
VIDC_QUANT_SHIFT
#define VIDC_QUANT_SHIFT
Definition: pcm_tablegen.h:42
VIDC_SIGN_BIT
#define VIDC_SIGN_BIT
Definition: pcm_tablegen.h:40
VIDC_QUANT_MASK
#define VIDC_QUANT_MASK
Definition: pcm_tablegen.h:41
SEG_MASK
#define SEG_MASK
Definition: pcm_tablegen.h:36
av_cold
#define av_cold
Definition: attributes.h:90
BIAS
#define BIAS
Definition: pcm_tablegen.h:38
SIGN_BIT
#define SIGN_BIT
Definition: pcm_tablegen.h:32
attributes.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
QUANT_MASK
#define QUANT_MASK
Definition: pcm_tablegen.h:33