ffmpeg.libavutil.downmix_info source code

1 /*
2  * Copyright (c) 2014 Tim Walker <tdskywalker@gmail.com>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
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  *
11  * FFmpeg is distributed in the hope that it will be useful,
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
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 module ffmpeg.libavutil.downmix_info;
22 
23 import ffmpeg.libavutil.frame;
24 
25 extern (C):
26 import ffmpeg; @nogc nothrow:
27 
28 /**
29  * @file
30  * audio downmix medatata
31  */
32 
33 /**
34  * @addtogroup lavu_audio
35  * @{
36  */
37 
38 /**
39  * @defgroup downmix_info Audio downmix metadata
40  * @{
41  */
42 
43 /**
44  * Possible downmix types.
45  */
46 enum AVDownmixType
47 {
48     AV_DOWNMIX_TYPE_UNKNOWN = 0, /**< Not indicated. */
49     AV_DOWNMIX_TYPE_LORO = 1, /**< Lo/Ro 2-channel downmix (Stereo). */
50     AV_DOWNMIX_TYPE_LTRT = 2, /**< Lt/Rt 2-channel downmix, Dolby Surround compatible. */
51     AV_DOWNMIX_TYPE_DPLII = 3, /**< Lt/Rt 2-channel downmix, Dolby Pro Logic II compatible. */
52     AV_DOWNMIX_TYPE_NB = 4 /**< Number of downmix types. Not part of ABI. */
53 }
54 
55 /**
56  * This structure describes optional metadata relevant to a downmix procedure.
57  *
58  * All fields are set by the decoder to the value indicated in the audio
59  * bitstream (if present), or to a "sane" default otherwise.
60  */
61 struct AVDownmixInfo
62 {
63     /**
64      * Type of downmix preferred by the mastering engineer.
65      */
66     AVDownmixType preferred_downmix_type;
67 
68     /**
69      * Absolute scale factor representing the nominal level of the center
70      * channel during a regular downmix.
71      */
72     double center_mix_level;
73 
74     /**
75      * Absolute scale factor representing the nominal level of the center
76      * channel during an Lt/Rt compatible downmix.
77      */
78     double center_mix_level_ltrt;
79 
80     /**
81      * Absolute scale factor representing the nominal level of the surround
82      * channels during a regular downmix.
83      */
84     double surround_mix_level;
85 
86     /**
87      * Absolute scale factor representing the nominal level of the surround
88      * channels during an Lt/Rt compatible downmix.
89      */
90     double surround_mix_level_ltrt;
91 
92     /**
93      * Absolute scale factor representing the level at which the LFE data is
94      * mixed into L/R channels during downmixing.
95      */
96     double lfe_mix_level;
97 }
98 
99 /**
100  * Get a frame's AV_FRAME_DATA_DOWNMIX_INFO side data for editing.
101  *
102  * If the side data is absent, it is created and added to the frame.
103  *
104  * @param frame the frame for which the side data is to be obtained or created
105  *
106  * @return the AVDownmixInfo structure to be edited by the caller, or NULL if
107  *         the structure cannot be allocated.
108  */
109 AVDownmixInfo* av_downmix_info_update_side_data (AVFrame* frame);
110 
111 /**
112  * @}
113  */
114 
115 /**
116  * @}
117  */
118 
119 /* AVUTIL_DOWNMIX_INFO_H */