audioconvert: add explanatory comments to channel_names array
[libav.git] / libavutil / audioconvert.c
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1/*
2 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3 *
2912e87a 4 * This file is part of Libav.
176a6157 5 *
2912e87a 6 * Libav is free software; you can redistribute it and/or
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7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
2912e87a 11 * Libav is distributed in the hope that it will be useful,
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12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
2912e87a 17 * License along with Libav; if not, write to the Free Software
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18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21/**
22 * @file
23 * audio conversion routines
24 */
25
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26#include "avstring.h"
27#include "avutil.h"
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28#include "audioconvert.h"
29
30static const char * const channel_names[] = {
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31 [0] = "FL", /* front left */
32 [1] = "FR", /* front right */
33 [2] = "FC", /* front center */
34 [3] = "LFE", /* low frequency */
35 [4] = "BL", /* back left */
36 [5] = "BR", /* back right */
37 [6] = "FLC", /* front left-of-center */
38 [7] = "FRC", /* front right-of-center */
39 [8] = "BC", /* back-center */
40 [9] = "SL", /* side left */
41 [10] = "SR", /* side right */
42 [11] = "TC", /* top center */
43 [12] = "TFL", /* top front left */
44 [13] = "TFC", /* top front center */
45 [14] = "TFR", /* top front right */
46 [15] = "TBL", /* top back left */
47 [16] = "TBC", /* top back center */
48 [17] = "TBR", /* top back right */
49 [29] = "DL", /* downmix left */
50 [30] = "DR", /* downmix right */
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51};
52
53static const char *get_channel_name(int channel_id)
54{
55 if (channel_id < 0 || channel_id >= FF_ARRAY_ELEMS(channel_names))
56 return NULL;
57 return channel_names[channel_id];
58}
59
60static const struct {
61 const char *name;
62 int nb_channels;
63 int64_t layout;
64} channel_layout_map[] = {
65 { "mono", 1, AV_CH_LAYOUT_MONO },
66 { "stereo", 2, AV_CH_LAYOUT_STEREO },
67 { "4.0", 4, AV_CH_LAYOUT_4POINT0 },
68 { "quad", 4, AV_CH_LAYOUT_QUAD },
69 { "5.0", 5, AV_CH_LAYOUT_5POINT0 },
70 { "5.0", 5, AV_CH_LAYOUT_5POINT0_BACK },
71 { "5.1", 6, AV_CH_LAYOUT_5POINT1 },
72 { "5.1", 6, AV_CH_LAYOUT_5POINT1_BACK },
73 { "5.1+downmix", 8, AV_CH_LAYOUT_5POINT1|AV_CH_LAYOUT_STEREO_DOWNMIX, },
74 { "7.1", 8, AV_CH_LAYOUT_7POINT1 },
75 { "7.1(wide)", 8, AV_CH_LAYOUT_7POINT1_WIDE },
76 { "7.1+downmix", 10, AV_CH_LAYOUT_7POINT1|AV_CH_LAYOUT_STEREO_DOWNMIX, },
77 { 0 }
78};
79
80int64_t av_get_channel_layout(const char *name)
81{
82 int i = 0;
83 do {
84 if (!strcmp(channel_layout_map[i].name, name))
85 return channel_layout_map[i].layout;
86 i++;
87 } while (channel_layout_map[i].name);
88
89 return 0;
90}
91
92void av_get_channel_layout_string(char *buf, int buf_size,
93 int nb_channels, int64_t channel_layout)
94{
95 int i;
96
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97 if (nb_channels <= 0)
98 nb_channels = av_get_channel_layout_nb_channels(channel_layout);
99
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100 for (i = 0; channel_layout_map[i].name; i++)
101 if (nb_channels == channel_layout_map[i].nb_channels &&
102 channel_layout == channel_layout_map[i].layout) {
103 av_strlcpy(buf, channel_layout_map[i].name, buf_size);
104 return;
105 }
106
107 snprintf(buf, buf_size, "%d channels", nb_channels);
108 if (channel_layout) {
3a0b5fa5 109 int i, ch;
176a6157 110 av_strlcat(buf, " (", buf_size);
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111 for (i = 0, ch = 0; i < 64; i++) {
112 if ((channel_layout & (1L << i))) {
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113 const char *name = get_channel_name(i);
114 if (name) {
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115 if (ch > 0)
116 av_strlcat(buf, "|", buf_size);
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117 av_strlcat(buf, name, buf_size);
118 }
119 ch++;
120 }
121 }
122 av_strlcat(buf, ")", buf_size);
123 }
124}
125
126int av_get_channel_layout_nb_channels(int64_t channel_layout)
127{
128 int count;
129 uint64_t x = channel_layout;
130 for (count = 0; x; count++)
131 x &= x-1; // unset lowest set bit
132 return count;
133}